WO2008085498A2

WO2008085498A2 - Method for aligning die to substrate

Info

Publication number: WO2008085498A2
Application number: PCT/US2007/026372
Authority: WO
Inventors: Fusao Ishii; Hirotoshi Ichikawa
Original assignee: Olympus Corporation; Silicon Quest Kabushiki-Kaisha
Priority date: 2006-12-26
Filing date: 2007-12-26
Publication date: 2008-07-17
Also published as: WO2008085495A3; US7848002B2; US7901969B2; WO2008085498A3; WO2008085498A8; WO2008085495A2; US20090149004A1; US20080212162A1

Abstract

A method for aligning a micro-mirror device die having a plurality of micro-mirror devices formed on a semiconductor substrate and fixing the micro-mirror device die on the semiconductor substrate can be provided. The method comprises a first alignment step of aligning a first guide portion of the micro-mirror device die and a second guide portion of the package substrate and a fixing step of fixing the micro-mirror device die on the package substrate in a position aligned by the first alignment step using the first and second guide portions.

Description

METHOD FOR ALIGNING DIE TO SUBSTRATE

Cross Reference

This application claims the benefit of priority by a previously filed U.S. Provisional Patent Application Serial No.60/877238 filed on December 26, 2006, the entire contents of which are incorporated by reference in this Application.

Background of the Invention Field of the Invention The present invention relates to a micro-mirror manufacturing method, and more particularly to a micro-mirror manufacturing method for dividing a plurality of micro-mirror devices formed on a wafer into individual micro-mirror devices.

Description of the Related Art

Generally projectors using a spatial optical modulator, such as a transparent LC, a reflective LC, a micro-mirror array and the like are widely known.

The spatial optical modulator forms a bi-dimensional array on which several tens thousand to several millions of fine modulation devices are arrayed and each individual array is enlarged and displayed on a screen through a projection lens as each of pixels corresponding to an image to be displayed.

The spatial optical modulator used for a projector falls roughly into two of an LC device for modulating the polarization direction of incident light by enclosing/fixing an LC between transparent substrates and giving a potential difference between the transparent substrates and a micro-mirror device for controlling the reflection direction of illumination light by deflecting a fine micro electric mechanical systems (MEMS) mirror by electro-static power, which are generally used.

US Patent 4229732discloses one example of the micro-mirror device. In Patent 4229732, a drive circuit using a metal oxide semiconductor field-effect transistor (MOSFET) and a transformable metal mirror are formed on a semiconductor wafer substrate. This mirror can be transformed by the electro-static power of the drive circuit to change the reflection direction of incident light.

US Patent 4662746 discloses an embodiment example for holding a mirror by one or two elastic hinges. When the mirror is held by one elastic hinge, the elastic hinge functions as a curved spring. When two elastic hinges hold the mirror, the elastic hinges function as a twisted spring to deflect the reflection direction of incident light by tilting the mirror toward different directions. The size of a mirror constituting the above-described micro-mirror device has each side of 4~20 μ m and the mirror is disposed on a semiconductor wafer substrate in such a way that a space in adjacent mirror surfaces can be miniaturized as much as possible. A micro-mirror device is implemented with a mirror device includes an appropriate number of mirror elements for controlling and modulating these mirror element to display images. In this case, the appropriate number as image display elements means, for example, a number based on the resolution of a display, which is stipulated by Video Electronics Standards Association (VESA) and a number based on the TV broadcast rating. A mirror pitch of 10μ m to provide a display area having diagonal length approximately 0.6 inch is implemented in a micro-mirror device formed with a large number of mirror elements configured as wide extended graphics array (WXGA) with a resolution of 1280 X 768 according to a Standard stipulated by VESA. . Thus the micro-mirror device is configured and manufactured as a very compact device. Therefore, when actually manufacturing micro-mirror devices, from the viewpoint of productivity improvement, a plurality of micro-mirror devices are formed on one piece of a semiconductor wafer substrate at one time and are divided into individual micro-mirror devices.

The unit of division, that is, dicing is called "die". When attention is paid to after dicing, an individual micro-mirror device separate from one piece of a semiconductor wafer substrate is sometime called "micro-mirror device die".

Since an individual mirror in such a micro-mirror device is very tiny, the attachment of a little foreign object sometimes causes a poor operation. Especially, in the dicing process of dividing a semiconductor wafer substrate into individual micro-mirror devices, sometimes a mechanical defect caused by the dicing process enters an MEMS structure to cause a poor operation and sometimes destroys the MEMS structure itself. Various methods for preventing it are disclosed.

For example, Patent 5817569 discloses a technology for forming a first sacrificial layer and a second sacrificial layer on a semiconductor wafer forming the mirror element of a micro-mirror device by a photoresist process and removing the first and second sacrificial layers by cleaning it with hydrogen Fluoride (HF) after forming a scribe line. Patent 6720206 also discloses an embodiment example of forming a protection layer on a mirror in the mirror element formed on a semiconductor wafer by a photoresist process and removing photoresist when completing the electric connection to a package substrate after dicing it. Furthermore, Patent 6753037 discloses an embodiment example of forming an organic protection layer in which resin is mixed in a solvent on an MEMS device. Furthermore, Patent 6787187 discloses an embodiment example of forming a protection layer on a mirror in a mirror element formed a semiconductor wafer by vacuum evaporation.

Here, for example, a case as described in Patents 5817569 and 6720206 where the reflection surface of a mirror in the mirror device of a micro-mirror device formed on a semiconductor wafer substrate is made of aluminum and photoresist is used as the protection layer of a mirror reflection surface is assumed and studied. In this case, as a method for removing the photoresist after dividing the semiconductor wafer substrate into individual micro-mirror devices there are two methods of a dry method and a wet method.

In the dry method, burning by oxygen plasma ashes is popular. However, in the dry method, there is a possibility of disturbing its optical usage since an aluminum mirror reflection surface distorts due to an inappropriate working condition and further undergoes oxidation by the reaction between the oxygen plasma and aluminum. Therefore, it is necessary to pay sufficient attention to the setting of the working condition.

In the wet method, there is a method for removing the photoresist using a solvent whose major component is a phenol and halogen family solvent in an organic family and a method for removing the photoresist using a mixed acid, such as a sulfuric acid hydrogen peroxide mixture (SPM), a hydrochloric acid hydrogen peroxide mixture (HPM), etc., an ammonia hydrogen peroxide mixture (APM) and the like in an inorganic family. Since the former organic halogen family solvent greatly affects an environment, recently it must be avoided to use it. Since the latter inorganic family mixed acid and the like corrodes the aluminum mirror reflection surface due to a sulfuric acid, hydrochloric acid and the like included in the mixed acid, there is a possibility of deteriorating the function of a mirror. In an example of forming a protection layer in which resin is mixed in a solvent, which is disclosed in Patent 6753037, resin coating is applied again, including the space between the mirror and the substrate after temporarily releasing the mirror. Since in this process, there is a possibility that resin-coating work itself may destroy the MEMS structure, sufficient attention must be paid.

Furthermore, according to Patent 7071025, when applying resin coating to this MEMS device, the resin protection layer deforms while dividing the semiconductor wafer substrate into individual MEMS devices and as a result, it does not function as the protector of the MEMS structure. Therefore, Patent 7071025 further discloses a technology for coating a harder protection layer (photoresist) over on the resin protection layer in order to solve this inconvenience. However, it has a problem that work becomes complicated and troublesome.

The micro-mirror device die separate by the above-described method is attached to a package substrate and is further covered with a transparent substrate being a lid. Thus a micro-mirror can be disposed in an almost enclosed space. Thus, a package structure in which a micro-mirror stably operates without any influences of external force, dust and the like. In this case, the semiconductor substrate of a micro-mirror device die can be also used as a package substrate.

In order to improve the function as the whole micro-mirror device die, it is preferable not only to protect the micro-mirror device die from the influences of external power and dust by package it but also to correctly dispose it in the desired position of the package substrate. It is because it is preferable to dispose a mask for shutting unnecessary light and the micro-mirror device die in correct relative positions and to simplify aligning in the case of inserting the packaged device in a device, such as a projector and the like. Therefore, it is preferable to position the micro-mirror device on the package substrate having high accuracy and fix it.

Patent 6649435 discloses an example used to position of the two sides of a chip (that is, die) for such alignment. Patent 6947200 discloses an example of adjusting their relative positions on the basis of an optical alignment mark. However, in Patent 6649435 it is presumed that the relative positions between the side of a chip (that is, die) and its display surface should be accurately processed. For example, if a cheap process of putting a groove and dividing by an anvil when separating dies from the wafer is adopted, it cannot be expected to obtain necessary accuracy. In the invention of Patent 6947200, one of alignment members is limited to a material through which light is transmitted and the device itself is large-scaled, which are inconveniences.

As described above, in order to stably operate a micro-mirror device it is necessary to protect it from the influences of dust, external force and the like. In order to protect it from the influences of dust, external force and the like, roughly speaking, there is two of protection in the manufacturing process of MEMS structures and protection by packaging after the completion of the MEMS structure. However, traditionally, either of these two kinds of protection has some practical difficulty or problems as described above. Therefore, a method for easily achieving these two kinds of protection without any special material and any complicated and troublesome process is desired.

There are nine Patent Documents discussed above in reviewing the background of this invention. These nine Patent Documents are listed below for convenience of reference.

Patent Document 1 : United States Patent No. 4229732

Patent Document 2: United States Patent No. 4662746 Patent Document 3: United States Patent No. 5817569 Patent Document 4: United States Patent No. 6720206 Patent Document 5: United States Patent No. 6753037 Patent Document 6: United States Patent No. 6787187 Patent Document 7: United States Patent No. 7071025 Patent Document 8: United States Patent No. 6649435 Patent Document 9: United States Patent No. 6947200

Summary of the Invention

It is an object of the present invention to provide a method for easily aligning a micro-mirror device die to a package substrate relatively. One aspect of the present invention can provide a method for aligning the micro-mirror die to the package substrate and fixing it. The method comprises a first alignment step of aligning a first guide of the micro-mirror device die to a second guide of the package substrate and a fixing step of fixing the micro-mirror device die on the package substrate in a position aligned by the first alignment step using the first and second guides.

The fixing step can also comprise a step of a protrusion into a hole. The fixing step can also comprise a support step of supporting the micro-mirror device die while maintaining its relative position against the package substrate, by touching a third guide to both the first and second guides. According to the above-described method, the micro-mirror device die can be easily aligned to and fixed on the package substrate.

Another aspect of the present invention can provide a micro-mirror device package provided with the micro-mirror device die and the package substrate. The micro-mirror device die comprises a plurality of micro-mirror devices formed on a semiconductor substrate and a first guide. The package substrate comprises a second guide. The micro-mirror device die is fixed on the package substrate by the first and second guides.

The first and second guides can be a hole and a protrusion, respectively, or vice versa. Alternatively, the micro-mirror device package can further comprise a third guide for touching both the first and second guides and supporting the micro-mirror device package while maintaining its relative position against the package substrate.

In the above-described micro-mirror device package, the micro-mirror device die can be easily fixed on the package substrate.

Brief Description of the Drawings

Fig. 1 is a perspective view showing one example of one micro-mirror device in which a plurality of mirror elements are bi-dimensionally disposed on a semiconductor wafer substrate.

Fig. 2A is a cross section view separate by a line M-Il in the optical ON state of a mirror element shown in Fig. 1.

Fig. 2B is a cross section view separate by a line H-Il in the optical OFF state of a mirror element shown in Fig. 1.

Figs. 3A and 3B are cross section views showing the summary of a micro-mirror manufacturing process in one embodiment.

Fig. 4 shows the summary of a dicing method for dividing a plurality of micro-mirror devices on a wafer, using an UN tape for maintaining the arrangement before dividing it into individual micro-mirror devices on the back of the semiconductor wafer substrate.

Fig. 5 is the disassembly/assembly view of the first example of the micro-mirror device package.

Fig. 6 is the disassembly/assembly view of the second example of the m i cro-m i rro r d evi ce pa ckag e .

Fig. 7A is a disassembly/assembly view showing the state in the middle of the assembly of the first example of the micro-mirror device package.

Fig. 7B is the perspective view of the first example of a micro-mirror device package. Fig. 8A is the disassembly/assembly view of the third example of the micro-mirror device package.

Fig. 8B is a disassembly/assembly view showing the state in the middle of the assembly of the third example of the micro-mirror device package.

Fig. 8C is the perspective view of the third example of the micro-mirror device package.

Fig. 9 is the disassembly/assembly view of the fourth example of the micro-mirror device package.

Fig. 10 is the disassembly/assembly view of the fifth example of the micro-mirror device package.

Fig. 11 is the cross section view of the fifth example of the micro-mirror device package.

Fig. 12 is the cross section view of the sixth example obtained by transforming the fifth example of the micro-mirror device package.

Fig. 13 is the disassembly/assembly view of the seventh example of the micro-mirror device package.

Fig. 14A is the disassembly/assembly view of the eighth example of the micro-mirror device package. Fig. 14B is the perspective view of the eighth example of the micro-mirror device package.

Fig. 15 is the disassembly/assembly view of the ninth example of the micro-mirror device package.

Figs. 16A-16D are disassembly/assembly views showing a method for regulating the rotation of the micro-mirror device package.

Fig. 17A is a cross section view showing a taper-shaped protrusion. Fig. 17B is a cross section view showing a taper-shaped hole. Fig. 17C is a cross section view showing a taper-shaped protrusion. Fig. 17D is a cross section view showing a taper-shaped hole.

Description of the Preferred Embodiments

The configuration and operation of a micro-mirror device manufactured by using the manufacturing method disclosed in the preferred embodiment of the present invention are described first. Fig. 1 shows an embodiment of a micro-mirror device 10 includes a plurality of mirror elements 1 disposed as two-dimensional arrays on a semiconductor wafer substrate.

Fig. 1 shows the micro-mirror device 10 with the micro-mirror element 1 disposed on the substrate 11. The micromirror device further includes an address pole (not specifically shown), elastic hinges (not shown), and micromirrors 16 supported by the elastic hinges on the substrate as two-dimensional micromirror array. Generally two address poles are implemented for each mirror element to control micromirrors. The dotted lines 72

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in Fig. 1 represent a deflection axis 2 implemented for deflecting the micromirror surface.

Fig. 2 as described below shows the configuration of one mirror element 1 of the mirror device 10. Specifically, Figs. 2Aand 2B are cross section views along the line H-Il of the mirror element shown in Fig. 1.

An address pole 3 for driving a mirror 16 is supported on a semiconductor wafer substrate 11. The address pole includes a drive circuit that is not shown in Fig. 1. The driving circuit is implemented for driving the mirror 16 for each of the mirror elements 1. An elastic member 13 supports the mirror 16 above the address pole 3.The elastic member 13 is supported and connected to the semiconductor wafer substrate 11. In this case, a hinge pole 4 connected to the elastic member 13 is grounded.

Each of the address poles 3 is electrically connected to the drive circuit to receive a control signal for generating a potential difference between the electrode poles and the mirror 16. Fig. 2A illustrates the mirror 16 is controlled to tilt toward deflection direction as the mirror 16 is drawn by a static force when a voltage is applied to the electrode poles. An insulation protection layer 18 is formed to cover the address pole 3 to prevent electric conduction between the address poles and the mirror 16 even when the mirror 16 tilts and touches the address pole 3. One micro-mirror device 10 is configured and formed by manufacturing a plurality of the above-described mirror elements on the semiconductor wafer substrate 11 as two-dimensional micromirror array as shown in Fig. 1.

Further details concerning the material of each component of the mirror element are described below. In an exemplary embodiment, the mirror 16 is made of a metal of high reflectance. All or a part of the elastic member 13 such as the joint, the neck and the middle portion of the elastic member 13 are composed of metal or materials having a elastic characteristics to allow for deflection and restored from a deflection. The materials may include silicon, ceramic and similar kinds of materials with the above mentioned characteristics. Fig. 2A shows an elastic member 13 with a cantilever structure and has elasticity to allow free oscillations of the mirror 16. The address pole 3 is made of conductive materials such as aluminum (Al), copper (Cu), tungsten (W) or similar kinds of conductive materials. The insulation layer 18 is made with silicon dioxide (SiO₂), silicon carbide (SiC) or the similar types of materials and silicon substrate is implemented as the semiconductor wafer substrate 11 to form and support the mirror device. Furthermore, the control of one mirror element 1 shown in Fig. 1 in an optical ON state where incident light is reflected to a prescribed optical projection path is briefly described with reference to Fig. 2A.

In Fig. 2A, the mirror 16 is initially at a horizontal position when there is no voltage applied to the address pole 3. Then a voltage applied to the address pole 3 generates a force F between the mirror 16 and the address pole 3. The force F draws and deflects the mirror 16 to tilt toward the address pole 3. The mirror is tilted to a prescribed angular position according to the voltage applied to the address pole. At a prescribed angular position, the incident light is reflected to an ON-light direction along a prescribed light path. Next, Fig. 2B is the cross section view of a mirror element of Fig. 1 inclined to a position for modulating the incident light to an OFF-light" direction away from the projection path.

In Fig. 2B, based on the same operational principle as shown in Fig. 2A, a voltage applied to another address pole causes the mirror surface to tilt to another inclination angle opposite from the direction of the mirror surface in reflecting the light along an ON-light direction. The incident light is reflected along an OFF-light away from the image projection path.

Therefore, by independently controlling each mirror element 1 corresponding to each pixel according to the data of the image, incident light to the micro-mirror device 10 can be spatially and optically -modulated to display a specified image on a screen or similar image display surface.

The following descriptions provide manufacturing method as an exemplary embodiment for fabricating the micro-mirror device 10 including the mirror element 1 and the deflectable mirror 16 formed on the semiconductor wafer substrate. The micro-mirror device manufactured by the following processes, as an exemplary embodiment of this invention is just an example and the scopes of this invention should not be limited by the following description of this exemplary embodiment. 72

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The following descriptions provide the details of a method for conveniently manufacturing a mirror element 1 with an MEMS structure. The mirror is protected from the dust contamination or other similar environmental hazards potentially affect the performance of the mirror device. The details of the manufacturing method are described with reference to Figs. 3A through 4 later, a summary is first described first as follows.

The micro-mirror manufacturing method according to the exemplary embodiment has the following features in contrast tithe above-described conventional method with technical difficulties and limitations. (1) The micromirrors devices are formed on the semiconductor wafer substrate and are protected by an inorganic protection layer. (2) The adverse effect caused by the removal of the mirror reflection surface after a dicing operation for dividing it into individual micromirrors is reduced. (3) Convenient and simplified manufacturing processes for providing the protecting layer are disclosed.

The micro-mirror manufacturing method in the exemplary embodiment includes a step of separating a micro-mirror device into mirror elements with deflectable mirrors on a wafer. The manufacturing method comprises a step of depositing an inorganic protection layer on a mirror before dividing individual micro-mirror devices from the wafer. The method further includes a step of removing the inorganic protection layer after dividing individual micro-mirror devices from the wafer.

In an exemplary embodiment, the inorganic protection layer is a silicon compound.

In another exemplary embodiment, the inorganic protection layer is SiO₂ or SiC.

In another exemplary embodiment, the inorganic protection layer is removed by applying HF as the removal etchant. In another exemplary embodiment, a dry etch process is applied to remove the inorganic protection layer.

In another exemplary embodiment, a sacrificial layer is formed to provide a space above the wafer and to form a mirror using the same material as the inorganic protection layer.

The micro-mirror manufacturing method can further comprise a step of dividing individual micro-mirror devices from a wafer in the environment having a temperature that is equal or lower than the melting point of the inorganic protection layer. The method further includes a step of removing the inorganic protection layer by exposing it in the environment with a temperature that is higher than the melting point of the inorganic protection layer after dividing individual micro-mirror devices from the wafer.

In the micro-mirror manufacturing method, it is preferable to form a groove. The groove is provided for separating the mirrors by removing a part of the inorganic protection layer and dicing and dividing individual micro-mirror devices from the wafer.

Furthermore, it is preferable to provide at least one auxiliary member on the back of the wafer in order to maintain the arranged positions of the individual mirrors before dividing individual micro-mirror devices from the wafer. The micro-mirror manufacturing method may further comprise a step of providing at least one auxiliary member on the back of the wafer in order to maintain the pre-arranged position of the mirrors before dividing individual micro-mirror devices from the wafer. The method further includes a step of removing the auxiliary member after dividing individual micro-mirror devices from the wafer.

The micro-mirror manufacturing method may further comprise a step of providing an opening on the bottom of the wafer between a package and the mirror with relative position accurately determined before dividing individual micro-mirror devices from the wafer.

Furthermore, ideally the inorganic protection layer is made of the same material as the sacrificial layer for forming a mirror. The sacrificial layer and the protection layer are also removed by the same etchant in the same process.

With summary described above, the following embodiment provides a micro-mirror manufacturing method with protection when dividing a plurality of micro-mirror devices formed on a wafer into individual micro-mirror devices.

Figs. 3A and 3B are the cross section views for illustrating the manufacturing process of a micro-mirror device. Figs. 2A and 2B show each component of the completed mirror element and Figs. 3A and 3B show the manufacturing processes and material used for manufacturing each component. The elements in Figs. 3A and 3B are designated by the same reference numeral designations for each component. Step 1 in Fig. 3A shows the formation of a drive circuit. The driving circuit formed on the semiconductor wafer substrate 11 is for driving a mirror and an address pole. The process further includes a step to check whether there are abnormal operational characteristics and also checking the conductivity of the address pole by testing the drive circuit formed on the semiconductor wafer substrate 11. The manufacturing process proceeds to step 2 after satisfactory test results are achieved.

In step 2 of Fig. 3A, a first sacrificial layer 12 is deposited on the semiconductor wafer substrate. This first sacrificial layer 12 is used to provide a space above between a mirror surface formed in a later step and the semiconductor wafer substrate 11. The sacrificial layer may be composed of SiO₂ or the similar kinds of materials. In this preferred embodiment, the thickness of this first sacrificial layer 12 determines the height of the elastic hinge for supporting a mirror. The first sacrificial layer 12 used to provide a space between the semiconductor wafer substrate 11 and the mirror can be also made of the same material as the inorganic protection layer described later.

The sacrificial layer in this preferred embodiment is deposited on the semiconductor wafer substrate 11 by a chemical vapor deposition (CVD) process. The chemical vapor deposition is a method for placing a wafer in a chamber, supplying a material according to the kind of a sacrificial in gaseous form and depositing a film utilizing a chemical catalytic reaction. The SiO₂ in this preferred embodiment could also be formed by a thermal oxidation method by placing a silicon wafer in an oxidation furnace of high temperature and growing a Siθ₂ film by oxidizing the silicon. In step 3 of Fig. 3A, a part of the first sacrificial layer 12 is removed by etching with the thickness of the first sacrificial layer determining the height and shape of an elastic member 13 formed in a later process.

In step 4 of Fig. 3A, the elastic member 13 including a joint for connecting it to a semiconductor wafer substrate on the semiconductor wafer substrate 11 and the first sacrificial layer 12 is deposited. The elastic member 13 forms as an elastic hinge for supporting a mirror later is made of Si or similar materials. The height of the elastic hinge is determined by adjusting the deposited amount of the elastic member 13 in this process.

In step 5 of Fig. 3A, a photoresist 14 is deposited on a structure formed on the semiconductor wafer substrate 11 in the former steps 2~4.

In step 6 of Fig. 3A, a predefined pattern is obtained by exposing the photoresist 14 using a mask for transcribing the predefined patterns and then etching the elastic member 13 deposited on the semiconductor wafer substrate 11. The elastic member 13 deposited on the semiconductor wafer substrate 11 in steps up to 5 of this process is divided into individual elastic hinges corresponding to individual mirrors in the mirror element of the micro-mirror device. In step 7 of Fig. 3A, the second sacrificial layer 15 is further deposited on the structure. The second sacrificial layer 15 can be made of the same material as the first sacrificial layer. A material composed of SiO₂ may be used. The material is deposited at least higher than the top of the elastic hinge.

In step 8 of Fig. 3A₁ the photoresist 14 and the second sacrificial layer 15 deposited on the semiconductor wafer substrate 11 in steps up to 7 are polished until the top of the elastic member 13 functioning as the elastic hinge is exposed. Alternatively, the photoresist 14 can be removed once after etching the elastic member 13 in step 6 and in step 8, the first sacrificial layer 12 and the elastic member 13 can be covered with only the second sacrificial layer 15. Then, in step 9 of Fig. 3B, a mirror layer 16 is deposited on the top of the photoresist 14 and the elastic member 13. Deposition of the mirror layer 16 may be processed by use of an aluminum (Al), gold (Au) or silver (Ag) or similar types of materials. Furthermore, in this process, a mirror support layer made of a material different from a mirror material can be also formed between the mirror layer 16 and the elastic member 13 to support the mirror layer 16. The support layer reinforces the connection between the elastic hinge and the mirror. The difficulty that the mirror cannot have a stable contact with the stopper when deflected to an ON or OFF positions is then resolved. The stopper is used to limit the deflection angle of the mirror. As shown in Figs. 2A and 2B, the address poles 3 and 5 are covered with the insulation protection layer 18. The stoppers are formed on the semiconductor substrate and protrude from the substrate. In Fig. 2A, the range of the deflection angle of the mirror 16 is limited by an angle at which the mirror 16 touches the address pole 3 and an angle at which the mirror 16 touches the address pole 5.

For the mirror support layer, titanium (Ti), tungsten (W) or the like is used.

Then, in step 10 of Fig. 3B, a photoresist, not shown in Fig. 2, is coated on the mirror layer 16 as that formed in step 9 and the mirror layer 16 is divided into individual mirrors 16 after exposing a mirror pattern using a mask to shape the mirror 16.

Since the first sacrificial layer 12, the photoresist 14 and the second sacrificial 15 still exist on the bottom of the mirror 16, no external force is applied to the elastic member 13. Although individual micro-mirror devices can be separated from the semiconductor wafer substrate 11 with this structure as conventional processes have commonly practiced, it is preferable to further protect the structure with a protection layer. A protection layer is formed on the top of the mirror layer. The protection layer is useful in preventing the deterioration of reflectance due to the attachment of a foreign object on the top of the mirror layer or a defect on the surface if damaged in the separation processes. It is also preferable to form the protection layer for preventing damages to the mirror surface due to manual work, such as the storage, movement and similar activities of the semiconductor wafer substrate 11. Therefore, in step 11 of Fig. 3B, an inorganic protection layer 17 made of a silicon compound is further formed on the top of the mirror 16 in the structure on the semiconductor wafer substrate 11. It is preferable to deposit a SiO₂ layer same as the first sacrificial layer 12 and the second sacrificial layer 15 to form this inorganic protection layer 17. Since the SiO∑ layer is transparent, the mirror surface can be observed in a state where the inorganic protection layer 17 attached to it. The inorganic protection layer 17 can be also used as a protection layer when performing the appearance inspection of the mirror 16. The inorganic material used for the inorganic protection layer 17 is not limited to SiO₂; a protection layer formed with SiC or similar type of materials can be also used.

The inorganic protection layer 17 deposited on the mirror layer 16 provides many benefits. There are potential problems of mixing a foreign object into the elastic member 13 and destroy of the elastic member 13. Also there may have a foreign object attached to the mirror 16. A defect in the mirror 16 may be generated during the operations of dicing to form plurality of divided individual micro-mirror devices. The protection layer 17 is useful in preventing these problems in the manufacturing processes. It is preferable to apply etching to the second sacrificial layer 15 and the inorganic protection layer 17 to forma scribe groove. The groove is useful for dicing and diving the mirror device into individual micro-mirrors after forming the inorganic protection layer 17 in the top of the mirror layer 16.

Then, in step 12 of Fig. 3B, the wafer 11 supported a plurality of micro-mirror devices is divided into individual micro-mirror devices. In the drawings of steps 1-11 , the left and right ends of the semiconductor wafer substrate 11 show the edges with broken lines. In the drawings of steps 12 and after, the left and right ends of the semiconductor substrate 11 have edge boundaries shown in solid lines after the dicing process. Fig. 4 shows a method for carrying out a dicing process for separating individual micro-mirror devices 10 from the left and right ends of the semiconductor wafer substrate 11 in step 12. Fig. 4 shows a method that uses at least one auxiliary member to prevent individual micro-mirror devices 10 from scattering around during the dicing process when separated from the semiconductor wafer substrate 11. Specifically, in the dicing method shown in Fig. 4, at least one auxiliary member for maintaining the individual micromirror devices at fixed position before and after the dicing operation.

In this preferred embodiment shown in Fig.4 a special tape e.g., an ultraviolet (UV) tape 52, with vanishing adhesiveness by ultra violet radiation generally known in a semiconductor manufacturing process is used as one auxiliary member.

In the dicing process shown in Fig. 4, the whole semiconductor wafer substrate 11 with the back attached to the UV tape is fixed to the dicing frame 51. The semiconductor wafer substrate 11 is separated using a round blade referred to as the diamond saw 53. By expanding the UV tape after separating individual micro-mirror devices 10 from the semiconductor wafer substrate 11, the separate micro-mirror devices 10 are expanded together with the UV tape 52. The individual micromirrors are separated with space between adjacent micromirrors to completely divide it into individual micro-mirror devices 10.

By applying an UV light to the back of the separated individual micro-mirror devices 10, the viscosity of the tape 52is lost and the micro-mirror devices 10 are easily separated from the UV tape 52. The appearance inspection of the completely divided individual micro-mirror devices 10 can be also conducted before and after the separation from the UV tape 52, using a microscope or a similar inspection instrument.

Instead of the applying the above-described process, a method for separating the wafer may include a step of applying the diamond saw 53. The methods may also include wafer separation by applying a laser beam or by applying a high-pressured water stream. Additional method may include the process of etching the scribe lines using another etchant.

Referring again to step 12 of Fig. 3B. The process includes a step of opening a small notch Z on the bottom of the semiconductor wafer substrate 11. The small notch Z is used to optimally fit the position of a mirror to the position corresponding to the mirror position of a package for storing the completed micro-mirror devices with designate position relative to each other. Specifically, in step 12, the mirror is already formed and its position is determined. Therefore, it is preferable to provide a notch Z on the bottom of the semiconductor wafer substrate 11 to accurately determine the relative position between the mirror 16 and the package. The small notch Z can also have greater depth and even penetrate the semiconductor wafer substrate 11. Although it is preferable to form this small notch Z on the structure of the semiconductor wafer substrate 11 in step 12, it can be also formed in a later step. Then, step 13 shown in Fig. 3B, the elastic member 13 and the mirror

16, protected by each layer, is made deflectable by removing the first sacrificial layer 12, the photoresist 14, the second sacrificial layer 15 and the inorganic protection layer 17. The removal processes are carried out by using an appropriate etchant (such as HF etc.). Thus the elastic member 13 and the mirror 16 are formed on the semiconductor wafer substrate 11. Application of voltage on the driving circuit mirror drive and deflect the mirror supported on the elastic member 13. The first sacrificial layer 12, the second sacrificial layer 15, the inorganic protection layer 17 and the photoresist 14 can be removed by any of dry etching and wet etching processes. However, in order to prevent a stiction problem from occurring, it is preferable to remove these sacrificial layers by a dry etching process.

In step 14 of Fig. 3B, an anti-stiction process is performed in order to prevent the movable portion from sticking to the stoppers or poles. The mirror may stick to the pole the sticking condition may prevent the mirror from being normally controlled. A new layer 18 is deposited on the address pole and the like of the semiconductor wafer substrate 11.

The layer 18 is formed for the purpose of anti-stiction is also used as the insulation protection layer 18 as that shown in Figs. 2A and 2B. In Figs. 3A and 3B, since the address pole is not shown, the layer 18 is shown flat. However, for example, as shown in Figs. 2A and 2B, the address poles 3 and 5 can be also protruded from the surface of the semiconductor wafer substrate 11. In that case, in step 14, the layer 18 is formed in such a way as to cover the protruded address poles 3 and 5.

Then, in step 15 of Fig. 3B, the operation inspection of the individual micro-mirror devices 10 already separated from the semiconductor wafer substrate 11 is conducted after the anti-stiction layer deposition process.

Lastly, in step 16 of Fig. 3B, the micro-mirror devices that passes the operation inspection in step 15 are selected and enclosed in a package 19 for storing one completed micro-mirror device 10 to produce one micro-mirror device package 30.

In this case, a protrusion 20 can be also further provided for the package 19 in order to appropriately fit the mirror position to the position of a package 19 corresponding to the mirror position. As described above, the small notch Z is provided on the bottom of the semiconductor wafer substrate 11 in order to precisely arrange the relative positions between the mirror 16 and the package 19 in the micro-mirror device 10. Therefore, a package 19 provided 72

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with a protrusion 20 to precisely align and fit to the small notch Z enhances the package placement operation. By fitting the small notch Z on the bottom of the semiconductor wafer substrate 11 to the protrusion 20 of the package 19 in this micro-mirror device 10, the position of the mirror 16 in the package 19 can be precisely arranged.

Specifically, the micro-mirror device 10 can be aligned to the package 19 with a high accuracy by using this small notch Z fitting to the protrusion 20 provided in their respective positions. Therefore, the relative positions between an individual mirror 16 and the package 19 are precisely arranged and processed. Such highly accurate alignment contributes to improve the overall function of the micro-mirror device package 30. For example, the package 19 not only protects the micro-mirror device 10 but also shuts out unnecessary light by providing the function as a mask. In this case, when the micro-mirror device 10 and the package 19 are precisely aligned, light not required for image projection may be arranged such that the light will not enter a certain mirror 16. The potential difficulties that some of the image projection light may be shut out from certain mirror 16 is resolved. Distortions of image projection is prevented. Specifically, the accuracy of the alignment of the micro-mirror device 10 and the package 19 affects the overall function of the micro-mirror device package 30.

As shown in Fig. 3B, the micro-mirror device 10 (that is, micro-mirror device die) can be aligned to the package 19 with high accuracy by the small notch Z and the protrusion 20. Various structures other than the structure exemplified in Fig. 3B can be also used to position them. Therefore, various embodiments of the micro-mirror device package, adopting those various structures are described below with reference to Figs. 5~17.

Fig. 5 is the disassembly/assembly view of the first embodiment of the micro-mirror device package. Fig. 5 illustrates the orientation by using the coordinate axes of a xyz coordinate system. In the following description, it is assumed that z-axis is a vertical axis for convenience of description.

The micro-mirror device die 104a shown in Fig. 5 corresponds to the micro-mirror device 10 after the dicing process, shown in Fig. 3B. In Fig. 5, the individual mirror elements 1 of the micro-mirror device die 104a are not specifically shown.

In Fig. 5, the package 19 shown in Fig. 3B comprises a window 101 , a mask 102 and a package substrate 120a.

The window 101 is a flat member made of a material through which light transmits.

The mask 102 is a flat member made of a material that shuts out unnecessary light. The center of the mask 102 is removed in the shape of a cutoff rectangle. In this preferred embodiment, the size of the cutoff portion is almost equal to that of the top of the micro-mirror device die 104a. A concavity 124 further dented than a fringe 125 is formed on the package substrate 120a.

By placing the micro-mirror device die 104a on the concavity 124 and covering the mask 102 and the window 101 over the micro-mirror device die 104a, the micro-mirror device die 104a is packaged to produce a micro-mirror device die 30a.

Since the packaged micro-mirror device die 104a is substantially sealed, the micromirror device is protected from dust and the like. Since the packaged micro-mirror device die 104a is enclosed the package substrate 120a, the mask 102 and the window 101 are also protected from external force. As illustrates in the drawings, the package substrate 120a accommodates the micro-mirror device die 104a in the concavity 124, holds it and protects it. Furthermore, the package substrate 120a provides an electrical connection between the package substrate 120a and an external power supply.

More particularly, in Fig. 5 a plurality of conductive lines 121a are formed along the surface of the package substrate 120a from the top 125a of the fringe 125 and extend to the base 124a of the concavity 124. The conductive lines are wrapping around the side 125b, which is a boundary between the fringe 125 and the concavity 124. Therefore, by electrically connecting the micro-mirror device 104 and the conductive lines 121a placed on the concavity 124, the micromirror device is connected to an external power supply through the conductive lines 121 a. The micro-mirror device die 104a can therefore be connected to the external power supply through the package substrate 120a. As described with reference to Fig. 3B₁ when packaging the micro-mirror device die 104a, it is preferable to accurately control the relation position of the micro-mirror device die 104a and the package substrate 120a.

In the embodiment shown in Fig. 5, in order to position them, a hole 110 formed on the bottom, of the micro-mirror device die 104a. The protrusion in the shape of a shaft and a rotation stopper 123 are formed on the base 124a of the concavity 124 of the package substrate 120 to fit to the hole 110.

The micro-mirror device package 30a is assembled, namely the micro-mirror device die 104a is packaged as follows by an assembly device, such as a robot having a handle etc., or alternate a human worker. For convenience of description, a mounting operation by the assembly device is described as an example.

The assembly device holds the micro-mirror device die 104a above the package substrate 120a. The micro-mirror device die 104a is moved up to a position where the x and y coordinates of the hole 110 coincide with those of the protrusion 122. Thus the hole 110 and the protrusion 122 are precisely aligned. Thus the hole 110 and the protrusion 122 function as the alignment guide for the mounting process.

The assembly device not only matches the x and y coordinates of the hole 110 with those of the protrusion 122, but also matches the direction of the micro-mirror device die 104a with that of the package substrate 120a. In this case, the orientations on the xy plane of the side 113a of the micro-mirror device 104a and the x and y coordinates of the rotation stopper 123 are applied as guide portions for matching their direction between the mirror and the package.

Then, the assembly device moves the micro-mirror device 104a downward horizontally along the z-axis to fit the protrusion into the hole 110. Thus the micro-mirror device 104a is fixed on the package substrate 120a. Specifically, the micro-mirror device die 104a is fixed on the package substrate 120a by the hole 110 and protrusion 122 which function as guide portions for the mounting operation.

However, there is a possibility that the micro-mirror device die 104a fixed on the package substrate 120a only by the fitting by the hole 110 and the protrusion 122 may rotate relatively against the package substrate 120a when the position of the hole 110 is place in the center. The possibility of the rotation sometimes cannot be neglected depending on the shapes and materials of the hole 110 and the protrusion 122. Therefore, in the embodiment shown in Fig. 5, the rotation stopper 123 for limiting the rotation of the micro-mirror device die 104a against the package substrate 120a is provided in the concavity 124 to prevent the rotation of the micro-mirror device die 104a. The position and shape of the rotation stopper 123 is determined in such a way that the side of the rotation stopper 123 touches the side 113a of the micro-mirror device die 104a when the micro-mirror device die 104a is fixed on the package substrate 120a in a correct direction. The rotation stopper 123 is formed in a specific position on the base 124a of the concavity 124 with a specific shape.

According to the installation direction of the micro-mirror device package 30a in the practical working environment it is sufficient to provide only one rotation stopper 123 for limiting the rotation in a specific direction. One rotation stopper may be sufficient taking consideration of the rotation in the specific direction and considering also the effect of the force of gravity. Therefore, as shown in Fig. 5, only one rotation stopper 123 is implemented on the package substrate 120a. Depending on an actual assembling embodiment, a plurality of rotation stoppers can be also provided on the package substrate 120a.

Although the hole 110 shown in Fig. 5 is not a through hole, it can be also a through hole. As described above, when fixing the micro-mirror device die 104a on the package substrate 120a, the hole 110, the protrusion 122 and the rotation stopper 123 regulates the relative position and direction of the micro-mirror device die 104a against the package substrate 120a. Therefore, the position of the hole 110 in the micro-mirror device die 104a and the positions of the protrusion 122 and the rotation stopper 123 on the package substrate 120a enable a mounting operation to carry out with a very high accuracy.

The package substrate 120a may be made of glass, silicon, ceramic and the like. In order to form the protrusion 122 and the rotation stopper 123 in specific positions with high accuracy, a process by horning, laser separating, blast, minting, grinding, milling or the like is suitable.

Although the hole 110 opened on the semiconductor wafer substrate 11 of the micro-mirror' device die 104a can be formed by the same process method, preferably the hole should be processed and formed by an etching process. When etching the hole 110, the hole 110 can be also processed using a photo mask in the same process as the formation of the mirror 16. In this case, the precision of the relative position against the mirror element 1 can be conveniently controlled and improved. Next, the second embodiment of the micro-mirror device package is described with reference to Fig. 6. Fig. 6 shows the disassembly/assembly perspective views of the second embodiment of the micro-mirror device package.

Since Figs. 5 and 6 have many common points, the differences between these two figures are the focus of the following descriptions. The embodiment shown in Fig. 6 differs from that shown in Fig. 5 only in that a protrusion 111 with a shape of a shaft is formed on the bottom of the micro-mirror device die 104b instead of the hole 110 and a hole 126 is formed on the base 124a of the concavity 124 of the package substrate 120b instead of the protrusion 122.

The protrusion 111 may be formed by applying a photolithography process. Alternatively, it can be formed by the same process method as the protrusion 122 and the rotation stopper 123 which are shown in Fig. 5.

The assembly of a micro-mirror device package 30b shown in Fig. 6 differs from that shown in Fig. 5 as follows.

-The protrusion 111 and the hole 126 function as the alignment guide for alignment.

-The assembly device holds a micro-mirror device die 104b above a package substrate 120b and moves the micro-mirror device die 104b up to a position where the x and y coordinates of the protrusion 111 coincides with those of the hole 126. Thus the protrusion 111 and the hole 126 are positioned. -In order to fix the micro-mirror device die 104b on the package substrate 120b, the assembly device moves the micro-mirror device die 104b downward horizontally along the z-axis while maintaining the x and y coordinates of the protrusion 111 to fit the protrusion 111 into the hole 126.

The operation to match the directions of the micro-mirror device die 104b and the package substrate 120b with each other is the same as that shown in Fig. 5. The direction match is achieved by matching the side 113a of the micro-mirror device die 104b and the rotation stopper 123 that is the same as that of the first embodiment shown in Fig. 5.

Referring to Figs. 7A and 7B for the processes for assembling the micro-mirror device packages 30a and 30b. Fig. 7A is a disassembly/assembly view showing the partially completed assembly according to the first embodiment of the micro-mirror device package 30a. In Fig. 7A, the micro-mirror device die 104a is already fixed on the package substrate 120a by the method described with reference to Fig. 5.

After the micro-mirror device die 104a is fixed on the package substrate 120a, each of it's the electrical terminals not specifically shown in Fig. 7A, is electrically connected to the conductive lines 121a on the package substrate 120a by wire bonding shown as a plurality of bonding wiring 130.

The assembly device for assembling the micro-mirror device package 30a coats an adhesive 131 on the top 125a of the fringe 125 of the package substrate 120a in such a way as to enclose around the concavity 124. Then, when covering a mask 102 over the package substrate 12Oa₁ the mask 102 is adhered to the top 125a of the package substrate 120a by the adhesive 131.

Then, the assembly device, coated with an adhesive on the top of the mask 102 and covered by a window 101 is adhered to the mask 102. Alternatively, the window 101 can be bolted to the mask 102 and the package substrate 120b by a bolting connection, such as a pin, a screw and the like, which is not shown in Fig. 7A. Thus the micro-mirror device package 30a is completed. Fig. 7B is the perspective view of the completed micro-mirror device package 30a. In Fig. 7B, the mask is shown as another individual component. The mask can also be implemented as a film layer printed on the window 101 using a silk screen or other similar covering structures.

The window 101 can be also mounted on the package substrate 120a 26372

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using frit glass or solder. Specific surface treatment such as metalization or surface activation when processing a jointing operation may be performed according to the material of the package substrate 120a. According to above-described method, the micro-mirror device can be tightly sealed; the enclosed space in the package can be protected to minimize external environmental impact to maintain a favorable and preferable constant condition.

The micro-mirror device package 30b shown in Fig. 6 may also assembled by the same assembly processes shown in Figs. 7A and 7B.

Figs. 8Ato 8C illustrate the third embodiment of the processes for packaging micro-mirror device. Since the third embodiment is similar to the first embodiment shown in Figs. 5, 7A and 7B, the differences between these processes are described.

Fig. 8A is the disassembly/assembly view of the micro-mirror device package 30c. Since the following processing steps are the same as Fig. 5, their detailed descriptions are omitted.

-The micro-mirror device package 30c comprises the window 101 and the mask 102.

-The hole 110 is formed on the bottom of the micro-mirror device die 104a. -The protrusion 122 and the rotation stopper 123 are formed in the concavity 124 of the package substrate 120c.

Fig. 8A differs from Fig. 5 in that the micro-mirror device package 30c further comprises a rectangular frame-shaped spacer 103 and that the conductive lines 121b are disposed on the package substrate 120c.

The spacer 103 in the third embodiment is larger than the outer circumference of the concavity 124 of the package substrate 120c and smaller than the outer circumference of the package substrate 120c. The conductive lines 121b in the third embodiment is formed only on the top 125a of the fringe 125 of the package substrate 120c. Therefore, in the third embodiment, the conductive lines 121b can be more conveniently formed on the package substrate 120c with more simplified process than the first embodiment.

Fig. 8B is a disassembly/assembly view showing a partially finished assembly of the third embodiment of the micro-mirror device package 30c. Like Fig. 7A₁ Fig. 8B shows the micro-mirror device die 104a after it is fixed on the package substrate 120c. The assembly device for assembling the micro-mirror device package 30c has an adhesive coated on the top 125a of the fringe 125 of the package substrate 120c around the concavity 124 and also covers the spacer 103 to adhere it to the package substrate 120c. Fig. 8B shows the configuration where wire bonding is applied between the micro-mirror device die 104a and the conductive lines 121b after mounting the spacer 103 on the package substrate 120c. The wire bonding may also be applied between the micro-mirror device die 104a and the conductive lines 121b before mounting the spacer 103 on the package substrate 120c. After mounting the spacer 103 and applying wire bonding to the assembly device, the adhesive coated on the top of the spacer 103 and covers the mask 102adheres the spacer 103 and the mask 102. Furthermore, the assembly device has an adhesive coated on the top of the mask 102 and covers the window 101. As described earlier, there may be different methods to assemble and join these members. Fig. 8C is the perspective view of a completely assembled micro-mirror device package 30c.

The spacer 103 appropriately sets a space between the micro-mirror device and the window disposed in the cavity, i.e., concavity 124, of the package that prevents the bonding wires from touching the window. However, as shown in Fig. 6, if the relative positions between the height of the micro-mirror device and the depth of the cavity are appropriately arranged bonding wires are also prevented from touching the window. In Fig. 6, there is a space where wires are exposed outside of the package. A pad for wire bonding is implemented for wires on the sidewalls (side 125b) of the cavity. The configuration and the assembling methods are more costly. Therefore, as shown in Fig. 8, it is preferable to arrange the bonding wires exposed outside and the pad for wire bonding on the same plane and to eliminate the requirement of the spacer 103.

Fig. 9 shows a fourth exemplary embodiment of the micro-mirror device package. The fourth embodiment uses the spacer 103 as in the third embodiment shown in Figs. 8A~8C.

Fig. 9 is the disassembly/assembly view of the fourth embodiment of the micro-mirror device package. Since the fourth embodiment discloses the window 101 , the mask 102 and the spacer 103 same as that in the third embodiment, the drawings and descriptions are not repeated here. Fig. 9 shows only the micro-mirror device die 104d and the package 12Od of the components of the micro-mirror device package. In the fourth embodiment Fig. 9 does not specifically show the combination of a hole 112 of the micro-mirror device die 104d and a protrusion 127 formed on the concavity 124 of the package substrate 12Od to align and guide the assembling operations as previously described.

The micro-mirror device die 104d and the package substrate 12Od are aligned with the protrusion 127 fitting into the hole 112. Specifically, the combination of the hole 112 and the protrusion 127 functions as a alignment guide portion as in the combination of the hole 110 and the protrusion 122 in the first embodiment shown in Fig. 5.

The shape of the cross section of each of the hole 112 and the protrusion 127 is formed substantially with a D-character shape by removing a circular segment from a circle. Therefore, the protrusion 127 fits into the hole 112 in specific angular orientation and does not allow a freedom of rotation. Specifically, the hole 112 and the protrusion 127 serves a function to limit the relative angular orientations of the micro-mirror device die 104d against the package substrate 12Od depending on the shape of the cross section. Therefore, in contrast to the first embodiment shown in Fig. 5, the fourth embodiment as shown in Fig. 9, the freedom of rotation of the micro-mirror device die 104d against the package substrate 12Od is eliminated and the rotation stopper 123 is no longer required. The shapes of the cross sections of the hole 112 and the protrusion

127 are not isotropic to serve the function of limiting the angular movement of the micro-mirror device die 104d relative to the package substrate 12Oe.

The shapes of the cross-sections of the hole 112 and the protrusion 127 can be flexibly configured other than that shown in Fig. 9. For example, it can be also a convex polygon, such as a regular hexagon, etc., a concave polygon, such as a stat-shape, etc. or any shape capable of limiting a rotation direction, such as an ellipse.

Figs. 10 and 11 are perspective views for showing the fifth embodiment of the micro-mirror device package of this invention. The fifth embodiment is a variation of the fourth embodiment shown in Fig. 9.

Fig. 10 is the disassembly/assembly view of the fifth embodiment of the micro-mirror device package. Like Fig. 5, Fig. 10 is also illustrated with coordinate axes.

Fig. 10 shows the micro-mirror device die 104d. A substantially D-shaped hole 112 is formed on the bottom as Fig. 9. A through hole 128 is formed in the concavity 124 of the package substrate 12Oe shown in Fig. 10 instead of the protrusion 127 shown in Fig. 9. The cross section of the through hole 128 is formed with substantially D-shape by removing a circular segment from a circle.

Fig. 10 further shows a heat sink 140. The heat sink 140 comprises a radiator 142 formed as saw teeth in order to increase the surface area to efficiently radiate the heat. The heat sink 140 further comprises a fitting protrusion member 141 having the same almost D-character-shaped cross section as the hole 112 and the through hole 128. The fitting protrusion member 141 protrudes from the top of the heat sink 140.

The entire heat sink 140 including both the fitting protrusion member 141 and the radiator 142 can also be formed by casting and incorporated as a single body component. Alternatively, the fitting protrusion member 141 and the radiator 142 can be connected after forming them individually. It is preferable to fabricate the fitting protrusion member 141 and the radiator 142 with a metal having high thermal conductivity, such as copper, aluminum, lead or the like. In the fifth embodiment shown in Fig. 10, the hole 112, the through hole

128 and the fitting protrusion member 141 function together as guide portions for aligning the micro-mirror device die 104d to the package substrate 12Oe. Specifically, the hole 112 and the through hole 128 and the fitting protrusion member 141 are matched with each other in the process of assembling the micro-mirror device package. The micro-mirror device die 104d is guided to correct position and direction against the package substrate 12Oe. Then, the protrusion member 141 is fitted into and passed through the through hole 128 while maintaining the guided position and direction by further fitting it into the hole 112. The micro-mirror device die 104d is properly assembled and supported on the package substrate 12Oe.

In Fig. 10, the cross section of each of the hole 112, the through hole

128 and the fitting protrusion member 141 is formed by removing a circular segment from a circle. Therefore, by matching the x and y coordinates of the two point at each end of its bowstring with those of the hole 112, the through hole 128 and the fitting protrusion member 141 , the micro-mirror device die

104d is guided to the correct position and direction against the package substrate 12Oe. In the embodiment shown in Fig. 10, the shape of the hole 112, the shape of the through hole 128 and the cross sectional shape of the fitting protrusion member 141 are almost the same. Therefore, in the state where the fitting protrusion member 141 passes through the through hole 128 and also fits into the hole 112, the outside of the fitting protrusion member 141 touches the inside of the through hole 128 and the hole 112. Thus the micro-mirror device die 104d is supported and fixed while maintaining the relative positions against the package substrate 12Oe.

The shape of the hole 112, the through hole 128 and the fitting protrusion member 141 limits its rotation as in the fourth embodiment shown in Fig. 9. Therefore, when the fitting protrusion member 141 passes through the through hole 128 and fits into the hole 112, the micro-mirror device die 104d is maintaining a correctly arranged relative position against the package substrate

12Oe with predefined relative angular position.

Fig. 11 is a cross sectional view that shows the micro-mirror device package assembly in the plane parallel with the xy plane of the fifth embodiment of the micro-mirror device package.

Fig. 11 also shows the window 101 , the mask 102, the spacer 103 and the mirror element 1 formed on the semiconductor substrate 11 of the micro-mirror device die 104d not specifically shown in Fig. 10. In the description of Fig. 11 and after, the wafer is separate by the dicing process therefore; a term "semiconductor substrate" is used instead of the word "semiconductor wafer substrate".

In Fig. 11, the fitting protrusion member 141 of the heat sink 140 passes through the through hole 128 of the package substrate 12Oe and also fits into the hole 112. The top of the heat sink 140 touches the bottom of the package substrate 12Oe.

As in the third embodiment shown in Figs. 8A~8C, the spacer 103 is mounted on the top 125a of the fringe 125 of the package substrate 12Oe. The mask 102 and the window 101 are mounted on the spacer 103. On the top 125a, the conductive lines not shown in Fig. 11 , is formed from a point C outside the range of the spacer 103 until a point B inside the range where the spacer 103 is enclosed. Therefore, the wire 130 interconnects the micro-mirror device die 104d and external equipment by connecting the point B to a point A with a terminal disposed on the top of the semiconductor substrate 11.

The heat sink 140 radiates heat generated by the drive of the mirror element 1. More particularly, heat is transmitted from the micro-mirror device die 104d to the heat sink 140 through the fitting protrusion member 141 touching the inside wall of the hole 112 of micro-mirror device die 104d. The heat is also irradiated from the radiator 142.

Heat generated in the micro-mirror device die 104d is sometimes transmitted to the package substrate 12Oe through the base 124a of the concavity 124 of the package substrate 12Oe touching the bottom of the package substrate 12Oe. Since the package substrate 12Oe touches the heat sink 140 on the bottom and inside the through hole 128, a part of the heat generated in the micro-mirror device die 104d is transmitted and radiated to the heat sink 141 through the package substrate 12Oe.

A heat transfer coefficient on the surface between the micro-mirror device die 104d and the fitting protrusion member 141 can increased than a heat transfer surface coefficient between the micro-mirror device die 104d and the package substrate 12Oe by selecting a material having an appropriate thermal conductivity. The fitting protrusion member 141 may also use materials of high thermal conductivities. Thus heat can be radiated without passing it through the package substrate 12Oe as much as possible to achieve more effective heat dissipation from the package.

The heat sink 140 prevents the temperature of the micro-mirror device die 104d from rising above a temperature limit to assure stable operation of the micro-mirror device.

Fig. 12 shows the sixth exemplary embodiment of the micro-mirror device package of this invention. Fig. 12 is the cross section view of the sixth embodiment obtained by modifying the fifth embodiment of the micro-mirror device package. Fig. 12 differs from Fig. 11 only in that no spacer 103 is used and the arrangement of the bonding wires 130.

In this embodiment, the conductive lines 121a not specifically shown in Fig. 12 is formed from a point C to a point D. The point C is disposed on a top surface 125a of the fringe 125 of the package substrate 12Of. The point D is disposed on the base 124a of the concavity 124 along the side 125b of the fringe 125. The purpose of such arrangement is to place the bonding wires 130 in the space of the concavity 124 of the package substrate 12Of covered with the window 101. The mask 102 protects the conductive pattern 121 a formed on three surfaces and specifically not shown in Fig. 12. In the sixth embodiment, the bonding wires interconnects the micro-mirror device die 104d to the external equipment by connecting the point D and a point A where a terminal is disposed on the semiconductor substrate 11.

Fig. 13 shows the seventh exemplary embodiment of the micro-mirror device package of this invention. Fig. 13 is the disassembly/assembly view of the seventh embodiment of the micro-mirror device package. The seventh exemplary embodiment is implemented with components for radiating heat generated in the micro-mirror device die 104d like the fifth and sixth embodiments. In Fig. 13, the window 101 , the mask 102. The spacer 103 is no longer necessary in this embodiment. Since the micro-mirror device die 104d and the package substrate 12Oe shown in Fig. 13 are the same of those of the fifth embodiment shown in Fig. 10, the descriptions of these elements will not be repeated here. Fig. 13 differs from Fig. 10 in the configuration of the heat radiation components. In Fig. 13, a heat sink main body 144 having the radiator142 formed in the shape of saw teeth in order to increase its surface area. The heat sink is mounted on the package substrate 12Oe through a plate 143 that is a flat plate.

A fitting protrusion member 141 similar to that shown in Fig. 10 is formed on the plate 143. The fitting protrusion member 141 and the plate 143 can be made of the same or different materials. The fitting protrusion member 141 and the plate 143 can be formed together and combined as a one-body structure. Alternatively, they can be formed individually and then be connected.

The cross sectional shape of the fitting protrusion member 141 is substantially the same as those of the through hole 128 of the package substrate 12Oe and the hole 112 of the micro-mirror device die 104d. Therefore, as in the fifth embodiment shown in Fig. 10, in the seventh embodiment shown in Fig. 13, the hole 112, the through hole 128 and the fitting protrusion member

141 function as guide portions for aligning the micro-mirror device die 104d to the package substrate 12Oe. The package substrate 12Oe, the hole 112, the through hole 128 and the fitting protrusion member 141 as shown in Fig. 13 have a combined function of alignment and further limiting the rotation of the micro-mirror device die 104d against the package substrate 12Oe.

Fig. 13 shows the seventh embodiment has a heat sink main body 144 with saw tooth formed on the bottom surface. The heat sink is manufactured separately from the fitting protrusion member 141 that requires a processing step with higher accuracy

Four screw holes 145 with female screw threads are separately formed on the plate 143. Four screw holes 146 are also formed on the heat sink main body 144 aligned with each screw hole 145. The screw hole 146 is a through hole. Although the screw hole 145 is shown as a through hole, the screw holes may also be formed as non-through holes too. The plate 143 and the heat sink main body 144 are joined by applying four bolts 147 to bolt through the screw holes 145 and 146. Fig. 13 shows four screw holes 145 and 146 for bolting together the plate 143 and the heat sink main body 144 with four bolts.

The plate 143 and the heat sink main body 144 that are jointed to each other to function as the heat sink 140 similar to that shown in Fig. 10. Therefore, heat generated in the micro-mirror device die 104d is radiated from the radiator

142 through the fitting protrusion member 141. Figs. 14A and 14B show the eighth embodiment of the micro-mirror device package. Fig. 14A is the disassembly/assembly view of the eighth embodiment of the micro-mirror device package. Fig. 14B is the perspective view of the eighth embodiment of the micro-mirror device package. In Figs. 14A and 14B, the window 101 , the mask 102 and the spacer 103 are not shown. Neither protrusion nor hole is formed on the micro-mirror device die 104g.

The package substrate 12Og is similar to the package substrate 12Oe in the fifth embodiment shown in Fig. 10. The concavity 124 in Fig. 10 is formed on the package substrate and the conductive lines 121 b are formed only on the top 125a of the fringe 125. However, the micro-mirror device 12Og in this embodiment is different from the micro-mirror device 12Oe. There are three through holes 129a, 129b and 129c formed on the concavity 124. In the embodiment shown in Fig. 14A, the cross sectional shapes of the through holes 129a and 129c are circles and the through hole 129b is a shape generated by extending a circle in one direction.

The heat sink 140b comprises a radiator 142 formed in the shape of saw teeth in order to efficiently radiate heat as the heat sink 140 shown in Fig. 10. The structure on the top of the heat sink 140 is different from that of the heat sink 140b.

As shown in Fig. 14A, three protrusions 148a, 148b and 148c are formed on the top of the heat sink 140b. These protrusions 148a~148c are almost cylinders. The protrusions 148a~148c are formed in positions corresponding to the through holes 129a~129c, respectively. A metal having high thermal conductivity is preferable as the materials of the protrusions 148a~148c.

The function of each component in the eighth embodiment is described below in reference to Fig. 14B. The protrusions 148a~148c together with the through holes 129a~129c and the sides 113a and 113b of the micro-mirror device die 104g serve the function to guide an alignment process for correctly aligning the micro-mirror device die 104g to the package substrate 12Og. . Specifically, the positions of the protrusions 148a~148c and the through holes 129a~129c are arranged in such a way that the protrusions 148a~148c may touch the side 113a and 113b of the micro-mirror device die 104g when the protrusions 148a~148c pass through the protrusions 148a~148c, respectively.

Therefore, as shown in Fig. 14B, in the package assembly processes, the protrusions 148a and 148b pass through the protrusions 148a and 148b respectively to engage to the side 113a of the micro-mirror device die 104g. The protrusion 148c passes through the through hole 129c and engaged to the side 113b of the micro-mirror device die 104g. By engaging to the edges of the plate 104g in these three places, the micro-mirror device die 104g is supported and fixed in the correct position and direction against the package substrate 12Og.

The function as a rotation stopper for limiting the relative rotation against the package substrate 12Og of the micro-mirror device die 104g is achieved by the protrusions 148a~148c, the through holes 129a~129c and the side 113a and 113b of the micro-mirror device die 104g. As described above, since the edges of the micro-mirror device die 104g is engaged to the protrusions pass through the through holes 129a~129c the package is fixed in specific angular positions relation to each other without a freedom of rotation. The function to radiate heat generated in the micro- mirror device die

104g is achieved by the heat sink 140b including the protrusions 148a~148c. The protrusions 148a~148c which engage to the micro-mirror device die 104g not only engage and fix the micro- mirror device die 104g in specified position and direction, the protrusions also constitutes a heat conductive path for conducting the heat to the heat sink. Heat generated in the micro-mirror device die 104g is conducted through the protrusions 148a-148c to the radiator and radiated from the radiator of the heat sink 140b. It is preferable for the protrusions 148a~148c to be made of a metal having high thermal conductivity. Although this preferred embodiment positions the micro-mirror device die 104g on the basis of two sides as in the publicly known example described in Patent Document 8, this preferred embodiment differs from the publicly known example in that two alignment protrusions also serve the heat conduction functions.

Fig. 15 shows the ninth embodiment of the micro-mirror device package of this invention. Fig. 15 is the disassembly/assembly view of the ninth embodiment of the micro-mirror device package. In the ninth embodiment, the descriptions of the same components as in the fifth embodiment shown in Fig. 11 may not be repeated below from time to time. In Fig. 15, the fitting protrusion member 141 functions as an alignment protrusion passing through the package substrate 12Oh and further fits into the hole 112 of the micro-mirror device die 104d. Thus the relative position and direction relative to the package substrate 12Oh of the micro-mirror device die 104 are fixed and securely maintained.

The fitting protrusion member 141 is made of a material having high thermal conductivity than the package substrate 12Oh. Therefore, heat generated in package substrate 12Oh is efficiently transmitted through heat conduction from the contact surfaces where the edges of the package substrate 12Oh engage the package substrate 12Oh.

In Fig. 15, in order to improve the heat dissipation efficiency, a heat conductor 149 vertically passing through package substrate 12Oh is provided in addition to the fitting protrusion member 141. Fig. 15 shows two heat conductors 149, the number of the heat conductors 149 may be flexibly adjusted. The heat conductor 149 is also made of a material having a higher thermal conductivity than the package substrate 12Oh. The heat conductor 149 contacts both the bottom of the micro-mirror device die 104 and the top of the heat sink 140 and efficiently transmit heat from the micro-mirror device die 104 to the heat sink 140. Thus in the ninth embodiment shown in Fig. 15 efficient heat dissipation is achieved by the heat conductor 149.

Although various embodiments have been described, some points common to these embodiments are described below.

When a protrusion is fitted into a hole for alignment for the micro-mirror device die (or the package substrate), the protrusion can be made of the same material as or different from that of the micro-mirror device die (or the package substrate). When making the protrusion of different material from that the micro-mirror device die (or the package substrate), it is preferable that the material is composed of a metal having a high thermal conductivity, such as copper, aluminum, zinc or the like. This is because the protrusion can serve two functions of alignment and heat conduction since the metal has a high thermal conductivity coefficient.

A protrusion made of a metal has a high thermal conductivity and may be formed into a heat sink. Alternatively, Figs. 10~15 show a configuration where a protrusion function as the fitting member passes through the package substrate and is connected to a radiation component of a heat sink.

The above-described embodiments can be roughly classified into the two groups according to the alignment and fixation method of the micro-mirror device die and the package substrate.

(1) A hole and a protrusion are formed on either the micro-mirror device die or the package substrate. The hole and the protrusion are used to guide the alignment. The micro-mirror device die is fixed on the package substrate by fitting the protrusion into the hole. (2) A common member engages to the prescribed portions (that is, portions functioning as alignment guide portions) on both the micro-mirror device die and the package substrate. The common member provides a function to support the micro-mirror device die in prescribed position and fixed direction relative to the package substrate. Either the hole or it's the edges of the substrate can serve the function for guiding the alignment.

The above-described embodiments can be modified according to two different basic functional features. These two basic functional features for modifying the configuration may be summarized below.

One basic functional feature of the modification is a structure that limit the relative rotation between the micro-mirror device die and the package substrate. This functional feature is described and implemented in embodiments shown in Fig. 5 and modified according to Figs. 16A-16D. Similar modifications can be applied to the other embodiments disclosed above too. Figs. 16A~16D are the section views on a plane parallel to the xv plane for showing methods for limiting the rotation of the micro-mirror device package. The coordinate axes shown in Fig. 16A and the same coordinate axes are also applied in Figs. 16B~16D.

Fig. 16A corresponds to the first embodiment shown in Fig. 5. Specifically, the hole 110 is formed in the micro-mirror device die 104a and the protrusion 122 is formed in the concavity 124 of the package substrate 120a for fitting to the hole 110. When the micro-mirror device die 104a is in the correct position and direction, the rotation stopper 123 touches the side 113a of the micro-mirror device die 104a to limit its rotation.

Fig. 16B shows an embodiment for limiting the rotation of the micro-mirror device die 104h by another method. In Fig. 16B₁ in addition to the hole 110, a hole 110b is further formed in the micro-mirror device die 104h. Then, a protrusion 122b is formed in the concavity of the package substrate in accordance with the position of the hole 110b.

The hole 110b is an elongated hole. The cross section of the hole 110b is formed in a shape obtained by sweeping a circle being the cross sectional shape of the protrusion 122b in the direction of a line 150 connecting the protrusions 122 and 122b. The purpose is to simplify its assembly that the cross section of the hole 110 is made larger than the cross section of the protrusion 122b.

The relative position and direction against the package substrate of the micro-mirror device die 104h are fixed by fitting the protrusions 122 and 122b into the holes 110 and 110b, respectively. The fittings are arranged in a plurality of locations inside the micro-mirror device die 104h. When the protrusion 122 fits into the hole 110 and also the protrusion 122b fits into the hole 110b, the protrusion 122b is fixed and does not allow linear movements or slides in the space of the hole 110b. Specifically, the protrusion contacts the inside of the hole 110 in a part of it's the outer edges, the protrusion 122b fits into the hole 110b while holding the position against the hole 110b.

Specifically, in Fig. 16B, the protrusions 122 and 122b and the holes 110 and 110b function as alignment guide to align the micro-mirror device die 104h to the package substrate. The protrusion fitting to the holes further limits the rotation of the package of the micro-mirror device die 104h.

Fig. 16C shows an embodiment obtained by further modifying the embodiment shown in Fig. 16B. Two sets of a hole and a protrusion (that is, the set of the hole 110 and the protrusion 122 and the set of the hole 110c and the protrusion 122c) in Fig. 16C, also function as alignment guide portions. The alignment further limits the rotation of the package of the micro-mirror device die 104i. Figs. 16C and 16B have the same functional features.

Fig. 16C differs from Fig. 16B in that the cross sectional shape of the hole 110c shown in Fig. 16C is a circle and that that of the protrusion 122c is an ellipse touching the inside of the hole 110. The cross sectional shape of the protrusion 122c is short in the direction of the line 150 and long in the direction of a line 151 orthogonal to the line 150. The protrusion 122c contacts the inside of the hole 110 at two points on the line 151. Fig. 16D shows an embodiment obtained by modifying the package shown in Fig. 16A. Fig. 16D differs from Fig. 16A only in the cross sectional shape of a protrusion 122d for fitting into the hole 110. The protrusion 122d contacts the hole 11 Oat three places corresponding to each end of a character Y. Even when the protrusion 122d is fitted into the hole 110 by partially contact, the micro-mirror device die 104a is securely positioned and fixed against the package substrate.

Next, the second functional feature of the modification involves the respective shapes of the protrusion and the hole for simplifying the assembly process. This functional feature is described with reference to Figs. 17A~17D. Figs. 17A~17D show the cross section views on a plane parallel to the xy plane. The coordinate axes are shown only in Fig. 17A. The same coordinate axes are also applied to Figs. 17B~16D.

For example, in Fig. 5, the inside of the hole 110 and the outside of the protrusion 122 can be formed with the same shape. The same shape may be a cylindrical shape or a tapered shaft shape or other similar kinds of shapes. Specifically, the hole 110 and the protrusion 122 can be also formed in such a way that the entire outer edges of the protrusion 122 contact the sidewalls of the hole 110.

In Fig. 6, the outer edges of the protrusion 111 and the inner sidewalls of the hole 126 can be also formed with a same shape. Specifically, the protrusion 111 and the hole 126 can be also formed in such a way that the entire outer edges of the protrusion 111 contact the sidewalls of the hole 126. When the outer edges of the protrusion and the sidewalls of the hole are formed with the same shape, it is required a high operational accuracy in the assembling process to fit the protrusion into the hole smoothly and quickly. When an assembling machine carries out the assembling processes, the assembling machine requires complex and highly accurate control. When the package is assembled by a human worker, a highly skillful assemble worker is required.

When the protrusion and the hole are formed in the tapered shape, the assembly process can be simplified. The fitting operation can be gradually advanced by allowing the micro-mirror device die and the package substrate to move relatively within the range of a space formed by the tapered shape. Therefore, there is no need to match the directions of the protrusion and the hole with a very high accuracy. The directions of the protrusion and the hole are gradually adjusted during the progress of the fitting operation and at the end of the assembling processes; the package is formed with components fitting together with highly controllable precision.

Fig. 17A is a cross section view showing a protrusion with a tapered shape. In Fig. 17A, the micro-mirror device die 104 and the package 120 are formed with a hole 11Oe and a protrusion 122e. The inside of the hole 111 is formed in a cylinder shape. The protrusion 122e is tapered towards the top. Fig. 17B is a cross section view showing a hole with a tapered shape.

In Fig. 17B, the micro-mirror device die 104 and the package 120 are provided with a hole 11Of and a protrusion 122f. The outside of the protrusion 122f is formed with a cylinder shape. The hole 11Of is extended towards the bottom opening. Fig. 17C is a cross section view showing a protrusion with a tapered shape. In Fig. 17C, the micro-mirror device die 104 and the package 120 are provided with a protrusion 111 b and a hole 126b. The inside of the hole 126b is formed with a cylinder shape. The protrusion 111 b is tapered towards the bottom. Fig. 17D is a cross section view showing a hole formed with a tapered shape. In Fig. 17D, the micro-mirror device die 104 and the package 120 are provided with a protrusion 111c and a hole 126c. The outer edges of the protrusion 111c is formed with a cylinder shape. The hole 126c is extended towards the top opening. In any of the embodiments shown in Figs. 17A~17D, at the beginning of the fitting operation by an assembly device or a human worker, there are greater range of flexibility in arranging the parts for assembling operating with protrusion and hole of tapered shape. As the assembling processes proceed, the range of flexibilities are gradually reduced. Therefore, the directions of the protrusion and the hole are gradually adjusted as the fitting operation progresses and are matched with high accuracy at the end as a result of the fitting operation. In any of the embodiments shown in Figs. 17A~17D, the cross sectional shapes of the protrusion and hole on a plane parallel to the xy plane can be flexibly changed. For example, the through hole 128 shown in Fig. 10 can be also changed to a tapered shape.

The present invention is not limited to the above-described preferred embodiments, and for example, the operation test in step 15 shown in Fig. 3B can also be conducted after the packaging assembly processes are completed. Alternatively, different processes for forming various types of MEMS structures can be applied. Although in step 12 of Fig. 3B discloses an a small notch Z, the timing of forming the notch Z may be flexibly adjusted. Concerning the protection of the micro-mirror device 10 at the time of the dicing, described in step 12 of Fig. 3B and Fig. 4, another preferred embodiment can be also adopted. Specifically, water (H₂O) or the like can be also used for the inorganic protection layer 17. The protection layer can be also deposited on the mirror layer 16 and the inorganic protection layer 17 can be also solidified in advance in the environment of being lower than the melting point. One specific embodiment is to apply a temperature of 0⁰C on the water H₂O. Then, the dicing operation can be also performed. In this preferred embodiment, the inorganic protection layer 17 can be also formed and removed by temperature control. For example, after the dicing, the inorganic protection layer 17 can be exposed to an environment with a temperature lower than its melting point to removed the protection layer.

The above-described preferred embodiments can provide a micro-mirror manufacturing method for protecting the micro-mirror device comprising at least one mirror element including a deflectable mirror when separating individual micro-mirror devices from a wafer. The above-described preferred embodiments can also provide a micro-mirror manufacturing method for reducing a likelihood of a surface damage on a mirror surface with improvement protection than the traditional method when removing an inorganic protection layer and for simplifying its process.

The above-described manufacturing method can conveniently prevent different factors that may cause the device to have a degraded operation. Such factors may include a deterioration of a mirror due to a foreign particle attached to a part of the device thus causing defect when performing a dicing operation The factor may include a mixture of a foreign object into the elastic hinge thus influences the drive circuit or the pole which are mounted on the semiconductor wafer substrate.

The above-described preferred embodiments can also position the micro-mirror device package securely on the package substrate with a highly accurate positional and angular alignment. The highly accurate alignment ' contributes to the improvement of the quality of image projection and display. The processes also simplify the adjustment of the mounting operation of the micro-mirror device package. Therefore, the highly accurate alignment improves the performance of the entire micro-mirror device package.

As described above, this invention discloses a preferred embodiment of a micro-mirror manufacturing method for separating the micro-mirror devices composed of mirror elements with a deflectable mirror, comprising a step of depositing an inorganic protection layer on a mirror before separating micro-mirror devices from a wafer and a step of removing the inorganic protection layer after separating the micro-mirror devices from a wafer.

This invention also discloses a preferred embodiment of a method for aligning and fixing a micro-mirror device die having a plurality of micro-mirrors formed on a semiconductor substrate to a package substrate. The method comprises a first alignment step of aligning a first guide portion of the micro-mirror device die to a second guide portion of the package substrate. The method further includes a fixing step of fixing the micro-mirror device die on the package substrate in a position arranged according to the first alignment step using the first and second guide portions. This specification also describes a preferred embodiment of a micro-mirror device package comprising a plurality of micro-mirrors formed on a semiconductor substrate, a micro-mirror device die having a first guide portion and a package substrate having a second guide portion. The micro-mirror device die is fixed on the package substrate by the first and second guide portions.

Although the reference examples as specific preferred embodiments of the present invention have been described, it is clear that these preferred embodiments can be modified and changed as long as the range of the present invention and its concept is not deviated. Therefore, this specification and drawings should not be considered to be limiting and should be considered to be specific examples.

Claims

ClaimsWhat is claimed is:

1. A method for aligning a micro-mirror device die having a plurality of micro-mirror devices formed to a semiconductor substrate and fixing the micro-mirror device die on the semiconductor substrate, comprising: aligning a first guide portion of the micro-mirror device die and a second guide portion of the package substrate( first alignment step); and fixing the micro-mirror device die on the package substrate in a position aligned by the first alignment step using the first and second guide portions.

2. The method according to claim 1 , wherein: the fixing step comprises fitting the second guide portion being a protrusion into the first guide portion being a hole (first fitting step).

3. The method according to claim 2, wherein: the first or second guide portion is formed in a tapered shape, and the first fitting step progresses while allowing the micro-mirror device die and the package substrate to relatively move in a space formed by the tapered shape.

4. The method according to claim 1 , wherein: the fixing step further comprises fitting the first guide portion being a protrusion into the second guide portion being a hole (second fitting step).

5. The method according to claim 4, wherein: the first or second guide portion is formed in a tapered shape, and the second fitting step progresses while allowing the micro-mirror device die and the package substrate to relatively move in a space formed by the tapered shape.

6. The method according to claim 1 , wherein: the fixing step comprises supporting the micro-mirror device die while maintaining its relative position against the package substrate by touching both the first and second guide portions on a third guide portion (support step).

7. The method according to claim 6, wherein: the support step comprises fitting a third guide portion being their common protrusion into both the first guide portion being a hole and the second guide portion being a hole (third fitting step).

8. The method according to claim 1 , wherein: the micro-mirror device die further comprises relatively aligning a rotation stopper for preventing the micro-mirror device die from relatively rotate against the package substrate (second alignment step).

9. A micro-mirror device package, comprising: a micro-mirror device die having a plurality of micro-mirror devices formed on a semiconductor substrate and a first guide portion; and a package substrate having a second guide portion, wherein the micro-mirror device die is fixed on the package substrate by the first and second guide portions.

10. The micro-mirror device package according to claim 9, wherein: one of the first and second guide portions is a hole, the other of the first and second guide portions is a protrusion which fits into the hole and the micro-mirror device die is fixed on the package substrate by the fitting of the protrusion into the hole.

11. The micro-mirror device package according to claim 10, wherein: at least one of the hole and the protrusion is formed in a tapered shape.

12. The micro-mirror device package according to claim 10, wherein: the protrusion fits into the hole unrotatably.

13. The micro-mirror device package according to claim 9, further comprising: a third guide portion touching both the first and second guide portions and supporting the micro-mirror device die while maintaining its relative position against the package substrate.

14. The micro-mirror device package according to claim 13, wherein: the first and second guide portions both are holes, and the third guide portion is a protrusion which fits into both the first and second guide portions.

15. The micro-mirror device package according to claim 13, wherein: the second guide portion is a plurality of through holes, the third guide portion is a plurality of protrusions each of which fits each of the plurality of through holes and passes through the package substrate, the first guide portion is an outside of the micro-mirror device die as a guide surface for aligning the micro-mirror device die in a position where the micro-mirror device die touches each of the plurality of protrusions that passes through each of the plurality of through holes, and each of the plurality of protrusions that passes through each of the plurality of through holes supports the micro-mirror device die by touching the micro-mirror device die on the guide surface.

16. The micro-mirror device package according to claim 13, wherein: a material forming the third guide portion has higher thermal conductivity than a material forming the package substrate.

17. The micro-mirror device package according to claim 13, wherein: a heat transfer surface coefficient between the micro-mirror device die and the third guide portion is higher than a heat transfer surface coefficient between the micro-mirror device die and the package substrate.

18. The micro-mirror device package according to claim 13, further comprising: a radiation member jointed to the third guide portion or incorporated into the third guide portion.

19. The micro-mirror device package according to claim 9, further comprising: a rotation stopper for preventing the micro-mirror device die from relatively rotating against the package substrate.

20. The micro-mirror device package according to claim 19, wherein: the rotation stopper is a protrusion provided on the package substrate and is provided in a position where the rotation stopper touches the micro-mirror device die when the micro-mirror device die is in a position and a direction in which the micro-mirror device die should be fixed.

21. The micro-mirror device package according to claim 9, wherein: the micro-mirror device die comprises a plurality of first guide portions, the package substrate comprises a plurality of second guide portions and a position and a direction against the package substrate of the micro-mirror device die is fixed by fixing the first and second guide portions which correspond to each other in a plurality of places.

21. The micro-mirror device package according to claim 9, further comprising: a heat transfer member passing from a first surface touching the micro-mirror device die to a second surface opposing the first surface of the package substrate.