FIELD OF THE INVENTION
This application is a continuation-in-part of U.S. patent application Ser. No. 10/434,493 filed on May 7, 2003 which in turn claims benefit of U.S. Provisional Patent Application Nos., 60/442,656, and 60/379,177 filed on Jan. 23, 2003, and May 7, 2002 respectively. These applications are incorporated herein by reference in their entirety.
Various embodiments of some aspects of the present invention relate generally to the field of Electrochemical Fabrication and the associated formation of three-dimensional structures (e.g. parts, objects, components, or devices) via a layer-by-layer build up of deposited materials and to the processing of such structures after layer formation is complete so that the structures are transferred from a build substrate (i.e. temporary substrate) to a structural substrate.
A technique for forming three-dimensional structures (e.g. parts, components, devices, and the like) from a plurality of adhered layers was invented by Adam L. Cohen and is known as Electrochemical Fabrication. It is being commercially pursued by Microfabrica™ Inc. (formerly MEMGen® Corporation) of Burbank, Calif. under the name EFAB®. This technique was described in U.S. Pat. No. 6,027,630, issued on Feb. 22, 2000. This electrochemical deposition technique allows the selective deposition of a material using a unique masking technique that involves the use of a mask that includes patterned conformable material on a support structure that is independent of the substrate onto which plating will occur. When desiring to perform an electrodeposition using the mask, the conformable portion of the mask is brought into contact with a substrate while in the presence of a plating solution such that the contact of the conformable portion of the mask to the substrate inhibits deposition at selected locations. For convenience, these masks might be generically called conformable contact masks; the masking technique may be generically called a conformable contact mask plating process. More specifically, in the terminology of Microfabrica™ Inc. (formerly MEMGen® Corporation) of Burbank, Calif. such masks have come to be known as INSTANT MASKS™ and the process known as INSTANT MASKING or INSTANT MASK™ plating. Selective depositions using conformable contact mask plating may be used to form single layers of material or may be used to form multi-layer structures. The teachings of the '630 patent are hereby incorporated herein by reference as if set forth in full herein. Since the filing of the patent application that led to the above noted patent, various papers about conformable contact mask plating (i.e. INSTANT MASKING) and electrochemical fabrication have been published:
- (1) A. Cohen, G. Zhang, F. Tseng, F. Mansfeld, U. Frodis and P. Will, “EFAB: Batch production of functional, fully-dense metal parts with micro-scale features”, Proc. 9th Solid Freeform Fabrication, The University of Texas at Austin, p161, August 1998.
- (2) A. Cohen, G. Zhang, F. Tseng, F. Mansfeld, U. Frodis and P. Will, “EFAB: Rapid, Low-Cost Desktop Micromachining of High Aspect Ratio True 3-D MEMS”, Proc. 12th IEEE Micro Electro Mechanical Systems Workshop, IEEE, p244, January 1999.
- (3) A. Cohen, “3-D Micromachining by Electrochemical Fabrication”, Micromachine Devices, March 1999.
- (4) G. Zhang, A. Cohen, U. Frodis, F. Tseng, F. Mansfeld, and P. Will, “EFAB: Rapid Desktop Manufacturing of True 3-D Microstructures”, Proc. 2nd International Conference on Integrated MicroNanotechnology for Space Applications, The Aerospace Co., April 1999.
- (5) F. Tseng, U. Frodis, G. Zhang, A. Cohen, F. Mansfeld, and P. Will, “EFAB: High Aspect Ratio, Arbitrary 3-D Metal Microstructures using a Low-Cost Automated Batch Process”, 3rd International Workshop on High Aspect Ratio MicroStructure Technology (HARMST'99), June 1999.
- (6) A. Cohen, U. Frodis, F. Tseng, G. Zhang, F. Mansfeld, and P. Will, “EFAB: Low-Cost, Automated Electrochemical Batch Fabrication of Arbitrary 3-D Microstructures”, Micromachining and Microfabrication Process Technology, SPIE 1999 Symposium on Micromachining and Microfabrication, September 1999.
- (7) F. Tseng, G. Zhang, U. Frodis, A. Cohen, F. Mansfeld, and P. Will, “EFAB: High Aspect Ratio, Arbitrary 3-D Metal Microstructures using a Low-Cost Automated Batch Process”, MEMS Symposium, ASME 1999 International Mechanical Engineering Congress and Exposition, November, 1999.
- (8) A. Cohen, “Electrochemical Fabrication (EFABTM)”, Chapter 19 of The MEMS Handbook, edited by Mohamed Gad-EI-Hak, CRC Press, 2002.
- (9) “Microfabrication—Rapid Prototyping's Killer Application”, pages 1-5 of the Rapid Prototyping Report, CAD/CAM Publishing, Inc., June 1999.
The disclosures of these nine publications are hereby incorporated herein by reference as if set forth in full herein.
The electrochemical deposition process may be carried out in a number of different ways as set forth in the above patent and publications. In one form, this process involves the execution of three separate operations during the formation of each layer of the structure that is to be formed:
- 1. Selectively depositing at least one material by electrodeposition upon one or more desired regions of a substrate.
- 2. Then, blanket depositing at least one additional material by electrodeposition so that the additional deposit covers both the regions that were previously selectively deposited onto, and the regions of the substrate that did not receive any previously applied selective depositions.
- 3. Finally, planarizing the materials deposited during the first and second operations to produce a smoothed surface of a first layer of desired thickness having at least one region containing the at least one material and at least one region containing at least the one additional material.
After formation of the first layer, one or more additional layers may be formed adjacent to the immediately preceding layer and adhered to the smoothed surface of that preceding layer. These additional layers are formed by repeating the first through third operations one or more times wherein the formation of each subsequent layer treats the previously formed layers and the initial substrate as a new and thickening substrate.
Once the formation of all layers has been completed, at least a portion of at least one of the materials deposited is generally removed by an etching process to expose or release the three-dimensional structure that was intended to be formed.
The preferred method of performing the selective electrodeposition involved in the first operation is by conformable contact mask plating. In this type of plating, one or more conformable contact (CC) masks are first formed. The CC masks include a support structure onto which a patterned conformable dielectric material is adhered or formed. The conformable material for each mask is shaped in accordance with a particular cross-section of material to be plated. At least one CC mask is needed for each unique cross-sectional pattern that is to be plated.
The support for a CC mask is typically a plate-like structure formed of a metal that is to be selectively electroplated and from which material to be plated will be dissolved. In this typical approach, the support will act as an anode in an electroplating process. In an alternative approach, the support may instead be a porous or otherwise perforated material through which deposition material will pass during an electroplating operation on its way from a distal anode to a deposition surface. In either approach, it is possible for CC masks to share a common support, i.e. the patterns of conformable dielectric material for plating multiple layers of material may be located in different areas of a single support structure. When a single support structure contains multiple plating patterns, the entire structure is referred to as the CC mask while the individual plating masks may be referred to as “submasks”. In the present application such a distinction will be made only when relevant to a specific point being made.
In preparation for performing the selective deposition of the first operation, the conformable portion of the CC mask is placed in registration with and pressed against a selected portion of the substrate (or onto a previously formed layer or onto a previously deposited portion of a layer) on which deposition is to occur. The pressing together of the CC mask and substrate occur in such a way that all openings, in the conformable portions of the CC mask contain plating solution. The conformable material of the CC mask that contacts the substrate acts as a barrier to electrodeposition while the openings in the CC mask that are filled with electroplating solution act as pathways for transferring material from an anode (e.g. the CC mask support) to the non-contacted portions of the substrate (which act as a cathode during the plating operation) when an appropriate potential and/or current are supplied.
An example of a CC mask and CC mask plating are shown in FIGS. 1(a)-1(c). FIG. 1(a) shows a side view of a CC mask 8 consisting of a conformable or deformable (e.g. elastomeric) insulator 10 patterned on an anode 12. The anode has two functions. FIG. 1(a) also depicts a substrate 6 separated from mask 8. One is as a supporting material for the patterned insulator 10 to maintain its integrity and alignment since the pattern may be topologically complex (e.g., involving isolated “islands” of insulator material). The other function is as an anode for the electroplating operation. CC mask plating selectively deposits material 22 onto a substrate 6 by simply pressing the insulator against the substrate then electrodepositing material through apertures 26 a and 26 b in the insulator as shown in FIG. 1(b). After deposition, the CC mask is separated, preferably non-destructively, from the substrate 6 as shown in FIG. 1(c). The CC mask plating process is distinct from a “through-mask” plating process in that in a through-mask plating process the separation of the masking material from the substrate would occur destructively. As with through-mask plating, CC mask plating deposits material selectively and simultaneously over the entire layer. The plated region may consist of one or more isolated plating regions where these isolated plating regions may belong to a single structure that is being formed or may belong to multiple structures that are being formed simultaneously. In CC mask plating as individual masks are not intentionally destroyed in the removal process, they may be usable in multiple plating operations.
Another example of a CC mask and CC mask plating is shown in FIGS. 1(d)-1(f). FIG. 1(d) shows an anode 12′ separated from a mask 8′ that includes a patterned conformable material 10′ and a support structure 20. FIG. 1(d) also depicts substrate 6 separated from the mask 8′. FIG. 1(e) illustrates the mask 8′ being brought into contact with the substrate 6. FIG. 1(f) illustrates the deposit 22′ that results from conducting a current from the anode 12′ to the substrate 6. FIG. 1(g) illustrates the deposit 22′ on substrate 6 after separation from mask 8′. In this example, an appropriate electrolyte is located between the substrate 6 and the anode 12′ and a current of ions coming from one or both of the solution and the anode are conducted through the opening in the mask to the substrate where material is deposited. This type of mask may be referred to as an anodeless INSTANT MASK™ (AIM) or as an anodeless conformable contact (ACC) mask.
Unlike through-mask plating, CC mask plating allows CC masks to be formed completely separate from the fabrication of the substrate on which plating is to occur (e.g. separate from a three-dimensional (3D) structure that is being formed). CC masks may be formed in a variety of ways, for example, a photolithographic process may be used. All masks can be generated simultaneously, prior to structure fabrication rather than during it. This separation makes possible a simple, low-cost, automated, self-contained, and internally-clean “desktop factory” that can be installed almost anywhere to fabricate 3D structures, leaving any required clean room processes, such as photolithography to be performed by service bureaus or the like.
An example of the electrochemical fabrication process discussed above is illustrated in FIGS. 2(a)-2(f). These figures show that the process involves deposition of a first material 2 which is a sacrificial material and a second material 4 which is a structural material. The CC mask 8, in this example, includes a patterned conformable material (e.g. an elastomeric dielectric material) 10 and a support 12 which is made from deposition material 2. The conformal portion of the CC mask is pressed against substrate 6 with a plating solution 14 located within the openings 16 in the conformable material 10. An electric current, from power supply 18, is then passed through the plating solution 14 via (a) support 12 which doubles as an anode and (b) substrate 6 which doubles as a cathode. FIG. 2(a), illustrates that the passing of current causes material 2 within the plating solution and material 2 from the anode 12 to be selectively transferred to and plated on the cathode 6. After electroplating the first deposition material 2 onto the substrate 6 using CC mask 8, the CC mask 8 is removed as shown in FIG. 2(b). FIG. 2(c) depicts the second deposition material 4 as having been blanket-deposited (i.e. non-selectively deposited) over the previously deposited first deposition material 2 as well as over the other portions of the substrate 6. The blanket deposition occurs by electroplating from an anode (not shown), composed of the second material, through an appropriate plating solution (not shown), and to the cathode/substrate 6. The entire two-material layer is then planarized to achieve precise thickness and flatness as shown in FIG. 2(d). After repetition of this process for all layers, the multi-layer structure 20 formed of the second material 4 (i.e. structural material) is embedded in first material 2 (i.e. sacrificial material) as shown in FIG. 2(e). The embedded structure is etched to yield the desired device, i.e. structure 20, as shown in FIG. 2(f).
Various components of an exemplary manual electrochemical fabrication system 32 are shown in FIGS. 3(a)-3(c). The system 32 consists of several subsystems 34, 36, 38, and 40. The substrate holding subsystem 34 is depicted in the upper portions of each of FIGS. 3(a) to 3(c) and includes several components: (1) a carrier 48, (2) a metal substrate 6 onto which the layers are deposited, and (3) a linear slide 42 capable of moving the substrate 6 up and down relative to the carrier 48 in response to drive force from actuator 44. Subsystem 34 also includes an indicator 46 for measuring differences in vertical position of the substrate which may be used in setting or determining layer thicknesses and/or deposition thicknesses. The subsystem 34 further includes feet 68 for carrier 48 which can be precisely mounted on subsystem 36.
The CC mask subsystem 36 shown in the lower portion of FIG. 3(a) includes several components: (1) a CC mask 8 that is actually made up of a number of CC masks (i.e. submasks) that share a common support/anode 12, (2) precision X-stage 54, (3) precision Y-stage 56, (4) frame 72 on which the feet 68 of subsystem 34 can mount, and (5) a tank 58 for containing the electrolyte 16. Subsystems 34 and 36 also include appropriate electrical connections (not shown) for connecting to an appropriate power source for driving the CC masking process.
The blanket deposition subsystem 38 is shown in the lower portion of FIG. 3(b) and includes several components: (1) an anode 62, (2) an electrolyte tank 64 for holding plating solution 66, and (3) frame 74 on which the feet 68 of subsystem 34 may sit. Subsystem 38 also includes appropriate electrical connections (not shown) for connecting the anode to an appropriate power supply for driving the blanket deposition process.
The planarization subsystem 40 is shown in the lower portion of FIG. 3(c) and includes a lapping plate 52 and associated motion and control systems (not shown) for planarizing the depositions.
In addition to the above teachings, the '630 patent indicates that electroplating methods can be used in combination with insulating materials. In particular it indicates that though the electroplating embodiments described therein have been described with respect to the use of two metals, a variety of materials, e.g., polymers, ceramics and semiconductor materials, and any number of metals can be deposited either by the electroplating methods described above, or in separate processes that occur throughout the electroplating method. It indicates that a thin plating base can be deposited, e.g., by sputtering, over a deposit that is insufficiently conductive (e.g., an insulating layer) so as to enable subsequent electroplating. It also indicates that multiple support materials (i.e. sacrificial materials) can be included in the electroplated element allowing selective removal of the support materials.
Another method for forming microstructures from electroplated metals (i.e. using electrochemical fabrication techniques) is taught in U.S. Pat. No. 5,190,637 to Henry Guckel, entitled “Formation of Microstructures by Multiple Level Deep X-ray Lithography with Sacrificial Metal layers”. This patent teaches the formation of metal structure utilizing mask exposures. A first layer of a primary metal is electroplated onto an exposed plating base to fill a void in a photoresist, the photoresist is then removed and a secondary metal is electroplated over the first layer and over the plating base. The exposed surface of the secondary metal is then machined down to a height which exposes the first metal to produce a flat uniform surface extending across the both the primary and secondary metals. Formation of a second layer may then begin by applying a photoresist layer over the first layer and then repeating the process used to produce the first layer. The process is then repeated until the entire structure is formed and the secondary metal is removed by etching. The photoresist is formed over the plating base or previous layer by casting and the voids in the photoresist are formed by exposure of the photoresist through a patterned mask via X-rays or UV radiation.
- SUMMARY OF THE INVENTION
A need still exists in the field for enhancing the combinability of conducting materials, dielectric materials, semi-conducting materials, other materials, processed materials, and/or configured materials within the EFAB process. Furthermore, a need exists in the field for combining electrochemically fabricated structures with dielectric bases or substrates, active bases or substrates (bases or substrates having elements that interact with the structure or that serve a purpose other than merely as a mount for the structure), and/or bases or substrates containing contoured structures. A need remains in the field for improved adhesion between bases or substrates and electrochemically fabricated structures. A need remains in the field for extending the range of capabilities, for expanding the range of materials, and processes available for forming desired structures (including their bases or substrates).
It is an object of various aspects of the present invention to supplement electrochemical fabrication techniques to expand the capabilities of electrochemical fabrication process to meet the structural and functional requirements for varying applications and thus to expand the potential applications available to the technology.
Other objects and advantages of various aspects of the invention will be apparent to those of skill in the art upon review of the teachings herein. The various aspects of the invention, set forth explicitly herein or otherwise ascertained from the teachings herein, may address any one of the above objects alone or in combination, or alternatively may not address any of the objects set forth above but instead address some other object ascertained from the teachings herein. It is not intended that all of these objects be addressed by any single aspect of the invention even though that may be the case with regard to some aspects.
A first aspect of the invention provides an electrochemical fabrication process for producing a three-dimensional structure from a plurality of adhered layers, the process including: (A) selectively depositing at least a portion of a layer onto a temporary substrate, wherein the temporary substrate may include previously deposited material; (B) forming a plurality of layers such that successive layers are formed adjacent to and adhered to previously deposited layers, wherein said forming includes repeating operation (A) a plurality of times; (C) after formation of a plurality of layers, attaching a structural substrate including a dielectric material to at least a portion of a layer of the structure and removing at least a portion of the temporary substrate from the structure.
A second aspect of the invention provides an electrochemical fabrication apparatus for producing a three-dimensional structure from a plurality of adhered layers, the apparatus including: (A) means for selectively depositing at least a portion of a layer onto a temporary substrate, wherein the temporary substrate may include previously deposited material; and (B) means for forming a plurality of layers such that successive layers are formed adjacent to and adhered to previously deposited layers, wherein said forming includes repeating operation (A) a plurality of times; (C) means for attaching a structural substrate including a dielectric material to at least a portion of a layer of the structure and removing at least a portion of the temporary substrate from the structure; and (D) a computer programmed to control the means for contacting, the means for conducting, the means for separating, and the means for attaching, such that the means for attaching is made to operate after formation of a plurality of layers of the structure.
A third aspect of the invention provides an electrochemical fabrication process for producing a three-dimensional structure from a plurality of adhered layers, the process including: (A) selectively depositing at least a portion of a layer onto a first temporary substrate, wherein the first temporary substrate may include previously deposited material; and (B) forming a plurality of layers such that successive layers are formed adjacent to and adhered to previously deposited layers; and (C) after formation of a plurality of layers attaching a second temporary substrate, which includes a dielectric material, to at least a portion of a layer of the structure and removing at least a portion of the first temporary substrate from the structure and then attaching a structural substrate to at least a portion of a layer of the structure that at least partially overlaps a location where the first temporary substrate was attached.
A fourth aspect of the invention provides an electrochemical fabrication process for producing a three-dimensional structure from a plurality of adhered layers, the process including: (A) selectively depositing at least a portion of a layer onto a sacrificial substrate, wherein the temporary substrate may include previously deposited material; (B) forming a plurality of layers such that each successive layer is formed adjacent to and adhered to a previously deposited layer, wherein said forming includes repeating operation (A) a plurality of times; (C) after formation of a plurality of layers attaching a structural substrate, including a plurality of materials and/or a patterned structure, to at least a portion of a layer of the structure and removing at least a portion of the temporary substrate from the structure.
A fifth aspect of the invention provides an electrochemical fabrication process for producing a three-dimensional structure from a plurality of adhered layers, the process including: (A) selectively depositing at least a portion of a layer onto a first temporary substrate, wherein the first temporary substrate may include previously deposited material; and (B) forming a plurality of layers such that successive layers are formed adjacent to and adhered to previously deposited layers; and (C) after formation of a plurality of layers attaching a second temporary substrate, which includes a plurality of materials and/or includes a patterned structure, to at least a portion of a layer of the structure and removing at least a portion of the first temporary substrate from the structure and then attaching a structural substrate to at least a portion of a layer of the structure that at least partially overlaps a location where the first temporary substrate was attached.
A sixth aspect of the invention provides an electrochemical fabrication process for producing a multi-part three-dimensional structure wherein at least one part is produced from a plurality of adhered layers, the process including: (A) forming at least one part of the multi-part structure, including: (1) selectively depositing at least a portion of a layer onto a substrate, wherein the substrate may include previously deposited material; (2) forming a plurality of layers such that successive layers are formed adjacent to and adhered to previously deposited layers, wherein said forming includes repeating operation (1) a plurality of times; (B) supplying at least one additional part of the multi-part structure; (C) attaching the at least one part to the at least one additional part to form the multi-part structure.
BRIEF DESCRIPTION OF THE DRAWINGS
Further aspects of the invention will be understood by those of skill in the art upon reviewing the teachings herein. Other aspects of the invention may involve combinations of the above noted aspects of the invention and/or addition of various features of one or more embodiments. Other aspects of the invention may involve apparatus that is configured to implement one or more of the above method aspects of the invention. These other aspects of the invention may provide various combinations of the aspects presented above as well as provide other configurations, structures, functional relationships, and processes that have not been specifically set forth above.
FIGS. 1(a)-1(c) schematically depict side views of various stages of a CC mask plating process, while FIGS. 1(d)-(g) schematically depict a side views of various stages of a CC mask plating process using a different type of CC mask.
FIGS. 2(a)-2(f) schematically depict side views of various stages of an electrochemical fabrication process as applied to the formation of a particular structure where a sacrificial material is selectively deposited while a structural material is blanket deposited.
FIGS. 3(a)-3(c) schematically depict side views of various example subassemblies that may be used in manually implementing the electrochemical fabrication method depicted in FIGS. 2(a)-2(f).
FIGS. 4(a)-4(i) schematically depict the formation of a first layer of a structure using adhered mask plating where the blanket deposition of a second material overlays both the openings between deposition locations of a first material and the first material itself.
FIG. 5 depicts a flow chart of the basic operations of a preferred embodiment of the invention.
FIGS. 6(a)-6(c) depict an example of a structure created according to a preferred embodiment of the invention where FIGS. 6(a) and 6(b) depict two different perspective views of the structure while FIG. 6(c) depicts a side view of the structure of FIGS. 6(a) and 6(b).
FIGS. 7(a)-7(o) illustrate the production of the structure of FIGS. 6(a)-6(c) from a plurality of adhered layers according to a preferred embodiment of the invention.
FIG. 8(a)-8(d) illustrate a variation to the formation of the last layer of the structure of FIGS. 6(a)-6(c) and how the permanent substrate mates with that layer.
FIGS. 9(a)-9(e) depict the results of various steps during the practice of an embodiment of the invention.
FIG. 10 provides a flowchart illustrating the basic operations of the embodiment exemplified in FIGS. 9(a)-9(e).
FIGS. 11(a)-11(j) depict the results of various operations performed during the practice of an embodiment of the invention.
FIG. 12 provides a flowchart illustrating basic operations of another embodiment of the invention.
FIGS. 13(a)-13(c) schematically depict a process for swapping a structure 702 from a first substrate 704 to a second substrate 706.
FIGS. 13(d) and 13(e) schematically depict side views of structures and substrates having modified configurations for enhancing attachment.
FIGS. 14(a)-14(c) schematically depict a process for modifying a configuration of an attachment layer of a structure to include notches as indicated in FIG. 13(d).
FIG. 15(a)-15(f) schematically depict a process for modifying a configuration of an attachment layer of a structure to include reentrant features for enhancing interlocking of the structure and the substrate.
Detailed Description of Embodiments of the Invention
FIGS. 1(a)-1(g), 2(a)-2(f), and 3(a)-3(c) illustrate various features of one form of electrochemical fabrication that are known. Other electrochemical fabrication techniques are set forth in the '630 patent referenced above, in the various previously incorporated publications, in various other patents and patent applications incorporated herein by reference, still others may be derived from combinations of various approaches described in these publications, patents, and applications, or are otherwise known or ascertainable by those of skill in the art from the teachings set forth herein. All of these techniques may be combined with those of the various embodiments of various aspects of the invention explicitly set forth herein to yield enhanced embodiments. Still other embodiments be may derived from combinations of the various embodiments explicitly set forth herein.
FIGS. 4(a)-4(i) illustrate various stages in the formation of a single layer of a multi-layer fabrication process where a second metal is deposited on a first metal as well as in openings in the first metal where its deposition forms part of the layer. In FIG. 4(a), a side view of a substrate 82 is shown, onto which patternable photoresist 84 is cast as shown in FIG. 4(b). In FIG. 4(c), a pattern of resist is shown that results from the curing, exposing, and developing of the resist. The patterning of the photoresist 84 results in openings or apertures 92(a)-92(c) extending from a surface 86 of the photoresist through the thickness of the photoresist to surface 88 of the substrate 82. In FIG. 4(d), a metal 94 (e.g. nickel) is shown as having been electroplated into the openings 92(a)-92(c). In FIG. 4(e), the photoresist has been removed (i.e. chemically stripped) from the substrate to expose regions of the substrate 82 which are not covered with the first metal 94. In FIG. 4(f), a second metal 96 (e.g., silver) is shown as having been blanket electroplated over the entire exposed portions of the substrate 82 (which is conductive) and over the first metal 94 (which is also conductive). FIG. 4(g) depicts the completed first layer of the structure which has resulted from the planarization of the first and second metals down to a height that exposes the first metal and sets a thickness for the first layer. In FIG. 4(h) the result of repeating the process steps shown in FIGS. 4(b)-4(g) several times to form a multi-layer structure are shown where each layer consists of two materials. For most applications, one of these materials is removed as shown in FIG. 4(i) to yield a desired 3-D structure 98 (e.g. component or device).
Though the embodiments discussed herein are primarily focused on conformable contact masks and masking operations, the various embodiments, alternatives, and techniques disclosed herein may have application to proximity masks and masking operations (i.e. operations that use masks that at least partially selectively shield a substrate by their proximity to the substrate even if contact is not made), non-conformable masks and masking operations (i.e. masks and operations based on masks whose contact surfaces are not significantly conformable), and adhered masks and masking operations (masks and operations that use masks that are adhered to a substrate onto which selective deposition or etching is to occur as opposed to only being contacted to it).
FIG. 5 presents the basic operations of a preferred embodiment of the invention in the form of a flowchart. The process starts with operation 102 which calls for supplying a substrate onto which successive layers of deposited material will be added. This substrate is typically made from a conductive material onto which electrodeposition can occur but may be a dielectric material onto which a seed layer of conductive material has been deposited.
The process continues with operation 104 which calls for the deposition of a layer onto the substrate or onto a previously formed layer that is already on the substrate. The layer deposited, according to certain embodiments of the invention will contain two or more materials one or more of which are patterned to have a desired configuration for the structure being formed and the other one or more materials acting as sacrificial material which will be removed from the structure after layer formation is completed. As preferred embodiments of the invention call for the separation of the structure from the substrate on which it was formed (i.e. the temporary substrate), and as it may be desirable for the substrate to be made from a structural material as opposed to a sacrificial material, in certain embodiments, the first one or more layers deposited on the substrate may be comprised solely of sacrificial material.
Furthermore, in preferred embodiments of the present invention, as the substrate on which structure is formed is not the permanent substrate on which the structure will reside, it is preferred in some embodiments for the first layers deposited (of the structure) to be the last layers of the structure relative to the permanent substrate and the last layers deposited to be the first layers relative to the permanent substrate. In other words, in some embodiments it is desirable for the structure's layers to be deposited in reverse order.
The electrochemical fabrication process used may be similar to the one illustrated in FIGS. 1(a)-1(c) and 2(a)-2(f) or it may be another process set forth in the '630 patent, a process set forth in one of the other previously incorporated publications, a process described in one of the patents or applications that is included in the table of incorporated patents and applications set forth hereafter, or the process may be a combination of various approaches described in these publications, patents, and applications, or the process may be otherwise known or ascertainable by those of skill in the art. Of course portions of the structures may be formed by other three-dimensional modeling or fabrication processes.
After deposition of a layer, the process proceeds to operation 106 in which an inquiry is made as to whether the last layer of the structure has been formed (i.e. the layer that will contact the permanent substrate in certain embodiments of the invention). If the answer is “no”, the process loops back to operation 104 for further depositions. If the answer is “yes”, the process moves forward to operation 108.
Operation 108 calls for the attachment of a permanent substrate (e.g. a dielectric material) to the last deposited layer of the structure. The attachment may occur via an adhesive (e.g. a pressure sensitive adhesive, a heat sensitive adhesive, or a radiation curable adhesive (if the substrate is transmissive of the appropriate radiation). The application of the adhesive may occur in various ways known to those of skill in the art (e.g. spreading, spinning, spraying, and the like). Attachment may alternatively occur via non-adhesive based bonding techniques, e.g. surface melting, sintering, brazing, ultrasonic welding, vibration welding, and the like.
After attaching the permanent substrate and the layers of deposited material together, the process proceeds to operation 110 where a permanent substrate and layers are separated from the temporary substrate and any sacrificial material is removed. The separation process may occur as a natural part of the sacrificial material removal process if one or more layers of sacrificial material are interposed between the temporary substrate and the structural material or if the temporary substrate is made of the sacrificial material or other material that is attacked by an etchant being used to selectively separate the sacrificial and structural materials.
In alternative embodiments, the three tasks set forth in operations 108 and 110 may be performed in varying orders, for example: (1) bonding and then simultaneous separation and removal of sacrificial material, (2) bonding, separation, then removal, (3) simultaneous separation and removal then bonding, (4) removal, bonding, then separation.
FIGS. 6(a)-6(c) depict an example of a structure (e.g. a switch) created according to a preferred embodiment of the invention. Two different perspective views of the structure are shown in FIGS. 6(a) and 6(b) and a side view is shown in FIG. 6(c). The view seen in FIG. 6(a) allows the structure 122 to be seen in its entirety while the structure is attached to permanent substrate 124. The view seen in FIG. 6(b) obscures a portion of structure 122 when it is attached to permanent substrate 124 but allows the layer formation process to be seen when the structure is being formed and attached to the temporary substrate as shown in FIGS. 7(a) to 7(n). As can be seen in FIG. 6(c) the structure consists of ten layers numbered 201-210.
FIG. 7(a)-7(o) illustrate various states of the process associated with the formation of the structure of FIGS. 6(a)-6(c). In this embodiment, successive layers are formed and adhered to the bottom of previously deposited layers. With the exception of the sacrificial material shown in FIG. 7(b), when showing structural material and sacrificial material on the current deposition layer, the structural material is fully illustrated while only an outline of the sacrificial material is shown. On a current deposition layer any order of depositing structural material and sacrificial material is acceptable. In alternative embodiments, the layers may be deposited one on top of the other or one beside the other. In this application, unless a different interpretation is required by the context, when a deposition is said to occur onto a previous deposition, no absolute inference of layer orientation should be made but only a relative orientation of deposition order should be inferred.
FIG. 7(a) illustrates that the process starts with a temporary substrate 212.
FIG. 7(b) indicates that the temporary substrate is supplied with a coating or first deposited layer 211 of sacrificial material. This layer 211 of sacrificial material will allow separation of the structural material from the temporary substrate during a later step of the formation process. Of course in actual practice, more than one such layer 211 may be formed or its thickness may be tailored to allow easy separation during a later step.
FIG. 7(c) shows the structural material 210′ of layer 210 that is patterned along with a dashed outline indicating the boundary of the sacrificial material that is also present.
FIG. 7(d)-7(l) increment through successive deposition layers ranging from layer 209 down to 201. The pattern of structural material 209′ to 201′ for each of the current deposition layers is also shown along with an outline of the sacrificial material associated with the current layer. Previously deposited layers are shown as solid blocks of material without distinction between the patterning of the structural and sacrificial materials.
FIGS. 7(m) and 7(n) depict the attachment of the permanent substrate 200 to (1) the stack of layers 201-210, (2) the release layer 211, and (3) the temporary substrate 212. FIG. 7(m) depicts the various elements of the partially formed structures as solid blocks, while FIG. 7(n) depicts the sacrificial material and permanent substrate as transparent so that the layers and configuration of the structural material 201′-210′ may be seen.
FIG. 7(o) depicts the released structural material 201′-210′ adhered to the permanent substrate 200. The substrate is shown as transparent for illustrative purposes but which may be opaque or transparent (e.g. glass) wherein some applications may require or benefit from such a material (e.g. when the structure includes a scanning mirror that is to receive radiation through the substrate and transmit it back out through the substrate). The temporary substrate may be removed along with the sacrificial material which may be removed by selective etching with an etchant (e.g. Enstrip C-38) that is selective to the sacrificial material (e.g. copper) but non-destructive to the structural material (e.g. nickel). The sacrificial material etchant may include an anti-pitting agent, or the like, to help ensure that it does not attack the structural material.
FIG. 8(a)-8(d) illustrate a variation to the formation of the last layer of the structure of FIGS. 6(a)-6(c) and a variation in how the permanent substrate mates with that layer. FIG. 8(a) shows the final layer including only the structural material 201′. FIG. 8(b) depicts the permanent substrate being formed or adhered to not only the bottom of the last layer but also to the sides of the last layer such that the structural material of the last layer becomes at least partially embedded in the substrate. FIGS. 8(c) and 8(d) depict two perspective views of the resulting structure. As can be seen, structural material 201′ is embedded in the substrate and only nine of the ten original layers of structural material extend above the surface of the permanent substrate. The surrounding of the structural material 201′ by the substrate may be achieved in various ways. For example, instead of the substrate being in the form of a performed sheet that is bonded to the layers, it may be in the form of a flowable material that can be molded to partially embed the structural material and to have a desired thickness extending beyond the surface of the last layer of structural material. As another example, the substrate may still be in the form of a sheet that is bonded to the structural material 201′ of the last layer but a portion of the last layer where the sacrificial material has been removed or never deposited may be filled with an epoxy or other flowable/solidifiable material. The permanent substrate may be placed in position and the hardening of the epoxy or other material may not only fill the region around structural material 201′ but also cause bonding between the layers and the substrate.
Various alternatives to the above embodiments exist. Even when not molding the substrate around, the sides of at least one layer, it is still possible to use a moldable material and form the substrate from a temporarily flowable material as opposed to a sheet of material. Contact pads and runners may be formed of the structural material and these may extend to desired locations on the surface of the substrate or may even be encapsulated by the substrate material except at desired contact points. A selective partial etching of the sacrificial material may occur before attachment or formation of the permanent substrate. Layers of material may be etched to a depth of less than one layer thickness or more than one layer thickness. In some embodiments, the depth of etching may be such that portions of the structural material may extend completely through the substrate that will be molded so as to form interconnects that protrude from the bottom of the substrate. In embodiments where it is desired to have interconnects extend through the bottom of the substrate, and when such extension does not occur during molding, the back side of the substrate may be planarized until the structural material is exposed. Substrates need not be planar and their lateral extents need not correspond to those of the layers.
If partially etching to a depth of more that one layer thickness, it is preferred that the pattern of structural material remain of fixed pattern, for all but maybe the deepest layer that will be exposed by the partial etching. This will help ensure a more uniform depth of etching since the sacrificial material will not be shielded by regions of extended structural material. However, in embodiments where the depth of etching is less critical or it is determined that a varying structural pattern will yield a desired etching pattern, no such restriction on structural material patterning need exist.
In some embodiments instead of the temporary substrate and permanent substrate being mounted on opposite sides of the deposited layers, the permanent substrate may be mounted in an orientation perpendicular to that of the temporary substrate. In other words, the permanent substrate may be mounted to the sides of a plurality of deposited layers.
In some embodiments, instead of attaching the permanent substrate to the opposite side of the stack of layers relative to the temporary substrate, the temporary substrate may be removed and the permanent substrate bonded in its place. This may occur by having the temporary substrate or its upper most surface formed of a material that can be selectively etched or otherwise removed from the layers of material preferably without damaging either the structural material or sacrificial material of those layers. And after removal, the bottom most layer of the structure would be exposed and the permanent substrate (e.g. dielectric substrate) attached thereto.
When desiring to mount the permanent substrate into the same position occupied by the temporary substrate, in some embodiments it may be desirable to first mount a second temporary substrate on the opposite side of the stack as compared to the first temporary substrate after which the first temporary substrate may be removed, followed by attachment of the permanent substrate, and then followed by the removal of the second temporary substrate. In still other embodiments, the permanent substrate can be mounted on the opposite side of the stack of layers as compared to the substrate on which the layers were formed and the substrate on which the layers were formed can remain.
In some embodiments of the invention, the permanent substrate may not be a dielectric but instead may be of some other material. For example, the permanent substrate might be made of a conductive material that can not be readily electrodeposited.
Though the use of the term “permanent substrate” has been used herein, it should be understood that it is not intended that the permanent substrate must exist throughout the life of the structure but instead that if form part of the structure for at least some portion of its useful life.
In some embodiments of the invention, a sacrificial material may not be used when depositing the layers one upon the other. In some embodiments, formation of layers may be by single or multiple selective depositions and potentially one or more blanket depositions and potentially one or more planarization operations.
Some embodiments of the invention may provide for attachment of electrochemically produced structures (e.g. structures formed using conformable contact masking techniques or adhered masking techniques) to substrates that may include active elements. This is illustrated in the embodiment of FIGS. 9(a)-9(e) where an electrochemically fabricated structure is attached to a piezoelectric element and the combination of the two provide a working piezoelectric device.
In FIG. 9(a), a structure 302 includes structural material 304 surrounded by a sacrificial material 306. The structure 302 is preferably fabricated via electrochemical fabrication from a plurality of adhered layers. The structure 302 is fabricated on a release material 308 which in turn is attached to a substrate 312. The release material 308 may be the same as the sacrificial material 306 or alternatively it may be another material that can be separated, e.g. by etching or melting (e.g., a solder) or otherwise removed. The release material 308 may have been coated onto a substrate 312 prior to the start of electrochemical fabrication of the structure 302 or it may be formed as a result of one or more initial depositions of the electrochemical fabrication process. The substrate is typically a conductive material though in some embodiments it may be dielectric material which may be coated with a seed layer of conductive material.
In FIG. 9(b), a pre-fabricated element or component 322 is shown located above the structure 302. The pre-fabricated element or component 322 has been prepared for attachment to the electrochemically fabricated structure 302. The element or component 322 is attached to a device substrate 324. Typically, the device substrate 324 will serve as the final substrate for the device which will be a combination of element or component 322 and the structural material of structure 302. Depending the final requirement of a particular device the device substrate may take on any desired properties (e.g. be a conductor, a dielectric, a transparent material, a flexible material, etc.). In the present example the device substrate 324 is a dielectric so that it may provide electrical isolation). On the device substrate a metal element 326 is patterned, on to which a region of piezoelectric material 328 is patterned, and on to which an adhesive 330 (which may be electrically conductive if desired) is patterned. An appropriate adhesive is one which provides good adhesion to the structural material 304 of the structure 302. The metal element 326 is provided and patterned to serve as an electrode to actuate the piezoelectric material and as a trace that interconnects the electrode to a power supply.
In FIG. 9(c), the pre-fabricated element or component 322 is shown as being adhered to structure 302 by means of the adhesive 330. In FIG. 9(d), the release material 308 is shown as being removed. Finally, in FIG. 9(e), the sacrificial material 306 has been removed from structural material 304 to release component 334 from structure 302 thereby yielding the completed device 336 which is a combination of component 334, component 322, and device substrate 324.
FIG. 10 provides a flow chart illustrating the process flow associated with the embodiment of FIGS. 9(a)-9(e). In FIG. 10, the process begins at two points as illustrated by blocks 402 and 406. Block 402 calls for the supplying of a substrate that is separable from a component that will be formed thereon. The substrate and component might be separable as a result of the substrate having a release layer thereon, or they might be separable as a result of a release layer that will be formed on the substrate.
Block 406 calls for the supplying of a second component, where the second component will have a desired shape or will be composed of multiple desired materials. The second component will have a surface that can be attached to the surface of the first component as supplied in association with block 402.
Block 404 calls for the formation of one or more layers on the substrate so as to form a first component (i.e. portion) of a device that is to be created. In the process of forming the first component, the component may be partially surrounded by a sacrificial material which will be eventually removed from the component portion of the layers that are formed. The first component will have a surface that is capable of being bonded or otherwise attached to the second component. Both blocks 404 and 406 are the starting points for the operation of block 208.
In block 408 either one or both of the first and second components are prepared for adhesion to the other component by the addition of an adhesive to at least one of the bonding surfaces. Of course in alternative embodiments block 408 may not be part of the process. In some embodiments, for example, an adhesive may be part of the second component that is supplied.
From block 408 the process moves forward to block 410 where the two components are bonded or otherwise attached to one another. This attachment may occur by use of a pressure sensitive adhesive, a hot melt adhesive, or by other means known to those of skill in the art.
The process then moves forward to block 412 where the first component is separated from the substrate on which it was formed.
Then the process moves forward to block 414 where the first component is separated from any sacrificial material that is not to remain part of the final device that is being created.
Next the process moves to block 416 where either additional manufacturing operations may be performed or where the device that was released in the operation of block 414 may be put to use.
In alternative embodiments, the order of operations associated with blocks 414 and 412 may be reversed. In still other embodiments the accomplishment of the operations of blocks 414 and 412 may occur simultaneously. In still further alternative embodiments either one of the operations of blocks 412 or 414 or both of them may occur between the operations of blocks 408 and 410. Various other alternatives will be apparent to those of skill of the art upon reviewing the teachings herein.
In some embodiments of the invention the attached substrate may be a passive device but the structure that is attached to it may include structures having electrochemically fabricated portions and portions fabricated by other deposition or patterning techniques. One or both the portions may include active components. This is illustrated in the embodiment of FIGS. 11(a)-11(j)
FIGS. 11(a)-11(j) illustrate another alternative embodiment of the invention which includes formation of a number of layers using similar operations followed by formation of additional portions of a structure using alternative operations. FIG. 11(a) depicts a side view of a first structure 502 which for illustrative purposes is identical to that of FIG. 9(a).
In FIG. 11(b), a piezoelectric material 528 has been deposited onto the top surface (i.e., last layer) of structure 502, and a photoresist 520 has been deposited on to the piezoelectric material 528.
In FIG. 11(c), a desired pattern of piezoelectric material 528 is shown. The patterning of this piezoelectric material may occur by first patterning the photoresist 520 which is then used as a pattern for selectively etching the piezoelectric material. In an alternative process, for example, the piezoelectric material may have been patterned by lift-off methods, and the like.
FIG. 11(d) illustrates an optional step for bringing the surface level of the partially formed device to a uniform height by using a dielectric material 532 to fill the voids that resulted from the etching of the piezoelectric material. In some alternative embodiments, it may be necessary, or at least desirable, to planarize the combined dielectric and piezoelectric material layer.
FIG. 11(e), depicts the resulting structure after deposition of a next layer that supplies a metal 534 on top of the piezoelectric and dielectric materials.
FIG. 11(f), illustrates the result of an operation that patterns the deposited metal. The pattern of the metal is selected to form an electrode for the piezoelectric element as well as an interconnect trace. The patterning of the metal may occur in a variety of ways, for example, it may occur in one of the ways noted above for patterning the piezoelectric material. FIG. 11(g) illustrates the result of an operation that fills the voids in the metal layer with a dielectric material 536 which may be the same as dielectric 532. The filling of the voids may be carried out in a manner similar to that used for filling the voids in the piezoelectric containing layer. For example, a material may be deposited in bulk, distributed, cured, and then planarized to yield a layer of desired thickness and uniformity. In FIG. 11(h), a device substrate 538 is illustrated as being applied over the metal/dielectric layer. The substrate may have any desired properties and in the present example it is a dielectric. In FIG. 11(i), a release material 508 is shown as having been removed. Finally, in FIG. 11(j), a sacrificial material 508 is shown as having been removed so as to yield a released device that may undergo additional processing operations or be put to use.
In a final functional device, an electric connection through the structural material 304 of FIG. 9(e) or 504 of FIG. 110) may be used to provide a second electrode for the piezoelectric element in order to produce a functional device.
FIG. 12 provides a flow chart illustrating the process exemplified in FIG. 11(a)-11(j). The process starts with block 602 where a substrate is supplied onto which a device is to be formed. Also as the device will be eventually transferred to a different substrate the substrate should either have a release layer already in place or alternatively an appropriate release material (e.g. sacrificial material) may be added during the first one or more layers of electrochemical fabrication.
Block 604 calls for the formation of one or more layers (e.g. by Electrochemical Fabrication) using a first process which will form a portion of the device which may be surrounded by a sacrificial material.
Block 606 calls for the use of at least one different deposition process to further build up and pattern the structure. In some embodiments additional electrochemical fabrication operations may be used in completing formation of the structure which will include the unreleased device.
Block 608 calls for the placement of an adhesive on the last layer of the formed structure and/or on a substrate that is going to be bonded to the structure. The use of such adhesive may or may not be necessary depending on the material that the substrate is made from and the process or processes that will be used to cause joining.
Block 610 calls for the formation of the substrate on the last formed layer of the structure or the adherence on the substrate to the last formed layer.
Block 612 calls for the separation of the structure from the original substrate on which it was formed.
Block 614 calls for the separation of the structure from any sacrificial material that is not to remain part of the final device. This separation will result in a release of the device.
Block 616 calls for the performance of any additional fabrication operations or the putting of the device into use. As with the flowchart of FIG. 10, various alternative operations may be performed as well as various reorderings of the blocks of the exemplified operations.
Two additional embodiments are depicted in FIGS. 13(a)-13(e), 14(a)-14(c), and 15(a)-15(f). These two additional embodiments depict substrate swapping techniques that include either enhanced surface area (interlacing) between the structure and the adhered substrate or the formation of features in the structure that allow interlocking with the swapped substrate.
FIGS. 13(a)-13(c) schematically depict a process for swapping a structure 702 from a first substrate 704 to a second substrate 706 where the contact area between the structure and the second substrate is substantially planar and thus no enhanced surface area or interlocking regions exist to aid in improving adhesion.
FIG. 13(d) depicts a modified structure 702′ and modified substrate 706′ where notches exist in what was a planar surface of the structure and where protrusions in either the swapped substrate or in an adhesive enter the notches and enhance adhesion between the structure and substrate.
FIG. 13(e) depicts a modified structure 702″ adhered to a modified swapped substrate 706″ where the structure includes notches with undercuts in which material from the swapped substrate or an adhesive becomes located such that adhesion between the structure and substrate is enhanced by mechanical interlocking between them.
The modified structure of FIG. 13(d) can be implemented via a number of different processes. One implementation is depicted in FIGS. 14(a)-14(c).
FIG. 14(a) depicts the final two layers of the structure 712 and 714 as they would have been produced when no interlocking would occur upon attachment of layer 714 to a substrate.
FIG. 14(b) depicts a modified version of layers 712 and 714′ where layer 714′ is modified to include holes, notches, slots, or the like in the structural material 718. These holes and notches may be filled with a sacrificial material 720 as part of the layer formation process. FIG. 14(c) depicts the state of the process after the sacrificial material 720 shown in FIG. 14(b) is removed from the openings 722 in layer 714′.
In some embodiments, the openings in layer 714′ may have occurred during the layer formation process as a result of modifying the data descriptive of the layer. Alternatively, in other embodiments the holes in layer 714′ may have been made after layer formation was completed by selectively etching holes into a layer 714 at desired locations. Such etching processes may be performed using contact masks or adhered masks. The etching out of sacrificial material 720 on the other hand may occur in bulk if one is not concerned about removing sacrificial material from other regions of the structure. Or alternatively, the etching may occur by use of one or more masks that at least shield regions of sacrificial material that are not to be removed or that also shield the structural material. After the openings are etched into the layer which is to contribute to adhesion, an adhesive or flowable substrate material may be applied and the substrate bonded to the structure or solidified in contact with the structure (which results in bonding).
In some embodiments, it is preferable that the sacrificial material located in regions outside the structural material portions of layer 714 not be etched away prior to occurrence of the bonding operation. Such ordering of bonding and removal of sacrificial material may allow for improved bonding orientation between the substrate and the structure and/or may help limit the movement of adhesive or flowable substrate material into regions surrounding the structure. In other embodiments it maybe preferable to remove the sacrificial material that is external to the structural material regions, for example, as the sacrificial material may be more accessible prior to bonding than after bonding.
In still other embodiments, external region etching may occur prior to bonding simply because the structures being bonded are relatively tolerant to non-uniformities in orientation or exact positioning and/or to the partial or complete filling of voids by flowable substrate material or adhesive. The obtainment of data associated with modifying the last layer of the structure (or even the last several layers of a structure) may be based upon a designer modifying a CAD file descriptive of the desired structure or by a data processing program that performs various Boolean operations (e.g. erosion or expansion operations) which may be based on fixed or user definable sets of parameters (e.g. a fixed grid of attachment locations and sizes which can be overlaid against the exact position of the structural material of the layer or layers). Such data processing operations may be based on structural data that has already been transformed into layer data or it may be based on structural data that remains in a three-dimensional format.
The gripping functionality of the transition region between the structure and the substrate of FIG. 13(e) may be obtainable in a variety of ways. For example, an etching operation may be used that has a tendency to undercut the material that it is cutting into. Such undercutting may be the result of the compression of a conformable contact mask into the hole as it is being formed which may offer protection for the upper portions of the side walls of the openings until a certain depth is reached at which point horizontal etching may form an undercut. Such gripping functionality may also be obtained by modifying the pattern of structural material on the last two or more layers of structure wherein the contacting layer (and maybe one or more additional layers will have relatively small openings in the structural material and one or more previous layers will have broader openings. These smaller openings and wider openings on different layers may be filled in with a sacrificial material during the layer formation process. The sacrificial material can be removed after layer formation is complete in much the same manner as described with regard to FIGS. 14(b) and 14(c). An example of the formation of these gripping, undercut, or interlocking structures is depicted in FIGS. 15(a)-15(f).
FIG. 15(a) depicts the last five layers of a sample structure formed by electrochemical fabrication wherein each of the five layers has the same configuration. As indicated, the structure includes regions of structural material 752 and regions of a sacrificial material 754 which are external to the structure itself.
FIG. 15(b) depicts the last several layers of a structure formed by electrochemical fabrication where the configuration of the last two layers has been modified to include openings in the structural material that have undercuts or reentrant configurations. As shown in FIG. 15(b), reentrant structures 762 and 764 as well as channels 772 and 774 that lead to them are temporarily filled with a second sacrificial material that may or may not be the same as the first sacrificial material 754.
FIG. 15(c) depicts the pocket or reentrant structures 762 and 764 and associated channels 772 and 774 with the second sacrificial material removed.
FIG. 15(d) depicts the structure after being coated with an adhesive 774 and with a swapping substrate 776 located in position for bonding.
FIG. 15(e) depicts the state of the process after the swapping substrate 776 has been lowered into position and bonded to the structure via adhesive 774. Not only has bonding occurred between the substrate and the structure, interlocking has occurred between the adhesive and the structure, and if the adhesive has better bonding characteristics with the substrate than the structure then the overall integrity of the combined substrate-structure system has been improved.
FIG. 15(f) depicts the state of the process after the external sacrificial material 754 has been removed.
Many alternatives to this interlocking approach as well as the increased surface area approach are possible. In either approach, the interlacing or interlocking elements may extend from a fraction of a layer to multiple layers in height. Instead of using an adhesive to bond the substrate and the structure together, flowable substrate material may have been made to fill the openings after which it would be allowed to solidify or otherwise be made to solidify.
In other embodiments the substrate itself could include openings or reentrant features which could assist in the gripping of an adhesive or filler material to it. In still other embodiments the reentrant features may not be such that any feature alone forms a locking pattern between the substrate and the structure but where a combination of two or more such structures result in a locking configuration (e.g. straight holes extending into the structure at different angles).
In still other embodiments, the two elements to be attached may not include a multi-layer structure and a substrate, they may instead include one or more multi-layer structures in combination with one or more other elements or components that may or may not be multi-layer structures, and may or may not be considered substrate-like.
One embodiment for forming interlock enhanced bonded structures may be summarized as follows: (1) obtain a file descriptive of the structure to be formed; (2) modify the data so as to include one or more branches or channels in the last one or more layers and pockets or reentrant structures in one or more layers that immediately proceed the layers that include the channels; (3) form the structure on a first substrate; (4) etch out the branches and pockets of the reentrant openings; (5) apply a flowable material to the surface of the structure that has the branches or channels where the applied flowable material may be an adhesive if a separate substrate will be bonded by it or it may be a solidifiable material that will be cast or otherwise made to take the shape of a desired substrate; (6) bond the substrate and structure using the adhesive or solidify the substrate material so as to form a substrate that is bonded to the structure; and (7) remove any other sacrificial material the remains and release the first substrate from the structure if desired and if not previously removed.
Many further alternative embodiments are possible and additional examples include: (1) the use of a single sacrificial material to fill the openings as well as the regions external to the structure or to use more then two sacrificial materials; (2) formation of the openings in the structural material in such a way that a sacrificial material is not needed to temporarily fill the openings; and/or (3) use of multiple structural materials. The channels or branches leading to the pockets or reentrant features may have any desired length, they may vary in cross-sectional dimension or they may have variable lengths. The pockets or reentrant features need not have a size difference from that of the channels as they may simply be offset from the position of the channels and in this regard they may actually have smaller cross-sectional area; (5) there need not be a one to one correspondence between pockets and channels; (6) the pockets themselves may have different heights, be located at different depths within the structure and or have different cross-sectional dimensions.
In other alternative embodiments, instead of using undercuts or reentrant features that penetrate into the interior of a structural element, it may be possible to form undercuts on the side walls of regions of structural material which undercuts may be filled with a bonding or substrate material and may act as interlocking elements when considered in association with oppositely oriented undercuts on other portions of the structural material.
In some embodiments, multi-layer structures may be formed starting with a “top” layer (i.e. intended last layer) which is formed adjacent to a temporary substrate, or possibly separated from the temporary substrate by one or more layers of sacrificial material and then adding on subsequent layers until the first layer is reached. In these cases substrate swapping may occur directly by attaching the structural (e.g. permanent substrate) to the last formed layer (e.g. intended first layer) and then, if not already done, the temporary substrate can be removed. In some other embodiments, the multi layer structure can be formed starting with the intended first layer which may be formed directly on a temporary substrate or may be spaced from the temporary substrate by a sacrificial material which may or may not be the same as the sacrificial material that forms part of the layers including structural material. The building may proceed from the first layer to the last layer and if desired one or more layers of sacrificial material may be formed above the last layer. The sacrificial material above the last layer may or may not be the same as the sacrificial material used in forming the layers that contain both structural and sacrificial materials. If necessary, a second temporary substrate may be attached to the last layer or the layers above it. The first temporary substrate (i.e. the initial substrate) may then be removed. If any layers of sacrificial material exist below the first layer they may be removed and thereafter a permanent (or structural substrate) may be attached to the first layer, after which the second temporary substrate may be removed along with any sacrificial material that has not yet been removed.
In some embodiments, the structural substrates may be rigid while in others they may be flexible. In still other embodiments, the permanent substrates may be integrated circuits or other electrical components to which attachment may be made by one or more of dielectric adhesives, wire bonds, re-flowed solder contacts, and/or other conductive or dielectric elements.
Many other alternative embodiments will be apparent to those of skill in the art upon reviewing the teachings herein. Further embodiments may be formed from a combination of the various teachings explicitly set forth in the body of this application. Even further embodiments may be formed by combining the teachings set forth explicitly herein with teachings set forth in the following patents and patent applications each of which is hereby incorporated herein by reference:
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|Dec. 31, 2003 |
|10/724,515 ||Cohen, et al., Method for Electrochemically Forming Structures |
|Nov. 26, 2003 ||Including Non-Parallel Mating of Contact Masks and Substrates |
Various other embodiments of the present invention exist. Some of these embodiments may be based on a combination of the teachings herein with various teachings incorporated herein by reference. Some embodiments may not use any blanket deposition process and/or they may not use a planarization process. Some embodiments may involve the selective deposition of a plurality of different materials on a single layer or on different layers. Some embodiments may use blanket depositions processes that are not electrodeposition processes. Some embodiments may use nickel as a structural material while other embodiments may use different materials such as gold, silver, or any other electrodepositable materials that can be separated from the copper and/or some other sacrificial material. Some embodiments may use copper as the structural material with or without a sacrificial material. Some embodiments may remove a sacrificial material while other embodiments may not. In some embodiments, the depth of deposition may be enhanced by pulling the conformable contact mask away from the substrate as deposition is occurring in a manner that allows the seal between the conformable portion of the CC mask and the substrate to shift from the face of the conformal material to the inside edges of the conformable material.
In view of the teachings herein, many further embodiments, alternatives in design and uses of the instant invention will be apparent to those of skill in the art. As such, it is not intended that the invention be limited to the particular illustrative embodiments, alternatives, and uses described above but instead that it be solely limited by the claims presented hereafter.