CN102063025B - Measurement method of two-faced registration error and lithographic equipment applying measurement method - Google Patents

Abstract

The invention relates to lithographic equipment for measuring two-faced registration, comprising a lamp optical system for providing radiation, a first support structure for supporting a pattern forming device, an optical projection system for imaging the pattern to a substrate, a second support structure for fixing the substrate, a front aiming system for determining the position of a marker on the front face of the substrate and a back aiming system for determining the marking positions of the back face of the substrate. The projecting beams emitted by the lamp optical system enter to the pattern forming device fixed on the first support structure; after penetrating through the pattern forming device, the projecting beams carrying pattern information are focused on the marking positions on the substrate through a projecting system; and the marking positions of the front face of the substrate can be accurately located through a front aiming system, and the marking positions of the back face of the substrate can be accurately located through a back aiming system. The two-faced registration error through measuring the making position error among different exposed markers on the same surface is determined.

Description

Two-sided registration error measuring method and use the lithographic equipment of this method

Technical field

The present invention relates to a kind of measuring method and use the lithographic equipment of this method, relate in particular to the measuring method of two-sided registration error in a kind of double-sided alignment lithographic equipment, and use the lithographic equipment that this method is measured two-sided registration error.

Background technology

In the semiconductor processing and manufacturing, silicon chip dual surface lithography technology has been applied to microelectromechanical systems MEMS, radio-frequency devices manufacturing and advanced encapsulation technology field.The typical products of MEMS (micro electro mechanical system) processing comprises that specifically inertial acceleration meter, pressure transducer, optically-variable attenuator, inkjet printing are first-class.Can reduce to deposit the signal attenuation that causes because of thick metal by dual surface lithography in the radio-frequency devices manufacture process.Advanced encapsulation technology is made the connecting line that vertical high density is striden chip by running through the silicon chip via process, realizes the three-dimensional integrated of multiple-level stack two dimensional surface device.The double treatment technology directly determines the said goods crudy.For example in the pressure transducer manufacture process, device performance and quality depend on front and the two bearing accuracy of back process layer; Advanced packaging inner connection tube road needs to arrange arbitrarily that also the alignment that the silicon chip front is aimed at the back side proposes requirements for high precision.For opaque silicon chip substrate, alignment system or alignment machine all can not be measured silicon chip front and back mark position simultaneously, the two-sided cover locating tab assembly research direction that the double-sided alignment The Application of Technology is derived and made new advances in the lithographic equipment.Two-sided alignment precision is defined as substrate face and back process interlayer positioning error.Two-sided alignment survey instrument need possess bigger measurement range, cover the big as far as possible zone of silicon chip surface, and measuring object is contained substrate or the film of multiple material and different-thickness.

Disclose among the US Patent No. 7528931B1 by top and bottom microscope, measured silicon chip front and rear indicia position respectively, thereby calculated the two-sided alignment precision measuring method of two-sided registration error.Two-sided microscopic system major defect is positive comparatively complicated, consuming time longer with back side microscopes optical axis trimming process; As the equipment that separates with lithographic equipment, off-line is surveyed school side's case can produce higher acquisition cost and extra equipment maintenance cost.

SPIE, Vol.5455, P398-406, a kind of two-sided alignment precision electrical performance test method is disclosed in " Characterization of Waferstepper and Processrelated Front-to Backwafer overlay Errors in Bulk Micro Machining using ElectricalOverlay Test Structures ", namely utilize the near infrared alignment light source to run through silicon chip and survey rear indicia, and in silicon chip, make a series of nonstandard devices, its electric property is positive linear with back side physical location with respect to silicon chip.Silicon chip front ground floor figure comprises one group of resistance and sensing point, the zone of the silicon chip back side second layer for being constituted by conducting medium, and conducting medium can be eliminated in subsequent etch technology.Therefore, the resistance value size depends on the positional precision of the second layer.By measuring electric property, can obtain corresponding two-sided alignment precision.The processing technology that this scheme relates to is comparatively complicated, and ground floor and the manufacturing of second layer electricity device need depend on special process equipment.

SPIE, Vol.5641, P152-162 discloses the scheme of utilizing glass substrate to realize two-sided cover locating tab assembly in " 3D Align overlay verification using glass wafers ".At the two-layer mark of glass substrate face exposure, run through substrate from the back side after the substrate upset mark is aimed at.The deviation that alignment precision that aligning measures is removed the back side deviation of the alignment introduced because of glass refraction and introduced because of substrate thickness namely gets two-sided alignment precision.This scheme needs to use transparent glass substrate especially, and result of calculation depends on substrate thickness, and also can introduce certain error in the aligned position deviation process introduced of definite glass refraction.

SPIE, Vol.6520,65202R1-10, disclose by means of the front reference marker in " Development and Characterization of a 300mmDual-Side Alignment Stepper ", in silicon chip, carry out the bilayer of two-layer aligning and two-layer exposure respectively and aim at testing scheme: when silicon chip last slice angle is 0 °, reference marker is aimed at, and at silicon chip back-exposure ground floor mark; When silicon chip last slice angle is 180 °, reference marker is aimed at, and at silicon chip back-exposure second layer mark.By the designing mask figure, make two-layer exposure pattern form cover locating tab assembly structure.Because through twice aligning and double exposure, alignment error can amplify twice in the alignment result, by measuring two-layer mark alignment precision, can calculate two-sided registration error.This scheme is aimed at the two-sided alignment precision of aiming at respect to the back side with the front and is converted to silicon chip with layer mark alignment precision, requires the silicon chip prealignment device to have rotation last slice function.

Summary of the invention

The object of the present invention is to provide a kind of measuring method of two-sided registration error of high measurement accuracy and the lithographic equipment of using this method.

A kind of two-sided registration error measuring method, step is as follows:

Substrate with front and back side is provided;

Make described substrate face form the pattern with first front alignment mark;

Utilize the front alignment system to determine the position of the first front alignment mark, set up the first substrate face coordinate system WFCS;

Flip substrate utilizes back side alignment system to determine the position of the described first front alignment mark, sets up substrate back coordinate system WBCS;

Based on WBCS, form the pattern with back side alignment mark at described substrate back;

Flip substrate utilizes back side alignment system to determine alignment mark position, the back side again, sets up the second substrate face coordinate system WFCS ';

Based on WFCS ', form the pattern with second front alignment mark in substrate face;

Measure the position deviation of two front alignment marks of substrate;

Calculate the two-sided registration error of double-sided alignment lithographic equipment.

Wherein, described substrate face and the back side are interchangeable.

Wherein, repeatedly using said method obtains a series of register mark groups in the substrate face exposure.

A kind ofly use the lithographic equipment that said method is implemented two-sided cover locating tab assembly, comprising:

-for the lamp optical system that radiation is provided;

-for supporting first supporting construction that pattern forms device;

-be used for the optical projection system of pattern imaging to substrate;

-be used for second supporting construction of stationary substrate;

-for the front alignment system of determining the substrate face mark position;

-for the back side alignment system of determining the substrate back mark position;

The projected light beam that is sent by lamp optical system is incident to the pattern that is fixed on first supporting construction and forms device, after seeing through pattern formation device, the projected light beam that carries pattern-information passes through optical projection system, focus on the mark position on the substrate, the front alignment system is the mark position in position substrate front accurately, and back side alignment system is the mark position at the position substrate back side accurately.

The present invention proposes a kind of measuring method of two-sided registration error, by the built-in double-sided alignment system of lithographic equipment based on this method of application, do not rely on special process and specialized substrates material, according to certain exposure order, expose in substrate face and the back side respectively, by measuring same face exposure mark position error, can determine the positive alignment precision of aiming at respect to the back side of aiming at of lithographic equipment.This invention implementation cost is comparatively cheap, and is consuming time shorter, only depends on general photoetching gluing developing process, and only relies on lithographic equipment self configuration and finish measurement, do not propose special hsrdware requirements; Measurement scheme self is not introduced fabrication error, can reach than high measurement accuracy.

Description of drawings

By the embodiment of the invention and in conjunction with the description of its accompanying drawing, can further understand purpose, specific structural features and the advantage of its invention.Wherein, accompanying drawing is:

Figure 1 shows that the lithographic equipment according to the embodiment of the invention;

Figure 2 shows that the synoptic diagram of double-sided alignment precision definition;

Fig. 3 is to the measuring method that Figure 7 shows that according to the embodiment of the invention.

Embodiment

Below, describe in detail according to a preferred embodiment of the invention by reference to the accompanying drawings.For convenience of description and highlight the present invention, omitted existing associated components in the prior art in the accompanying drawing, and will omit the description to these well-known components.

Figure 1 shows that the lithographic equipment according to the embodiment of the invention, comprising:

-for the luminaire 1 that radiation is provided;

-for the mask platform 3 that supports mask 2;

-be used for the projection objective 4 of pattern imaging to substrate 5;

-be used for the wafer station 6 of stationary substrate 5;

-for the front alignment system 7 of determining substrate 5 front marks 8 positions;

-for the back side alignment system 9 of determining substrate 5 rear indicia 10 positions.

Projected light beam is incident to the mask 2 that is fixed on the mask platform 3, through behind the mask 2, carries the projected light beam of mask images information by projection objective 4, focuses on substrate 5 target locations 8.Mask platform 3 and wafer station 6 all can be accurate mobile, and its position can utilize measurement mechanism such as interference measuring instrument accurately to measure.Utilize the accurately position of the mark 8 in position substrate 5 fronts of front alignment system, utilize the accurately position of position substrate 5 rear indicia 10 of back side alignment system.

Figure 2 shows that front alignment system and back side alignment system alignment precision synoptic diagram.Substrate 5 positive FS exposure ground floor marks 8, its virtual image in substrate 5 back side correspondences is 11.In substrate back BS target location (for example, the position of Reference numeral 12 expressions) exposure second layer mark, it does not overlap with mark physical location (second layer mark 10 actual residing positions), and then target location and the physical location deviation between the two is defined as two-sided registration error.

Fig. 3 is to the measuring method that Figure 7 shows that according to the embodiment of the invention.At first, by known methods at substrate 5 positive FS exposure ground floor marks 13.Mark 13 can adopt any form easily, grating pair as known in the art, cross mark etc., and gluing, developing process are known technologies in the industry in the exposure process.Known for the skilled person of relevant field of lithography, for obtaining expectation exposure result, at the certain electric magnetic energy that luminaire 1 produces, need to select the kind of photoresist, and the processing procedure after the strict control exposure.Mark 13 positions can be determined by front alignment system 7, substrate face coordinate system WFCS can be set up.Flip substrate, make have the mark 13 that exposes positive FS down, as shown in Figure 4, former positive FS is the back side with respect to present substrate location, can be by the position of back side alignment system snoop tag 13, thereby set up substrate back coordinate system WBCS.In the substrate switching process, substrate face and back side coordinate system close and are

$\left(\begin{array}{c}{x}^{\mathrm{WBCS}}\\ y^{\mathrm{WBCS}}\end{array}\right)=\left(\begin{array}{c}\mathrm{Mx}\\ \mathrm{My}\end{array}\right)\left(\begin{array}{cc}\cos \mathrm{\θ}& \sin \mathrm{\θ}\\ -\sin \mathrm{\θ}& \cos \mathrm{\θ}\end{array}\right)\left[\begin{array}{c}\left(\begin{array}{c}{x}^{\mathrm{WFCS}}\\ y^{\mathrm{WFCS}}\end{array}\right)-\left(\begin{array}{c}{\mathrm{WBo}}_x^{\mathrm{WFCS}}\\ {\mathrm{WBo}}_y^{\mathrm{WFCS}}\end{array}\right)\end{array}\right]$

Wherein, Mx, My be WBCS with respect to the WFCS scaling, θ is WBCS with respect to the anglec of rotation of WFCS (being two coordinate origins when overlapping, coordinate system transverse axis angle), WBo _x ^WFCS, WBo _y ^WFCSBe respectively WBCS with respect to the WFCS origin offset.

Based on WBCS, can determine target location exposure mark 14 at substrate BS face.Flip substrate is recovered substrate FS and is faced up again, as shown in Figure 6, can be determined the position of FS face mark 13 by the front alignment system, determines BS face mark 14 positions by back side alignment system, can set up substrate face coordinate system WFCS ' again and be

$\left(\begin{array}{c}{x}^{{\mathrm{WFCS}}^{,}}\\ y^{\mathrm{WFC}{S}^{,}}\end{array}\right)=\left(\begin{array}{c}{\mathrm{Mx}}^{,}\\ {\mathrm{My}}^{,}\end{array}\right)\left(\begin{array}{cc}\cos {\mathrm{\θ}}^{,}& \sin {\mathrm{\θ}}^{,}\\ -\sin {\mathrm{\θ}}^{,}& \cos {\mathrm{\θ}}^{,}\end{array}\right)\left[\begin{array}{c}\left(\begin{array}{c}{x}^{\mathrm{WBCS}}\\ y^{\mathrm{WBCS}}\end{array}\right)-\left(\begin{array}{c}{\mathrm{WFo}}_x^{\mathrm{WBCS}}\\ {\mathrm{WFo}}_y^{\mathrm{WBCS}}\end{array}\right)\end{array}\right]$

Wherein, Mx ', My ' be WFCS ' with respect to the WBCS scaling, θ ' is that WFCS ' is with respect to the WBCS anglec of rotation, WFo _x ^WBCS, WFo _y ^WBCSBe respectively WFCS ' with respect to the WBCS origin offset.

Calculate substrate face mark desired locations and exposure based on WFCS ', form mark 15 in the exposure of FS face, as shown in Figure 7.Mark 13 and 15 forms the registered graphic group, can be piece mark in known frame center or the piece.Utilize front alignment system or special-purpose alignment measuring equipment, can obtain the two relative position deviation.

Through twice back side alignment procedures, establish two-sided registration error and be (mean+3 σ) in the above-mentioned embodiment _DSO, mark 13 and 15 position deviation averages are mean _m, standard deviation is σ _m, then the two satisfies following relation:

${(\mathrm{mean}+3\mathrm{\σ})}_{\mathrm{DSO}}={\mathrm{mean}}_m/2+{3\mathrm{\σ}}_m/\sqrt{2}.$

Although the present invention is especially in conjunction with utilizing Apparatus and method for of the present invention in the integrated circuit manufacturing, for the personnel institute of relevant field of lithography understands ground easily, this Apparatus and method for can be widely used in the optical system that other can be integrated.

Described in this instructions is several preferred embodiment of the present invention, and above embodiment is only in order to illustrate technical scheme of the present invention but not limitation of the present invention.All those skilled in the art all should be within the scope of the present invention under this invention's idea by the available technical scheme of logical analysis, reasoning, or a limited experiment.

Claims (4)

1. two-sided registration error measuring method, step is as follows:

Substrate with front and back side is provided;

Make described substrate face form the pattern with first front alignment mark;

Utilize the front alignment system to determine the position of the first front alignment mark, set up the first substrate face coordinate system WFCS;

Flip substrate utilizes back side alignment system to determine the position of the described first front alignment mark, sets up substrate back coordinate system WBCS;

Based on WBCS, form the pattern with back side alignment mark at described substrate back;

Flip substrate utilizes back side alignment system to determine alignment mark position, the back side again, sets up the second substrate face coordinate system WFCS ', and the described second substrate face coordinate system WFCS ' with the pass of described substrate back coordinate system WBCS is:

$\left(\begin{array}{c}{x}^{{\mathrm{WFCS}}^{\′}}\\ y^{{\mathrm{WFCS}}^{\′}}\end{array}\right)=\left(\begin{array}{c}{\mathrm{Mx}}^{\′}\\ {\mathrm{My}}^{\′}\end{array}\right)\left(\begin{array}{cc}\cos {\mathrm{\θ}}^{\′}& \sin {\mathrm{\θ}}^{\′}\\ -\sin {\mathrm{\θ}}^{\′}& \cos {\mathrm{\θ}}^{\′}\end{array}\right)[\left(\begin{array}{c}{x}^{\mathrm{WBCS}}\\ y^{\mathrm{WBCS}}\end{array}\right)-\left(\begin{array}{c}{\mathrm{WFo}}_x^{\mathrm{WBCS}}\\ {\mathrm{WFo}}_y^{\mathrm{WBCS}}\end{array}\right)]$

Wherein, Mx ', My ' be WFCS ' with respect to the WBCS scaling, θ ' be WFCS ' with respect to the WBCS anglec of rotation,

Be respectively WFCS ' with respect to the WBCS origin offset;

Based on WFCS ', form the pattern with second front alignment mark in substrate face;

Measure the position deviation of two front alignment marks of substrate;

Calculate the two-sided registration error of double-sided alignment lithographic equipment.

2. method according to claim 1 is characterized in that, described substrate face and the back side are interchangeable.

3. method according to claim 1 and 2 is characterized in that, repeatedly using said method obtains a series of register mark groups in the substrate face exposure.

4. an application rights requires each described method among the 1-3 to implement the lithographic equipment of two-sided cover locating tab assembly, comprising:

-for the lamp optical system that radiation is provided;

-for supporting first supporting construction that pattern forms device;

-be used for the optical projection system of pattern imaging to substrate;

-be used for second supporting construction of stationary substrate;

-for the front alignment system of determining the substrate face mark position;

-for the back side alignment system of determining the substrate back mark position;

The projected light beam that is sent by lamp optical system is incident to the pattern that is fixed on first supporting construction and forms device, after seeing through pattern formation device, the projected light beam that carries pattern-information passes through optical projection system, focus on the mark position on the substrate, the front alignment system is the mark position in position substrate front accurately, and back side alignment system is the mark position at the position substrate back side accurately.

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