CN113515018A

CN113515018A - Alignment mark design method of 60-micrometer scribing groove

Info

Publication number: CN113515018A
Application number: CN202110396935.6A
Authority: CN
Inventors: 安静; 宁磊; 胡晓洲; 杨森虎; 高敏; 邓佩蓉; 张晶
Original assignee: Xi'an Weiguang Technology Co ltd
Current assignee: Xi'an Weiguang Technology Co ltd
Priority date: 2021-04-13
Filing date: 2021-04-13
Publication date: 2021-10-19
Anticipated expiration: 2041-04-13
Also published as: CN113515018B

Abstract

The invention discloses a design method of alignment marks of 60um scribing grooves, which comprises the steps of forming a mark pattern on a 60um scribing groove of a photoetching plate, transferring the mark pattern on the photoetching plate to a wafer covered with photoresist by adopting a photoetching process, and using the alignment marks on the wafer for alignment of the next layer, wherein the alignment marks comprise Search alignment marks, EGA LSA alignment marks and EGA FIA alignment marks. The invention solves the problem of area waste caused by excessive scribing groove occupied area in the current wafer process flow, reduces the scribing groove width occupied by the universal alignment mark, effectively improves the chip occupation ratio, reduces the chip cost and realizes the maximization of the wafer area utilization.

Description

Alignment mark design method of 60-micrometer scribing groove

Technical Field

The invention belongs to the technical field of semiconductor chip manufacturing, and particularly relates to a design method of an alignment mark of a 60-micrometer scribing groove.

Background

At present, scribing grooves commonly used in the 6-inch wire core chip manufacturing industry are generally in a uniform specification, and the width of the scribing grooves is mostly 100 micrometers or 80 micrometers. Many measurement marks need to be stored in the scribing groove, including a process control monitoring mark, a photoetching critical dimension measurement mark, a photoetching alignment mark and an overlay mark, a film thickness measurement mark and the like. Wherein the place most occupying the width of the scribing groove is the corresponding alignment mark. The Alignment marks include Search Alignment marks and EGA (Enhanced Global Alignment) Alignment marks, wherein the EGA Alignment marks include lsa (laser step Alignment) and fia (field Image Alignment) Alignment marks, and the Alignment marks are distributed in the scribe line as shown in fig. 1.

The general Search alignment mark is shown as 110 and 120 in fig. 1, and the specific size is shown in fig. 2, taking 110 as an example, that is, the Y-T Search alignment mark, and each stripe includes 3 parallel arranged stripes, where each stripe includes a number of dots, the number of dots in fig. 2 is only schematic, the dots refer to small square blocks of 4 μm × 4 μm, and the distances between the dots are unified to 4 μm. In the figure, 210 is 20 μm, and 220 is 26 μm; the LSA alignment marks of the EGA alignment marks are shown as 130 and 140 in fig. 1, and the specific dimension is shown in fig. 3, taking 130 as an example, that is, the Y EGA LSA alignment mark, is 7 parallel strips, each strip is composed of 9 dots, the pitch between the dots is unified to 4 μm, and 310 in the figure is 20 μm; the FIA alignment marks of the EGA alignment marks are shown as 150 and 160 in fig. 1, and the specific dimension is shown as fig. 4 by taking 150, i.e., Y EGA FIA alignment marks as an example, and is 9 parallel strips, wherein 410 is 50 μm, 420 is 6 μm, and 430 is 12 μm. Based on the data, the width of the scribing groove suitable for the universal alignment mark is at least 80 μm, the occupied area of the wafer is large, and the area waste is caused. However, in consideration of the recognition capability of the lithography machine and the accurate effectiveness of alignment, the alignment mark can only design the internal spacing and length of the mark within a certain range.

Disclosure of Invention

The technical problem to be solved by the present invention is to provide a method for designing alignment marks of 60 μm scribe lines, which solves the problem of area waste caused by excessive occupied area of scribe lines in the current wafer process, improves the effective chip area ratio, and reduces the chip cost, in view of the above-mentioned deficiencies in the prior art.

The invention adopts the following technical scheme:

a design method for alignment marks of 60 mu m scribing grooves comprises the steps of forming a mark pattern on the 60 mu m scribing grooves of a photoetching plate, transferring the mark pattern on the photoetching plate to a wafer covered with photoresist through a photoetching process, and using the alignment marks on the wafer for alignment of the next layer, wherein the alignment marks comprise Search alignment marks, LSA alignment marks of EGA and FIA alignment marks of EGA.

Specifically, the Search alignment marks include 110 and 120, where 110 is a Y Search alignment mark and 120 is an X Search alignment mark.

Further, Search alignment marks are 3 strips arranged in parallel, each strip comprises a plurality of dots, and the dots are square blocks with the size of 4 μm by 4 μm.

Furthermore, the distance between the Dot is 4 μm, the distance between the 3 stripes is 14 μm and 20 μm, and the distance is the distance between the center points of the two patterns.

Specifically, the LSA alignment marks of EGA include 130 and 140, 130 being Y EGA LSA alignment mark, 140 being X EGA LSA alignment mark.

Further, the LSA alignment of the EGA alignment mark is marked by 7 bars arranged in parallel, each bar includes 5 dots, and Dot is a square block of 4 μm by 4 μm.

Furthermore, the distance between 5 dots is 4 μm, and the distance between 7 stripes is 20 μm.

Specifically, the FIA alignment marks of EGA include 150 and 160, 150 is Y-T EGA LSA alignment mark, and 160 is X EGA LSA alignment mark.

Further, the FIA alignment of EGA is marked as 9 bars, each bar has a length of 50um and a width of 6 μm, and the spacing between bars is 12 μm.

Specifically, the photolithography mask is a quartz photolithography mask.

Compared with the prior art, the invention has at least the following beneficial effects:

the alignment mark design method of the 60 mu m scribing groove is designed and completed on the premise of not influencing the alignment accuracy and the recognition capability of a photoetching machine, the internal space of the Search alignment mark is redesigned compared with the general Search alignment mark, and the total length of the EGA alignment mark is shortened, so that the method is applied to the 60 mu m scribing groove.

Furthermore, the alignment precision of the photoetching machine in the alignment Y direction, the alignment T direction and the alignment X direction is ensured, wherein 110 is placed in a transverse scribing groove, 120 is placed in a longitudinal scribing groove, when the photoetching machine is used for alignment scanning, three points can be used for positioning the plane of the wafer by respectively scanning in Y, T and the X direction, meanwhile, 3 alignment marks can avoid the problem of peripheral signal interference caused by fewer alignment marks such as single or double marks, and the like, and the width of the narrow scribing groove of 60um is considered at the same time.

Furthermore, the total number of the alignment marks of 3 alignment marks still remains in the alignment marks set according to the method, so that the characteristics of high validity and high recognition degree of alignment signals are ensured; the size of the alignment mark Dot is 4 μm, which mainly considers that the subsequent processes of the current level operation will not disappear due to too small mark, and will not excessively occupy the area of the scribe line due to too large mark.

Furthermore, the distance between two adjacent strips is respectively 14 micrometers and 20 micrometers, the distance is the distance between the central points of the two patterns, the initial Search mark interval difference is kept to a certain degree, the phenomenon that signals collected by a photoetching machine are poor and difficult to identify due to excessively reduced distance is avoided, meanwhile, the overall occupied width is relatively reduced, and the scribing groove can be reduced to 60 micrometers.

Furthermore, on the basis of Search alignment, enhanced global alignment is introduced, LSA alignment marks are mainly used for medium layers with smooth film quality and flat crystal grains, when the LSA of the EGA is used for alignment, the alignment marks can be scanned respectively in a narrow scribing groove of 60um through laser stepping scanning, Y, T, X scanning, and complete and identifiable waveforms are collected through detection of diffracted light or scattered light, so that the EGA alignment is completed.

Further, in the LSA alignment mark of EGA, the LSA alignment mark of EGA is 7 parallel strips, each strip is composed of 5 dots, and the dots are square blocks of 4 μm by 4 μm.

Furthermore, Dot number in the LSA alignment mark of the EGA is 5, so that the LSA alignment mark of the EGA can be placed in a 60-micrometer scribing groove, and the identifiability of the alignment mark is unchanged after the number is reduced, thereby ensuring the alignment precision.

Furthermore, on the basis of Search alignment, enhanced global alignment is introduced, the FIA alignment mark is mainly used for a dielectric layer with coarse film quality and large crystal grains, when the FIA alignment of the EGA is carried out, the design can adopt image acquisition alignment mark signals in a narrow scribing groove of 60um, and Y, T, X respectively carries out figure reading, so that complete and recognizable waveforms are collected, and the EGA alignment is completed.

Further, the FIA alignment of EGA is marked as 9 bars, each bar being 50 μm long, 6 μm wide and 12 μm apart. The FIA alignment mark of the EGA can be placed in a 60-micrometer scribing groove, and the identifiability of the alignment mark is unchanged after the length of the long mark strip is shortened, so that the alignment precision is ensured.

Furthermore, the photoetching plate is made of quartz, the quartz transmittance is considered to be better, the operation product has clear requirements on line width and alignment precision, and other alignment problems caused by the over-poor material of the photoetching plate are reduced.

In conclusion, the invention solves the problem of area waste caused by excessive scribing groove occupied area in the current wafer process flow, reduces the scribing groove width occupied by the universal alignment mark, effectively improves the chip occupation ratio, reduces the chip cost and realizes the maximization of the wafer area utilization.

The technical solution of the present invention is further described in detail by the accompanying drawings and embodiments.

Drawings

FIG. 1 is a diagram of the alignment mark distribution of 60 μm scribe lines according to the present invention;

FIG. 2 is a diagram illustrating the dimensions of a prior art universal Y-T Search alignment mark;

FIG. 3 is a schematic diagram showing the dimension of a Y LSA alignment mark of a general EGA alignment mark of the prior art;

FIG. 4 is a schematic diagram showing the dimension of a Y FIA alignment mark of a general EGA alignment mark of the prior art;

FIG. 5 is a schematic diagram illustrating dimensions of a Y-T Search alignment mark according to an embodiment of the present invention;

FIG. 6 is a schematic diagram showing dimensions of Y LSA alignment marks of EGA alignment marks according to one embodiment of the present invention;

FIG. 7 is a schematic diagram showing the dimension of the Y FIA alignment mark of the EGA alignment mark according to the present invention;

FIG. 8 is a comparative plot of the alignment accuracy of the 80 μm scribe line and the corresponding universal mark and the 60 μm scribe line;

FIG. 9 is a comparison graph of the mean alignment accuracy of 80 μm scribe lines and corresponding universal marks and 60 μm scribe lines.

Detailed Description

The invention provides a design method of an alignment mark of a 60 mu m scribing groove, wherein the alignment mark is designed based on a photoetching plate scribing groove graph, a mark graph is firstly formed on a photoetching plate and then is transferred on a wafer through a photoetching process, and the alignment mark on the wafer can be used for alignment of the next layer.

The method comprises the following steps:

s1, forming an alignment mark in a scribing groove of the photoetching plate;

referring to FIG. 1, 110 and 120 are Search alignment marks, 110 is a Y-T Search alignment mark, and 120 is an X Search alignment mark; 130 and 140 are the LSA alignment marks of the EGA alignment marks, 130 is the Y EGA LSA alignment mark, 140 is the X EGA LSA alignment mark; 150 and 160 are the FIA alignment marks of the EGA alignment marks, 150 is the Y EGA FIA alignment mark, and 160 is the X EGA FIA alignment mark.

The dimensions of the alignment marks are further described by taking the Y-T alignment marks as an example.

The X alignment mark is formed by rotating the Y-T alignment mark 90 degrees counterclockwise when designing the pattern.

Referring to fig. 5, Search alignment marks are 3 parallel stripes, each stripe is composed of a plurality of dots, the number of dots in fig. 5 is only a schematic diagram, and the number of dots in this embodiment is 22. Here Dot refers to 4 μm by 4 μm small square blocks, and the pitch between dots is 4 μm, which is the distance between the center points of two patterns. In the figure, 510 is 14 μm and 520 is 20 μm.

Referring to FIG. 6, EGA LSA alignment marks 7 parallel stripes, each stripe consisting of 5 dots. Here Dot refers to 4 μm by 4 μm small square blocks, and the pitch between dots is 4 μm, which is the distance between the center points of two patterns. In the figure 610 is 20 μm.

Referring to FIG. 7, EGA FIA alignment is marked with 9 parallel stripes. In the figure, 710 is 50 μm, 720 is 6 μm, and 730 is 12 μm.

The Y-T alignment mark is rotated 90 degrees anticlockwise to be an X alignment mark, and the Y-T alignment mark and the X alignment mark need to be designed simultaneously in actual use, wherein the Y-T search alignment mark is placed in the transverse scribing groove, and the X search alignment mark is placed in the longitudinal scribing groove; y EGA LSA and FIA alignment marks are placed in the longitudinal scribing grooves, and X EGA LSA and FIA alignment marks are placed in the transverse scribing grooves.

And S2, exposing the wafer covered with the photoresist by using the photoetching plate in the step S1, finally developing and etching, and transferring the mark to the wafer for next-level alignment.

The alignment mark meets the following requirements:

firstly, the method comprises the following steps: the photoetching plate is made of quartz;

secondly, the method comprises the following steps: the wafer is a 6-inch silicon wafer and is applied to alignment of a Nikon photoetching machine.

Thirdly, the method comprises the following steps: the photoetching process is to glue, expose, develop and etch the wafer in sequence;

during exposure, the design of alignment mark parameters is different from that of the prior art, and the corresponding parameters of the Search alignment mark are 14-20 μm.

In product design, the alignment mark is formed by etching to leave a step. Taking the field oxide layer as an example, the alignment mark can be designed to have a 60 μm scribe line width, 110 and 120 are shown in fig. 5, 510 is designed to be 14 μm, 520 is designed to be 20 μm, 110 is placed in the transverse scribe line, the narrow side is upward, 120 is placed in the longitudinal scribe line, and the narrow side is leftward, the total mark length should not be less than 180 μm, and 180 μm is taken this time. 130 and 140 are detailed in fig. 6, and are 7 strips arranged in parallel, each strip is composed of 5 dots, the distance between the dots is unified to 4 μm, 130 is placed in a longitudinal scribing groove, 140 is placed in a transverse scribing groove, and 610 in the figure is 20 μm; 150 and 160 are shown in detail in fig. 7, and are designed as 9 parallel strips, 710 50 μm, 720 6 μm, 730 12 μm, 150 placed in the longitudinal scribe lanes and 160 placed in the lateral scribe lanes. And (3) making both Dot and a strip-shaped pattern area in a hollowed state during the manufacture of a photoetching plate, etching to carry out wet etching after the photoetching operation of the field oxide layer is completed, and leaving a pit-shaped mark at the position of the alignment mark, wherein the mark can be used for aligning the next layer. After being applied to the product, the alignment mark can be clearly and accurately obtained in the 60um scribing groove, the signal peak is clear, and the alignment mark can be directly used for production.

Taking the polysilicon layer as an example, the design of the alignment mark can be as follows: the alignment mark can be designed with a 60um scribe line width, 110 and 120 are detailed in fig. 5, in which 510 is designed to be 14 μm, 520 is designed to be 20 μm, 110 is placed in the transverse scribe line, and the narrow side is upward, 120 is placed in the longitudinal scribe line, and the narrow side is leftward, the total mark length should not be less than 180 μm, and this time 180 μm is taken. 130 and 140 are detailed in fig. 6, and are 7 strips arranged in parallel, each strip is composed of 5 dots, the distance between the dots is unified to 4 μm, 130 is placed in a longitudinal scribing groove, 140 is placed in a transverse scribing groove, and 610 in the figure is 20 μm; 150 and 160 are shown in detail in fig. 7, and are designed as 9 parallel strips, 710 50 μm, 720 6 μm, 730 12 μm, 150 placed in the longitudinal scribe lanes and 160 placed in the lateral scribe lanes. And both the Dot and the strip-shaped pattern area are made into a metal filling state during the manufacture of the photoetching plate, after the photoetching operation of the polycrystalline silicon layer is finished, the etching is carried out by dry etching, a convex mark is left at the position of the alignment mark, and the mark can be used for aligning the next layer. After the alignment mark is applied to a product, the alignment mark can be clearly and accurately obtained in a 60-micrometer scribing groove, the signal peak is clear, and the alignment mark can be directly used for production.

In order to verify the difference between the identifiability and the alignment precision of the alignment mark of the invention and the general mark during alignment, a simulated lithography experiment was performed with an 80 μm scribe line and a corresponding general alignment mark and a 60 μm scribe line and the alignment mark of the invention, respectively. Experiments show that the design has no difference between the identifiability and the universal mark, and can carry out the alignment operation normally. Further, the alignment accuracy is analyzed by comparison, and a contrast graph of the range of the alignment accuracy is shown in fig. 8, and a contrast graph of the mean value of the alignment accuracy is shown in fig. 9. As can be seen by comparison, the alignment accuracy of the alignment mark designed by the invention is not obviously different from that of the common alignment mark, and the alignment mark designed by the invention can be completely applied to a 60-micrometer scribing groove.

In summary, according to the alignment mark design method for the 60 μm scribe line of the present invention, by designing the alignment mark to include the Search alignment mark and the EGA alignment mark, when a 6-inch wafer is produced, the alignment accuracy and the alignment precision are ensured, and the scribe line width is reduced to 60 μm, thereby solving the problem of area waste caused by too much occupied area of the scribe line in the current wafer process flow, effectively improving the chip occupation ratio, and reducing the chip cost.

The above-mentioned contents are only for illustrating the technical idea of the present invention, and the protection scope of the present invention is not limited thereby, and any modification made on the basis of the technical idea of the present invention falls within the protection scope of the claims of the present invention.

Claims

1. A design method for alignment marks of 60 mu m scribing grooves is characterized in that mark patterns are formed on the 60 mu m scribing grooves of a photoetching plate, then the mark patterns on the photoetching plate are transferred to a wafer covered with photoresist through a photoetching process, the alignment marks on the wafer are used for alignment of the next layer, and the alignment marks comprise Search alignment marks, LSA alignment marks of EGA and FIA alignment marks of EGA.

2. The method of claim 1, wherein the Search alignment marks comprise 110 and 120, wherein 110 is a Y-T Search alignment mark and 120 is an X Search alignment mark.

3. The method of claim 2, wherein the Search alignment marks 3 stripes arranged in parallel, each stripe comprising a number of dots of square blocks with Dot of 4 μm by 4 μm.

4. The method of claim 3, wherein the pitch between the plurality of dots is 4 μm, the pitch between the 3 stripes is 14 μm and 20 μm, respectively, and the pitch is the distance between the center points of the two patterns.

5. The method of claim 1, wherein the EGA LSA alignment marks comprise 130 and 140, wherein 130 is a Y EGA LSA alignment mark and 140 is an X EGA LSA alignment mark.

6. The method of claim 5, wherein the LSA alignment marks of the EGA alignment marks are 7 parallel bars, each bar comprising 5 dots with Dot of 4 μm by 4 μm square.

7. The method of claim 6, wherein the pitch between 5 dots is 4 μm and the pitch of 7 stripes is 20 μm.

8. The method of claim 1 wherein the FIA alignment marks of EGA include 150 and 160, 150 being the Y EGA LSA alignment mark and 160 being the X EGA LSA alignment mark.

9. The method of claim 8, wherein the FIA alignment marks of the EGA are 9 stripes, each stripe is 50um long and 6 μm wide, and the spacing between stripes is 12 μm.

10. The method of claim 1, wherein the reticle is a quartz reticle.