A method for aligning a photolithography machine

Abstract

The present application discloses a method for aligning a photolithography machine, and relates to the field of semiconductor manufacturing technology. The method comprises: providing a wafer including an alignment mark and an auxiliary mark, wherein the alignment mark and the auxiliary mark are arranged in the cutting path of the wafer, and a plurality of auxiliary marks are evenly distributed on both sides or around the alignment mark; wherein, when the alignment mark is a coarse alignment mark including a dot-shaped graphic unit, the auxiliary mark does not include a dot-shaped graphic unit; when the alignment mark is a fine alignment mark including a horizontal straight bar graphic unit and a vertical straight bar graphic unit, the auxiliary mark does not include a dot-shaped graphic unit, a horizontal straight bar graphic unit and a vertical straight bar graphic unit; transferring the wafer to the photolithography machine, and aligning the wafer and the mask through the alignment mark. Through the above-mentioned technical means, a plurality of auxiliary marks can be evenly arranged in the blank area around the alignment mark to ensure that the alignment system can accurately identify the alignment mark while balancing the grinding rate of the cutting path and the chip in the wafer.

Description

Technical Field

[0001] The present application relates to the field of semiconductor manufacturing technology, and in particular to a photolithography machine alignment method. Background Art

[0002] The photolithography machine is one of the most critical and complex process equipment in the semiconductor chip manufacturing process. It is used to accurately project the pattern on the mask onto the wafer, and then use chemical or physical methods to etch it to form the microstructure required for the chip. The alignment system of the photolithography machine is responsible for aligning the pattern on the mask with the existing pattern on the wafer to ensure accurate overlay between the patterns after exposure. The alignment system mainly includes the mask worktable, the wafer worktable and the optical detection system. The alignment process is divided into the following four steps: first, the pre-alignment and positioning of the mask, followed by the pre-alignment and positioning of the wafer, then the mask worktable and the wafer worktable, and finally the alignment of the mask and the wafer. The alignment of the mask and the wafer is an extremely important step in the entire alignment process, and is generally aligned through specific alignment marks.

[0003] In the prior art, the mask and the wafer can be roughly aligned by using a coarse alignment mark, and then the mask and the wafer can be finely aligned by using a fine alignment mark. The coarse alignment mark and the fine alignment mark are generally periodic structures composed of dots or strips. Such marks can produce diffraction under the irradiation of the alignment laser so that they can be accurately identified by the alignment system. If there are dot-shaped or strip-shaped patterns in the wafer, it is easy to cause signal interference to the alignment mark. Therefore, a certain blank area will be reserved around the alignment mark, which leads to different grinding rates of the cutting path and the chip during chemical mechanical grinding of the wafer, resulting in severe depression of the wafer, affecting the production quality and efficiency of the chip. Summary of the invention

[0004] The present application provides a photolithography machine alignment method, in which a plurality of auxiliary marks are evenly arranged in a blank area around an alignment mark, and the auxiliary marks have obvious graphic differences from the alignment marks, so as to ensure that the alignment system can accurately identify the alignment marks while balancing the grinding rates of the cutting paths and chips in the wafer, thereby solving the problem in the prior art of severe concavity of the wafer caused by the different grinding rates of the cutting paths and chips, and improving the production quality and efficiency of the chips.

[0005] In a first aspect, the present application provides a method for aligning a lithography machine, comprising:

[0006] A wafer including an alignment mark and an auxiliary mark is provided, wherein the alignment mark and the auxiliary mark are arranged in a cutting path of the wafer, and a plurality of the auxiliary marks are evenly distributed on both sides or around the alignment mark; wherein when the alignment mark is a coarse alignment mark including a dot-shaped graphic unit, the auxiliary mark does not include a dot-shaped graphic unit; and when the alignment mark is a fine alignment mark including a transverse straight-strip graphic unit and a longitudinal straight-strip graphic unit, the auxiliary mark does not include a dot-shaped graphic unit, a transverse straight-strip graphic unit, and a longitudinal straight-strip graphic unit;

[0007] The wafer is transferred to a photolithography machine, and the wafer and the mask are aligned using the alignment mark.

[0008] Optionally, the auxiliary marks of the coarse alignment mark and the fine alignment mark are the same.

[0009] Optionally, a minimum distance between the auxiliary mark and the alignment mark is 30 um.

[0010] Optionally, when the alignment mark is the coarse alignment mark, the maximum spacing between the auxiliary mark and the coarse alignment mark is 500um; when the alignment mark is the fine alignment mark, the maximum lateral spacing between the auxiliary mark and the fine alignment mark is 230um, and the maximum longitudinal spacing between the auxiliary mark and the fine alignment mark is 170um.

[0011] Optionally, if the alignment mark is set in the horizontal cutting street of the wafer, the multiple auxiliary marks are evenly distributed on the left and right sides of the alignment mark; if the alignment mark is set in the longitudinal cutting street of the wafer, the multiple auxiliary marks are evenly distributed on the upper and lower sides of the alignment mark; if the alignment mark is set in the empty cutting street of the wafer, the multiple auxiliary marks are evenly distributed around the alignment mark.

[0012] Optionally, a line width of the auxiliary mark is greater than or equal to a line width of a structural layer of the wafer.

[0013] Optionally, the auxiliary mark is formed by a photolithography process, and the ratio of the photoresist thickness of the photolithography process to the lateral spacing or longitudinal spacing between any two adjacent auxiliary marks is less than or equal to 4, and the ratio of the photoresist thickness of the photolithography process to the lateral spacing or longitudinal spacing between two adjacent graphic units in the auxiliary mark is less than or equal to 4.

[0014] Optionally, the auxiliary mark is a non-closed graphic or the auxiliary mark does not include a closed graphic unit.

[0015] Optionally, the auxiliary logo includes a first graphic unit and a second graphic unit, the first graphic unit and the second graphic unit are both composed of horizontal straight segments and vertical straight segments, the vertical straight segments of the first graphic unit are located at the upper end and close to the horizontal straight segments of the second graphic unit, the horizontal straight segments of the first graphic unit are located at the lower end and close to the vertical straight segments of the second graphic unit, and the first graphic unit and the second graphic unit form a rectangular frame with gaps at the upper and lower ends.

[0016] Optionally, the auxiliary mark includes a third graphic unit, a fourth graphic unit, a fifth graphic unit and a sixth graphic unit, and the third graphic unit, the fourth graphic unit, the fifth graphic unit and the sixth graphic unit are inclined straight segments with different inclination angles, the third graphic unit and the fourth graphic unit are located at the upper end, and the fifth graphic unit and the sixth graphic unit are located at the lower end.

[0017] In the present application, by adding alignment marks and auxiliary marks in the cutting path of the wafer, multiple auxiliary marks are evenly distributed on both sides or around the alignment mark, when the alignment mark is a coarse alignment mark including dot-shaped graphic units, the auxiliary mark does not include dot-shaped graphic units, and when the alignment mark is a fine alignment mark including transverse straight bar graphic units and longitudinal straight bar graphic units, the auxiliary mark does not include dot-shaped graphic units, transverse straight bar graphic units and longitudinal straight bar graphic units; the wafer and the mask are aligned according to the alignment mark. Through the above technical means, multiple auxiliary marks can be evenly set in the blank area around the alignment mark, and the auxiliary marks and the alignment marks have obvious graphic differences, so as to ensure that the alignment system can accurately identify the alignment mark while balancing the grinding rate of the cutting path and the chip in the wafer, solving the problem of serious concavity of the wafer due to the different grinding rates of the cutting path and the chip in the prior art, and improving the production quality and production efficiency of the chip. In addition, the auxiliary mark can increase the specificity of the alignment mark, so that the alignment system is not easily disturbed by similar graphics on the wafer when identifying the alignment mark, improving the recognition accuracy of the alignment mark, thereby improving the alignment accuracy of the wafer and the mask. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic diagram of a TVPA logo provided in an embodiment of the present application;

[0019] Figure 2 is a schematic diagram of an AGA logo provided in an embodiment of the present application;

[0020] Figure 3 is a flow chart of a photolithography machine alignment method provided in an embodiment of the present application;

[0021] Figure 4It is one of the schematic diagrams of the first auxiliary identification provided in the embodiment of the present application;

[0022] Figure 5 This is the second schematic diagram of the first auxiliary identification provided in the embodiment of the present application;

[0023] Figure 6 It is one of the schematic diagrams of the second auxiliary identification provided in the embodiment of the present application;

[0024] Figure 7 This is the second schematic diagram of the second auxiliary identification provided in the embodiment of the present application;

[0025] Figure 8 is a schematic diagram of an auxiliary mark composed of a first graphic unit and a second graphic unit provided in an embodiment of the present application;

[0026] Fig. 9 A schematic diagram of an auxiliary mark composed of a third graphic unit, a fourth graphic unit, a fifth graphic unit and a sixth graphic unit provided in an embodiment of the present application;

[0027] Fig.10 is a schematic diagram of the TVPA logo and the auxiliary logos on both sides provided in an embodiment of the present application;

[0028] Fig.11 is a schematic diagram of the AGA logo and the auxiliary logos on both sides provided in an embodiment of the present application;

[0029] Fig.12 It is a schematic diagram of the TVPA logo and surrounding auxiliary logos provided in an embodiment of the present application;

[0030] Fig.13 It is a schematic diagram of the AGA logo and surrounding auxiliary logos provided in an embodiment of the present application. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical scheme and advantages of the present application clearer, the specific embodiments of the present application are further described in detail below in conjunction with the accompanying drawings. It is understood that the specific embodiments described herein are only used to explain the present application, rather than to limit the present application. It should also be noted that, for the convenience of description, only part of the present application is shown in the accompanying drawings, but not all of the content. Before discussing the exemplary embodiments in more detail, it should be mentioned that some exemplary embodiments are described as processes or methods depicted as flow charts. Although the flow chart describes each operation (or step) as a sequential process, many of the operations therein can be implemented in parallel, concurrently or simultaneously. In addition, the order of the operations can be rearranged. The process can be terminated when its operation is completed, but it can also have additional steps not included in the accompanying drawings. The process can correspond to a method, a function, a procedure, a subroutine, a subprogram, etc.

[0032] The terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described here, and the objects distinguished by "first", "second", etc. are generally of one type, and the number of objects is not limited. For example, the first object can be one or more. In addition, "and / or" in the specification and claims represents at least one of the connected objects, and the character " / " generally indicates that the objects associated with each other are in an "or" relationship.

[0033] In the more common existing implementation methods, any periodic structure that can produce diffraction under the irradiation of the alignment laser can be used as an alignment mark. However, under actual process conditions, the alignment mark needs to meet four conditions: first, the mark on the wafer must not be easily damaged by the process; second, it must be easy to place on the mask without affecting the device; third, it can be effectively detected by the alignment optical system and can provide the maximum signal strength; fourth, the alignment marks on the wafer and the mask used for alignment must be within a certain range so that the alignment system of the lithography machine can capture them. Different models of lithography machines may use different alignment marks. For Canon lithography machines, the alignment operation needs to be performed twice. The first is coarse alignment, using the TVPA mark, and the second is fine alignment, using the AGA mark. The alignment mark of the Canon lithography machine has the following advantages: the graphics are smaller and the space occupied is smaller. Secondly, except for the graphics defined by Canon, special graphics can be set as coarse alignment marks. However, the alignment mark of the Canon lithography machine has strict distance restrictions for certain graphics. For example, Figure 1 It is a schematic diagram of the TVPA logo provided in the embodiment of the present application. Figure 2 Schematic diagram of the AGA logo provided in the embodiment of the present application. Figure 1As described above, the TVPA logo is composed of a plurality of dot-shaped graphic units 10, and the AGA logo is composed of a plurality of transverse straight-strip graphic units 11 and longitudinal straight-strip graphic units 12, which are prone to signal interference similar to other dot-shaped graphics. Therefore, it is limited that there cannot be dot-shaped graphics or straight-strip graphics within the 500um range of the TVPA logo, and there cannot be dot-shaped graphics or straight-strip graphics within the range of 230um in the X direction and 170um in the Y direction centered on the AGA logo. This graphic distance limitation is very unfriendly for processes that require dummy graphics to be placed in certain cutting paths. For example, for the active area of ​​the wafer, this structural layer needs to undergo a chemical mechanical polishing (CMP) step, so it is necessary to place dummy graphics in the cutting path to reduce the burden of chemical mechanical polishing. The commonly used dummy graphics are generally dot-shaped. Due to the distance limitation of the alignment mark for the dot-shaped graphics or straight-strip graphics, large blocks of shallow trench isolation or large blocks of active areas will appear near the alignment mark (depending on which structural layer of the wafer the alignment mark is located). If there are large shallow trench isolations near the alignment mark, and the chip has an active area with a certain pattern density, the grinding rate of the cutting path will be faster than the grinding speed of the chip during chemical mechanical polishing, causing the area near the alignment mark to be ground more strongly than other places, resulting in severe depressions on the wafer and even affecting the chip near the alignment mark. If there are large active areas near the alignment mark, during chemical mechanical polishing, the area near the alignment mark is not ground enough compared to other places, which can also cause severe depressions on the wafer and even affect the chip near the alignment mark. In addition, for the etching process, if there are large continuous blank areas near the alignment mark, it will increase the burden of the etching process and reduce etching efficiency.

[0034] To solve the above problems, the present embodiment provides a lithography machine alignment method, wherein a plurality of auxiliary marks are evenly arranged in the blank area around the alignment mark, and the auxiliary marks have obvious graphic differences from the alignment marks, so as to ensure that the alignment system can accurately identify the alignment marks while balancing the grinding rates of the cutting paths and chips in the wafer, avoiding the problem of over-grinding or under-grinding of the cutting paths, thereby avoiding serious dents in the wafer and improving the production quality and efficiency of the chips.

[0035] Figure 3 A flow chart of a photolithography machine alignment method provided in an embodiment of the present application is given. Figure 3 As shown, the lithography machine alignment method includes:

[0036] S110. Provide a wafer including an alignment mark and an auxiliary mark, wherein the alignment mark and the auxiliary mark are arranged in a cutting path of the wafer, and a plurality of auxiliary marks are evenly distributed on both sides or around the alignment mark; wherein, when the alignment mark is a coarse alignment mark including dot-shaped graphic units, the auxiliary mark does not include the dot-shaped graphic units; wherein, when the alignment mark is a fine alignment mark including transverse straight strip graphic units and longitudinal straight strip graphic units, the auxiliary mark does not include the dot-shaped graphic units, the transverse straight strip graphic units and the longitudinal straight strip graphic units.

[0037] Exemplarily, the wafer includes a plurality of cutting lanes, and coarse alignment marks and fine alignment marks can be formed in different cutting lanes, so that the alignment system of the photoresist first performs coarse alignment of the wafer and the mask through the coarse alignment marks, and then performs fine alignment of the wafer and the mask through the fine alignment marks. Corresponding auxiliary marks are arranged on both sides or around the coarse alignment marks and the fine alignment marks, so as to balance the grinding rate of the cutting lanes where the coarse alignment marks and the fine alignment marks are located and the chips nearby through the auxiliary marks. In order to distinguish the auxiliary marks arranged near the coarse alignment marks and the fine alignment marks, this embodiment is described by taking the auxiliary marks arranged on both sides or around the coarse alignment marks as the first auxiliary marks, and the auxiliary marks arranged on both sides or around the fine alignment marks as the second auxiliary marks as an example.

[0038] The coarse alignment mark, the fine alignment mark, the first auxiliary mark and the second auxiliary mark can be formed on the wafer through a photolithography process. First, a layer of photoresist is coated on the surface of the wafer, and the wafer is exposed using a mask containing the coarse alignment mark, the fine alignment mark, the first auxiliary mark and the second auxiliary mark. During the exposure process, light is irradiated onto the photoresist through the pattern on the mask, causing the photoresist to undergo a chemical reaction. Subsequently, the unexposed photoresist is removed by development and cleaning, thereby forming the coarse alignment mark, the fine alignment mark, the first auxiliary mark and the second auxiliary mark on the wafer. Similarly, the pattern of the coarse alignment mark in the mask includes a plurality of patterns of the first auxiliary marks around or on both sides, and the pattern of the fine alignment mark includes a plurality of patterns of the second auxiliary marks around or on both sides. Among them, the exposure area on the wafer includes the area where the coarse alignment mark, the fine alignment mark, the first auxiliary mark and the second auxiliary mark are located.

[0039] Since the coarse alignment mark includes a dot-shaped graphic unit, in order to avoid the first auxiliary mark from causing signal interference to the coarse alignment mark, the first auxiliary mark does not include a dot-shaped graphic unit. That is, the first auxiliary mark may include a straight bar-shaped graphic unit, or a graphic unit composed of straight bar-shaped graphics. For example, Figure 4 and Figure 5 is a schematic diagram of the first auxiliary identification provided in the embodiment of the present application. Figure 4As shown, the first auxiliary mark includes three horizontal straight stripe graphic units 11 and three vertical straight stripe graphic units 12. The three horizontal straight stripe graphic units 11 are arranged in parallel at the right end, and the three vertical straight stripe graphic units 12 are arranged in parallel at the right end. Figure 5 As shown, the first auxiliary mark is a graphic unit formed by splicing a transverse straight segment 14 and an inclined straight segment 13.

[0040] Since the fine alignment mark includes horizontal straight strip graphic units and vertical straight strip graphic units, in order to avoid the second auxiliary mark from causing signal interference to the fine alignment mark, the second auxiliary mark does not include horizontal straight strip graphic units and vertical straight strip graphic units. The fine alignment mark requires a higher alignment accuracy. Graphics similar to horizontal straight strip graphic units and vertical straight strip graphic units, or graphics similar to horizontal straight strip graphic units and vertical straight strip graphic units that can be formed by multiple graphic units cannot be set near the fine alignment mark. When multiple dot-shaped graphic units are arranged along the same straight line, they can present an effect similar to horizontal straight strip graphic units and vertical straight strip graphic units. In order to ensure the accuracy of the fine alignment mark, the second auxiliary mark also does not include dot-shaped graphic units. Therefore, the first auxiliary mark may include inclined straight strip graphic units, or include graphic units spliced ​​by straight strip graphics. Exemplary, Figure 6 and Figure 7 is a schematic diagram of a second auxiliary identifier provided in an embodiment of the present application. Figure 6 As shown, the second auxiliary mark includes three inclined straight stripe graphic units 15, and the three inclined straight stripe graphic units are arranged in parallel to form the second auxiliary mark. Figure 7 As shown, the second auxiliary mark is a graphic unit formed by splicing a horizontal straight line segment 14 and a vertical straight line segment 16.

[0041] The first auxiliary mark and the second auxiliary mark may be different. For example, the first auxiliary mark may include a straight bar graphic unit, such as Figure 4 The graphic shown is used as the first auxiliary mark. The second auxiliary mark may include an inclined straight bar graphic unit, or a graphic unit composed of straight bar graphics, for example, Figure 7 The graphic shown is used as the second auxiliary mark. Of course, in order to uniformly manage the auxiliary marks, the auxiliary marks of the coarse alignment mark and the fine alignment mark are the same, that is, the first auxiliary mark and the second auxiliary mark are the same. For example, the first auxiliary mark and the second auxiliary mark may include inclined straight strip graphic units, or include graphic units composed of straight strip graphics. For example, it can be used Figure 5 , Figure 6 or Figure 7 The graphics shown serve together as the first auxiliary identification and the second auxiliary identification.

[0042] It should be noted that although some complex graphics, such as curved strips and irregular graphics, can be used as auxiliary marks, these graphics cannot be photolithographically produced on the wafer at some low process nodes, which will cause the auxiliary marks on the wafer to become a source of defects. Therefore, auxiliary marks tend to choose simple graphics, or simple splicing of simple graphics.

[0043] Furthermore, the auxiliary mark is a non-closed graphic or the auxiliary mark does not include a closed graphic unit. Exemplarily, when the auxiliary mark includes multiple graphic units, the multiple graphic units can form a non-closed graphic, and each graphic unit is a non-closed graphic. For details, please refer to Figure 4 and Figure 6 When the auxiliary logo includes a graphic unit, the graphic unit is a non-closed graphic. For details, please refer to Figure 5 and Figure 7 It is understandable that when the auxiliary mark is designed as a closed figure or includes a closed figure unit, after the auxiliary mark is photolithographically formed on the wafer, the center point of the auxiliary mark is a dot figure, which will cause signal interference to the coarse alignment mark and the fine alignment mark, thereby affecting the alignment accuracy of the wafer and the mask. The auxiliary mark can be designed as a non-closed figure or does not include a closed figure unit to ensure the alignment accuracy of the wafer and the mask.

[0044] In one embodiment, the auxiliary logo includes a first graphic unit and a second graphic unit, both of which are composed of horizontal straight segments and vertical straight segments, the vertical straight segments of the first graphic unit are located at the upper end and close to the horizontal straight segments of the second graphic unit, the horizontal straight segments of the first graphic unit are located at the lower end and close to the vertical straight segments of the second graphic unit, and the first graphic unit and the second graphic unit form a rectangular frame with gaps at the upper and lower ends. Exemplary, Figure 8 is a schematic diagram of an auxiliary mark composed of a first graphic unit and a second graphic unit provided in an embodiment of the present application. Figure 8As shown, the horizontal straight segment 14 of the first graphic unit 17 is located at the lower end of the auxiliary mark and is spliced ​​with the vertical straight segment 16 of the first graphic unit 17 located at the left end of the auxiliary mark, and the horizontal straight segment 14 of the second graphic unit 18 is located at the upper end of the auxiliary mark and is spliced ​​with the vertical straight segment 16 of the second graphic unit 18 located at the right end of the auxiliary mark. The first graphic unit 17 and the second graphic unit 18 can cooperate with each other to form a rectangular frame with gaps at the upper and lower ends of the auxiliary mark. The length of the horizontal straight segment 14 of the first graphic unit 17 is equal to the length of the horizontal straight segment 14 of the second graphic unit 18, and the length of the vertical straight segment 14 of the first graphic unit 17 is equal to the length of the horizontal straight segment 14 of the second graphic unit 18, so the length of the upper end gap of the rectangular frame is equal to the length of the lower end gap. The widths of the horizontal straight segment 14 and the vertical straight segment 16 of the first graphic unit 17 and the horizontal straight segment 14 and the vertical straight segment 16 of the second graphic unit 18 are equal. It should be noted that, due to the gap in the rectangular frame, the auxiliary mark is not a closed graphic, so the auxiliary mark will not be mistakenly identified as the alignment mark during alignment recognition. Although it contains horizontal straight segments and vertical straight segments, the horizontal straight segments and vertical straight segments are spliced ​​into an "L"-shaped graphic unit, which is consistent with the Figure 3 There is a clear difference between the horizontal straight strip graphic unit 11 and the vertical straight strip graphic unit 12 shown, so the auxiliary mark will not be mistakenly identified as the alignment mark during alignment and recognition.

[0045] In another embodiment, the auxiliary mark includes a third graphic unit, a fourth graphic unit, a fifth graphic unit and a sixth graphic unit, the third graphic unit, the fourth graphic unit, the fifth graphic unit and the sixth graphic unit are inclined straight segments with different inclination angles, the third graphic unit and the fourth graphic unit are located at the upper end, and the fifth graphic unit and the sixth graphic unit are located at the lower end. Exemplarily, Fig. 9 A schematic diagram of an auxiliary mark composed of a third graphic unit, a fourth graphic unit, a fifth graphic unit and a sixth graphic unit provided in an embodiment of the present application. Fig. 9 As shown, the third graphic unit 19, the fourth graphic unit 20, the fifth graphic unit 21 and the sixth graphic unit 22 are inclined straight segments with the same width but different inclination angles, and the third graphic unit 19 and the fourth graphic unit 20 are symmetrical to the fifth graphic unit 21 and the sixth graphic unit 22 along the horizontal line. The longitudinal spacing between the graphic units at the upper end and the lower end is equal to the lateral spacing between the graphic units at the left end and the right end. It should be noted that the third graphic unit 19, the fourth graphic unit 20, the fifth graphic unit 21 and the sixth graphic unit 22 are not connected to each other, so the auxiliary mark is not a closed graphic, so the auxiliary mark will not be mistakenly identified as an alignment mark during alignment recognition. Moreover, the inclined straight segment and Figure 3There is a clear difference between the horizontal straight strip graphic unit 11 and the vertical straight strip graphic unit 12 shown, so the auxiliary mark will not be mistakenly identified as the alignment mark during alignment and recognition.

[0046] In this embodiment, in order to form an auxiliary mark on the wafer, the minimum size of the auxiliary mark design, that is, the line width, cannot violate the design rules of the structural layer of the wafer, that is, the line width of the auxiliary mark is greater than or equal to the line width of the structural layer of the wafer. Figure 8 and Fig. 9 The line width of the auxiliary mark can be regarded as the width S1 of the horizontal straight segment 14 and the vertical straight segment 16 in the first graphic unit 17 and the second graphic unit 18, and as the width S2 of the inclined straight segment in the third graphic unit 19, the fourth graphic unit 20, the fifth graphic unit 21 and the sixth graphic unit 22. The width S1 and the width S2 are greater than or equal to the line width of the wafer structure layer etched by the auxiliary mark, so as to ensure that the auxiliary mark can be successfully formed on the wafer.

[0047] Furthermore, when the auxiliary mark includes multiple graphic units, the spacing between two adjacent graphic units should not be too small, otherwise the glue is likely to fall back. And the spacing between two adjacent auxiliary marks should not be too small, otherwise the glue is likely to fall back. The auxiliary mark is formed by a photolithography process, and for this, the ratio of the photoresist thickness of the photolithography process to the lateral spacing or longitudinal spacing between any two adjacent auxiliary marks is less than or equal to 4, and the ratio of the photoresist thickness of the photolithography process to the lateral spacing or longitudinal spacing between two adjacent graphic units in the auxiliary mark is less than or equal to 4. Reference Figure 8 and Fig. 9 , the distance between two adjacent graphic units in the auxiliary mark is L1 or L2. If L1 or L2 is 1um, the photoresist thickness is less than or equal to 40000A.

[0048] In one embodiment, when the cutting path is regular and uniform, that is, when the cutting path is a horizontal cutting path or a vertical cutting path, the auxiliary mark is horizontally or vertically arranged on both sides of the alignment mark. If the cutting path is not regular and it is a large open area, the auxiliary mark is horizontally and vertically arranged around the alignment mark. Specifically, if the alignment mark is arranged in the horizontal cutting path of the wafer, the multiple auxiliary marks are evenly distributed on the left and right sides of the alignment mark; if the alignment mark is arranged in the vertical cutting path of the wafer, the multiple auxiliary marks are evenly distributed on the upper and lower sides of the alignment mark; if the alignment mark is arranged in the open cutting path of the wafer, the multiple auxiliary marks are evenly distributed around the alignment mark. In this embodiment, the coarse alignment mark is the TVPA mark, the fine alignment mark is the AGA mark, and the first auxiliary mark and the second auxiliary mark are both Figure 8 The auxiliary identification shown is used as an example for description.

[0049] Fig.10Schematic diagram of the TVPA logo and auxiliary logos on both sides provided in the embodiment of the present application. Fig.10 As shown, the TVPA mark is set in the horizontal cutting road of the wafer, and multiple auxiliary mark arrays are set on the left and right sides of the TVPA mark. The longitudinal width of the array formed by the multiple auxiliary marks on one side of the TVPA mark is greater than or equal to the longitudinal width of the TVPA mark, that is, the multiple auxiliary marks can be set in parallel so that the longitudinal width of the array is greater than or equal to the longitudinal width of the TVPA. Similarly, when the TVPA mark is set in the longitudinal cutting road of the wafer, multiple auxiliary mark arrays are set on the upper and lower sides of the TVPA mark, and the lateral width of the array formed by the multiple auxiliary marks on one side of the TVPA mark is greater than or equal to the lateral width of the TVPA mark, that is, the multiple auxiliary marks can be set in parallel so that the lateral width of the array is greater than or equal to the lateral width of the TVPA. Furthermore, the minimum spacing between the auxiliary mark and the alignment mark is 30um. When the alignment mark is a coarse alignment mark, the maximum spacing between the auxiliary mark and the coarse alignment mark is 500um. Reference Fig.10 , multiple auxiliary identification arrays are set in an area 30um outside and 500um away from the TVPA identification.

[0050] Fig.11 Schematic diagram of the AGA logo and the auxiliary logos on both sides provided in the embodiment of the present application. Fig.11 As shown, the AGA mark is set in the horizontal cutting road of the wafer, and multiple auxiliary mark arrays are set on the left and right sides of the AGA mark. The longitudinal width of the array formed by the multiple auxiliary marks on one side of the AGA mark is greater than or equal to the longitudinal width of the AGA mark, that is, the multiple auxiliary marks can be arranged in parallel so that the longitudinal width of the array is greater than or equal to the longitudinal width of the AGA. Similarly, when the AGA mark is set in the longitudinal cutting road of the wafer, multiple auxiliary mark arrays are set on the upper and lower sides of the AGA mark, and the lateral width of the array formed by the multiple auxiliary marks on one side of the AGA mark is greater than or equal to the lateral width of the AGA mark, that is, the multiple auxiliary marks can be arranged in parallel so that the lateral width of the array is greater than or equal to the lateral width of the AGA. Furthermore, the minimum spacing between the auxiliary mark and the alignment mark is 30um. When the alignment mark is a fine alignment mark, the maximum lateral spacing between the auxiliary mark and the fine alignment mark is 230um, and the maximum longitudinal spacing between the auxiliary mark and the fine alignment mark is 170um. Reference Fig.11 When the AGA logo is set in the horizontal cutting path, multiple auxiliary logo arrays are set in the area outside the AGA logo by 30um and within 230um. When the AGA logo is set in the vertical cutting path, multiple auxiliary logo arrays are set in the area outside the AGA logo by 30um and within 170um.

[0051] Fig.12Schematic diagram of the TVPA logo and surrounding auxiliary logos provided in the embodiment of the present application. Fig.12 As shown, multiple auxiliary mark arrays are arranged on the upper side, lower side, left side and right side of the TVPA mark. Further, the minimum spacing between the auxiliary mark and the alignment mark is 30um. When the alignment mark is a coarse alignment mark, the maximum spacing between the auxiliary mark and the coarse alignment mark is 500um. Fig.12 , a rectangular frame area can be formed around the TVPA logo based on the maximum spacing and the minimum spacing, and a plurality of auxiliary logos can be arranged in an array in the rectangular frame area.

[0052] Fig.13 Schematic diagram of the AGA logo and surrounding auxiliary logos provided in the embodiment of the present application. Fig.13 As shown, multiple auxiliary mark arrays are arranged on the upper side, lower side, left side and right side of the AGA mark. Furthermore, the minimum spacing between the auxiliary mark and the alignment mark is 30um. When the alignment mark is a fine alignment mark, the maximum lateral spacing between the auxiliary mark and the fine alignment mark is 230um, and the maximum longitudinal spacing between the auxiliary mark and the fine alignment mark is 170um. Fig.12 A rectangular frame area can be formed around the AGA logo based on the maximum horizontal spacing, the maximum vertical spacing and the minimum spacing, and a plurality of auxiliary logos can be arranged in an array in the rectangular frame area.

[0053] It should be noted that the maximum spacing between the auxiliary mark and the alignment mark is set to avoid forming large patterns on the wafer, which will also increase the workload of chemical mechanical polishing and etching. The minimum spacing between the auxiliary mark and the alignment mark is set to avoid the auxiliary mark interfering with the signal of the alignment mark, ensuring the effectiveness and efficiency of alignment.

[0054] In one embodiment, in order to facilitate operation, the auxiliary mark can be used as a dummy graphic of the alignment mark, that is, the auxiliary mark is written into the script so as to automatically match it to the range defined by the alignment mark.

[0055] S120, transferring the wafer to a photolithography machine, and aligning the wafer and the mask through alignment marks.

[0056] Exemplarily, a wafer provided with auxiliary marks and alignment marks is transferred to a photolithography machine, and the alignment system of the photolithography machine identifies the coarse alignment marks of the wafer, and then the wafer and the mask are coarsely aligned through the coarse alignment marks. After that, the alignment system identifies the fine alignment marks of the wafer, and then the fine alignment marks of the wafer finely align the wafer and the mask. If the wafer is to be subjected to chemical mechanical grinding before being transferred to the photolithography machine, the presence of the auxiliary marks can balance the grinding rates of the cutting lanes and the chips, and avoid the problem of severe depression of the wafer. Since the auxiliary marks are located around the alignment marks, the alignment system can determine that there are alignment marks nearby when the auxiliary marks are identified, and then search and identify the alignment marks from the vicinity. Therefore, the auxiliary marks added near the alignment aids increase the specificity and distinctiveness of the alignment marks, so that the alignment system is not easily disturbed by similar patterns on the wafer when identifying the alignment marks, and the recognition accuracy of the alignment marks is improved, thereby improving the alignment accuracy of the wafer and the mask.

[0057] In summary, the lithography machine alignment method provided by the embodiment of the present application adds alignment marks and auxiliary marks in the cutting path of the wafer, and multiple auxiliary marks are evenly distributed on both sides or around the alignment mark. When the alignment mark is a coarse alignment mark including dot-shaped graphic units, the auxiliary mark does not include dot-shaped graphic units. When the alignment mark is a fine alignment mark including transverse straight bar graphic units and longitudinal straight bar graphic units, the auxiliary mark does not include dot-shaped graphic units, transverse straight bar graphic units and longitudinal straight bar graphic units; the wafer and the mask are aligned according to the alignment mark. Through the above technical means, multiple auxiliary marks can be evenly set in the blank area around the alignment mark, and the auxiliary marks and the alignment marks have obvious graphic differences, so as to ensure that the alignment system can accurately identify the alignment mark while balancing the grinding rate of the cutting path and the chip in the wafer, solving the problem of severe concavity of the wafer due to the different grinding rates of the cutting path and the chip in the prior art, and improving the production quality and production efficiency of the chip. Moreover, the auxiliary mark can increase the specificity of the alignment mark, so that the alignment system is not easily disturbed by similar patterns on the wafer when identifying the alignment mark, thereby improving the recognition accuracy of the alignment mark and thus improving the alignment accuracy of the wafer and the mask.

[0058] The above are only preferred embodiments of the present application and the technical principles used. The present application is not limited to the specific embodiments herein, and various obvious changes, readjustments and substitutions that can be made by those skilled in the art will not deviate from the protection scope of the present application. Therefore, although the present application is described in more detail through the above embodiments, the present application is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present application, and the scope of the present application is determined by the scope of the claims.

Claims

1. A method for aligning a photolithography machine, characterized in that: include: A wafer including an alignment mark and an auxiliary mark is provided, wherein the alignment mark and the auxiliary mark are arranged in a cutting path of the wafer, and a plurality of the auxiliary marks are evenly distributed on both sides or around the alignment mark; wherein, when the alignment mark is a coarse alignment mark including a dot-shaped graphic unit, the auxiliary mark does not include a dot-shaped graphic unit; when the alignment mark is a fine alignment mark including a transverse straight strip graphic unit and a longitudinal straight strip graphic unit, the auxiliary mark does not include a dot-shaped graphic unit, a transverse straight strip graphic unit and a longitudinal straight strip graphic unit; the minimum spacing between the auxiliary mark and the alignment mark is 30um; when the alignment mark is the coarse alignment mark, the maximum spacing between the auxiliary mark and the coarse alignment mark is 500um; when the alignment mark is the fine alignment mark, the maximum lateral spacing between the auxiliary mark and the fine alignment mark is 230um, and the maximum lateral spacing between the auxiliary mark and the fine alignment mark is 150um. The maximum longitudinal spacing of the logo is 170um; the auxiliary logo includes a first graphic unit and a second graphic unit, the first graphic unit and the second graphic unit are both composed of transverse straight segments and longitudinal straight segments, the longitudinal straight segments of the first graphic unit are located at the upper end and close to the transverse straight segments of the second graphic unit, the transverse straight segments of the first graphic unit are located at the lower end and close to the longitudinal straight segments of the second graphic unit, and the first graphic unit and the second graphic unit form a rectangular frame with gaps at the upper and lower ends; or, the auxiliary logo includes a third graphic unit, a fourth graphic unit, a fifth graphic unit and a sixth graphic unit, the third graphic unit, the fourth graphic unit, the fifth graphic unit and the sixth graphic unit are inclined straight segments with different inclination angles, the third graphic unit and the fourth graphic unit are located at the upper end, and the fifth graphic unit and the sixth graphic unit are located at the lower end; The wafer is transferred to a photolithography machine, and the wafer and the mask are aligned using the alignment mark.

2. The method for aligning a photolithography machine according to claim 1, characterized in that: The auxiliary marks of the coarse alignment mark and the fine alignment mark are the same.

3. The method for aligning a photolithography machine according to claim 1, characterized in that: If the alignment mark is set in the horizontal cutting street of the wafer, the multiple auxiliary marks are evenly distributed on the left and right sides of the alignment mark; if the alignment mark is set in the longitudinal cutting street of the wafer, the multiple auxiliary marks are evenly distributed on the upper and lower sides of the alignment mark; if the alignment mark is set in the empty cutting street of the wafer, the multiple auxiliary marks are evenly distributed around the alignment mark.

4. The method for aligning a photolithography machine according to claim 1, characterized in that: The line width of the auxiliary mark is greater than or equal to the line width of the structural layer of the wafer.

5. The method for aligning a photolithography machine according to claim 1, characterized in that: The auxiliary mark is formed by a photolithography process, and the ratio of the photoresist thickness of the photolithography process to the lateral spacing or longitudinal spacing between any two adjacent auxiliary marks is less than or equal to 4, and the ratio of the photoresist thickness of the photolithography process to the lateral spacing or longitudinal spacing between two adjacent graphic units in the auxiliary mark is less than or equal to 4.

6. The method for aligning a photolithography machine according to claim 1, characterized in that: The auxiliary mark is a non-closed graphic or the auxiliary mark does not include a closed graphic unit.

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