Quality optimization method for contact hole graph in mask

Abstract

The invention relates to mask manufacturing, in particular to a quality optimization method for a contact hole pattern in a mask, which comprises the following steps of: designing and adding a compensation pattern at each of four corners inside an original contact hole pattern; during photoetching, performing cell-division photoetching on the original contact hole pattern and the compensation pattern, namely, firstly performing photoetching on the original contact hole pattern by utilizing a photoetching machine, and then performing photoetching on the compensation pattern; according to the technical scheme provided by the invention, the defect that the pattern quality is relatively poor after photoetching of the contact hole pattern with a relatively small design size in the prior art can be effectively overcome.

Description

Technical Field

[0001] The invention relates to mask manufacturing, and in particular to a method for optimizing the quality of contact hole patterns in a mask. Background Art

[0002] The principle of mask production is that the photolithography machine uses direct laser exposure to lithograph various circuit patterns on a substrate with photoresist, and then goes through back-end development, etching, stripping, measurement and repair processes to make the lithographed patterns perfectly presented on the substrate. This is the basic process of mask production.

[0003] However, the lithography effect of the pattern on the mask is limited by the lithography accuracy of the lithography machine. When the width of the pattern line seam is small, the lithography effect of the pattern will be poor, especially for the contact hole pattern. For example, when Mycronic's P series lithography machine lithography contact hole patterns smaller than 2.2μm*2.2μm, the final effect is that the hole is not a square, and there will be obvious rounded corners and deformation problems at its four corners, such as Figure 3 As shown, the pattern quality is poor. In severe cases, the square holes may be made into circular holes, which will have a great impact on the quality of the mask product. Summary of the Invention

[0004] (1) Technical problems solved

[0005] In view of the above shortcomings of the prior art, the present invention provides a method for optimizing the quality of contact hole patterns in a mask, which can effectively overcome the defect of the prior art that the pattern quality of contact hole patterns with smaller design sizes is poor after photolithography.

[0006] (2) Technical solution

[0007] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0008] A method for optimizing the quality of contact hole patterns in a mask, comprising the following steps:

[0009] S1. Design and add a compensation pattern at each of the four corners inside the original contact hole pattern;

[0010] S2. During photolithography, the original contact hole pattern and the compensation pattern are subjected to cell-by-cell photolithography, that is, the original contact hole pattern is first photolithographically processed using a photolithography machine, and then the compensation pattern is photolithographically processed.

[0011] Preferably, in S1, a compensation pattern is designed and added at each of the four corners inside the original contact hole pattern, including:

[0012] Due to the cell-by-cell lithography of the original contact hole pattern and the compensation pattern, the original contact hole pattern and the compensation pattern will be misaligned in the X / Y directions, with the misalignment values ​​being Px and Py respectively. Therefore, there must be an offset between the edges of the compensation pattern and the original contact hole pattern in the X / Y directions, with the offset values ​​being Dx and Dy respectively. Otherwise, the deformation of the original contact hole pattern will be more serious.

[0013] Among them, the misalignment values ​​Px and Py need to be tested, and the misalignment direction and distance of each lithography machine are different.

[0014] Preferably, in S1, a compensation pattern is designed and added at each of the four corners inside the original contact hole pattern, including:

[0015] It is necessary to reserve the CD variation △x and △y of the compensation pattern in the X / Y direction to prevent the actual pattern from exceeding the design pattern due to the CD of the compensation pattern being too large;

[0016] The CD variation amounts Δx and Δy need to be determined based on the actual photolithography data of the compensation pattern.

[0017] Preferably, the method for calculating the CD variation Δx includes:

[0018] If the actual CD value of the compensation pattern in the X direction is The design CD value of the compensation pattern in the X direction is Then use the following formula to calculate the CD change △x:

[0019]

[0020] The method for calculating the CD variation Δy includes:

[0021] If the actual CD value of the compensation pattern in the Y direction is The design CD value of the compensation pattern in the Y direction is Then use the following formula to calculate the CD change △y:

[0022]

[0023] in,

[0024] Preferably, the designed CD values ​​of the compensation pattern in the X / Y directions are Need to be based on the design CD value of the original contact hole pattern 设计 The minimum size is not less than one pixel and the maximum size is not greater than the design CD value of the original contact hole pattern. 设计 Half:

[0025]

[0026] Among them, the design CD value This needs to be determined through multiple sets of tests.

[0027] Preferably, the method for calculating the offset value Dx includes:

[0028] The offset value Dx is calculated using the following formula:

[0029] Dx=|Px|-Δx;

[0030] The calculation method of the offset value Dy includes:

[0031] The offset value Dy is calculated using the following formula:

[0032] Dy=|Py|-Δy.

[0033] Preferably, the compensation pattern is a small hole pattern.

[0034] (3) Beneficial effects

[0035] Compared with the existing technology, the method for optimizing the quality of contact hole patterns in a mask provided by the present invention addresses the problem that due to the different lithography precision of the lithography machines, the pattern quality of the contact hole patterns with smaller design sizes is poor after lithography by low-end lithography machines, and the resulting pattern is not a square hole but a circular hole. The present invention does not require the use of higher-end lithography equipment with higher lithography precision. It only needs to modify the pattern design and effectively optimize the pattern quality by increasing the exposure amount and number of exposures at the corners of the original contact hole pattern. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort.

[0037] Figure 1 A schematic diagram of designing and adding a compensation pattern at each of the four corners inside the original contact hole pattern in the present invention;

[0038] Figure 2 This is a comparison chart of the pattern quality obtained by photolithography of contact hole patterns using the technical solution of the present invention;

[0039] Figure 3 This is a comparison chart showing the impact of pattern design size on pattern quality when existing photolithography machines are performing photolithography on contact hole patterns. DETAILED DESCRIPTION

[0040] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0041] A method for optimizing the quality of contact hole patterns in a mask, such as Figure 1 As shown, S1, a compensation pattern is designed and added at each of the four corners inside the original contact hole pattern.

[0042] 1) Design and add a compensation pattern at each of the four corners inside the original contact hole pattern, including:

[0043] Due to the cell-by-cell lithography of the original contact hole pattern and the compensation pattern, the original contact hole pattern and the compensation pattern will be misaligned in the X / Y directions, with the misalignment values ​​being Px and Py respectively. Therefore, there must be an offset between the edges of the compensation pattern and the original contact hole pattern in the X / Y directions, with the offset values ​​being Dx and Dy respectively. Otherwise, the deformation of the original contact hole pattern will be more serious.

[0044] Among them, the misalignment values ​​Px and Py need to be tested, and the misalignment direction and distance of each lithography machine are different.

[0045] 2) Design and add a compensation pattern at each of the four corners inside the original contact hole pattern, including:

[0046] It is necessary to reserve the CD variation △x and △y of the compensation pattern in the X / Y direction to prevent the actual pattern from exceeding the design pattern due to the CD of the compensation pattern being too large;

[0047] The CD variation amounts Δx and Δy need to be determined based on the actual photolithography data of the compensation pattern.

[0048] Specifically, the method for calculating the CD change Δx includes:

[0049] If the actual CD value of the compensation pattern in the X direction is The design CD value of the compensation pattern in the X direction is Then use the following formula to calculate the CD change △x:

[0050]

[0051] The calculation method of CD change △y includes:

[0052] If the actual CD value of the compensation pattern in the Y direction is The design CD value of the compensation pattern in the Y direction is Then use the following formula to calculate the CD change △y:

[0053]

[0054] in,

[0055] Specifically, the design CD value of the compensation pattern in the X / Y direction Need to be based on the design CD value of the original contact hole pattern 设计 The minimum size is not less than one pixel and the maximum size is not greater than the design CD value of the original contact hole pattern. 设计 Half:

[0056]

[0057] Among them, the design CD value This needs to be determined through multiple sets of tests.

[0058] Specifically, the calculation method of the offset value Dx includes:

[0059] The offset value Dx is calculated using the following formula:

[0060] Dx=|Px|-Δx;

[0061] The calculation method of the offset value Dy includes:

[0062] The offset value Dy is calculated using the following formula:

[0063] Dy=|Py|-Δy.

[0064] In the technical solution of this application, Figure 1 As shown, the compensation pattern is a small hole pattern.

[0065] S2. During photolithography, the original contact hole pattern and the compensation pattern are subjected to cell-by-cell photolithography, that is, the original contact hole pattern is first photolithographically processed using a photolithography machine, and then the compensation pattern is photolithographically processed.

[0066] like Figure 2 As shown in FIG, a comparison diagram of the graphic quality obtained by photolithography of a contact hole graphic (designed CD value is 2.5 μm) using the technical solution of the present application, wherein the beam pixel beampixel of the photolithography machine is 0.4 μm. It can be seen from the figure that the graphic quality after compensation is significantly better than that before compensation.

[0067] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for optimizing the quality of contact hole patterns in a mask, characterized by: The following steps are involved: S1. Design and add a compensation pattern at each of the four corners inside the original contact hole pattern; S2. During photolithography, the original contact hole pattern and the compensation pattern are subjected to cell-by-cell photolithography, that is, the original contact hole pattern is first photolithographically processed using a photolithography machine, and then the compensation pattern is photolithographically processed.

2. The method for optimizing the quality of contact hole patterns in a mask according to claim 1, wherein: In S1, a compensation pattern is designed and added at each of the four corners inside the original contact hole pattern, including: Due to the cell-by-cell lithography of the original contact hole pattern and the compensation pattern, the original contact hole pattern and the compensation pattern will be misaligned in the X / Y directions, with the misalignment values ​​being Px and Py respectively. Therefore, there must be an offset between the edges of the compensation pattern and the original contact hole pattern in the X / Y directions, with the offset values ​​being Dx and Dy respectively. Otherwise, the deformation of the original contact hole pattern will be more serious. Among them, the misalignment values ​​Px and Py need to be tested, and the misalignment direction and distance of each lithography machine are different.

3. The method for optimizing the quality of contact hole patterns in a mask according to claim 2, wherein: In S1, a compensation pattern is designed and added at each of the four corners inside the original contact hole pattern, including: It is necessary to reserve the CD variation △x and △y of the compensation pattern in the X / Y direction to prevent the actual pattern from exceeding the design pattern due to the CD of the compensation pattern being too large; The CD variation amounts Δx and Δy need to be determined based on the actual photolithography data of the compensation pattern.

4. The method for optimizing the quality of contact hole patterns in a mask according to claim 3, wherein: The method for calculating the CD variation Δx includes: If the actual CD value of the compensation pattern in the X direction is The design CD value of the compensation pattern in the X direction is Then use the following formula to calculate the CD change △x: The method for calculating the CD variation Δy includes: If the actual CD value of the compensation pattern in the Y direction is The design CD value of the compensation pattern in the Y direction is Then use the following formula to calculate the CD change △y: in, 5. The method for optimizing the quality of contact hole patterns in a mask according to claim 4, wherein: Design CD value of the compensation pattern in the X / Y directions Need to be based on the design CD value of the original contact hole pattern 设计 The minimum size is not less than one pixel and the maximum size is not greater than the design CD value of the original contact hole pattern. 设计 Half: Among them, the design CD value This needs to be determined through multiple sets of tests.

6. The method for optimizing the quality of contact hole patterns in a mask according to claim 4, wherein: The method for calculating the offset value Dx includes: The offset value Dx is calculated using the following formula: The calculation method of the offset value Dy includes: The offset value Dy is calculated using the following formula:

7. The method for optimizing the quality of contact hole patterns in a mask according to any one of claims 1 to 6, wherein: The compensation pattern is a small hole pattern.

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