Calculation method of secondary etching deviation, secondary etching pattern and production method thereof

Abstract

The invention relates to a secondary etching deviation calculation method, a secondary etching pattern and a production method thereof. The secondary etching deviation calculation method comprises the following steps: receiving a secondary etching pattern; the secondary etching pattern comprises an overlay calibration pattern obtained through the same overlay and a defect control group; the defect secondary exposure pattern is a pattern obtained after light-proof defects formed in primary exposure are repaired through secondary exposure; measuring the overlay calibration pattern to obtain an alignment error, measuring the defect-free reference pattern to obtain a corresponding reference size value, and then measuring the defect secondary exposure pattern to obtain a corresponding test size value; the alignment error, the reference dimension value and the test dimension value are dimension values after photoresist removal; and obtaining a mask secondary etching deviation value according to the alignment error, the reference size value and the test size value. After the alignment error is eliminated, the accuracy of the secondary etching deviation value of the mask is improved, and the success rate of secondary repair is improved.

Description

Technical Field

[0001] The invention relates to the field of integrated circuit manufacturing, and in particular to a calculation method for secondary etching deviation, a secondary etching pattern and a production method thereof. Background Art

[0002] In the process of integrated circuit manufacturing, masks are essential components of the photolithography process. The mask carries the design pattern, which is transferred to the wafer through projection lithography. After subsequent process steps, the corresponding circuit device can be finally formed.

[0003] The production of masks generally includes the following processes: the first is mask data preparation (Data Prepare), which divides the data of the design graphics and converts it into a file that can be read by the subsequent exposure equipment (referred to as exposure file). The second is exposure, which can transfer the design graphics to the photoresist (Photo resist, Pr) of the mask substrate. The third is baking (Bake), developing (Develop), etching (Etch) and stripping (Strip), which can transfer the design graphics from the photoresist to the light shielding layer underneath it. The subsequent steps of registration difference (Registration, REG) measurement, critical dimension or line width (Critical Dimension, CD) measurement, defect inspection (Defect Inspection), defect repair (Defect Repair), aerial image measurement (Aerial Image Measurement System, AIMS), cleaning, film pasting and final inspection can complete the mask production. In the process of mask production, defects are inevitable due to various reasons. Some defects will cause errors in the design graphics on the mask, so the relevant defects on the mask need to be repaired to meet the customer's design requirements. Currently, defects on the mask can usually be repaired by etching (Etch) or deposition (Deposit) (Opaque defects are repaired by etching, and translucent defects are repaired by deposition), so that the repaired pattern meets the design requirements. However, the size and number of the repaired pattern are limited. For large quantities or large areas of opaque defects, secondary repair (SR) is generally used.

[0004] Of course, the edge of the graphic obtained by the secondary repair cannot completely overlap with the edge of the defective area in the first exposure that needs to be repaired, and there will be a certain deviation between the edges of the two. It is generally believed that this deviation is generated during the etching process of the secondary repair (hereinafter referred to as the secondary etching), which is called the secondary etching deviation. Therefore, the current calculation of the secondary etching deviation is generally obtained by subtracting the critical dimension (CD) of the graphic after the secondary repair from the critical dimension of the graphic with the same design line width before the secondary repair. However, due to the alignment error generated during the alignment process before exposure (the alignment error is generally around tens of nanometers), the etching deviation obtained by this method (i.e., without the influence of the error removed) has a low accuracy. In actual production, the secondary etching deviation will still be inaccurate, which will eventually cause the secondary repair to fail, increasing the risk of secondary repair.

[0005] Therefore, how to improve the calculation accuracy of the secondary etching deviation, thereby improving the success rate of the secondary repair, is a problem that needs to be solved urgently by those skilled in the art. Summary of the invention

[0006] The purpose of the present invention is to provide a method for calculating a secondary etching deviation, a secondary etching pattern and a production method thereof, so as to solve the problems of low calculation accuracy of the secondary etching deviation and poor success rate of secondary repair in the prior art.

[0007] In order to solve the above technical problems, the present invention provides a method for calculating secondary etching deviation, comprising:

[0008] receiving a secondary etching pattern; the secondary etching pattern comprises an overlay calibration pattern obtained through the same overlay and a defect control group, the defect control group comprises a defective secondary exposure pattern and a corresponding non-defective reference pattern, and the design line width of all patterns in the same defect control group is the same; the defective secondary exposure pattern is a pattern obtained after the opaque defect formed in the first exposure is repaired through the secondary exposure;

[0009] The alignment error is obtained by measuring the overlay calibration pattern, the corresponding reference dimension value is obtained by measuring the defect-free reference pattern, and the corresponding test dimension value is obtained by measuring the defective secondary exposure pattern; the alignment error, the reference dimension value and the test dimension value are all dimension values ​​after debonding;

[0010] A mask secondary etching deviation value is obtained according to the alignment error, the reference dimension value and the test dimension value.

[0011] Optionally, in the calculation method of the secondary etching deviation, the defect-free reference pattern is a square hole pattern;

[0012] Measuring the overlay calibration pattern to obtain an alignment error, measuring the defect-free reference pattern to obtain a corresponding reference size value, and then measuring the defective secondary exposure pattern to obtain a corresponding test size value, including:

[0013] The overlay calibration pattern is measured to obtain a first direction alignment error and a second direction alignment error, the defect-free reference pattern is measured to obtain a corresponding first direction reference size value and a second direction reference size value, and then the defective secondary exposure pattern is measured to obtain a corresponding first direction test size value and a second direction test size value, wherein the first direction is perpendicular to the second direction;

[0014] Correspondingly, according to the alignment error, the reference dimension value and the test dimension value, obtaining the mask secondary etching deviation value includes:

[0015] Obtaining a second etching deviation value in the first direction according to the first direction alignment error, the first direction reference dimension value, and the first direction test dimension value;

[0016] Obtaining a secondary etching deviation value in the second direction according to the second direction alignment error, the second direction reference dimension value and the second direction test dimension value;

[0017] The secondary etching deviation value in the first direction and the secondary etching deviation value in the second direction are averaged to obtain the secondary etching deviation value of the mask corresponding to the square hole pattern.

[0018] Optionally, in the calculation method of the secondary etching deviation, before measuring the defect secondary exposure pattern to obtain the corresponding test dimension value, the method further includes:

[0019] Obtaining the defect type and the corresponding repair margin direction corresponding to the defect secondary exposure pattern; the repair margin direction is a specific moving direction of the secondary exposure area in the secondary exposure repair, and the offset of the secondary exposure area along the repair margin direction will cause at least one end of the measurement position of the secondary exposure area to move from the opaque area to the translucent area;

[0020] Determining a moving direction of a secondary exposure area corresponding to the defect secondary exposure pattern according to the secondary etching pattern;

[0021] Determining whether the moving direction of the secondary exposure area is the repair margin direction;

[0022] When the moving direction of the secondary exposure area is the repair margin direction, the secondary etching deviation value of the mask is obtained according to the alignment error, the reference size value and the test size value, including:

[0023] The mask secondary etching deviation value is obtained by the following formula:

[0024] CD SR Etch Bias =(CD Test -CD Base -REG)*2;

[0025] Among them, CD SR Etch Bias is the secondary etching deviation value of the mask, CD Test For the test size value, CD Base is the reference dimension value, and REG is the alignment error.

[0026] Optionally, in the calculation method of the secondary etching deviation, after determining whether the moving direction of the secondary exposure area is the repair margin direction, the method further includes:

[0027] When the moving direction of the secondary exposure area is not the repair margin direction, the secondary etching deviation value of the mask is obtained according to the alignment error, the reference size value and the test size value, including:

[0028] The mask secondary etching deviation value is obtained by the following formula:

[0029] CD SR Etch Bias =CD Test -CD Base ;

[0030] Among them, CD SR Etch Bias is the secondary etching deviation value of the mask, CD Test For the test size value, CD Base is the reference size value.

[0031] Optionally, in the method for calculating the secondary etching deviation, determining the moving direction of the secondary exposure area corresponding to the defective secondary exposure pattern according to the secondary etching pattern includes:

[0032] The moving direction of the secondary exposure area corresponding to the defective secondary exposure pattern is determined according to the alignment error.

[0033] Optionally, in the calculation method of the secondary etching deviation, the secondary etching pattern includes a plurality of defect control groups with different design line widths;

[0034] Obtaining the mask secondary etching deviation value according to the alignment error, the reference dimension value and the test dimension value includes:

[0035] According to the alignment error, the reference dimension value and the test dimension value in the same defect control group, obtaining the group secondary etching deviation value corresponding to each defect control group;

[0036] The secondary etching deviation values ​​of all defect control groups corresponding to the groups are averaged to obtain the mask secondary etching deviation value.

[0037] Optionally, in the calculation method of the secondary etching deviation, the same defect control group includes a plurality of the defective secondary exposure patterns and a plurality of the non-defective reference patterns;

[0038] Obtaining the mask secondary etching deviation value according to the alignment error, the reference dimension value and the test dimension value includes:

[0039] Calculating the average value of the reference size values ​​of all defect-free reference patterns in the same defect control group as the average reference size value within the group; calculating the average value of the test size values ​​of all defective secondary exposure patterns in the same defect control group as the average test size value within the group;

[0040] A mask secondary etching deviation value is obtained according to the alignment error, the average reference size value within the group and the average test size value within the group.

[0041] A secondary etching pattern, the secondary etching pattern used in any one of the above-mentioned secondary etching deviation calculation methods, including an overlay calibration pattern and a defect control group obtained by the same overlay;

[0042] The defect control group includes defective secondary exposure patterns and corresponding non-defective reference patterns, and all patterns in the defect control group have the same design line width;

[0043] The defective secondary exposure pattern is a pattern obtained after the opaque defect formed in the first exposure is repaired by secondary exposure.

[0044] Optionally, in the secondary etching pattern, all pattern arrays in the same defect control group are arranged to form a corresponding pattern to be tested;

[0045] The positions of the setting areas of the patterns to be tested of different defect control groups do not overlap;

[0046] or

[0047] The secondary etching pattern includes a defect area and a reference area; the position of the defect area does not overlap with the position of the reference area;

[0048] All defect secondary exposure patterns of the defect control group are located in the defect area, and all non-defect reference patterns of the defect control group are located in the reference area.

[0049] A method for producing a secondary etching pattern, wherein the secondary etching pattern as described above is obtained by the method for producing a secondary etching pattern, comprising:

[0050] Laying a layer to be etched on a transparent substrate;

[0051] Laying a photoresist layer on the surface of the layer to be etched, and performing exposure, baking, development, etching and de-gumming once, so as to transform the layer to be etched into a patterned primary etching layer; the primary etching layer includes a defect-free reference pattern and a corresponding defect pattern; and an opaque defect is arranged on the defect pattern;

[0052] A photoresist layer is laid on the surface of the primary etching layer, and secondary exposure, baking, development, etching and de-resisting are performed to etch away the area corresponding to the opaque defect to obtain the secondary etching pattern.

[0053] The calculation method of the secondary etching deviation provided by the present invention includes receiving a secondary etching pattern; the secondary etching pattern includes an overlay calibration pattern and a defect control group obtained through the same overlay, the defect control group includes a defective secondary exposure pattern and a corresponding defect-free reference pattern, and the design line width of all patterns in the same defect control group is the same; the defective secondary exposure pattern is a pattern obtained after the opaque defect formed in the first exposure is repaired through the secondary exposure; the overlay calibration pattern is measured to obtain an alignment error, the defect-free reference pattern is measured to obtain a corresponding reference size value, and then the defective secondary exposure pattern is measured to obtain a corresponding test size value; the alignment error, the reference size value and the test size value are all size values ​​after debonding; according to the alignment error, the reference size value and the test size value, the mask secondary etching deviation value is obtained.

[0054] The success rate of the secondary exposure repair is actually determined by the alignment step in the exposure process and the subsequent etching step. In other words, the alignment step of the secondary exposure repair may have an alignment error. Etching should be performed on this basis, and a secondary etching deviation value should be superimposed. The calculation of the secondary etching deviation value in the traditional technology is actually the calculation of the result after the alignment error of the sample and the secondary etching deviation value are superimposed. Using this result value as the etching deviation value in the subsequent secondary etching process for correction will inevitably not bring too high a repair success rate. In the present invention, an overlay calibration pattern is added to the secondary etching pattern, that is, the alignment error in the secondary exposure repair process can be separated out separately during the measurement and calculation of the secondary etching deviation. Combining the alignment error with the actual final deviation of the two etchings, the deviation caused purely by the misalignment in the secondary etching can be calculated, that is, the mask secondary etching deviation value. Compared with the traditional technology, the accuracy of the mask secondary etching deviation value obtained after eliminating the alignment error will be greatly improved, thereby improving the success rate of the secondary repair. The present invention also provides a secondary etching pattern having the above beneficial effects and a production method thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0056] Figure 1 A schematic flow chart of a specific implementation of a method for calculating a secondary etching deviation provided by the present invention;

[0057] Figure 2 A schematic diagram of the structure of the opaque defect involved in the calculation method of the secondary etching deviation provided by the present invention;

[0058] Figure 3 A schematic diagram of a process flow structure of a specific implementation of a method for calculating a secondary etching deviation provided by the present invention;

[0059] Figure 4 A schematic flow chart of another specific implementation of the method for calculating the secondary etching deviation provided by the present invention;

[0060] Figure 5 A schematic structural diagram of a specific implementation of a device for calculating secondary etching deviation provided by the present invention;

[0061] Figure 6 , Figure 7 A structural schematic diagram of a specific implementation mode of the secondary etching pattern provided by the present invention;

[0062] Figure 8 A schematic flow chart of a specific implementation of the method for producing a secondary etching pattern provided by the present invention;

[0063] Fig. 9 A SEM image diagram of a specific implementation of the method for calculating the secondary etching deviation provided by the present invention;

[0064] Fig.10 A schematic diagram of a process flow structure of a specific implementation of a method for calculating a secondary etching deviation provided by the present invention;

[0065] Fig.11 This is a SEM image of another specific implementation of the method for calculating the secondary etching deviation provided by the present invention.

[0066] In the figure, it includes 100-receiving module, 200-measuring module, and 300-deviation calculation module. DETAILED DESCRIPTION

[0067] In order to enable those skilled in the art to better understand the scheme of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0068] Secondary repair generally includes the following process: first, locate the design pattern according to the coordinates of the defect to be repaired, and obtain the area of ​​the design pattern corresponding to the defect according to the size of the defect (its area must be larger than the actual area of ​​the defect). Then, by comparing the area pattern with the original full-page pattern area, cut out the design pattern of the area to be repaired, and convert it into a file that can be read by the exposure device through the data preparation process (referred to as the secondary exposure file). At the same time, the mask to be repaired is cleaned and re-coated with photoresist. Then, the mask to be repaired is passed through the exposure device and secondary exposure is performed using the secondary exposure file obtained above. The subsequent process is the same as the aforementioned mask production process, which will not be repeated here.

[0069] The core of the present invention is to provide a method for calculating the secondary etching deviation, and a flow chart of a specific implementation method thereof is shown as follows: Figure 1 As shown, it is called specific implementation mode 1, including:

[0070] S101: receiving a secondary etching pattern; the secondary etching pattern comprises an overlay calibration pattern and a defect control group obtained through the same overlay, the defect control group comprises a defective secondary exposure pattern and a corresponding defect-free reference pattern, and the design line width of all patterns in the same defect control group is the same; the defective secondary exposure pattern is a pattern obtained after the opaque defect formed in the first exposure is repaired through secondary exposure.

[0071] The secondary etching pattern includes the pattern after the secondary exposure repair, and before the secondary exposure repair, the pattern after the primary exposure already includes the designed opaque defect.

[0072] Preferably, the overlay calibration pattern is a Box-in-Box pattern, which can more conveniently measure the critical dimensions in two mutually perpendicular directions, and then obtain the alignment error, so as to improve the test efficiency.

[0073] The opaque defects include two design defects: "bridging" and "protrusions", which can be referred to Figure 2 The defect that contains the "bridging" is Figure 2 The a, b, and e figures in the figure contain the "convex" defect. Figure 2 In the c, d, f, and g figures, the opaque defects in the secondary etching pattern include Figure 2 At least one of the a, b, c, d, e, f, and g patterns in the figure (the dot-filled area in the figure represents the opaque defect, the white color represents the transparent area, and the oblique line-filled area represents the opaque area. The same is true for the following figures and will not be repeated hereafter). For the line-shaped pattern, the measurement direction is divided into the horizontal direction (a, c) and the vertical direction (b, d); for the square hole-shaped pattern, the measurement direction is divided into the horizontal direction (e, f) and the vertical direction (e, g), that is, pattern e includes two measurement directions at the same time. In actual production, the aspect ratio of the "bridge" defect is 2:1 for the line-shaped pattern and 1:1 for the square hole-shaped pattern; the aspect ratio of the "protrusion" defect is 4:1 for the line-shaped pattern and 2:1 for the square hole-shaped pattern. Combined with the minimum resolution line width of the exposure equipment and the maximum measurement line width of the line width measurement equipment, the design line width range of the pattern is 0.3 microns to 2 microns. For linear graphics, the design line width is specifically 0.3, 0.4, 0.5, 0.6, 0.8, 1.0, 1.2, 1.5 and 2.0 microns; for square hole graphics, the design line width is specifically 0.4, 0.6, 0.8, 1.2, 1.6 and 2.0 microns. In addition, the unit graphics also include a Chinese-shaped pattern (h), whose line width is a fixed value, specifically 2 microns. The line width range of the opaque defect is set to 0.15 microns to 2 microns according to the field of view (FOV) size of the measurement window of the line width measurement equipment and the minimum line width of the exposure equipment, and its aspect ratio range is 1:1 to 4:1. The line width of the second exposure pattern corresponding to the opaque defect of the design ranges from 0.3 microns to 2 microns, and its aspect ratio range is 2:1 to 5:1 for the line pattern, and its aspect ratio range for the square hole pattern is equal to the aspect ratio range of the first exposure pattern of the same design line width near the location of the opaque defect pattern. The other part of the pattern used to calculate the alignment error is a Chinese-shaped pattern commonly used in the industry, which will not be described here.

[0074] S102: Measure the overlay calibration pattern to obtain an alignment error, measure the defect-free reference pattern to obtain a corresponding reference dimension value, and then measure the defective secondary exposure pattern to obtain a corresponding test dimension value; the alignment error, the reference dimension value and the test dimension value are all dimension values ​​after debonding.

[0075] S103: Obtaining a mask secondary etching deviation value according to the alignment error, the reference dimension value and the test dimension value.

[0076] As a specific implementation, the defect-free reference pattern is a square hole pattern;

[0077] Measuring the overlay calibration pattern to obtain an alignment error, measuring the defect-free reference pattern to obtain a corresponding reference size value, and then measuring the defective secondary exposure pattern to obtain a corresponding test size value, including:

[0078] A1: Measure the overlay calibration pattern to obtain the first direction alignment error and the second direction alignment error, measure the defect-free reference pattern to obtain the corresponding first direction reference dimension value and the second direction reference dimension value, and then measure the defective secondary exposure pattern to obtain the corresponding first direction test dimension value and the second direction test dimension value, wherein the first direction is perpendicular to the second direction.

[0079] The first direction and the second direction can be regarded as the extension directions of two mutually perpendicular sides of the square hole-shaped pattern. Of course, the two adjacent sides of the square hole-shaped pattern may not be perpendicular in actual production, in which case the adjacent sides may not be referenced.

[0080] Correspondingly, according to the alignment error, the reference dimension value and the test dimension value, obtaining the mask secondary etching deviation value includes:

[0081] A2: Obtain the secondary etching deviation value in the first direction according to the alignment error in the first direction, the reference dimension value in the first direction and the test dimension value in the first direction.

[0082] A3: Obtain the second-direction secondary etching deviation value according to the second-direction alignment error, the second-direction reference dimension value and the second-direction test dimension value.

[0083] A4: averaging the secondary etching deviation value in the first direction and the secondary etching deviation value in the second direction to obtain the secondary etching deviation value of the mask corresponding to the square hole pattern.

[0084] In this preferred embodiment, a corresponding solution for performing secondary etching repair on a square hole-shaped pattern is provided, that is, the secondary etching deviation values ​​in two directions perpendicular to each other are calculated respectively, and then the secondary etching deviation value in the first direction and the secondary etching deviation value in the second direction are averaged to obtain the mask secondary etching deviation value corresponding to the square hole-shaped pattern. This specific embodiment will be a square hole-shaped pattern, that is, a pattern that needs to perform key dimension measurement in both the first direction and the second direction, and the corresponding single mask secondary etching deviation value finally obtained can be applied to the two directions of the square hole-shaped pattern in subsequent production. Compared with the conventional technology that does not distinguish between line-shaped patterns and square hole-shaped patterns, this preferred embodiment specifically measures the key dimensions of the square hole-shaped pattern in two perpendicular directions, thereby calculating the secondary etching deviation values ​​in the two directions respectively, and finally determining the mask secondary etching deviation value based on the secondary etching deviation values ​​in the two directions, which greatly improves the calculation accuracy of the mask secondary etching deviation value of the square hole-shaped pattern.

[0085] Furthermore, before measuring the defect secondary exposure pattern to obtain the corresponding test size value, the method further includes:

[0086] B1: Obtain the defect type and the corresponding repair margin direction corresponding to the defective secondary exposure pattern; the repair margin direction is a specific moving direction of the secondary exposure area in the secondary exposure repair, and the offset of the secondary exposure area along the repair margin direction will cause at least one end of the measurement position of the secondary exposure area to move from the opaque area to the transparent area.

[0087] The defect type and the corresponding repair margin direction corresponding to the defect secondary exposure pattern may be preset and stored in the system, or may be obtained through manual or machine recognition, such as directly entering the design information of the secondary etching pattern into the system, so that the program can directly obtain the defect type of the defect at different positions of the secondary etching pattern, and obtain the repair margin direction corresponding to the defect type through the pre-stored defect type-repair margin direction correspondence relationship; or directly determine the corresponding defect type through the pre-trained machine vision model based on the pattern information of the secondary etching pattern obtained by scanning (which may be image information such as a scanning electron microscope image), and then determine the corresponding repair margin direction; it is also possible to directly determine the corresponding defect type and the corresponding repair margin direction from the secondary etching pattern obtained manually from the scanning electron microscope image. Of course, other means can also be used to determine the corresponding defect type and the corresponding repair margin direction according to actual conditions, and the present invention is not limited here. In addition, the area of ​​the secondary exposure area should be larger than the area of ​​the corresponding opaque defect.

[0088] For the repair margin direction, please refer to Figure 3 Further understand a, b, c, and d in the figure. Figure 3 ① is the alignment error size (i.e., REG), and ③ is the average line width measured based on the actual secondary exposure position (i.e., the test size value, CD Test ), ④ is the average line width measured based on the same design line width pattern formed by one exposure at the defect location (i.e., the reference size value, CD Base ). Figure 3 The dotted box indicates where the double exposure area would appear under ideal circumstances (i.e., there is no alignment error), and the solid box indicates where the double exposure area would appear after a shift occurs (mainly due to the alignment error). Figure 3The result of ③ in Figures a, b, and d is equal to the width of the secondary exposure area, and the length of the double-headed arrow corresponding to ③ is equal to the width of the solid-line box. However, Figure c is different. The secondary exposure area in Figure c moves to the right, so that the left edge of the solid-line box moves from the opaque area to the translucent area, and after the subsequent secondary etching, the solid-line box also becomes a translucent area. Therefore, the actual measured ③ from the left is not the left side of the solid-line box, but the boundary between the translucent area and the opaque area. On the left side of the solid-line area, the measured ③ is greater than the width of the solid-line box.

[0089] B2: Determine the moving direction of the secondary exposure area corresponding to the defective secondary exposure pattern according to the secondary etching pattern.

[0090] Of course, when determining the moving direction of the secondary exposure area in this step, only the moving direction in the same direction as the effective critical dimension of the corresponding pattern is considered. Figure 3 For example, although the defect secondary exposure pattern in Figure b moves both to the left and upward, since the corresponding pattern is a linear pattern, only its horizontal movement in the figure is considered, that is, Figure 3 The moving direction of the secondary exposure area corresponding to the middle figure b is leftward.

[0091] Furthermore, according to the secondary etching pattern, determining the moving direction of the secondary exposure area corresponding to the defective secondary exposure pattern includes:

[0092] The moving direction of the secondary exposure area corresponding to the defective secondary exposure pattern is determined according to the alignment error.

[0093] Since an overlay calibration pattern that can characterize the offset direction of the overlay alignment stage is separately set in the secondary etching pattern of the present invention, and usually, the offset distance of the secondary etching area is much smaller than the overlay alignment error, the moving direction of the secondary exposure area can be directly determined based on the alignment error obtained from the overlay calibration pattern, thereby greatly simplifying the calculation process of obtaining the moving direction of the secondary exposure area, reducing the difficulty of acquisition, and improving calculation efficiency.

[0094] B3: Determine whether the moving direction of the secondary exposure area is the repair margin direction.

[0095] B4: When the moving direction of the secondary exposure area is the repair margin direction, the secondary etching deviation value of the mask is obtained according to the alignment error, the reference size value and the test size value, including:

[0096] The mask secondary etching deviation value is obtained by the following formula (1):

[0097] CD SR Etch Bias =(CDTest -CD Base -REG)*2; (1)

[0098] Among them, CD SR Etch Bias is the secondary etching deviation value of the mask, CD Test For the test size value, CD Base is the reference dimension value, and REG is the alignment error.

[0099] Please continue to refer to Figure 3 When the moving direction of the secondary exposure area is the repair margin direction, it means that at least one end of the measurement position of the secondary exposure area moves from the opaque area to the transparent area. For the machine for measuring the critical dimension, only the edge position of the transparent area and the opaque area is used as the starting point and the end point. This makes the edge lines of the transparent area and the opaque area at both ends of the critical dimension measured by the machine not the real edge of the secondary exposure area. The critical dimension of the transparent area actually measured is larger than the critical dimension of the secondary exposure area. Figure 3 It is easy to see from Figure c in that the mask secondary etching deviation value at this time should conform to the above formula (1).

[0100] In addition, after determining whether the moving direction of the secondary exposure area is the repair margin direction, the method further includes:

[0101] B5: When the moving direction of the secondary exposure area is not the repair margin direction, the secondary etching deviation value of the mask is obtained according to the alignment error, the reference size value and the test size value, including:

[0102] The mask secondary etching deviation value is obtained by the following formula (2):

[0103] CD SR Etch Bias =CD Test -CD Base ; (2)

[0104] Among them, CD SR Etch Bias is the secondary etching deviation value of the mask, CD Test For the test size value, CD Base is the reference size value.

[0105] Of course, steps B4 and B5 are two situations after judging step B3, and there is no order of precedence between B4 and B5.

[0106] The situation in step B5 corresponds to Figure 3In the case of Figure a, Figure b and Figure d, the key size of the defect-free reference figure (that is, the reference size value) and the key size of the defective secondary exposure figure (that is, the test size value) can be directly obtained on the figure. Therefore, after obtaining the corresponding sizes, the corresponding mask secondary etching deviation value can be obtained by directly subtracting them. This way, the calculation power is low, the calculation speed is fast, and the processing efficiency is high.

[0107] It should be noted that the dimension values ​​(also called line width) obtained in the above process are all line widths (dimensional values) after stripping (After Strip Inspection CD, ASI CD).

[0108] The calculation method of the secondary etching deviation provided by the present invention includes receiving a secondary etching pattern; the secondary etching pattern includes an overlay calibration pattern and a defect control group obtained through the same overlay, the defect control group includes a defective secondary exposure pattern and a corresponding defect-free reference pattern, and the design line width of all patterns in the same defect control group is the same; the defective secondary exposure pattern is a pattern obtained after the opaque defect formed in the first exposure is repaired through secondary exposure; the overlay calibration pattern is measured to obtain an alignment error, the defect-free reference pattern is measured to obtain a corresponding reference size value, and then the defective secondary exposure pattern is measured to obtain a corresponding test size value; the alignment error, the reference size value and the test size value are all size values ​​after degumming; according to the alignment error, the reference size value and the test size value, the mask secondary etching deviation value is obtained. The success rate of the secondary exposure repair is actually determined by the alignment step in the exposure process and the subsequent etching step. In other words, the alignment step of the secondary exposure repair may result in an alignment error. Etching on this basis should also require the addition of a secondary etching deviation value. The calculation of the secondary etching deviation value in the traditional technology is actually the calculation of the result of superimposing the alignment error of the sample and the secondary etching deviation value. Using this result value as the etching deviation value in the subsequent secondary etching process for correction will inevitably not bring too high a repair success rate. In the present invention, an overlay calibration pattern is added to the secondary etching pattern, that is, the alignment error in the secondary exposure repair process can be separated out separately during the measurement and calculation of the secondary etching deviation. Combining the alignment error with the actual final deviation of the two etchings, the deviation caused purely by the misalignment in the secondary etching can be calculated, that is, the mask secondary etching deviation value. Compared with the traditional technology, the accuracy of the mask secondary etching deviation value obtained after eliminating the alignment error will be greatly improved, thereby improving the success rate of the secondary repair.

[0109] On the basis of the first specific implementation mode, the information on the secondary etching pattern is further limited to obtain the second specific implementation mode, and the corresponding flow chart is as follows: Figure 4 As shown, including:

[0110] S201: receiving a secondary etching pattern; the secondary etching pattern includes an overlay calibration pattern and a defect control group, the defect control group includes a defective secondary exposure pattern and a corresponding defect-free reference pattern, and the design line width of all patterns in the same defect control group is the same; the defective secondary exposure pattern is a pattern obtained after the opaque defect formed in the first exposure is repaired by secondary exposure; the secondary etching pattern includes defect control groups with multiple different design line widths.

[0111] S202: measuring the overlay calibration pattern to obtain an alignment error, measuring the defect-free reference pattern to obtain a corresponding reference size value, and then measuring the defective secondary exposure pattern to obtain a corresponding test size value.

[0112] S203: Obtaining the group secondary etching deviation value corresponding to each defect control group according to the alignment error, the reference size value and the test size value in the same defect control group.

[0113] S204: averaging the secondary etching deviation values ​​of all defect control groups corresponding to the group to obtain the mask secondary etching deviation value.

[0114] The difference between this specific implementation and the above-mentioned specific implementation (i.e., specific implementation one) is that, in this specific implementation, a more accurate method for calculating the mask secondary etching deviation value is proposed for a defect control group with a variety of design line widths, and the remaining steps are the same as the above-mentioned specific implementation and will not be repeated here.

[0115] In this preferred embodiment, a plurality of defect control groups with different line widths are set on the secondary etching pattern to test whether the corresponding mask secondary etching deviation value changes under different line width conditions, and at the same time make the final mask secondary etching deviation value more representative, so as to maintain a high repair success rate when actually repairing a plurality of patterns with different line widths. For example, assuming that three defect control groups are set in the secondary etching pattern, and the design line widths of the three defect control groups are 50 nanometers, 10 nanometers and 20 nanometers respectively, the secondary etching deviation values ​​of each defect control group are calculated respectively as the secondary etching deviation value of the group, for example, the secondary etching deviation value corresponding to the 50 nanometer group is 3 nanometers, the secondary etching deviation value corresponding to the 10 nanometer group is 4 nanometers, and the secondary etching deviation value corresponding to the 20 nanometer group is 5 nanometers. Finally, the secondary etching deviation values ​​of all groups are averaged, and the obtained mask secondary etching deviation value is (3+4+5) / 3=4 nanometers.

[0116] Furthermore, in the same defect control group, a plurality of defect secondary exposure patterns and a plurality of non-defective reference patterns are included;

[0117] Obtaining the mask secondary etching deviation value according to the alignment error, the reference dimension value and the test dimension value includes:

[0118] C1: Calculate the average value of the reference size values ​​of all defect-free reference patterns in the same defect control group as the average reference size value within the group; calculate the average value of the test size values ​​of all defective secondary exposure patterns in the same defect control group as the average test size value within the group.

[0119] C2: Obtaining a mask secondary etching deviation value according to the alignment error, the average reference dimension value within the group and the average test dimension value within the group.

[0120] In this preferred embodiment, a plurality of defect-free reference patterns and defective secondary exposure patterns are further set in the defect control group. Of course, the number of defect-free reference patterns and defective secondary exposure patterns in the same group can be the same, such as setting 3 defect-free reference patterns and 3 defective secondary exposure patterns, or they can be different, such as setting 5 defect-free reference patterns and 4 defective secondary exposure patterns. The present invention does not limit this. In this preferred embodiment, a plurality of defect-free reference patterns and defective secondary exposure patterns are further set in the same defect control group, so that each line width pattern can first calculate its own average value, and then use the calculated average value to represent the reference size value and test size value of the corresponding pattern. The representativeness and accuracy of the secondary etching deviation value of the mask are further improved, the accidental errors caused by the exposure and subsequent measurement process are reduced, and the large errors in the secondary etching deviation value of the mask due to the deviation of the etching of individual patterns are avoided, and the test stability is further improved.

[0121] The following is an introduction to a calculation device for a secondary etching deviation provided by an embodiment of the present invention. The calculation device for a secondary etching deviation described below and the calculation method for a secondary etching deviation described above can be referred to each other.

[0122] Figure 5 The structural block diagram of the calculation device of the secondary etching deviation provided by the embodiment of the present invention is referred to as the specific implementation mode three, and the reference Figure 5 The device may include:

[0123] The receiving module 100 is used to receive a secondary etching pattern; the secondary etching pattern includes an overlay calibration pattern obtained by the same overlay and a defect control group, the defect control group includes a defective secondary exposure pattern and a corresponding non-defective reference pattern, and the design line width of all patterns in the same defect control group is the same; the defective secondary exposure pattern is a pattern obtained after the opaque defect formed in the first exposure is repaired by the secondary exposure;

[0124] The measuring module 200 is used to measure the overlay calibration pattern to obtain an alignment error, measure the defect-free reference pattern to obtain a corresponding reference dimension value, and then measure the defective secondary exposure pattern to obtain a corresponding test dimension value; the alignment error, the reference dimension value and the test dimension value are all dimension values ​​after debonding;

[0125] The deviation calculation module 300 is used to obtain the mask secondary etching deviation value according to the alignment error, the reference dimension value and the test dimension value.

[0126] As a preferred implementation, the defect-free reference pattern is a square hole pattern; the measurement module 200 includes:

[0127] A vertical direction measurement unit, used for measuring the overlay calibration pattern to obtain a first direction alignment error and a second direction alignment error, measuring the defect-free reference pattern to obtain a corresponding first direction reference size value and a second direction reference size value, and then measuring the defective secondary exposure pattern to obtain a corresponding first direction test size value and a second direction test size value, wherein the first direction is perpendicular to the second direction;

[0128] Accordingly, the deviation calculation module 300 includes:

[0129] A first direction calculation unit, used for obtaining a first direction secondary etching deviation value according to the first direction alignment error, the first direction reference dimension value and the first direction test dimension value;

[0130] A second direction calculation unit, used for obtaining a second-direction secondary etching deviation value according to the second-direction alignment error, the second-direction reference dimension value and the second-direction test dimension value;

[0131] The vertical direction averaging unit is used to average the secondary etching deviation value in the first direction and the secondary etching deviation value in the second direction to obtain the secondary etching deviation value of the mask corresponding to the square hole-shaped pattern.

[0132] As a preferred implementation, the deviation calculation module 300 further includes:

[0133] A defect information unit, used to obtain the defect type and the corresponding repair margin direction corresponding to the defective secondary exposure pattern; the repair margin direction is a specific moving direction of the secondary exposure area in the secondary exposure repair, and the offset of the secondary exposure area along the repair margin direction will cause at least one end of the measurement position of the secondary exposure area to move from the opaque area to the translucent area;

[0134] A region moving unit, used for determining a moving direction of a secondary exposure region corresponding to the defective secondary exposure pattern according to the secondary etching pattern;

[0135] A direction judging unit, used for judging whether the moving direction of the secondary exposure area is the repair margin direction;

[0136] Accordingly, the deviation calculation module 300 includes:

[0137] The alignment error correction calculation unit is used to obtain the mask secondary etching deviation value by the following formula when the moving direction of the secondary exposure area is the repair margin direction:

[0138] CD SR Etch Bias =(CD Test -CD Base -REG)*2;

[0139] Among them, CD SR Etch Bias is the secondary etching deviation value of the mask, CD Test For the test size value, CD Base is the reference dimension value, and REG is the alignment error.

[0140] As a preferred implementation, the deviation calculation module 300 further includes:

[0141] A direct calculation unit, used for obtaining the mask secondary etching deviation value according to the alignment error, the reference size value and the test size value when the moving direction of the secondary exposure area is not the repair margin direction, includes:

[0142] The mask secondary etching deviation value is obtained by the following formula:

[0143] CD SR Etch Bias =CD Test -CD Base ;

[0144] Among them, CD SR Etch Bias is the secondary etching deviation value of the mask, CD Test For the test size value, CD Base is the reference size value.

[0145] As a preferred implementation, the deviation calculation module 300 includes:

[0146] The alignment error deviation unit is used to determine the moving direction of the secondary exposure area corresponding to the defective secondary exposure pattern according to the alignment error.

[0147] As a preferred implementation, the deviation calculation module 300 includes:

[0148] A group deviation calculation unit is used to obtain a group secondary etching deviation value corresponding to each defect control group in the secondary etching pattern (including different defect control groups of multiple design line widths) according to the alignment error, the reference size value and the test size value in the same defect control group;

[0149] The group averaging unit is used to average the group secondary etching deviation values ​​corresponding to all defect control groups to obtain the mask secondary etching deviation value.

[0150] As a preferred implementation, the deviation calculation module 300 includes:

[0151] The intra-group deviation calculation unit is used to calculate the average value of the reference size values ​​of all the non-defective reference patterns in the same defect control group, including a plurality of the defective secondary exposure patterns and a plurality of the non-defective reference patterns, as the intra-group average reference size value; calculate the average value of the test size values ​​of all the defective secondary exposure patterns in the same defect control group as the intra-group average test size value;

[0152] The intra-group averaging unit is used to obtain the mask secondary etching deviation value according to the alignment error, the intra-group average reference size value and the intra-group average test size value.

[0153] The calculation device of the secondary etching deviation provided by the present invention includes a receiving module 100, which is used to receive the secondary etching pattern; the secondary etching pattern includes an overlay calibration pattern obtained by the same overlay and a defect control group, the defect control group includes a defective secondary exposure pattern and a corresponding non-defective reference pattern, and the design line width of all patterns in the same defect control group is the same; the defective secondary exposure pattern is a pattern obtained after the opaque defect formed in the first exposure is repaired by the secondary exposure; a measuring module 200 is used to measure the overlay calibration pattern to obtain an alignment error, measure the non-defective reference pattern to obtain a corresponding reference size value, and then measure the defective secondary exposure pattern to obtain a corresponding test size value; the alignment error, the reference size value and the test size value are all size values ​​after debonding; a deviation calculation module 300 is used to obtain the mask secondary etching deviation value according to the alignment error, the reference size value and the test size value. The success rate of the secondary exposure repair is actually determined by the alignment step in the exposure process and the subsequent etching step. In other words, the alignment step of the secondary exposure repair may have an alignment error. Etching on this basis should also require the addition of a secondary etching deviation value. The calculation of the secondary etching deviation value in the traditional technology is actually the calculation of the result of superimposing the alignment error of the sample and the secondary etching deviation value. Using this result value as the etching deviation value in the subsequent secondary etching process for correction will inevitably not bring too high a repair success rate. In the present invention, an overlay calibration pattern is added to the secondary etching pattern, that is, the alignment error in the secondary exposure repair process can be separated out separately during the measurement and calculation of the secondary etching deviation. Combining the alignment error with the actual final deviation of the two etchings, the deviation caused purely by the misalignment in the secondary etching can be calculated, that is, the mask secondary etching deviation value. Compared with the traditional technology, the accuracy of the mask secondary etching deviation value obtained after eliminating the alignment error will be greatly improved, thereby improving the success rate of the secondary repair.

[0154] The calculation device of the secondary etching deviation of this embodiment is used to implement the calculation method of the secondary etching deviation described above, so the specific implementation of the calculation device of the secondary etching deviation can be seen in the embodiment of the calculation method of the secondary etching deviation described above. For example, the receiving module 100, the measuring module 200, and the deviation calculation module 300 are respectively used to implement steps S101, S102, and S103 in the calculation method of the secondary etching deviation described above. Therefore, its specific implementation can refer to the description of the corresponding embodiments of each part, and will not be repeated here.

[0155] The present invention also provides a device for calculating a mask secondary etching deviation, comprising:

[0156] Memory for storing computer programs;

[0157] A processor is used to implement the steps of the method for calculating the secondary etching deviation as described in any one of the above when executing the computer program. The method for calculating the secondary etching deviation provided by the present invention includes receiving a secondary etching pattern; the secondary etching pattern includes an overlay calibration pattern and a defect control group obtained through the same overlay, the defect control group includes a defective secondary exposure pattern and a corresponding non-defective reference pattern, and the design line width of all patterns in the same defect control group is the same; the defective secondary exposure pattern is a pattern obtained after the opaque defect formed in the first exposure is repaired through the secondary exposure; the overlay calibration pattern is measured to obtain an alignment error, the non-defective reference pattern is measured to obtain a corresponding reference size value, and then the defective secondary exposure pattern is measured to obtain a corresponding test size value; the alignment error, the reference size value and the test size value are all size values ​​after degumming; the mask secondary etching deviation value is obtained according to the alignment error, the reference size value and the test size value. The success rate of the secondary exposure repair is actually determined by the alignment step in the exposure process and the subsequent etching step. In other words, the alignment step of the secondary exposure repair may have an alignment error. Etching should be performed on this basis, and a secondary etching deviation value should be superimposed. The calculation of the secondary etching deviation value in the traditional technology is actually the calculation of the result after the alignment error of the sample and the secondary etching deviation value are superimposed. Using this result value as the etching deviation value in the subsequent secondary etching process for correction will inevitably not bring too high a repair success rate. In the present invention, an overlay calibration pattern is added to the secondary etching pattern, that is, the alignment error in the secondary exposure repair process can be separated out separately during the measurement and calculation of the secondary etching deviation. Combining the alignment error with the actual final deviation of the two etchings, the deviation caused purely by the misalignment in the secondary etching can be calculated, that is, the mask secondary etching deviation value. Compared with the traditional technology, the accuracy of the mask secondary etching deviation value obtained after eliminating the alignment error will be greatly improved, thereby improving the success rate of the secondary repair.

[0158] The present invention also provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the steps of the method for calculating the secondary etching deviation described in any one of the above can be implemented. The method for calculating the secondary etching deviation provided by the present invention includes receiving a secondary etching pattern; the secondary etching pattern includes an overlay calibration pattern obtained by the same overlay and a defect control group, the defect control group includes a defective secondary exposure pattern and a corresponding non-defective reference pattern, and the design line width of all patterns in the same defect control group is the same; the defective secondary exposure pattern is a pattern obtained after the opaque defect formed in the first exposure is repaired by the secondary exposure; the overlay calibration pattern is measured to obtain an alignment error, the non-defective reference pattern is measured to obtain a corresponding reference size value, and then the defective secondary exposure pattern is measured to obtain a corresponding test size value; the alignment error, the reference size value and the test size value are all size values ​​after degumming; according to the alignment error, the reference size value and the test size value, the mask secondary etching deviation value is obtained. The success rate of the secondary exposure repair is actually determined by the alignment step in the exposure process and the subsequent etching step. In other words, the alignment step of the secondary exposure repair may have an alignment error. Etching should be performed on this basis, and a secondary etching deviation value should be superimposed. The calculation of the secondary etching deviation value in the traditional technology is actually the calculation of the result after the alignment error of the sample and the secondary etching deviation value are superimposed. Using this result value as the etching deviation value in the subsequent secondary etching process for correction will inevitably not bring too high a repair success rate. In the present invention, an overlay calibration pattern is added to the secondary etching pattern, that is, the alignment error in the secondary exposure repair process can be separated out separately during the measurement and calculation of the secondary etching deviation. Combining the alignment error with the actual final deviation of the two etchings, the deviation caused purely by the misalignment in the secondary etching can be calculated, that is, the mask secondary etching deviation value. Compared with the traditional technology, the accuracy of the mask secondary etching deviation value obtained after eliminating the alignment error will be greatly improved, thereby improving the success rate of the secondary repair.

[0159] The present invention also provides a secondary etching pattern, a structural schematic diagram of a specific implementation method thereof is shown as follows: Figure 6 and Figure 7 As shown, it is called specific implementation mode 4, the secondary etching pattern is used for the calculation method of the secondary etching deviation as described in any one of the above, including the overlay calibration pattern and the defect control group obtained by the same overlay;

[0160] The defect control group includes defective secondary exposure patterns and corresponding non-defective reference patterns, and all patterns in the defect control group have the same design line width;

[0161] The defective secondary exposure pattern is a pattern obtained after the opaque defect formed in the first exposure is repaired by secondary exposure.

[0162] The secondary etching pattern provided in this specific embodiment is used in the calculation method of the secondary etching deviation in the previous text. The specific technical details can be referred to in the previous text and will not be described in detail here.

[0163] As a preferred embodiment, all the pattern arrays in the same defect control group are arranged to form a corresponding pattern to be tested;

[0164] The locations of the setting areas for different defect control groups do not overlap;

[0165] or

[0166] The secondary etching pattern includes a defect area and a reference area; the position of the defect area does not overlap with the position of the reference area;

[0167] All defect secondary exposure patterns of the defect control group are located in the defect area, and all non-defect reference patterns of the defect control group are located in the reference area.

[0168] This preferred embodiment provides two distribution schemes of defective secondary exposure patterns and non-defective reference patterns. Figure 6 and Figure 7 ,like Figure 6 As shown, in a preferred embodiment including defective areas and reference areas, all defective secondary exposure patterns are separately arranged from all non-defective reference patterns, which reduces the possibility of affecting the process of surrounding non-defective reference patterns when defects are arranged in the defective secondary exposure patterns, further improves the pattern quality, and makes the final pattern more in line with the design expectations; and another preferred embodiment in which different areas are arranged with the defective control group as a unit is closer to the actual situation, as shown in FIG. Figure 7 As shown, the graphics of the same defect control group are all set in the same area, which can greatly reduce the difficulty of data acquisition and program compilation during measurement, save computing power and make the final data more representative.

[0169] The calculation method of the secondary etching deviation provided by the present invention includes receiving a secondary etching pattern; the secondary etching pattern includes an overlay calibration pattern and a defect control group obtained through the same overlay, the defect control group includes a defective secondary exposure pattern and a corresponding defect-free reference pattern, and the design line width of all patterns in the same defect control group is the same; the defective secondary exposure pattern is a pattern obtained after the opaque defect formed in the first exposure is repaired through secondary exposure; the overlay calibration pattern is measured to obtain an alignment error, the defect-free reference pattern is measured to obtain a corresponding reference size value, and then the defective secondary exposure pattern is measured to obtain a corresponding test size value; the alignment error, the reference size value and the test size value are all size values ​​after degumming; according to the alignment error, the reference size value and the test size value, the mask secondary etching deviation value is obtained. The success rate of the secondary exposure repair is actually determined by the alignment step in the exposure process and the subsequent etching step. In other words, the alignment step of the secondary exposure repair may result in an alignment error. Etching on this basis should also require the addition of a secondary etching deviation value. The calculation of the secondary etching deviation value in the traditional technology is actually the calculation of the result of superimposing the alignment error of the sample and the secondary etching deviation value. Using this result value as the etching deviation value in the subsequent secondary etching process for correction will inevitably not bring too high a repair success rate. In the present invention, an overlay calibration pattern is added to the secondary etching pattern, that is, the alignment error in the secondary exposure repair process can be separated out separately during the measurement and calculation of the secondary etching deviation. Combining the alignment error with the actual final deviation of the two etchings, the deviation caused purely by the misalignment in the secondary etching can be calculated, that is, the mask secondary etching deviation value. Compared with the traditional technology, the accuracy of the mask secondary etching deviation value obtained after eliminating the alignment error will be greatly improved, thereby improving the success rate of the secondary repair.

[0170] The present invention also provides a method for producing a secondary etching pattern, a flow chart of a specific implementation method thereof is as follows: Figure 8 As shown, it is called specific implementation mode five, and the secondary etching pattern as described above is obtained by the production method of the secondary etching pattern, including:

[0171] S301: Laying a layer to be etched on a transparent substrate.

[0172] S302: Laying a photoresist layer on the surface of the layer to be etched, and performing exposure, baking, development, etching and de-gumming once to transform the layer to be etched into a patterned primary etching layer; the primary etching layer includes a defect-free reference pattern and a corresponding defect pattern; and an opaque defect is arranged on the defect pattern.

[0173] S303: Laying a photoresist layer on the surface of the primary etching layer, and performing secondary exposure, baking, development, etching and de-bonding to etch away the area corresponding to the opaque defect to obtain the secondary etching pattern.

[0174] The secondary etching pattern described above can be obtained by the method for producing the secondary etching pattern provided in this specific embodiment. The specific details can be referred to above, and the present invention will not be repeated here.

[0175] As mentioned above, the mask substrate is subjected to a process of exposure, baking, development, etching and degumming to obtain a primary etching layer, and then the substrate is re-coated with photoresist, and then subjected to a secondary exposure, baking, development, secondary etching and degumming process to obtain a secondary etching pattern to form the final substrate. Specifically, it includes three parts: ① The layer to be etched (i.e., defective layer) formed by the primary exposure pattern and multiple mask patterns formed on the layer to be etched; ② The etching layer formed by the secondary exposure and multiple mask patterns formed on the etching layer; ③ The U-shaped mask pattern formed by the primary exposure and the secondary exposure (i.e., the overlay calibration pattern). It should be noted that the etching deviation defined in the exposure file (including primary exposure and secondary exposure) corresponding to the mask pattern formed by the above process is all 0, that is, the interference of etching deviation correction is not added by default, and the mask patterns formed by the above process are all patterns after degumming. The material of the above-mentioned layer to be etched (i.e., the defective layer) is metal chromium (Cr) or chromium oxide (CrOx), and the material of the etching layer (i.e., the transparent area exposed after etching) is quartz. The etching process is carried out by dry etching, and positive photoresist (Positive Pr) is used as the photoresist material of the mask substrate.

[0176] The calculation method of the secondary etching deviation provided by the present invention includes receiving a secondary etching pattern; the secondary etching pattern includes an overlay calibration pattern and a defect control group obtained through the same overlay, the defect control group includes a defective secondary exposure pattern and a corresponding defect-free reference pattern, and the design line width of all patterns in the same defect control group is the same; the defective secondary exposure pattern is a pattern obtained after the opaque defect formed in the first exposure is repaired through secondary exposure; the overlay calibration pattern is measured to obtain an alignment error, the defect-free reference pattern is measured to obtain a corresponding reference size value, and then the defective secondary exposure pattern is measured to obtain a corresponding test size value; the alignment error, the reference size value and the test size value are all size values ​​after degumming; according to the alignment error, the reference size value and the test size value, the mask secondary etching deviation value is obtained. The success rate of the secondary exposure repair is actually determined by the alignment step in the exposure process and the subsequent etching step. In other words, the alignment step of the secondary exposure repair may result in an alignment error. Etching on this basis should also require the addition of a secondary etching deviation value. The calculation of the secondary etching deviation value in the traditional technology is actually the calculation of the result of superimposing the alignment error of the sample and the secondary etching deviation value. Using this result value as the etching deviation value in the subsequent secondary etching process for correction will inevitably not bring too high a repair success rate. In the present invention, an overlay calibration pattern is added to the secondary etching pattern, that is, the alignment error in the secondary exposure repair process can be separated out separately during the measurement and calculation of the secondary etching deviation. Combining the alignment error with the actual final deviation of the two etchings, the deviation caused purely by the misalignment in the secondary etching can be calculated, that is, the mask secondary etching deviation value. Compared with the traditional technology, the accuracy of the mask secondary etching deviation value obtained after eliminating the alignment error will be greatly improved, thereby improving the success rate of the secondary repair.

[0177] The following is a complete process for calculating the secondary etching deviation in actual production as a specific embodiment, including:

[0178] Step 1.1: Provide a substrate.

[0179] As described in the background technology, the mask substrate is subjected to a process of exposure, baking, development, etching and degumming to obtain a first exposure pattern, and then the substrate is re-coated with photoresist, and then subjected to a second exposure, baking, development, second etching and degumming process to obtain a second exposure pattern to form the final substrate. Specifically, it includes three parts: first, the layer to be etched (i.e., the defective layer) formed by the first exposure pattern and a plurality of mask patterns formed on the layer to be etched; second, the etching layer formed by the second exposure and a plurality of mask patterns formed on the etching layer; third, the U-shaped mask pattern formed by the first exposure and the second exposure. It should be noted that the etching deviation defined in the exposure file (including the first exposure and the second exposure) corresponding to the mask pattern formed by the above process is 0, and the mask patterns formed by the above process are all patterns after degumming. In addition, the exposure pattern defined in the second exposure file has multiple layers (in this embodiment, there are 9 layers in total), and each layer of the second exposure pattern corresponds to a defective pattern formed by the first exposure and a U-shaped pattern.

[0180] Step 1.2: Obtain actual measured values ​​of different designed line widths of the substrate described in step 1.1.

[0181] Step 1.1 The substrate includes multiple measurement patterns, which are measured using a line width scanning electron microscope (Critical Dimension Scanning Electronic Microscope, CDSEM) to obtain the measurement line width of the corresponding pattern. Specifically, it includes two parts: first, the line width average value of multiple measurement patterns of the same design line width formed after one exposure (i.e., defect-free reference pattern) is obtained, and this value is used as the reference value (recorded as CDSEM). Base ); second, obtain the average line width of multiple measurement patterns of the same design line width formed after the secondary exposure (the pattern is located at the pattern after the secondary etching, that is, the defective secondary exposure pattern), and use this value as the test value 1 (recorded as CD Test It should be noted that the line widths obtained by the above measurement patterns are all the line widths after stripping (ASI CD). The SEM images are shown in Fig. 9 As shown, a total of 8 cases are given. Fig. 9 The eight cases (1), (2), (3), (4), (5), (6), (7), and (8) correspond to Figure 2 In the cases c, a, e, f, d, b, e, and g, the positions outlined by the white dotted lines are the positions of the corresponding defects.

[0182] Step 1.3: Obtain the marking difference (REG) obtained from the U-shaped mask pattern of the substrate described in step 1.1, and use this value as the alignment error, recorded as test value 2 (expressed as REG).

[0183] Step 1.4: Subtract the reference value from the test value 1 in step 1.2, and subtract the test value 2 in step 1.3 according to the actual alignment deviation, and you can get the deviation values ​​of different designed line widths in two directions (X and Y). Then calculate the average value of the deviation values ​​of the above different designed line widths (calculate the average values ​​in the two directions together), and use this value as the final mask secondary etching deviation value (recorded as CD SR Etch Bias ). It should be noted that the exposure equipment has corresponding line width linearity (CD Linearity, which refers to the deviation trend between the actual CD measurement value and the design value of different target value graphics at the same graphic density) for different types of graphics. The corresponding minimum design line width within its allowable range is 0.5 microns for the linear graphics in this embodiment; and 0.6 microns for the square hole graphics. Therefore, the "calculation of the average value of the deviation value of different design line widths" described in this step needs to be greater than or equal to 0.5 microns for the linear graphics, and greater than or equal to 0.6 microns for the square hole graphics.

[0184] The calculation method described in step 1.4 is further described below with reference to a specific schematic diagram.

[0185] The alignment error of the double exposure can be divided into four directions: left or right (horizontal direction X), upward or downward (vertical direction Y). Combined with the pattern type (line and square hole) and defect type (bridge and protrusion) in this embodiment, it can be divided into 8 types in the horizontal direction and vertical direction respectively. The horizontal direction X is taken as an example for explanation below, and the vertical direction is the same as the horizontal direction.

[0186] Please refer to Figure 3 , the figure shows four actual situations of secondary etching deviation of line-shaped patterns. a and b are for bridging defects, c and d are for protrusion defects (the alignment error direction of a and c is to the right, and the alignment error direction of b and d is to the left); ① is the alignment error size (i.e. REG), ③ is the average line width measured based on the actual secondary exposure position (i.e. the test size value, CD Test ), ④ is the average line width measured based on the same design line width pattern formed by one exposure at the defect location (i.e., the reference size value, CD Base ), the same applies to Fig.10 , which will not be described in detail later. x1, x2, x3 and x4 are the single-sided secondary etching deviations corresponding to the above four situations a, b, c and d, respectively. Figure 3 The following formula (I) and formula (II) can be obtained:

[0187] x1 = x2 = x4 = 0.5*(CD Test -CD Base ); (I)

[0188] x3= CD Test -CD Base -REG; (II)

[0189] Please refer to Fig.10 , which shows four actual situations of secondary etching deviation of square hole pattern. Figure 3 x5, x6, x7 and x8 are the single-sided secondary etching deviations corresponding to the four situations a, b, c and d respectively. Fig.10 The following formulas (III) and (IV) can be obtained:

[0190] x8 = 0.5*(CD Test -CD Base ); (III)

[0191] x5 = x6 = x7 = CD Test -CD Base -REG; (IV)

[0192] In summary, the secondary etching deviation calculation method described in step 1.4 can be described by the following formula (V) and formula (VI):

[0193] ; (V)

[0194] ; (VI)

[0195] Where n is the type of different design line widths, that is, the number of defect control groups; Formula (V) corresponds to Figure 3 Figure a, Figure b and Figure d in Fig.10 Figure d in formula (VI) corresponds to Fig.10 Figure a, Figure b, Figure c, and Figure 3 In the present embodiment, there are 7 types of line-shaped patterns, and the line width is greater than or equal to 0.5 micrometers; there are 5 types of square hole-shaped patterns, and the line width is greater than or equal to 0.6 micrometers.

[0196] The secondary etching deviation results calculated through the above steps are shown in Table 1.

[0197] Table 1 Secondary etching deviation results of different types of patterns

[0198] Pattern Type Design line width (micrometer) Secondary etching deviation (micrometer) Linear bridge pattern ≥0.5 0.0342 Linear raised pattern ≥0.5 0.0490 Square hole bridge pattern ≥0.6 0.0463 Square hole convex pattern ≥0.6 0.0547

[0199] In order to make the etching deviation added to the secondary exposure file more applicable when the subsequent product is repaired for the second time, the secondary etching deviation in the above table is calculated according to the line and square hole types. For the line pattern, the final secondary etching deviation is 0.0416 microns; for the square hole pattern, the final secondary etching deviation is 0.0505 microns.

[0200] The following is another embodiment of a process for verifying the actual pattern of the mask of the secondary etching deviation obtained in the above embodiment, including:

[0201] Step 2.1: Provide a substrate.

[0202] As mentioned above, there are a total of 9 layers of secondary exposure patterns in the above embodiment, among which one layer of secondary exposure patterns has been used in step 1.1. Next, the substrate in the above step 1.1 is re-coated with positive photoresist, and then another layer of secondary exposure pattern (not limited to which specific layer) is used for secondary exposure again. After completion, baking, development, etching and degumming are performed to form a new etching layer and multiple mask patterns formed on the new etching layer. At the same time, a new layer of U-shaped mask patterns is formed. It should be noted that the etching deviation defined in the secondary exposure file corresponding to the new etching layer formed in the above process is not all 0, and its specific values ​​are shown in Table 2. In addition, the condition parameters used in each process section of the above process are exactly the same as those in step 1.1.

[0203] Table 2 Deviation values ​​defined in the exposure file for different types of patterns

[0204] Pattern Type Etch deviation defined in the double exposure file (micrometers) Line graphics -0.0416 Square hole pattern -0.0505 Hui-shaped pattern 0

[0205] Step 2.2: Obtain actual measured values ​​of different designed line widths of the substrate described in step 2.1.

[0206] The specific implementation of this step is the same as step 1.2. It should be noted that this time, only the average line width of multiple measurement patterns of the same design line width of the new etched layer formed in step 2.1 (located at the new pattern after the secondary etching) needs to be obtained, and this value is used as the new test value 1 (recorded as CD New Test ). It should be noted that the above line widths are also the line widths after stripping (ASI CD), and the SEM images are as follows Fig.11 As shown, the same is given as Fig. 9 8 situations.

[0207] Step 2.3: Obtain the new marking difference (REG) obtained from the new U-shaped pattern of the substrate described in step 2.1, and use this value as the new alignment error, recorded as the new test value 2 (expressed as REG New ).

[0208] Step 2.4: Calculate the new test value 1 and the new test value 2 obtained in step 2.2 and step 2.3 with reference to the calculation method of the secondary etching deviation described in step 1.4. It should be noted that the reference value used in this step is the same as the reference value obtained in step 1.2. The final etching deviation result is shown in Table 3. It can be found that after adding the deviation value described in Table 2 to the exposure file, the final secondary etching deviation value is less than 0.01 microns. This shows that the secondary etching calculation method described in the present invention is effective.

[0209] Table 3 Secondary etching deviation results of different types of patterns 2

[0210] Pattern Type Design line width (micrometer) Secondary etching deviation (micrometer) Linear bridge pattern ≥0.5 -0.0063 Linear raised pattern ≥0.5 -0.0033 Square hole bridge pattern ≥0.6 0.0048 Square hole convex pattern ≥0.6 -0.0096

[0211] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0212] It should be noted that, in this specification, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0213] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether these functions are specifically performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0214] The steps of the method or algorithm described in conjunction with the embodiments disclosed herein may be implemented directly using hardware, a software module executed by a processor, or a combination of the two. The software module may be placed in a random access memory (RAM), a memory, a read-only memory (ROM), an electrically programmable ROM, an electrically erasable programmable ROM, a register, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.

[0215] The calculation method of the secondary etching deviation, the secondary etching pattern and the production method thereof provided by the present invention are introduced in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications should also fall within the scope of protection of the present invention.

Claims

1. A method for calculating secondary etching deviation, characterized in that: include: receiving a secondary etching pattern; the secondary etching pattern comprises an overlay calibration pattern obtained through the same overlay and a defect control group, the defect control group comprises a defective secondary exposure pattern and a corresponding non-defective reference pattern, and all patterns in the same defect control group have the same design line width; The defect secondary exposure pattern is a pattern obtained after the opaque defect formed in the first exposure is repaired by secondary exposure; The alignment error is obtained by measuring the overlay calibration pattern, the corresponding reference dimension value is obtained by measuring the defect-free reference pattern, and the corresponding test dimension value is obtained by measuring the defective secondary exposure pattern; the alignment error, the reference dimension value and the test dimension value are all dimension values ​​after debonding; A mask secondary etching deviation value is obtained according to the alignment error, the reference dimension value and the test dimension value.

2. The method for calculating the secondary etching deviation according to claim 1, characterized in that: The defect-free reference pattern is a square hole pattern; Measuring the overlay calibration pattern to obtain an alignment error, measuring the defect-free reference pattern to obtain a corresponding reference size value, and then measuring the defective secondary exposure pattern to obtain a corresponding test size value, including: The overlay calibration pattern is measured to obtain a first direction alignment error and a second direction alignment error, the defect-free reference pattern is measured to obtain a corresponding first direction reference size value and a second direction reference size value, and then the defective secondary exposure pattern is measured to obtain a corresponding first direction test size value and a second direction test size value, wherein the first direction is perpendicular to the second direction; Correspondingly, according to the alignment error, the reference dimension value and the test dimension value, obtaining the mask secondary etching deviation value includes: Obtaining a second etching deviation value in the first direction according to the first direction alignment error, the first direction reference dimension value, and the first direction test dimension value; Obtaining a secondary etching deviation value in the second direction according to the second direction alignment error, the second direction reference dimension value and the second direction test dimension value; The secondary etching deviation value in the first direction and the secondary etching deviation value in the second direction are averaged to obtain the secondary etching deviation value of the mask corresponding to the square hole pattern.

3. The method for calculating the secondary etching deviation according to claim 1, characterized in that: Before measuring the defect secondary exposure pattern to obtain the corresponding test size value, the method further includes: Obtaining the defect type and the corresponding repair margin direction corresponding to the defect secondary exposure pattern; the repair margin direction is a specific moving direction of the secondary exposure area in the secondary exposure repair, and the offset of the secondary exposure area along the repair margin direction will cause at least one end of the measurement position of the secondary exposure area to move from the opaque area to the translucent area; Determining a moving direction of a secondary exposure area corresponding to the defect secondary exposure pattern according to the secondary etching pattern; Determining whether the moving direction of the secondary exposure area is the repair margin direction; When the moving direction of the secondary exposure area is the repair margin direction, the secondary etching deviation value of the mask is obtained according to the alignment error, the reference size value and the test size value, including: The mask secondary etching deviation value is obtained by the following formula: CD SR Etch Bias =(CD Test -CD Base -REG)*2; Among them, CD SR Etch Bias is the secondary etching deviation value of the mask, CD Test For the test size value, CD Base is the reference dimension value, and REG is the alignment error.

4. The method for calculating the secondary etching deviation according to claim 3, characterized in that: After determining whether the moving direction of the secondary exposure area is the repair margin direction, the method further includes: When the moving direction of the secondary exposure area is not the repair margin direction, the secondary etching deviation value of the mask is obtained according to the alignment error, the reference size value and the test size value, including: The mask secondary etching deviation value is obtained by the following formula: CD SR Etch Bias =CD Test -CD Base ; Among them, CD SR Etch Bias is the secondary etching deviation value of the mask, CD Test For the test size value, CD Base is the reference size value.

5. The method for calculating the secondary etching deviation according to claim 3, characterized in that: Determining, according to the secondary etching pattern, a moving direction of the secondary exposure area corresponding to the defect secondary exposure pattern comprises: The moving direction of the secondary exposure area corresponding to the defective secondary exposure pattern is determined according to the alignment error.

6. The method for calculating the secondary etching deviation according to claim 1, characterized in that: The secondary etching pattern includes a plurality of defect control groups with different designed line widths; Obtaining the mask secondary etching deviation value according to the alignment error, the reference dimension value and the test dimension value includes: According to the alignment error, the reference dimension value and the test dimension value in the same defect control group, obtaining the group secondary etching deviation value corresponding to each defect control group; The secondary etching deviation values ​​of all defect control groups corresponding to the groups are averaged to obtain the mask secondary etching deviation value.

7. The method for calculating the secondary etching deviation according to claim 1, characterized in that: The same defect control group includes a plurality of defect secondary exposure patterns and a plurality of non-defective reference patterns; Obtaining the mask secondary etching deviation value according to the alignment error, the reference dimension value and the test dimension value includes: Calculating the average value of the reference size values ​​of all defect-free reference patterns in the same defect control group as the average reference size value within the group; calculating the average value of the test size values ​​of all defective secondary exposure patterns in the same defect control group as the average test size value within the group; A mask secondary etching deviation value is obtained according to the alignment error, the average reference size value within the group and the average test size value within the group.

8. A secondary etching pattern, characterized in that: The secondary etching pattern is used in the calculation method of the secondary etching deviation according to any one of claims 1 to 7, including an overlay calibration pattern and a defect control group obtained through the same overlay; The defect control group includes defective secondary exposure patterns and corresponding non-defective reference patterns, and all patterns in the defect control group have the same design line width; The defective secondary exposure pattern is a pattern obtained after the opaque defect formed in the first exposure is repaired by secondary exposure.

9. The secondary etching pattern according to claim 8, characterized in that: All the pattern arrays in the same defect control group are arranged to form a corresponding pattern to be tested; The positions of the setting areas of the patterns to be tested of different defect control groups do not overlap; or The secondary etching pattern includes a defect area and a reference area; The position of the defective area does not overlap with the position of the reference area; All defect secondary exposure patterns of the defect control group are located in the defect area, and all non-defect reference patterns of the defect control group are located in the reference area.

10. A method for producing a secondary etching pattern, characterized in that: The secondary etching pattern as claimed in claim 8 or 9 is obtained by the production method of the secondary etching pattern, comprising: Laying a layer to be etched on a transparent substrate; Laying a photoresist layer on the surface of the layer to be etched, and performing exposure, baking, development, etching and de-gumming once, so as to transform the layer to be etched into a patterned primary etching layer; the primary etching layer includes a defect-free reference pattern and a corresponding defect pattern; and an opaque defect is arranged on the defect pattern; A photoresist layer is laid on the surface of the primary etching layer, and secondary exposure, baking, development, etching and de-resisting are performed to etch away the area corresponding to the opaque defect to obtain the secondary etching pattern.

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