Optical proximity correction method

Abstract

An optical proximity correction method comprises: providing a target pattern, the target pattern having a first contrast section on an edge thereof; obtaining a first correction pattern, the first correction pattern having a first correction section on an edge thereof; performing exposure processing on the first correction pattern to obtain a first aerial image pattern, the first aerial image pattern having a second contrast section corresponding to the first contrast section on an edge thereof; obtaining a first deviation value between edge placement errors of two adjacent sampling points on the first contrast section and the second contrast section; and compensating the first correction section of the first correction pattern according to the first deviation value to obtain a second correction pattern. The first deviation value is used to obtain a section in the first correction section that is relatively weak in correction in the optical proximity correction process, and the first correction section is compensated to improve the profile effect of a subsequently obtained etching pattern.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing technology, and more particularly to an optical proximity correction method. Background Technology

[0002] Photolithography is a crucial technology in semiconductor manufacturing. It transfers patterns from a photomask to the surface of a silicon wafer, forming semiconductor products that meet design requirements. The photolithography process includes an exposure step, a development step following exposure, and an etching step following development. In the exposure step, light passes through the light-transmitting areas of the photomask and shines onto the silicon wafer coated with photoresist, causing a chemical reaction in the photoresist. In the development step, the different solubility of the developer in the photoresist and the non-photoresist is used to form a photolithographic pattern, transferring the photomask pattern onto the photoresist. In the etching step, the silicon wafer is etched based on the photolithographic pattern formed by the photoresist layer, further transferring the photomask pattern onto the silicon wafer.

[0003] In semiconductor manufacturing, as design dimensions continue to shrink and approach the limits of photolithography imaging systems, the diffraction effect of light becomes increasingly pronounced, leading to optical image degradation of the final design pattern. The actual photolithographic pattern formed is severely distorted relative to the pattern on the mask, resulting in a difference between the actual pattern formed on the silicon wafer and the design pattern. This phenomenon is called the Optical Proximity Effect (OPE).

[0004] To correct the optical proximity effect, Optical Proximity Correction (OPC) was developed. The core idea of ​​OPC is to establish an OPC model based on the consideration of counteracting the optical proximity effect. The photomask pattern is designed according to the OPC model. In this way, although the lithographic pattern and the corresponding photomask pattern have an optical proximity effect, the cancellation of this phenomenon has been considered when designing the photomask pattern according to the OPC model. Therefore, the lithographic pattern after photolithography is close to the target pattern actually desired by the user.

[0005] However, existing optical proximity correction technologies still have many problems. Summary of the Invention

[0006] The technical problem solved by this invention is to provide an optical proximity correction method to improve the contour effect of the subsequently acquired etched pattern.

[0007] To address the aforementioned problems, the present invention provides an optical proximity correction method, comprising: providing a target image, wherein the target image has a first contrast segment on its edge; obtaining a first corrected image, wherein the first corrected image has a first correction segment on its edge corresponding to the first contrast segment; performing exposure processing on the first corrected image to obtain a first spatial image, wherein the first spatial image has a second contrast segment on its edge corresponding to the first contrast segment; obtaining a first deviation value between the edge placement errors of two adjacent sampling points on the first contrast segment and the second contrast segment; and compensating the first correction segment of the first corrected image according to the first deviation value to obtain a second corrected image.

[0008] Optionally, the step of compensating the first correction segment of the first correction pattern according to the first deviation value to obtain the second correction pattern includes: providing a first deviation threshold; when the first deviation value is less than the first deviation threshold, using the first correction pattern as the second correction pattern; when the first deviation value is greater than or equal to the first deviation threshold, compensating the first correction segment of the first correction pattern according to the first deviation value to obtain the second correction pattern.

[0009] Optionally, the range of the first deviation threshold is 0.4 nm to 0.6 nm.

[0010] Optionally, obtaining the first deviation value between the edge placement errors of two adjacent sampling points on the first comparison segment and the second comparison segment includes: obtaining the first edge placement error between corresponding first sampling points on the first comparison segment and the second comparison segment; obtaining the second edge placement error between corresponding second sampling points on the first comparison segment and the second comparison segment; obtaining the third edge placement error between corresponding third sampling points on the first comparison segment and the second comparison segment, wherein the second sampling point and the third sampling point are respectively adjacent to the first sampling point; and obtaining the first deviation value based on the first edge placement error, the second edge placement error, and the third edge placement error.

[0011] Optionally, obtaining the first deviation value based on the first edge placement error, the second edge placement error, and the third edge placement error includes: comparing the second edge placement error and the third edge placement error; subtracting the first edge placement error from the larger of the second edge placement error and the third edge placement error to obtain the first deviation value.

[0012] Optionally, the second comparison segment includes a first sampling segment, and the first correction segment includes a first compensation segment corresponding to the first sampling segment; the step of compensating the first correction segment of the first correction pattern according to the first deviation value to obtain the second correction pattern includes: obtaining a first compensation size according to the first deviation value; shifting the first compensation segment of the first correction pattern outward by the first compensation size to obtain the second correction pattern.

[0013] Optionally, obtaining the first compensation size based on the first deviation value includes: obtaining a compensation coefficient; and multiplying the compensation coefficient by the first deviation value to obtain the first compensation size.

[0014] Optionally, obtaining the compensation coefficient includes: providing an exposure and development target pattern of the target pattern, the exposure and development target pattern having a first major axis and a first minor axis; providing an etching and development target pattern of the target pattern, the etching and development target pattern having a second major axis and a second minor axis; subtracting the second major axis from the first major axis to obtain a first deviation value for the major axis; subtracting the second minor axis from the first minor axis to obtain a first deviation value for the minor axis; and dividing the first deviation value for the major axis by the first deviation value for the minor axis as the compensation coefficient.

[0015] Optionally, after obtaining the second corrected image, the method further includes: performing exposure processing on the second corrected image to obtain a second spatial image, wherein the second spatial image has a third contrast segment on its edge corresponding to the second contrast segment; obtaining a first spacing between the third contrast segment and the first sampling point corresponding to the second contrast segment; subtracting the first compensation size from the first spacing to obtain a second deviation value; and compensating the first correction segment in the second corrected image according to the second deviation value to obtain a third corrected image.

[0016] Optionally, the step of compensating the first correction segment in the second correction pattern according to the second deviation value to obtain the third correction pattern includes: providing a second deviation threshold; when the second deviation value is less than the second deviation threshold, no compensation is needed for the first correction segment in the second correction pattern, and the second correction pattern is used as the third correction pattern; when the second deviation value is greater than or equal to the second deviation threshold, the first correction segment of the second correction pattern is shifted towards the inside of the second correction pattern by a preset compensation size until the second deviation value is less than the second deviation threshold, and the third correction pattern is obtained.

[0017] Optionally, the range of the preset compensation size is 0.9 nanometers to 3.6 nanometers.

[0018] Optionally, obtaining the first corrected image includes: performing several optical proximity corrections on the target image to obtain the first corrected image.

[0019] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0020] In the optical proximity correction method of the present invention, a first deviation value of the placement error of two adjacent edges between the first comparison segment and the second comparison segment is obtained; the first correction segment of the first correction pattern is compensated according to the first deviation value to obtain the second correction pattern. By using the first deviation value, weaker segments in the first correction segment are identified during the optical proximity correction process, thereby compensating the first correction segment and improving the contour effect of the subsequently obtained etching pattern.

[0021] Furthermore, the method for obtaining the compensation coefficient includes: providing an exposure-developed target pattern of the target pattern, the exposure-developed target pattern having a first major axis and a first minor axis; providing an etching-developed target pattern of the target pattern, the etching-developed target pattern having a second major axis and a second minor axis; subtracting the second major axis from the first major axis to obtain a first deviation value for the major axis; subtracting the second minor axis from the first minor axis to obtain a first deviation value for the minor axis; and dividing the first deviation value for the major axis by the first deviation value for the minor axis as the compensation coefficient. Since the obtained second corrected pattern is used to improve the contour effect of the subsequently obtained etching pattern, obtaining the compensation coefficient based on the etching-developed target pattern and the exposure-developed target pattern makes the compensation process more efficient and accurate.

[0022] Furthermore, after obtaining the second corrected image, the method further includes: performing exposure processing on the second corrected image to obtain a second spatial image, wherein the edge of the second spatial image has a third contrast segment corresponding to the second contrast segment; obtaining a first spacing between the third contrast segment and the first sampling point corresponding to the second contrast segment; subtracting the first compensation size from the first spacing to obtain a second deviation value; and compensating the first correction segment in the second corrected image according to the second deviation value to obtain a third corrected image. Compensating the second corrected image according to the second deviation value further improves the contour effect of the subsequently obtained etched image. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of each step in an optical proximity correction method and etching process.

[0024] Figure 2 This is a flowchart of the optical proximity correction method in an embodiment of the present invention;

[0025] Figures 3 to 9This is a schematic diagram of the structure of each step of an optical proximity correction method in an embodiment of the present invention. Detailed Implementation

[0026] As described in the background section, existing optical proximity correction techniques still have many problems. These will be explained in detail below with reference to the accompanying drawings.

[0027] Figure 1 This is a schematic diagram of the structure of each step in an optical proximity correction method and etching process.

[0028] Please refer to Figure 1 The process involves providing a target pattern 100; performing several optical proximity corrections on the target pattern 100 to obtain a corrected pattern 101; performing an exposure process on the corrected pattern 101 to obtain an exposed pattern 102; and using the exposed pattern 102 as a mask to perform an etching process to obtain an etched pattern 103.

[0029] In this embodiment, although the edge placement errors between the obtained exposure pattern 102 and the target pattern 100 are all within the deviation threshold range, meeting the requirements of optical proximity correction, the obtained etched pattern 103 still exhibits a phenomenon of interruption in the middle of the pattern when the exposure pattern 102 is used as a mask for etching (e.g., ...). Figure 1 As shown in Part A, this causes problems with the semiconductor structure formed on the substrate (not shown), such as the inability to cut metal lines.

[0030] Based on this, the present invention provides an optical proximity correction method, which obtains a first deviation value of the placement error of two adjacent edges between the first contrast segment and the second contrast segment; compensates the first correction segment of the first correction pattern according to the first deviation value to obtain a second correction pattern. By using the first deviation value to identify the weaker segments in the first correction segment during the optical proximity correction process, the first correction segment is compensated to improve the contour effect of the subsequently obtained etching pattern.

[0031] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0032] Figure 2 This is a flowchart of an optical proximity correction method according to an embodiment of the present invention, including:

[0033] Step S101: Provide a target graphic, wherein the edge of the target graphic has a first contrast segment;

[0034] Step S102: Obtain a first corrected graphic, wherein the edges of the first corrected graphic have a first corrected segment corresponding to the first comparison segment;

[0035] Step S103: Exposure processing is performed on the first corrected image to obtain a first spatial image image, wherein the first spatial image image has a second contrast segment on its edge that corresponds to the first contrast segment.

[0036] Step S104: Obtain the first deviation value between the edge placement errors of two adjacent sampling points on the first comparison segment and the second comparison segment;

[0037] Step S105: Compensate the first correction segment of the first correction graphic according to the first deviation value to obtain the second correction graphic.

[0038] The steps of the optical proximity correction method are described in detail below with reference to the accompanying drawings.

[0039] Figures 3 to 9 This is a schematic diagram of the structure of each step of the optical proximity correction method in an embodiment of the present invention.

[0040] Please refer to Figure 3 A target graphic 200 is provided, wherein the target graphic 200 has a first contrast segment c1 on its edge.

[0041] In this embodiment, the target pattern 200 is an ideally small pattern (i.e., without optical proximity effect). However, in the actual exposure process, due to the existence of optical proximity effect, light interference and diffraction occur during exposure. Therefore, the final pattern obtained after exposure processing differs from the target pattern 200. For example, if the target pattern 200 is a regular rectangle, the pattern obtained after exposure processing is similar to an ellipse, i.e., rounded corners are formed at both ends of the rectangle.

[0042] In this embodiment, the first contrast segment c1 of the edge of the target graphic 200 refers to the line segment corresponding to the non-rounded corner segment of the exposed graphic.

[0043] Please refer to Figure 4 A first corrected graphic 300 is obtained, and the first corrected graphic 300 has a first corrected segment f1 on its edge that corresponds to the first comparison segment c1.

[0044] In this embodiment, the method for obtaining the first corrected pattern 300 includes: performing optical proximity correction on the target pattern 200 several times to obtain the first corrected pattern 300.

[0045] In this embodiment, performing several optical proximity corrections on the target graphic 200 is a conventional optical proximity correction, in order to reduce the edge placement error between the graphic obtained after exposure of the first corrected graphic 300 and the target graphic 200, so that the edge placement error is within the threshold range.

[0046] Please refer to Figure 5 The first corrected image 300 is exposed to obtain a first spatial image 400, and the first spatial image 400 has a second contrast segment c2 on its edge, which corresponds to the first contrast segment c1.

[0047] The first spatial image pattern 400 refers to the image of light intensity distribution formed on the photoresist by light emitted from the light source and projected onto the photoresist through a projection system. The first spatial image pattern 400 is a pattern obtained without considering the photoresist's photoresist effect, and can more intuitively reflect the characteristics of the pattern itself.

[0048] In this embodiment, the recessed position of the first spatial image pattern 400 is the position where the subsequently obtained etched pattern is prone to breakage. Therefore, the first correction pattern 300 is subsequently compensated to improve the contour effect of the etched pattern.

[0049] Please refer to Figure 6 The first deviation value δEPE is obtained between the edge placement errors of two adjacent sampling points on the first comparison segment c1 and the second comparison segment c2.

[0050] In this embodiment, taking three sampling points as an example, the method for obtaining the first deviation value δEPE between the edge placement errors of two adjacent sampling points on the first comparison segment c1 and the second comparison segment c2 includes: obtaining the first edge placement error EPE1 between the corresponding first sampling point p1 on the first comparison segment c1 and the second comparison segment c2; obtaining the second edge placement error EPE2 between the corresponding second sampling point p2 on the first comparison segment c1 and the second comparison segment c2; and obtaining the third edge placement error EPE3 between the corresponding third sampling point p2 on the first comparison segment c1 and the second comparison segment c2, wherein the second sampling point p2 and the third sampling point p3 are adjacent to the first sampling point p1 respectively; comparing the second edge placement error EPE2 and the third edge placement error EPE3; and subtracting the first edge placement error EPE1 from the larger of the second edge placement error EPE2 and the third edge placement error EPE3 to obtain the first deviation value δEPE.

[0051] Please refer to Figure 7 The first correction segment f1 of the first correction pattern 300 is compensated according to the first deviation value δEPE to obtain the second correction pattern 500.

[0052] In this embodiment, a first deviation value δEPE is obtained for the placement error of two adjacent edges between the first comparison segment c1 and the second comparison segment c2. Based on the first deviation value δEPE, the first correction segment f1 of the first correction pattern 300 is compensated to obtain the second correction pattern 500. The first deviation value δEPE is used to identify the weakly corrected segments in the first correction segment f1 during the optical proximity correction process, thereby compensating for the first correction segment f1 to improve the contour effect of the subsequently obtained etched pattern.

[0053] In this embodiment, the method for compensating the first correction segment f1 of the first corrected pattern 300 according to the first deviation value δEPE to obtain the second corrected pattern 500 includes: providing a first deviation threshold spec1; when the first deviation value δEPE is less than the first deviation threshold spec1, the first correction segment f1 of the first corrected pattern 300 does not need to be compensated, and the first corrected pattern 300 is used as the second corrected pattern 500; when the first deviation value δEPE is greater than or equal to the first deviation threshold spec1, the first correction segment f1 of the first corrected pattern 300 is compensated to obtain the second corrected pattern 500.

[0054] The first deviation threshold spec1 ranges from 0.4 nm to 0.6 nm. In this embodiment, the first deviation threshold spec1 is 0.5 nm.

[0055] In this embodiment, the second comparison segment c2 includes a first sampling segment s1, and the first sampling point p1 is located at the midpoint of the first sampling segment s1; the first correction segment f1 includes a first compensation segment m1 corresponding to the first sampling segment s1; when the first deviation value δEPE is greater than or equal to the first deviation threshold spec1, the first correction segment f1 of the first correction pattern 300 is compensated, and the method for obtaining the second correction pattern 500 includes: shifting the first compensation segment f1 of the first correction pattern 300 to the outside of the first correction pattern 300 by a first compensation size cs1 to obtain the second correction pattern 500.

[0056] In this embodiment, the method for obtaining the first compensation size cs1 includes: obtaining the compensation coefficient coef; and multiplying the compensation coefficient coef by the first deviation value δEPE to obtain the first compensation size cs1.

[0057] Please refer to Figure 8In this embodiment, the method for obtaining the compensation coefficient coef includes: providing an exposure and development target pattern 201 of the target pattern 200, the exposure and development target pattern 201 having a first major axis la1 and a first minor axis sa1; providing an etching and development target pattern 202 of the target pattern 200, the etching and development target pattern 202 having a second major axis la2 and a second minor axis sa2; subtracting the second major axis la2 from the first major axis la1 to obtain a first deviation δla of the major axis; subtracting the second minor axis sa2 from the first minor axis sa1 to obtain a first deviation value δsa of the minor axis; and dividing the first deviation value δla of the major axis by the first deviation value δsa of the minor axis as the compensation coefficient coef.

[0058] Since the second corrected pattern 500 is used to improve the contour effect of the subsequently acquired etched pattern, the compensation coefficient coef is obtained based on the etched and developed target pattern 202 and the exposed and developed target pattern 201, making the compensation process more efficient and accurate.

[0059] Please refer to Figure 9 After obtaining the second corrected image 500, the second corrected image 500 is exposed to obtain a second spatial image 600. The second spatial image 600 has a third contrast segment c3 on its edge, which corresponds to the second contrast segment c2. The first distance d1 between the third contrast segment c3 and the first sampling point p1 corresponding to the second contrast segment c2 is obtained. The first compensation size cs1 is subtracted from the first distance d1 to obtain a second deviation value δD. The first correction segment f1 in the second corrected image 500 is compensated according to the second deviation value δD to obtain a third corrected image 700.

[0060] It should be noted that the first correction segment f1 in the second correction figure 500 is the line segment after compensation of the first correction segment f1 in the first correction figure 300.

[0061] In this embodiment, the second correction pattern 500 is compensated based on the second deviation value δD to further improve the contour effect of the subsequently obtained etched pattern.

[0062] In this embodiment, the method for obtaining a third corrected pattern 700 by compensating the first corrected segment f1 in the second corrected pattern 500 according to the second deviation value δD includes: providing a second deviation threshold spec2; when the second deviation value δD is less than the second deviation threshold spec2, the first corrected segment f1 in the second corrected pattern 500 does not need to be compensated, and the second corrected pattern 500 is used as the third corrected pattern 700; when the second deviation value δD is greater than or equal to the second deviation threshold spec2, the first corrected segment f1 of the second corrected pattern 500 is shifted towards the inside of the second corrected pattern 500 by a preset compensation size dcs until the second deviation value δD is less than the second deviation threshold spec2, and the third corrected pattern 700 is obtained.

[0063] In this embodiment, the range of the preset compensation size dcs is 0.9 nanometers to 3.6 nanometers.

[0064] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. An optical proximity correction method, characterized in that, include: A target graphic is provided, wherein the edges of the target graphic have a first contrast segment; Obtain a first corrected graphic, wherein the edges of the first corrected graphic have a first corrected segment corresponding to the first comparison segment; The first corrected image is exposed to obtain a first spatial image, and the first spatial image has a second contrast segment on its edge that corresponds to the first contrast segment. Obtain the first deviation value between the edge placement errors of two adjacent sampling points on the first comparison segment and the second comparison segment; The first correction segment of the first correction graphic is compensated based on the first deviation value to obtain the second correction graphic; wherein... The process of obtaining the second corrected graphic includes obtaining the first compensation dimension, and the process of obtaining the first compensation dimension includes obtaining the compensation coefficient; Obtaining the compensation coefficient includes: providing an exposed and developed target pattern of the target pattern, the exposed and developed target pattern having a first major axis and a first minor axis; providing an etched and developed target pattern of the target pattern, the etched and developed target pattern having a second major axis and a second minor axis; subtracting the second major axis from the first major axis to obtain a first deviation value for the major axis; subtracting the second minor axis from the first minor axis to obtain a first deviation value for the minor axis; and dividing the first deviation value for the major axis by the first deviation value for the minor axis as the compensation coefficient.

2. The optical proximity correction method as described in claim 1, characterized in that, The step of compensating the first correction segment of the first correction graphic based on the first deviation value to obtain the second correction graphic includes: Provide a first deviation threshold; When the first deviation value is less than the first deviation threshold, the first corrected pattern is used as the second corrected pattern; When the first deviation value is greater than or equal to the first deviation threshold, the first correction segment of the first correction pattern is compensated according to the first deviation value to obtain the second correction pattern.

3. The optical proximity correction method as described in claim 2, characterized in that, The first deviation threshold ranges from 0.4 nanometers to 0.6 nanometers.

4. The optical proximity correction method as described in claim 1, characterized in that, The step of obtaining the first deviation value between the edge placement errors of two adjacent sampling points on the first comparison segment and the second comparison segment includes: Obtain the first edge placement error between the corresponding first sampling points on the first comparison segment and the second comparison segment; Obtain the second edge placement error between the corresponding second sampling points on the first comparison segment and the second comparison segment; Obtain the third edge placement error between the corresponding third sampling points on the first comparison segment and the second comparison segment, wherein the second sampling point and the third sampling point are respectively adjacent to the first sampling point; A first deviation value is obtained based on the first edge placement error, the second edge placement error, and the third edge placement error.

5. The optical proximity correction method as described in claim 4, characterized in that, The step of obtaining the first deviation value based on the first edge placement error, the second edge placement error, and the third edge placement error includes: Compare the second edge placement error and the third edge placement error; The first deviation value is obtained by subtracting the first edge placement error from the larger of the second edge placement error and the third edge placement error.

6. The optical proximity correction method according to any one of claims 1 to 5, characterized in that, The second comparison segment includes a first sampling segment, and the first correction segment includes a first compensation segment corresponding to the first sampling segment; The step of compensating the first correction segment of the first correction graphic based on the first deviation value to obtain the second correction graphic includes: Based on the first deviation value, the first compensation size is obtained; The first compensation segment of the first corrected graphic is shifted outward by a first compensation size to obtain the second corrected graphic.

7. The optical proximity correction method as described in claim 6, characterized in that, The step of obtaining the first compensation size based on the first deviation value includes: Obtain the compensation coefficient; The compensation coefficient is multiplied by the first deviation value to obtain the first compensation size.

8. The optical proximity correction method as described in claim 4, characterized in that, After obtaining the second corrected image, the process further includes: The second corrected image is exposed to obtain a second spatial image, the second spatial image having a third contrast segment on its edge corresponding to the second contrast segment; Obtain the first spacing between the first sampling points corresponding to the third comparison segment and the second comparison segment; Subtract the first compensation dimension from the first spacing to obtain the second deviation value; The first correction segment in the second correction pattern is compensated based on the second deviation value to obtain the third correction pattern.

9. The optical proximity correction method as described in claim 8, characterized in that, The step of compensating the first correction segment in the second correction pattern according to the second deviation value to obtain the third correction pattern includes: Provide a second deviation threshold; When the second deviation value is less than the second deviation threshold, the first correction segment in the second correction pattern does not need to be compensated, and the second correction pattern is used as the third correction pattern. When the second deviation value is greater than or equal to the second deviation threshold, the first correction segment of the second correction pattern is shifted toward the inside of the second correction pattern by a preset compensation size until the second deviation value is less than the second deviation threshold, and the third correction pattern is obtained.

10. The optical proximity correction method as described in claim 9, characterized in that, The range of the preset compensation size is 0.9 nanometers to 3.6 nanometers.

11. The optical proximity correction method as described in claim 1, characterized in that, The process of obtaining the first corrected image includes: The target image is subjected to several optical proximity corrections to obtain a first corrected image.

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