Pattern correction method

Abstract

A graph correction method comprises the steps that a to-be-corrected layout is provided, and the to-be-corrected layout comprises a plurality of to-be-corrected graphs; the layout to be corrected is exposed and developed, a photoetching layout is obtained, the photoetching layout comprises a plurality of photoetching patterns, and the photoetching patterns are in one-to-one correspondence with the patterns to be corrected; obtaining a three-dimensional contour of the photoetching pattern; judging whether the side wall of the three-dimensional outline deviates or not; according to the condition that whether the side wall of the three-dimensional outline deviates or not, a first graph and a second graph are obtained, the first graph is a to-be-corrected graph which does not need to be corrected, and the second graph is a to-be-corrected graph except the first graph; and performing optical proximity effect correction on the second pattern. The correction efficiency of the method is improved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductors, and in particular to a pattern correction method. Background Art

[0002] In order to transfer the pattern from the mask to the surface of the silicon wafer, it is usually necessary to go through an exposure step, a development step after the exposure step, and an etching step after the development step. In the exposure step, light is irradiated onto the silicon wafer coated with photoresist through the light-transmitting area of ​​the mask, and the photoresist undergoes a chemical reaction under the irradiation of light; in the development step, the photolithography pattern is formed by utilizing the different degrees of solubility of the photosensitive and non-photosensitive photoresists in the developer, and the mask pattern is transferred to the photoresist; in the etching step, the silicon wafer is etched based on the photolithography pattern formed by the photoresist layer, and the mask pattern is further transferred to the silicon wafer.

[0003] In semiconductor manufacturing, as the design size continues to shrink, the design size is getting closer and closer to the limit of the lithography imaging system, and the diffraction effect of light becomes more and more obvious, resulting in optical image degradation of the design pattern. The actual lithography pattern is seriously distorted relative to the pattern on the mask. Finally, the actual pattern formed by lithography on the silicon wafer is different from the designed pattern. This phenomenon is called the optical proximity effect (OPE: Optical Proximity Effect).

[0004] In order to correct the optical proximity effect, optical proximity correction (OPC) was created. The core idea of ​​optical proximity correction is to establish an optical proximity correction model based on the consideration of offsetting the optical proximity effect, and to design the photomask pattern according to the optical proximity correction model. In this way, although the optical proximity effect occurs in the photolithography pattern corresponding to the photomask pattern after photolithography, since the offset of this phenomenon has been considered when designing the photomask pattern according to the optical proximity correction model, the photolithography pattern after photolithography is close to the target pattern that the user actually wants to obtain.

[0005] As the device feature size continues to decrease, the pattern irradiated onto the photoresist layer will be significantly deformed and distorted. The calibration of these correction models requires the acquisition of the three-dimensional profile features of the photoresist. Summary of the invention

[0006] The technical problem solved by the present invention is to provide a graphics correction method to improve the efficiency of graphics correction.

[0007] In order to solve the above technical problems, the technical solution of the present invention provides a method for correcting graphics, including: providing a to-be-corrected layout, the to-be-corrected layout including a plurality of to-be-corrected graphics; exposing and developing the to-be-corrected layout to obtain a photolithography layout, the photolithography layout including a plurality of photolithography graphics, the photolithography graphics corresponding one-to-one to the graphics to be corrected; obtaining a three-dimensional contour of the photolithography graphics; judging whether a side wall of the three-dimensional contour is offset; obtaining a first graphic and a second graphic according to whether the side wall of the three-dimensional contour is offset, the first graphic being a graphic to be corrected that does not need to be corrected, and the second graphic being a graphic to be corrected other than the first graphic; and performing optical proximity effect correction on the second graphic.

[0008] Optionally, the method for determining whether the side wall of the three-dimensional contour is offset includes: obtaining a number of equipotential lines between adjacent side walls of the three-dimensional contour, wherein the number of equipotential lines are parallel to the surface of the photolithography pattern; obtaining the length difference between the longest equipotential line and the shortest equipotential line among the number of equipotential lines; and determining whether the side wall of the three-dimensional contour is offset based on whether the absolute value of the length difference is within a preset range.

[0009] Optionally, whether the side wall of the three-dimensional contour has shifted is judged based on whether the absolute value of the length difference is within a preset range: if the absolute value of the length difference is not within the preset range, it is judged that the side wall of the three-dimensional contour has shifted; if the absolute value of the length difference is within the preset range, it is judged that the side wall of the three-dimensional contour has not shifted.

[0010] Optionally, the method for obtaining the first figure and the second figure includes: if the side wall of the three-dimensional contour is offset, the figure to be corrected corresponding to the three-dimensional contour does not need to be corrected for optical proximity effect, and the first figure is obtained; if the side wall of the three-dimensional contour is not offset, the figure to be corrected corresponding to the three-dimensional contour needs to be corrected for optical proximity effect, and the second figure is obtained.

[0011] Optionally, the method for correcting the optical proximity effect of the second graphic includes: obtaining an edge placement error between the second graphic and the corresponding three-dimensional contour; determining whether the edge placement error within a preset area of ​​the three-dimensional contour is within a preset range; and determining whether an area of ​​the second graphic corresponding to the preset area of ​​the three-dimensional contour needs to be corrected for the optical proximity effect based on whether the edge placement error within the preset area of ​​the three-dimensional contour is within the preset range.

[0012] Optionally, a method for determining whether a second graphic area corresponding to a three-dimensional contour preset area needs to be corrected for an optical proximity effect based on whether an edge placement error within a three-dimensional contour preset area is within a preset range includes: if an edge placement error greater than a first preset ratio within the three-dimensional contour preset area is within a preset value range, then the second graphic area corresponding to the three-dimensional contour preset area does not need to be corrected for an optical proximity effect; if an edge placement error greater than a second preset ratio within the three-dimensional contour preset area exceeds a preset value range, then the second graphic area corresponding to the three-dimensional contour preset area needs to be corrected for an optical proximity effect.

[0013] Optionally, the preset value range is 2% to 7% of the feature size.

[0014] Optionally, the first preset ratio is 80%; the second preset ratio is 20%.

[0015] Optionally, the method for obtaining the edge placement error between the second graphic and the corresponding three-dimensional contour includes: obtaining a plurality of projection graphics of the three-dimensional contour on the surface of the lithography plate; obtaining a target graphic among the plurality of projection graphics, wherein the target graphic corresponds to the second graphic; cutting the contour of the target graphic into a plurality of line segments; and obtaining a plurality of edge placement errors between the plurality of line segments and the corresponding contour lines of the second corrected graphic.

[0016] Optionally, the method for obtaining the three-dimensional profile of the photolithography pattern includes: obtaining the three-dimensional profile of the photolithography pattern using an atomic force microscope.

[0017] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0018] The technical solution of the present invention obtains the three-dimensional contour of the lithography pattern, first determines whether the side wall of the three-dimensional contour is offset, and then obtains the second pattern to be corrected from the pattern to be corrected based on whether the side wall of the three-dimensional contour is offset, thereby reducing the correction range and improving the efficiency and accuracy of optical proximity effect correction.

[0019] Furthermore, an atomic force microscope is used to obtain the three-dimensional profile of the lithographic pattern. By obtaining the three-dimensional profile of the lithographic pattern, the internal features of the lithographic pattern can be observed, so that the cause of the distortion of the lithographic pattern can be effectively analyzed, and then the optical proximity effect correction can be accurately performed. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figures 1 to 4 is a flow chart of a graphics correction method in an embodiment of the present invention;

[0021] Figures 5 to 7 Schematic diagram of a photolithography pattern in an embodiment of the present invention. DETAILED DESCRIPTION

[0022] In order to make the above-mentioned objects, features and beneficial effects of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0023] Figures 1 to 4 It is a flow chart of a graphics correction method in an embodiment of the present invention.

[0024] Please refer to Figure 1 , the graphics correction method comprises:

[0025] Step S10: providing a layout to be corrected, wherein the layout to be corrected includes a plurality of graphics to be corrected;

[0026] Step S20: exposing and developing the to-be-corrected layout to obtain a photolithography layout, wherein the photolithography layout includes a plurality of photolithography patterns, and the photolithography patterns correspond one-to-one to the to-be-corrected patterns;

[0027] Step S30: obtaining a three-dimensional profile of the lithography pattern;

[0028] Step S40: determining whether the side wall of the three-dimensional profile is offset;

[0029] Step S50: acquiring a first figure and a second figure according to whether the side wall of the three-dimensional contour is offset, wherein the first figure is a figure to be corrected that does not need to be corrected, and the second figure is a figure to be corrected other than the first figure;

[0030] Step S60: performing optical proximity effect correction on the second pattern.

[0031] The method obtains the three-dimensional profile of the lithography pattern, first determines whether the side wall of the three-dimensional profile is offset, and then obtains the second pattern to be corrected from the pattern to be corrected based on whether the side wall of the three-dimensional profile is offset, thereby reducing the correction range and improving the efficiency and accuracy of optical proximity effect correction.

[0032] Next, each step is analyzed and explained.

[0033] Please continue to refer to Figure 1 , executing step S10: providing a layout to be corrected, wherein the layout to be corrected includes a plurality of graphics to be corrected.

[0034] The layout to be corrected is a mask layout that needs to be corrected for optical proximity effect.

[0035] Please continue to refer to Figure 1 , executing step S20: exposing and developing the to-be-corrected layout to obtain a photolithography layout, wherein the photolithography layout includes a plurality of photolithography patterns, and the photolithography patterns correspond one-to-one to the to-be-corrected patterns.

[0036] The photolithography pattern of the photolithography plate is a photoresist pattern.

[0037] Please continue to refer to Figure 1 , execute step S30: obtain the three-dimensional profile of the lithography pattern.

[0038] The method for obtaining the three-dimensional profile of the photolithography pattern includes: using an atomic force microscope to obtain the three-dimensional profile of the photolithography pattern.

[0039] The working principle of the atomic force microscope is as follows: a micro-cantilever that is extremely sensitive to weak forces is fixed at one end, and a tiny needle tip is at the other end. The needle tip is in light contact with the sample surface. Since there is a very weak repulsive force between the atoms at the tip of the needle tip and the atoms on the sample surface, by controlling the constancy of this force during scanning, the micro-cantilever with the needle tip will fluctuate in a direction perpendicular to the surface of the sample corresponding to the equipotential surface of the force between the needle tip and the atoms on the sample surface. Using optical detection or tunnel current detection, the position change of the micro-cantilever corresponding to each scanning point can be measured, thereby obtaining information on the surface morphology of the sample.

[0040] By acquiring the three-dimensional profile of the lithographic pattern, the internal features of the lithographic pattern can be observed, so that the cause of the distortion of the lithographic pattern can be effectively analyzed, and then the optical proximity effect correction can be accurately performed.

[0041] Please continue to refer to Figure 1 , execute step S40: determine whether the side wall of the three-dimensional contour is offset.

[0042] Please refer to Figure 2 In this embodiment, the method for determining whether the side wall of the three-dimensional profile is offset includes:

[0043] Step S401: obtaining a plurality of equipotential lines between side walls of adjacent three-dimensional contours, wherein the plurality of equipotential lines are parallel to the surface of the photolithography pattern;

[0044] Step S402: obtaining the length difference between the longest equipotential line and the shortest equipotential line among a plurality of equipotential lines;

[0045] Step S403: determining whether the side wall of the three-dimensional contour is offset according to whether the absolute value of the length difference is within a preset range.

[0046] Whether the side wall of the three-dimensional contour is offset is determined based on whether the absolute value of the length difference is within a preset range: if the absolute value of the length difference is not within the preset range, it is determined that the side wall of the three-dimensional contour is offset; if the absolute value of the length difference is within the preset range, it is determined that the side wall of the three-dimensional contour is not offset.

[0047] Please refer to Figures 5 to 7 , Figures 5 to 71 is a schematic diagram of a structure of different forms of a three-dimensional profile side wall of a photolithography pattern, wherein the photolithography pattern is located on a wafer 100. Figure 5 The absolute value of the length difference between the longest equipotential line L1 and the shortest equipotential line L1 among the plurality of equipotential lines L1 between the three-dimensional contour sidewalls of the lithographic pattern 101 is within a preset range, Figure 6 The absolute value of the length difference between the longest equipotential line L2 and the shortest equipotential line L2 among the plurality of equipotential lines L2 between the three-dimensional contour sidewalls of the middle lithography pattern 201 is not within a preset range, Figure 7 The absolute value of the length difference between the longest equipotential line L3 and the shortest equipotential line L3 among the plurality of equipotential lines L3 between the three-dimensional contour sidewalls of the middle lithography pattern 301 is not within a preset range.

[0048] Please continue to refer to Figure 1 , execute step S50: according to whether the side wall of the three-dimensional contour is offset, obtain a first figure and a second figure, the first figure is a figure to be corrected that does not need to be corrected, and the second figure is a figure to be corrected other than the first figure.

[0049] The method for obtaining a first figure and a second figure includes: if the side wall of the three-dimensional contour is offset, the figure to be corrected corresponding to the three-dimensional contour does not need to be corrected for optical proximity effect, and the first figure is obtained; if the side wall of the three-dimensional contour is not offset, the figure to be corrected corresponding to the three-dimensional contour needs to be corrected for optical proximity effect, and the second figure is obtained.

[0050] The material of the photolithographic pattern is photoresist, and the photoacid in the photoresist will diffuse unevenly in different directions. If the absolute value of the length difference is not within the preset range, it means that the photoresist is seriously distorted (such as Figure 6 and Figure 7 ), the distortion of the photolithographic pattern is caused by the photoresist itself, then the pattern to be corrected corresponding to the three-dimensional profile does not need to be corrected for the optical proximity effect. If the absolute value of the length difference is within the preset range, it means that the distortion of the photoresist is within the acceptable range, the distortion of the photolithographic pattern is caused by the optical proximity effect, then the pattern to be corrected corresponding to the three-dimensional profile needs to be corrected for the optical proximity effect.

[0051] According to whether the side wall of the three-dimensional profile is offset, a second pattern to be corrected is obtained from the pattern to be corrected, thereby reducing the correction range and improving the optical proximity effect correction efficiency.

[0052] Please continue to refer to Figure 1 , executing step S60: performing optical proximity effect correction on the second graphic.

[0053] Please refer to Figure 3In this embodiment, the method for correcting the optical proximity effect of the second graphic includes:

[0054] Step S601: obtaining an edge placement error between a second graphic and a corresponding three-dimensional contour;

[0055] Step S602: determining whether the edge placement error in the preset area of ​​the three-dimensional contour is within a preset range;

[0056] Step S603: judging whether the second graphic area corresponding to the preset three-dimensional contour area needs to be corrected for the optical proximity effect according to whether the edge placement error in the preset three-dimensional contour area is within a preset range.

[0057] The method for determining whether a second graphic area corresponding to a three-dimensional contour preset area needs to be corrected for an optical proximity effect based on whether an edge placement error within a three-dimensional contour preset area is within a preset range includes: if an edge placement error greater than a first preset ratio within the three-dimensional contour preset area is within a preset value range, then the second graphic area corresponding to the three-dimensional contour preset area does not need to be corrected for an optical proximity effect; if an edge placement error greater than a second preset ratio within the three-dimensional contour preset area exceeds a preset value range, then the second graphic area corresponding to the three-dimensional contour preset area needs to be corrected for an optical proximity effect.

[0058] The three-dimensional contour preset area is selected according to actual needs and can be a corner, an angle or a line end of the three-dimensional contour.

[0059] In this embodiment, the first preset ratio is 80%; and the second preset ratio is 20%.

[0060] In this embodiment, the preset value range is 2% to 7% of the feature size. The feature size is determined according to the actual layout.

[0061] Please refer to Figure 4 In this embodiment, the method for obtaining the edge placement error between the second graphic and the corresponding three-dimensional contour includes:

[0062] Step S6011: obtaining a plurality of projection patterns of the three-dimensional contour on the surface of the photolithography plate;

[0063] Step S6012: obtaining a target graphic from among the plurality of projection graphics, wherein the target graphic corresponds to the second graphic;

[0064] Step S6013: cutting the outline of the target figure into a number of line segments;

[0065] Step S6014: Obtaining a number of edge placement errors between a number of line segments and corresponding second corrected graphic contour lines.

[0066] The target pattern corresponds to the second pattern, that is, the coordinates of the target pattern on the photolithography layout correspond to the coordinates of the second pattern on the layout to be corrected.

[0067] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A graphics correction method, characterized in that: include: Providing a layout to be revised, wherein the layout to be revised includes a plurality of graphics to be revised; Expose and develop the to-be-corrected pattern to obtain a photolithography pattern, wherein the photolithography pattern includes a plurality of photolithography patterns, and the photolithography patterns correspond one to one to the to-be-corrected pattern; Obtaining a three-dimensional profile of a lithographic pattern; determining whether a side wall of the three-dimensional profile is offset; According to whether the side wall of the three-dimensional contour is offset, a first figure and a second figure are obtained, wherein the first figure is a figure to be corrected that does not need to be corrected, and the second figure is a figure to be corrected other than the first figure; The optical proximity effect correction is performed on the second pattern.

2. The image correction method according to claim 1, characterized in that: The method for determining whether the side wall of the three-dimensional contour is offset includes: obtaining a number of equipotential lines between adjacent side walls of the three-dimensional contour, wherein the number of equipotential lines are parallel to the surface of the photolithography pattern; obtaining the length difference between the longest equipotential line and the shortest equipotential line among the number of equipotential lines; and determining whether the side wall of the three-dimensional contour is offset based on whether the absolute value of the length difference is within a preset range.

3. The image correction method according to claim 2, characterized in that: Whether the side wall of the three-dimensional contour is offset is determined based on whether the absolute value of the length difference is within a preset range: if the absolute value of the length difference is not within the preset range, it is determined that the side wall of the three-dimensional contour is offset; if the absolute value of the length difference is within the preset range, it is determined that the side wall of the three-dimensional contour is not offset.

4. The image correction method according to claim 3, characterized in that: The method for obtaining a first figure and a second figure includes: if the side wall of the three-dimensional contour is offset, the figure to be corrected corresponding to the three-dimensional contour does not need to be corrected for optical proximity effect, and the first figure is obtained; if the side wall of the three-dimensional contour is not offset, the figure to be corrected corresponding to the three-dimensional contour needs to be corrected for optical proximity effect, and the second figure is obtained.

5. The image correction method according to claim 1, characterized in that: The method for correcting the optical proximity effect of the second graphic includes: obtaining an edge placement error between the second graphic and the corresponding three-dimensional contour; determining whether the edge placement error within a preset area of ​​the three-dimensional contour is within a preset range; and determining whether an area of ​​the second graphic corresponding to the preset area of ​​the three-dimensional contour needs to be corrected for the optical proximity effect based on whether the edge placement error within the preset area of ​​the three-dimensional contour is within the preset range.

6. The image correction method according to claim 5, characterized in that: The method for determining whether a second graphic area corresponding to a three-dimensional contour preset area needs to be corrected for an optical proximity effect based on whether an edge placement error within a three-dimensional contour preset area is within a preset range includes: if an edge placement error greater than a first preset ratio within the three-dimensional contour preset area is within a preset value range, then the second graphic area corresponding to the three-dimensional contour preset area does not need to be corrected for an optical proximity effect; if an edge placement error greater than a second preset ratio within the three-dimensional contour preset area exceeds a preset value range, then the second graphic area corresponding to the three-dimensional contour preset area needs to be corrected for an optical proximity effect.

7. The image correction method according to claim 6, characterized in that: The preset value range is 2% to 7% of the characteristic size.

8. The image correction method according to claim 6, characterized in that: The first preset ratio is 80%; the second preset ratio is 20%.

9. The image correction method according to claim 5, characterized in that: The method for obtaining the edge placement error between the second figure and the corresponding three-dimensional contour includes: obtaining a plurality of projection figures of the three-dimensional contour on the surface of the photolithography plate; obtaining a target figure among the plurality of projection figures, wherein the target figure corresponds to the second figure; cutting the contour of the target figure into a plurality of line segments; and obtaining a plurality of edge placement errors between the plurality of line segments and the corresponding contour lines of the second correction figure.

10. The image correction method according to claim 1, characterized in that: The method for obtaining the three-dimensional profile of the photolithography pattern includes: using an atomic force microscope to obtain the three-dimensional profile of the photolithography pattern.

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