Optical proximity correction method, mask and readable storage medium

Abstract

The present invention relates to an optical proximity correction method, a mask plate and a readable storage medium, the method comprising: obtaining a mask plate design pattern; analyzing and dividing the outer edge of the mask plate design pattern into multiple segments, including: for a line pattern that is not parallel to a line end and is adjacent to the line end in the extension direction of the line end, according to the spacing between the line end and the line pattern, and the optical diameter used when establishing an OPC model, calculating the length of the segmented line of the line pattern at a position adjacent to the line end; simulating the mask plate design pattern according to the OPC model to obtain a simulated exposure pattern; adjusting the mask plate design pattern according to the simulated exposure pattern to obtain a mask plate making pattern. The present invention can effectively improve the "ripple" phenomenon, improve the OPC correction accuracy and OPC correction efficiency, and reduce process risks.

Description

Technical Field

[0001] The present application relates to the field of semiconductor manufacturing technology, and in particular to an optical proximity correction method, a mask plate and a readable storage medium. Background Art

[0002] With the rapid development of ultra-large scale integrated circuits (ULSI), integrated circuit manufacturing processes have become increasingly complex and sophisticated. Among them, photolithography is the driving force behind the development of integrated circuit manufacturing processes and is also one of the most complex technologies. Compared with other individual manufacturing technologies, the improvement of photolithography is of great significance to the development of integrated circuits. Before the photolithography process begins, the pattern must first be copied to the mask through a specific device, and then the pattern structure on the mask is copied to the silicon wafer for producing chips through a photolithography machine. However, due to the reduction in the size of semiconductor devices, the wavelength used for exposure is larger than the size of the ideal graphics designed in the physical layout and the spacing between the graphics. The interference and diffraction effects of light waves cause a large difference between the physical graphics produced by actual photolithography and the ideal graphics designed in the physical layout. The shape and spacing of the actual graphics change greatly, and even affect the performance of the circuit.

[0003] An important reason for this difference is that when the wavelength of the light beam used in lithography is larger than the size of the ideal pattern in the physical layout design and the spacing between the patterns, the optical proximity effect occurs. Therefore, in order to solve the problem, the optical proximity correction (OPC) can be performed on the mask.

[0004] Currently, OPC is done by correcting the mask to solve the distortion of the graphics after lithography as much as possible. Major manufacturers use computer-aided software tools to do this. Summary of the invention

[0005] Based on this, it is necessary to provide an optical proximity correction method that can improve the correction accuracy of OPC.

[0006] An optical proximity correction method comprises: obtaining a mask design pattern; analyzing and dividing the outer edge of the mask design pattern into multiple segments, including: for a line pattern adjacent to a line end in the extension direction of the line end, according to the spacing between the line end and the line pattern, and the optical diameter used when establishing an OPC model, calculating the length of the segment of the line pattern at a position adjacent to the line end; wherein the straight line where the line end is located forms an angle with the line pattern; simulating the mask design pattern according to the OPC model to obtain a simulated exposure pattern; adjusting the mask design pattern according to the simulated exposure pattern to obtain a mask plate making pattern.

[0007] The above optical proximity correction method improves the segmentation algorithm during the analytical segmentation (Dissection) of the outer edge of the mask design pattern. At the position where the line pattern is adjacent to other line ends, segmentation segments of different lengths are adopted according to different optical environments, thereby effectively improving the "ripple" phenomenon, improving OPC correction accuracy and OPC correction efficiency, and reducing process risks.

[0008] In one of the embodiments, the step of adjusting the mask design pattern according to the simulated exposure pattern to obtain the mask plate making pattern includes: calculating the edge placement error between the simulated exposure pattern and the mask design pattern, and adjusting the mask design pattern according to the edge placement error to obtain the mask plate making pattern.

[0009] In one of the embodiments, the step of adjusting the mask design pattern according to the edge placement error to obtain a mask plate making pattern includes: step A, adjusting the mask design pattern according to the edge placement error; step B, simulating the adjusted mask design pattern according to the OPC model to obtain a re-simulated exposure pattern; step C, calculating the edge placement error between the re-simulated exposure pattern and the adjusted mask design pattern; step D, judging whether a preset condition is met according to the edge placement error calculated in step C, and if so, using the adjusted mask design pattern as the mask plate making pattern; otherwise, returning to step A.

[0010] In one of the embodiments, before the step of simulating the mask design pattern according to the OPC model, it also includes the step of placing a target point on the outer edge of the mask design pattern; the step of adjusting the mask design pattern according to the edge placement error includes: according to the value of the edge placement error corresponding to each section of the outer edge, adjusting the mask design pattern so that the value of the edge placement error tends to zero.

[0011] In one embodiment, the length of the segment is Wherein cd is the distance between the line end and the line pattern, OD is the optical diameter used when establishing the OPC model, l is an empirical value, [] indicates rounding up, and the unit of Δx is nanometer.

[0012] In one embodiment, Δx is not less than the minimum limit size of the photolithography plate in actual plate making and is not greater than the longest length that can be defined by the cutting line segment.

[0013] In one embodiment, l depends on the critical dimension of the process node.

[0014] In one embodiment, the extension direction of the line end is perpendicular to the line pattern.

[0015] In one of the embodiments, the preset condition is that the absolute value of the edge placement error corresponding to the outer edge of each section of the mask design pattern is smaller than a preset value.

[0016] It is also necessary to provide a mask, which is made of a mask making pattern obtained according to the optical proximity correction method described in any of the above embodiments.

[0017] It is also necessary to provide a readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the steps of the optical proximity correction method described in any of the above embodiments.

[0018] It is also necessary to provide a computer device, including a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the optical proximity correction method described in any of the above embodiments when executing the computer program.

[0019] It is also necessary to provide a computer program product, comprising a computer program, which, when executed by a processor, implements the steps of the optical proximity correction method described in any of the aforementioned embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0021] Figure 1 A schematic diagram of an exemplary mask design pattern and a pattern after exposure simulated by OPC software;

[0022] Figure 2It is a schematic diagram of the analysis and segmentation of the mask design pattern and the simulated exposure in an exemplary OPC process;

[0023] Figure 3 This is a schematic diagram of an exemplary parsing and segmentation by using the Inter-feature segmentation command;

[0024] Figure 4 is a flow chart of an optical proximity correction method in one embodiment;

[0025] Figure 5 yes Figure 4 The sub-step flow chart of step S440 in the embodiment shown;

[0026] Figure 6 It is an exemplary partial mask design pattern at a critical dimension of 110nm node;

[0027] Figure 7 It is a schematic diagram of analytical segmentation and placement of target points in a pair of ratios;

[0028] Figure 8 yes Figure 7 The mask plate making pattern corresponding to the comparative example shown;

[0029] Fig. 9 is a schematic diagram of parsing segmentation and placing target points in one embodiment;

[0030] Fig.10 yes Figure 8 The corresponding comparison ratio is Fig. 9 Contour comparison diagram of the mask plate making pattern at the line pattern segment obtained in the corresponding embodiment. DETAILED DESCRIPTION

[0031] In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. Embodiments of the present application are provided in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0033] It should be understood that when an element or layer is referred to as being "on, "adjacent to, "connected to, or "coupled to" other elements or layers, it may be directly on, adjacent to, connected to, or coupled to other elements or layers, or there may be intervening elements or layers. In contrast, when an element is referred to as being "directly on, "directly adjacent to, "directly connected to, or "directly coupled to" other elements or layers, there may be no intervening elements or layers. It should be understood that, although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers, doping types, and / or portions, these elements, components, regions, layers, doping types, and / or portions should not be limited by these terms. These terms are merely used to distinguish one element, component, region, layer, doping type, or portion from another element, component, region, layer, doping type, or portion. Therefore, without departing from the teachings of the present invention, the first element, component, region, layer, doping type or portion discussed below may be represented as a second element, component, region, layer or portion; for example, the first doping type may be referred to as the second doping type, and similarly, the second doping type may be referred to as the first doping type; the first doping type and the second doping type are different doping types, for example, the first doping type may be P-type and the second doping type may be N-type, or the first doping type may be N-type and the second doping type may be P-type.

[0034] Spatially relative terms such as "under," "beneath," "below," "under," "above," "above," and the like may be used herein to describe the relationship of an element or feature shown in the figures to other elements or features. It should be understood that, in addition to the orientations shown in the figures, spatially relative terms also include different orientations of the device in use and operation. For example, if the device in the accompanying drawings is flipped, an element or feature described as "under other elements" or "under it" or "under it" will be oriented as being "above" the other elements or features. Thus, the exemplary terms "under" and "under" may include both upper and lower orientations. In addition, the device may also include additional orientations (e.g., rotated 90 degrees or other orientations), and the spatial descriptors used herein are interpreted accordingly.

[0035] When used herein, the singular forms "a", "an", and "said / the" may also include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" and the like specify the presence of stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not exclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. At the same time, in this specification, the term "and / or" includes any and all combinations of the relevant listed items.

[0036] Embodiments of the invention are described herein with reference to cross-sectional views which are schematic diagrams of ideal embodiments (and intermediate structures) of the invention, such that variations in the shapes shown due to, for example, manufacturing techniques and / or tolerances are anticipated. Thus, embodiments of the invention should not be limited to the specific shapes of the regions shown herein, but rather include deviations in shapes due to, for example, manufacturing techniques. For example, an implanted region shown as a rectangle typically has rounded or curved features and / or an implant concentration gradient at its edges rather than a binary change from an implanted region to a non-implanted region. Similarly, a buried region formed by implantation may result in some implantation in the region between the buried region and the surface through which the implantation is performed. Thus, the regions shown in the figures are schematic in nature, their shapes do not represent the actual shape of the region of the device, and do not limit the scope of the invention.

[0037] An exemplary computer-aided software tool for optical proximity correction (OPC) is to first identify the edge of the mask design pattern through the OPC software, and divide the edge of the mask design pattern into many small correction line segments, so that each edge segment can move freely. Then the OPC software simulates the pattern after photolithography exposure and compares it with the mask design pattern (such as Figure 1 The difference between them is called edge placement error (EPE), which is an indicator used to measure the quality of correction. OPC software moves the edge position of the mask design pattern during operation and calculates the corresponding edge placement error. This process is repeated until the calculated edge placement error reaches an acceptable value. The mask design pattern segmentation and corresponding results in the OPC process are shown in Figure 1. Figure 2 As shown, Figure 2 The left half shows the position of the mask design pattern and the cutting point. The black dots on the edge of the original layout represent the cutting points that divide the edge into several correction line segments of different lengths. The OPC result obtained after correction (i.e., the corrected mask plate pattern) is as follows: Figure 2 Shown in the right half.

[0038] The positions with the largest OPC correction are usually at the corners and ends of the lines. OPC software sets smaller grids at the corners and end points of the graphics, making the EPE calculation at these positions more intensive and the correction more complete. There are two typical methods for processing inflection points, namely rule matching segmentation and marked manual segmentation. Taking mentor calibre-WB as an example, the rule matching segmentation command inter-feature is used to project the vertices of adjacent graphics to the opposite edge, and several small segments are segmented according to the command parameters, see Figure 3 The small dots in the figure are the split points. This command has two important parameters: -num is used to set the number of ripple segments; -ripplelen is used to control the length of the ripple segment.

[0039] Since rule-matching segmentation is based on the entire layout graphics, but complex two-dimensional graphics are distributed in the layout graphics, under the influence of the optical proximity effect, a unified parameter configuration is difficult to meet the needs. Therefore, OPC engineers need to spend a lot of time experimenting to find a satisfactory segmentation solution, and then use the method of marking manual segmentation to process the key parts of the layout to obtain satisfactory segmentation results.

[0040] The present application proposes an optical proximity correction method, which improves the segmentation algorithm during the analytical segmentation (Dissection) of the outer edge of the mask design pattern, adopts a dynamic segmentation method, and adopts segmentation segments of different lengths according to different optical environments. Figure 4 is a flow chart of an optical proximity correction method in one embodiment, comprising the following steps:

[0041] S410, obtaining a mask design pattern.

[0042] After the integrated circuit is designed according to actual requirements, design graphics at various levels that meet the requirements are obtained as mask design graphics.

[0043] S420, analyzing and segmenting the outer edge of the mask design pattern into multiple segments.

[0044] Analytical segmentation is to divide the edge of the mask design pattern into many small correction fragments (line segments), and each segmentation point divides the edge of the pattern into several correction line segments of different lengths. Analytical segmentation can be performed using OPC software. Step S420 For the line pattern adjacent to the line end (and the line pattern is adjacent to the line end in the extension direction of the line end, and the line pattern is not parallel to the line end), according to the spacing between the line end and the line pattern and the optical diameter used when establishing the OPC model, calculate the length of the segment Δx of the line pattern at the position adjacent to the line end. Exemplarily, the line pattern and the straight line where the line end is located are at an angle, for example, the line pattern is perpendicular to the straight line where the line end is located.

[0045] S430, simulating the mask design pattern according to the OPC model to obtain a simulated exposure pattern.

[0046] OPC software can be used to simulate exposure of the mask design pattern. These software may have preset simulation exposure rules, and those skilled in the art may modify these rules. This application does not limit the specific simulation exposure rules.

[0047] S440, adjusting the mask design pattern according to the simulated exposure pattern to obtain the mask making pattern.

[0048] The above-mentioned optical proximity correction method improves the segmentation algorithm during the analytical segmentation of the outer edge of the mask design pattern. At the position where the line pattern is adjacent to other line ends, segmentation segments of different lengths are adopted according to different optical environments, thereby effectively improving the "ripple" phenomenon, improving the OPC correction accuracy and OPC correction efficiency, increasing the process window, and reducing process risks.

[0049] In one embodiment of the present application, step S440 includes: calculating the edge placement error between the simulated exposure pattern and the mask design pattern, adjusting the mask design pattern according to the edge placement error, and obtaining the mask plate making pattern.

[0050] In one embodiment of the present application, the method further includes placing a target point (ie, a cutting point) on the outer edge (line end and adjacent edge) of the mask design pattern.

[0051] See also Figure 5 In one embodiment of the present application, step S440 includes:

[0052] S452, adjusting the mask design pattern according to the edge placement error.

[0053] In one embodiment of the present application, each correction segment of the mask design pattern is moved according to the edge placement error so that the edge placement error value of each correction segment approaches zero, or the absolute value of the edge placement error of each correction segment approaches a very small value.

[0054] S454, simulating the adjusted mask design pattern according to the OPC model to obtain a re-simulated exposure pattern.

[0055] Step S454 is similar to step S430 and will not be described again here.

[0056] S456, calculating the edge placement error between the re-simulated exposure pattern and the adjusted mask design pattern.

[0057] In one embodiment of the present application, the edge placement error is the position of the simulated exposure pattern minus the position of the mask design pattern, and the value of the edge placement error can be positive or negative.

[0058] After step S456 is executed, it is determined whether the second preset condition is met based on the edge placement error obtained in step S456. If so, the adjusted mask design pattern is used as the mask plate making pattern; otherwise, return to step S452 and adjust the correction segments of the mask design pattern again.

[0059] In one embodiment of the present application, the second preset condition is that the absolute value of the edge placement error corresponding to each correction segment is less than a preset value. The preset value may be an empirical value.

[0060] In one embodiment of the present application, if the number of adjustments in step S452 reaches a preset number, no further adjustments are performed, and the mask design pattern obtained by the last adjustment is used as the mask making pattern.

[0061] Specifically, step S420 may be an algorithm for changing the rule matching segmentation command inter-feature. In one embodiment of the present application, the segmentation line length

[0062] Where cd is the distance between the line end and the line pattern, OD is the optical diameter used when establishing the OPC model, l is an empirical value, [] means rounding up, and the unit of Δx is nanometers; the optical diameter defines the size of the square affected by the optical system space, and when calculating the light intensity of the pattern, the influence of all patterns within the range of OD / 2 will be considered. In one embodiment of the present application, the units of cd, OD and l are also nanometers.

[0063] In one embodiment of the present application, Δx is not less than the minimum limit size of the photoresist plate actually made in a mask shop, and is not greater than the longest length that can be defined by the cutting line segment.

[0064] In one embodiment of the present application, l depends on the critical dimension of the process node.

[0065] Figure 6 This is an exemplary critical dimension (Critical Dimension) of a portion of the mask design pattern at the 110nm node. Figure 6 The line end is perpendicular to the line pattern in its extension direction, and the distance cd between the line end and the line pattern is 120nm. As a comparative example, a regular segmentation method is used in the analytical segmentation step, and the segmentation segment length is 120nm. Target points are placed at the line end 12 and the line pattern segment 14, such as Figure 7 Then, the mask design pattern is simulated according to the OPC model to obtain the simulated exposure pattern, and then the edge placement error between the simulated exposure pattern and the mask design pattern at the target position is calculated. Then, the mask design pattern is corrected according to the value of the edge placement error. After repeated iterations, the mask plate making pattern is obtained, as shown in Figure 8 As shown. Figure 8 It can be seen that due to the influence of the optical proximity effect, the line end will affect the adjacent line pattern, resulting in a "ripple" phenomenon, causing the risk of "short circuit" (bridge) or "open circuit" (pinch), resulting in reduced OPC accuracy and causing process risks.

[0066] In one embodiment of the present application, when establishing the OPC model, the value of OD is 960nm. At the node of 110nm, the recommended value of l is 720nm. At this time, the length of Δx is 90nm. Fig. 9 . Fig.10 yes Figure 8 The corresponding comparison ratio is Fig. 9 From the contour comparison diagram of the mask plate making pattern at the line pattern segment obtained in the corresponding embodiment, it can be seen that the "ripple" phenomenon has converged significantly, and the line width of the mask plate making pattern has converged from the original 138.5nm to 132nm, which improves the OPC correction accuracy, increases the process window, and reduces the process risk.

[0067] The present application accordingly provides a mask made from a mask plate making pattern obtained by the optical proximity correction method described in any of the above embodiments.

[0068] The present application also provides a readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the steps of the optical proximity correction method described in any of the above embodiments are implemented.

[0069] The present application also provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the steps of the optical proximity correction method described in any of the above embodiments are implemented.

[0070] The present application also provides a computer program product, including a computer program, which implements the steps of the optical proximity correction method described in any of the aforementioned embodiments when executed by a processor.

[0071] It should be understood that, although the various steps in the flowchart of the present application are displayed in sequence according to the indication of the arrows, these steps are not necessarily executed in sequence according to the order indicated by the arrows. Unless there is a clear explanation in this article, the execution of these steps is not strictly limited in order, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowchart of the present application may include multiple steps or multiple stages, and these steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily carried out in sequence, but can be executed in turn or alternately with other steps or at least a part of the steps or stages in other steps.

[0072] In the description of this specification, the description with reference to the terms "some embodiments", "other embodiments", "ideal embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example.

[0073] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features of the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0074] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

1. An optical proximity correction method, comprising: Obtain mask design graphics; Analytically dividing the outer edge of the mask design pattern into multiple segments, including: for a line pattern adjacent to the line end in the extension direction of the line end, according to the spacing between the line end and the line pattern, and the optical diameter used when establishing the OPC model, calculating the length of the segment of the line pattern at the position adjacent to the line end; wherein the straight line where the line end is located forms an angle with the line pattern; Simulating the mask design pattern according to the OPC model to obtain a simulated exposure pattern; The mask design pattern is adjusted according to the simulated exposure pattern to obtain a mask plate making pattern.

2. The optical proximity correction method according to claim 1, characterized in that: The step of adjusting the mask design pattern according to the simulated exposure pattern to obtain the mask plate making pattern comprises: The edge placement error between the simulated exposure pattern and the mask design pattern is calculated, and the mask design pattern is adjusted according to the edge placement error to obtain a mask plate making pattern.

3. The optical proximity correction method according to claim 2, characterized in that: The step of adjusting the mask design pattern according to the edge placement error to obtain the mask plate making pattern comprises: Step A, adjusting the mask design pattern according to the edge placement error; Step B, simulating the adjusted mask design pattern according to the OPC model to obtain a re-simulated exposure pattern; Step C, calculating the edge placement error between the re-simulated exposure pattern and the adjusted mask design pattern; Step D, judging whether the edge placement error calculated in step C meets the preset conditions, if so, taking the adjusted mask design pattern as the mask plate making pattern; otherwise, returning to step A.

4. The optical proximity correction method according to claim 2 or 3, characterized in that: Before the step of simulating the mask design pattern according to the OPC model, the method further includes the step of placing a target point on the outer edge of the mask design pattern; The step of adjusting the mask design pattern according to the edge placement error includes: adjusting the mask design pattern according to the value of the edge placement error corresponding to each section of the outer edge so that the value of the edge placement error tends to zero.

5. The optical proximity correction method according to claim 1, characterized in that: The length of the segment ; Wherein cd is the distance between the line end and the line pattern, OD is the optical diameter used when establishing the OPC model, l is an empirical value, [] indicates rounding up, The unit is nanometer.

6. The optical proximity correction method according to claim 5, characterized in that: lDepends on the critical dimensions of the process node.

7. The optical proximity correction method according to claim 1, characterized in that: The extension direction of the line end is perpendicular to the line pattern.

8. The optical proximity correction method according to claim 3, characterized in that: The preset condition is that the absolute value of the edge placement error corresponding to the outer edge of each section of the mask design pattern is less than a preset value.

9. A mask, characterized in that: The mask is made of a mask plate-making pattern obtained by the optical proximity correction method according to any one of claims 1-8.

10. A readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 8 are implemented.

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