Optical proximity correction method, electronic equipment and computer readable storage medium

Abstract

The invention relates to an optical proximity correction method, electronic equipment and a computer readable storage medium. The optical proximity correction method comprises the following steps: cutting the outline of an initial layout graph into a plurality of line segments; cutting a line segment in a preset area of the contour into a plurality of first points; determining a corresponding light intensity error aiming at the plurality of line segments and each first point in the plurality of first points, wherein the light intensity error indicates the deviation between the simulation graph and the target layout graph; comparing the light intensity error with a first threshold value; and moving the line segment having a light intensity error greater than the first threshold and the first point to generate an updated layout pattern having a smaller light intensity error. According to the scheme provided by the embodiment of the invention, the shrinkage effect at the preset position of the layout graph can be remarkably reduced while the calculation cost is effectively controlled.

Description

Technical Field

[0001] The embodiments of this disclosure primarily relate to the field of integrated circuits, and more specifically, to optical proximity correction methods, electronic devices, and computer-readable storage media. Background Technology

[0002] Chip manufacturing typically begins by processing the designed circuit diagram into a photomask (also known as a mask) layout. After exposure by a photolithography system, the photomask layout is projected onto the photoresist on the wafer. Subsequently, a series of chemical and physical reactions complete the chip etching process. However, as the size of high-end chip circuit diagrams continues to shrink, the optical proximity effect becomes increasingly severe during photomask exposure, distorting the lithographic pattern on the wafer and making it difficult to achieve the intended circuit design goals. To address this, resolution enhancement technologies have been proposed to expand the chip manufacturing process window and improve yield at a lower cost, such as Optical Proximity Correction (OPC) technology.

[0003] OPC technology primarily modifies the layout pattern to ensure that the pattern on the wafer after photolithography is as close as possible to the target pattern. Figure 1 In conventional OPC techniques, to correct the layout, the layout is cut into a series of movable line segments based on certain rules, and evaluation points are placed on these segments to control their movement. Because the OPC problem is a complex nonlinear problem, an analytical solution for layout correction cannot be obtained; therefore, OPC solvers are typically designed using iterative optimization methods. However, due to the square topological connection structure between the movable line segments, traditional OPC methods are insufficient in handling the shrinkage effect at the corners of the layout, resulting in greater distortion at these corners. Summary of the Invention

[0004] According to exemplary embodiments of this disclosure, an optical proximity correction method, an electronic device, and a computer-readable storage medium are provided to at least partially address the above-described or other potential drawbacks.

[0005] In a first aspect of this disclosure, an optical proximity correction method is provided. The method includes: cutting an outline of an initial layout graphic into multiple line segments; cutting the line segments in a predetermined region of the outline into multiple first points; determining a corresponding light intensity error for each of the multiple line segments and the multiple first points, wherein the light intensity error indicates the deviation between a simulated graphic and a target layout graphic; comparing the light intensity error with the first threshold; and moving the line segments and first points having a light intensity error greater than the first threshold to generate an updated layout graphic with a smaller light intensity error.

[0006] In a second aspect of this disclosure, an electronic device is provided. The electronic device includes a processor and a memory coupled to the processor, the memory having instructions stored therein, the instructions causing the electronic device to perform actions when executed by the processor. The actions include: cutting an outline of an initial layout graphic into multiple line segments; cutting the line segments in a predetermined region of the outline into multiple first points; determining a corresponding light intensity error for each of the multiple line segments and the multiple first points, wherein the light intensity error indicates the deviation between a simulated graphic and a target layout graphic; comparing the light intensity error with the first threshold; and moving the line segments and first points having light intensity errors greater than the first threshold to generate an updated layout graphic with smaller light intensity errors.

[0007] In some embodiments, moving a line segment and a first point with an intensity error greater than a first threshold to generate an updated layout pattern with a smaller intensity error includes: iteratively moving a line segment and a first point with an intensity error greater than a first threshold to generate an updated layout pattern until the intensity error is less than the first threshold, so as to use the corresponding updated layout pattern as the corrected layout pattern.

[0008] In some embodiments, the line segment and the first point are offset according to their respective offsets to generate an offset line segment and an offset point; and the offset line segment and the offset point are connected in a predetermined order to generate a first corrected layout graphic.

[0009] In some embodiments, the method further includes performing a smoothing process on the first corrected layout graphic, the smoothing process including: forming an angle between the offset point as a vertex and other points adjacent to the offset point on both sides; determining the radius of curvature of the offset point at the angle; comparing the radius of curvature with a second threshold; and reducing the amount of movement of the offset point in response to the radius of curvature being less than the second threshold, such that the radius of curvature of the offset point at the angle increases to not less than the second threshold; wherein the other points include at least one of the following: an offset point different from the offset point as a vertex, an endpoint of an offset line segment, an endpoint of an unoffset line segment, and a first point that is not offset.

[0010] In some embodiments, in response to a light intensity error being greater than or equal to a first threshold, the light intensity error is iteratively calculated; and the line segment and the first point are iteratively moved based on the light intensity error until the light intensity error is less than the first threshold.

[0011] In some embodiments, determining the corresponding light intensity error for each of the plurality of line segments and the plurality of first points includes: calculating the light intensity error based on a forward lithography model simulation, wherein the forward lithography model simulation includes simulating the chemical reaction process of the photoresist.

[0012] In some embodiments, determining the corresponding light intensity error for each of a plurality of line segments and a plurality of first points includes: assigning a first evaluation point for calculating the light intensity error to the midpoint of each line segment; setting each first point as a second evaluation point for calculating the light intensity error; determining the light intensity error at each first evaluation point as the light intensity error of the corresponding line segment; and determining the light intensity error at each second evaluation point as the light intensity error of the corresponding first point.

[0013] In some embodiments, moving a line segment and a first point having a light intensity error greater than a first threshold includes: determining a corresponding second point with a light intensity error of zero corresponding to each of the first and second evaluation points based on a gradient descent method; determining a corresponding offset based on the distance between each evaluation point and the second point; and moving the line segment and the first point based on the offset such that the first and second evaluation points of the moved line segment coincide with the corresponding second point, respectively.

[0014] In some embodiments, connecting the offset line segments and offset points in a predetermined order further includes connecting the unmoved line segments with light intensity errors less than a first threshold and the first point.

[0015] In some embodiments, the offset remains constant in response to a radius of curvature greater than or equal to a second threshold.

[0016] In some embodiments, reducing the amount of movement of the offset point includes adjusting the offset of the offset point based on a predetermined smoothing coefficient and radius of curvature.

[0017] In some embodiments, adjusting the amount of movement of the offset point includes: constructing a spline curve based on the positions of the endpoints of the line segment adjacent to the offset point and / or other first points and a second threshold; and moving the offset point onto the spline curve.

[0018] In some embodiments, moving a line segment and a first point having an intensity error greater than a first threshold includes: moving the first point in any direction in the plane of the initial layout pattern; and moving the line segment along the normal direction of the line segment in the plane of the initial layout pattern.

[0019] In some embodiments, the preset area of ​​the outline of the initial layout graphic may be the corner area of ​​the outline of the initial layout graphic.

[0020] In a third aspect of this disclosure, a computer-readable storage medium is provided having a computer program stored thereon that, when executed by a processor, implements the method according to a first aspect of this disclosure.

[0021] The solutions implemented using the embodiments of this disclosure can achieve at least the following beneficial effects:

[0022] By breaking the vertical and horizontal geometric constraints of optical proximity effect correction at the corners of the layout, a corrected layout that is closer to the target layout can be obtained, and the shrinkage effect of the layout at the corners can be significantly reduced.

[0023] It integrates layout correction methods based on movable points and movable line segments, combining the advantages of high correction accuracy of movable points in preset areas and fast correction speed of movable line segments in other positions.

[0024] By employing a modified layout smoothing algorithm, the modified layout graphics are made to better meet manufacturability standards.

[0025] It should be understood that the description in the Summary of the Invention is not intended to limit the key or essential features of the embodiments of this disclosure, nor is it intended to restrict the scope of this disclosure. Other features of this disclosure will become readily apparent from the following description. Attached Figure Description

[0026] The above and other features, advantages, and aspects of the embodiments of this disclosure will become more apparent from the accompanying drawings and the following detailed description. In the drawings, the same or similar reference numerals denote the same or similar elements, wherein:

[0027] Figure 1 A schematic diagram of an example environment in which several embodiments of the present disclosure can be implemented is shown;

[0028] Figure 2 The illustration shows a flowchart of an optical proximity correction method according to some embodiments of the present disclosure;

[0029] Figures 3A-3D A schematic diagram of a layout pattern obtained by performing different steps of an optical proximity correction method according to an embodiment of the present disclosure is shown;

[0030] Figure 4 A flowchart illustrating the iterative modification of an initial layout pattern based on light intensity error according to some embodiments of the present disclosure is shown;

[0031] Figure 5 A schematic diagram illustrating the movement of a first point and a line segment based on gradient descent according to some embodiments of the present disclosure is shown;

[0032] Figure 6 A flowchart illustrating the movement of a first point and a line segment based on gradient descent according to some embodiments of this disclosure is shown;

[0033] Figure 7 A flowchart illustrating a process for smoothing modified layout graphics according to some embodiments of the present disclosure is shown;

[0034] Figure 8A schematic diagram of a layout graphic adjustment method based on radius of curvature is shown;

[0035] Figure 9 The illustration shows the optical proximity correction effect using some embodiments of the present disclosure;

[0036] Figure 10 A block diagram of a computing device capable of implementing several embodiments of the present disclosure is shown. Detailed Implementation

[0037] Embodiments of this disclosure will now be described in more detail with reference to the accompanying drawings. While some embodiments of this disclosure are shown in the drawings, it should be understood that this disclosure can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of this disclosure. It should be understood that the accompanying drawings and embodiments of this disclosure are for illustrative purposes only and are not intended to limit the scope of protection of this disclosure.

[0038] In the description of embodiments of this disclosure, the term "comprising" and similar terms should be understood as open-ended inclusion, i.e., "including but not limited to". The term "based on" should be understood as "at least partially based on". The term "one embodiment" or "the embodiment" should be understood as "at least one embodiment". The terms "first", "second", etc., may refer to different or the same objects. Other explicit and implicit definitions may also be included below.

[0039] As mentioned earlier, OPC technology mainly modifies the layout pattern to make the pattern on the wafer after photolithography as close as possible to the target pattern. Figure 1 OPC technology is mainly divided into traditional OPC technology and reverse lithography technology (ILT).

[0040] In conventional OPC techniques, to correct the layout, the layout is cut into a series of movable line segments according to certain rules, and evaluation points are placed on these segments to control their movement. Because the OPC problem is a complex nonlinear problem, an analytical solution for layout correction cannot be obtained. Therefore, OPC solvers are typically designed using an iterative optimization approach. Most existing OPC solvers are designed based on edge placement error (EPE) or light intensity error at evaluation points. They directly use the measured light intensity signal error value to determine the offset of the movable line segments in the next iteration. However, due to the square topological connection structure between the movable line segments, traditional OPC methods are insufficient in handling the shrinkage effect at the corners of the layout, resulting in greater distortion at these corners.

[0041] The so-called shrinkage effect at the corners of a layout refers to the greater distortion of the wafer edge pattern at corners compared to other locations. ILT (Integrated Light Tracing) technology pixelates the layout pattern and optimizes the pixels based on a lithography model, thus removing the square topological constraints of the layout pattern and obtaining a fuller contour at the corners. However, ILT technology has high computational resource requirements, and its solution speed is much slower than traditional OPC solvers, so it is generally not used for global layout correction. To balance the efficiency of traditional OPC solvers with the correction accuracy of ILT technology, curvilinear OPC (also known as curve OPC) technology was proposed.

[0042] In curvilinear OPC, the layout graphic is divided into a series of closed connections of movable points. A curvilinear mask layout is obtained by moving these movable points, rather than moving line segments. Curvilinear mask layouts can solve the shrinkage effect problem at layout corners. However, decomposing the layout graphic into a series of movable points significantly increases computational costs.

[0043] Given the aforementioned shortcomings of the traditional approach, an improved approach is still needed.

[0044] According to embodiments of this disclosure, an optical proximity correction method is proposed. In this method, line segments are first cut along the outline of an initial layout pattern to form a first pattern composed of line segments. Then, the line segments at a predetermined region of the first pattern are divided into a plurality of first points, and an evaluation point is assigned to each first point and line segment. Next, a light intensity error corresponding to the first point and the line segment is calculated for each evaluation point. The light intensity error is compared to the first threshold; and the line segments and first points having a light intensity error greater than the first threshold are moved such that the moved line segments and first points have a light intensity error less than the first threshold, thereby forming a modified layout pattern.

[0045] The method of this disclosure uses movable points for correction in a preset area of ​​the layout graphic, while using movable line segments for correction in other positions of the layout graphic. This significantly reduces the shrinkage effect in the preset area of ​​the layout graphic while effectively controlling computational costs. In this way, the layout graphic can be modified quickly with low computational costs, thereby reducing development costs.

[0046] The embodiments of this disclosure will now be described in detail with reference to the accompanying drawings.

[0047] Figure 1A schematic diagram of an example environment 100 in which various embodiments of the present disclosure can be implemented is shown. The computing device 102 in the example environment 100 can be any device with computing capabilities. As a non-limiting example, the computing device 102 can be any type of fixed computing device, mobile computing device, or portable computing device, including but not limited to desktop computers, laptop computers, notebook computers, netbook computers, tablet computers, multimedia computers, mobile phones, etc.; all or some components of the computing device 102 can be distributed in the cloud.

[0048] In this example environment 100, computing device 102 may include or be deployed with an acquisition module 103, an offset module 104, and a smoothing module 105. The actions described below with respect to computing device 102 may specifically be performed by the acquisition module 103, the offset module 104, or the smoothing module 105.

[0049] The acquisition module 103 can be configured to acquire a layout pattern 110. The layout pattern 110 can be acquired from a client (not shown). As used herein, the layout pattern can also be referred to as a layout design. The layout pattern 110 may include a target circuit layout pattern (e.g., the initial layout pattern 111 shown). The initial circuit layout pattern in the layout pattern 110 may include one or more layers of geometry.

[0050] The acquisition module 103 may be further configured to determine an initial layout pattern 111 from the layout pattern 110. In some embodiments, the initial layout pattern may be a test pattern in the layout pattern 110. Alternatively or additionally, in some embodiments, the initial layout pattern may be a fragment of a circuit layout in the layout pattern 110.

[0051] The offset module 104 and the smoothing module 105 can be configured to generate corrected layout graphics based on the initial layout graphics 111, either individually or collaboratively. Figure 1 The correction pattern 120 is shown. Specifically, the offset module 104 can cut and move points and line segments on the outline of the initial layout pattern 111, and the smoothing module 105 can smooth the outline of the initial layout pattern 111 or the intermediate layout pattern processed by the offset module 104. In some embodiments, the offset module 104 and the smoothing module 105 can be configured to iteratively generate updated patterns, and finally generate the correction pattern 120 when a threshold condition is met.

[0052] It should be understood that Figure 1 The number and style of circuit layouts in the layout diagram 110 shown are merely illustrative and not intended to be limiting. Furthermore, Figure 1 The module division shown is for illustrative purposes only and is not intended to be restrictive.

[0053] refer to Figure 2 The illustration shows the general process of an optical proximity correction method 200 according to an embodiment of the present disclosure.

[0054] exist Figure 2 At box 202, the outline of the initial layout graphic can be cut into multiple line segments. In some embodiments, a conventional method can be used to cut the outline of the initial layout graphic. For example, in Figure 3A The diagram illustrates cutting the outline of the initial layout graphic into multiple line segments 12 to form a first graphic 300. Specifically, in Figure 3A In the first graphic 300 shown, adjacent line segments 12 share the same line segment endpoints 11. In other words, the first graphic 300, which represents the outline of the initial layout graphic, is formed by multiple line segments 12 connected end to end.

[0055] In some embodiments, each line segment 12 of the first pattern 300 may have the same length. In other embodiments, the length of each line segment 12 may be different.

[0056] return Figure 2 At box 204, the line segment of the preset area of ​​the contour is cut into a plurality of first points. In some embodiments, conventional methods may be used for cutting. For example, Figure 3B The image shows what will be obtained after execution box 202. Figure 3A The preset area of ​​the first graphic 300 is further divided, and a schematic diagram of the divided layout graphic 301 of multiple first points 13 is obtained. Specifically, Figure 3B Line segment 12 of a preset area of ​​the first graphic 300 is shown to be cut into a plurality of first points 13, and the cut layout graphic 301 of line segment 12 is retained in other areas of the first graphic 300.

[0057] In some embodiments, a preset region can be determined according to predetermined rules. For example, the positions of each vertex on the initial layout graphic outline can be determined first, and then the outline on the initial layout graphic outline that is within a threshold distance from the vertex can be determined as the preset region. In other words, in a non-limiting example, the preset region on the outline of the initial layout graphic can be a corner region. In some embodiments, the cutting rules can be formulated by combining the cutting line segments, the surrounding environment of the points, and the actual experience of the field engineers.

[0058] In some embodiments, the preset regions of the cut layout pattern 301 may have the same density of first points 13. For example, in different preset regions of the cut layout pattern 301, the distance between adjacent first points 13 is the same. In some embodiments, the preset regions of the cut layout pattern 301 may have different densities of first points 13. For example, in different preset regions of the cut layout pattern 301, the distance between adjacent first points 13 is different. In some embodiments, the distance between multiple first points 13 in the same preset region may be different.

[0059] According to some embodiments of this disclosure, the first point 13 and line segment 12 can be configured as the smallest correction unit for modifying the initial layout graphic 10.

[0060] Back Figure 2 At box 206, a corresponding light intensity error is determined for each of the plurality of line segments and each of the plurality of first points, wherein the light intensity error indicates the deviation between the simulated graphic and the target layout graphic.

[0061] In some embodiments, light intensity error can be determined using conventional methods. In some embodiments, determining the corresponding light intensity error for each of the plurality of line segments 12 and the plurality of first points 13 in the cut layout pattern 301 may at least include assigning an evaluation point 14 for light intensity error measurement to each line segment 12 and each first point 13. For example, in Figure 3C The diagram shows an evaluation layout graphic 302 that assigns evaluation points 14 for determining the corresponding light intensity error to each first point 13 and each line segment 12. According to a non-limiting example, the midpoint of each line segment 12 can be set as the first evaluation point, and the first point 13 itself can be set as the second evaluation point. For simplicity, the first and second evaluation points are collectively referred to as evaluation points 14 in the subsequent light intensity error determination process.

[0062] In other non-limiting examples, evaluation points 14 can also be assigned to line segments 12 in other ways. For example, in some examples, the endpoints 11 of each line segment 12 can be set as evaluation points 14.

[0063] According to some embodiments, the photolithography model simulation can be a forward photolithography model simulation. According to some embodiments, the light intensity error can be calculated based on the forward photolithography model simulation, and the forward photolithography model simulation includes simulating the chemical reaction process of the photoresist.

[0064] In some embodiments, the light intensity error can be determined by looking up a table. In other embodiments, the light intensity error can be determined by calculation.

[0065] Back Figure 2In box 208, the light intensity error determined at each evaluation point 14 is compared with a first threshold. For example, the first threshold may be a predetermined light intensity error threshold. In some embodiments, the predetermined light intensity error threshold may be predetermined. In some embodiments, the predetermined light intensity error threshold may be the same for each evaluation point 14.

[0066] Next, at box 210, the line segment with a light intensity error greater than the first threshold and the first point are moved to generate an updated layout graphic with a smaller light intensity error.

[0067] For example, in Figure 3D The updated layout pattern 15 shown here has a smaller light intensity error compared to the initial layout pattern 10.

[0068] According to some embodiments, based on the comparison results, line segment 12 and first point 13 with light intensity error greater than a predetermined light intensity error threshold can be moved, and the moved first point 13, line segment 12, and the unmoved first point 13 and line segment 12 (if any) can be connected end to end in sequence to obtain an updated layout graphic 15. Figure 3D It is also shown that only a portion of the first point 13 and line segment 12 are moved. This is because line segment 12 and first point 13 already have a light intensity error less than a predetermined light intensity error threshold in the initial layout pattern 10 and do not need to be moved. According to some embodiments of this disclosure, the light intensity error of each first point 13 and line segment 12 in the updated layout pattern 15 is less than the predetermined light intensity error threshold. According to some embodiments of this disclosure, if the light intensity error of each first point 13 and line segment 12 in the updated layout pattern 15 is not completely less than the predetermined light intensity error threshold, iterative processing is performed, as further described below. According to some embodiments, moving line segments 12 and first points 13 with light intensity errors greater than a first threshold to generate an updated layout pattern 15 with a smaller light intensity error may include: iteratively moving line segments 12 and first points 13 with light intensity errors greater than the first threshold to generate an updated layout pattern until the light intensity errors of all line segments 12 and first points 13 are less than the first threshold. The corresponding updated layout pattern 15 can then be used as a corrected layout pattern.

[0069] The following is for reference. Figure 4 . Figure 4 A flowchart is shown of a method 400 for iteratively modifying an initial layout pattern 10 based on light intensity error according to a non-limiting embodiment of the present disclosure.

[0070] For example, at box 401, a layout pattern with assigned evaluation points can be input into the photolithography model for simulation. According to some embodiments, light intensity error can be calculated based on forward photolithography model simulation, where the forward photolithography model simulation includes simulating the chemical reaction process of the photoresist. By incorporating the chemical reaction process of the photoresist into the forward photolithography model simulation process, more comprehensive simulation results can be obtained.

[0071] According to some embodiments, at block 403, a corresponding light intensity signal can be determined for each evaluation point 14, thereby determining the light intensity error relative to the desired light intensity value. For example, the light intensity error relative to the desired light intensity value can be calculated for each evaluation point 14 in the layout pattern 100 to which the evaluation points 14 are assigned.

[0072] At box 405, it is determined whether the light intensity error determined at each evaluation point 14 is less than a predetermined threshold. If it is determined that the light intensity error at not all evaluation points 14 is less than the predetermined light intensity error threshold, then method 400 proceeds to box 407, and the new offset is recalculated in the Curvilinear OPC solver.

[0073] The following is for reference. Figure 5 To more illustratively describe a method for calculating the offset of the first point 13 and line segment 12 in a Curvilinear OPC solver according to embodiments of the present disclosure.

[0074] For example, if the light intensity error calculated for evaluation point 14 exceeds a predetermined threshold, parameters such as the light intensity error and the rate of change of light intensity error at evaluation point 14 can be passed to the curvilinear OPC solver. For instance, the solver can use these parameters to calculate the offsets of the corresponding first point 13 and line segment 12 in the next iteration, thereby generating an initial layout pattern 10 for the next iteration. According to one or more embodiments, the above-described process of forward lithography model simulation and offset calculation can be performed iteratively until the light intensity error at all evaluation points 14 is below the preset threshold.

[0075] For example, Figure 5 The process of calculating the offset between the first point 13 and line segment 12 in one iteration using the curvilinear OPC solver according to this disclosure is illustrated. Figure 5 The first evaluation point 12a represents the evaluation point assigned to line segment 12, and the second evaluation point 14a represents the evaluation point assigned to the first point 13. According to some embodiments, the position at the second evaluation point 14a, denoted as [position not specified], can be calculated based on a known light intensity distribution map. Light intensity error ,in These represent the coordinates of the second evaluation point 14a in the x and y directions in the known Cartesian coordinate system, respectively. According to some embodiments, the light intensity error... It can be obtained through the following formula:

[0076] (1)

[0077] in For the second evaluation point 14a The light intensity value is determined (e.g., calculated), and the predetermined light intensity threshold is the critical value at which the photoresist begins to react. For a specific photolithography simulation, the predetermined light intensity threshold can be a constant.

[0078] In some embodiments, the light intensity change gradient at the second evaluation point 14a It can be represented as:

[0079] (2)

[0080] The aforementioned gradient of light intensity change can be calculated using the following formula via a difference method:

[0081] (3)

[0082] (4)

[0083] In equations (3) and (4), and The second evaluation point 14a is located at and Offset in direction.

[0084] According to some embodiments, after calculating the second evaluation point 14a Light intensity error at the location and gradient Then, the contour point 14c can be determined along the gradient descent direction according to the following formula (5). .

[0085] (5)

[0086] For example, contour point 14c is located on contour line 17 where the light intensity value is equal to a given light intensity threshold. Contour line 17 constitutes the wafer end pattern obtained after processing the current layout pattern using a photolithography model. In this embodiment, since contour point 14c represents the actual wafer end position, and the second evaluation point 14a is the desired target position, the second evaluation point 14a needs to be moved along the direction from contour point 14c to evaluation point 14a by a distance 141 from contour point 14c to evaluation point 14a to reach the desired target position. That is, the second evaluation point 14a corresponding to the first point 13 needs to be moved to the position of the second point 14b. The distance 142 from the second evaluation point 14a to the second point 14b is the offset of the first point 13 assigned the second evaluation point 14a, calculated based on the gradient descent method.

[0087] In some examples, for the midpoint 12a of the movable line segment 12, the corresponding contour point 12c can also be found by referring to formulas (1)-(5). For example, the expected target position of the midpoint 12a of the line segment 12 can be obtained by calculating the offset 121 from the contour point 12c on the contour line 17 to the midpoint 12a of the line segment. However, unlike the movable first point 13, the direction of movement of the movable line segment 12 is restricted to its normal direction. Therefore, it is necessary to calculate the component 122 of the distance from the midpoint 12a of the line segment 12 to the midpoint 12b of the moving line segment in the normal direction of the line segment 12. The component 122 is the offset of the movable line segment 12.

[0088] The following reference Figure 6 , Figure 6 A flowchart 600 illustrates a method for moving a movable first point 13 and a movable line segment 12 based on light intensity error according to one or more embodiments of the present disclosure. For example, a corresponding evaluation point 14 is assigned to each first point 13 and each line segment 12 (e.g., ...). Figure 5 After the first evaluation point 12a and the second evaluation point 14a, the steps in box 601 are executed first. For example, in box 601, the light intensity error of the light intensity value at each evaluation point 14 relative to the expected value can be calculated.

[0089] Subsequently, in box 603, the position where the light intensity error is zero relative to each evaluation point 14 can be calculated using the gradient descent method. The distance between the calculated position where the light intensity error is zero and each corresponding evaluation point 14 is the offset corresponding to that evaluation point 14, which is a two-dimensional vector, and can be referred to here as the two-dimensional initial offset.

[0090] After obtaining the initial two-dimensional offset for each evaluation point 14, the steps in box 605 can be performed. For example, in box 605, it is determined whether each evaluation point 14 is an evaluation point 14 assigned to line segment 12. For example, it is determined whether the evaluation point is the first evaluation point 12a or the second evaluation point 14a.

[0091] For the first evaluation point 12a belonging to line segment 12, the method proceeds to box 611. At box 611, the component of the two-dimensional initial offset in the normal direction of line segment 12 can be calculated. This calculated component can be configured as the corresponding offset of line segment 12. Next, the method proceeds to box 613, where line segment 12 is moved by the corresponding offset in its normal direction.

[0092] Returning to box 605, for the second evaluation point 14a not assigned to line segment 12, the method continues to box 607. For example, at box 607, the movable first point 13 can be moved in the x and y directions respectively based on the two-dimensional initial offset. Subsequently, boxes 609 and 615 represent obtaining the moved first point 13 and the moved line segment 12 after executing boxes 607 and 613, respectively. Next, at box 617, adjacent moved first points 13 and line segments 12 can be connected end-to-end in sequence to form an updated layout graphic. According to a non-limiting embodiment, it is possible that there are unmoved first points 13 and line segments 12. In this case, adjacent moved first points 13 and line segments 12 and unmoved first points 13 and line segments 12 can be connected in the corresponding order to form an updated layout graphic. For example, in Figure 3D The diagram shown includes a first point 13 that has been moved, a line segment 12 that has not been moved, and a first point 13 that has been moved, and a line segment 12 that has not been moved, connected to form a first iterative layout graphic.

[0093] Back Figure 4 After obtaining the offset for each first point 13 and line segment 12, method 400 proceeds to block 411. At block 411, the positions of line segment 12 and first point 13 of the evaluation point 14, which have an error greater than a predetermined light intensity threshold, are adjusted. For example, based on the above... Figure 5 and Figure 6 The method discussed allows for the movement of line segment 12 and first point 13, which have an evaluation point 14 with an intensity error greater than a predetermined threshold, based on the corresponding offsets obtained in box 407.

[0094] Subsequently, at box 413, all line segments 12 and the first point 13 (whether or not they have been moved) are connected end to end in a predetermined order to form the first iteration layout graphic for processing in the new iteration.

[0095] Subsequently, method 400 proceeds again to block 403 to calculate the light intensity error for each evaluation point 14 of the first iteration layout graphic from block 413 in a new iteration. In some embodiments, a new light intensity error threshold may be determined for each iteration. For example, the new light intensity error threshold may be determined by looking up a table or by calculation.

[0096] In some embodiments, the light intensity error threshold for each iteration may be the same or different. For example, in some embodiments, the predetermined light intensity error threshold may be gradually reduced as the number of iterations increases.

[0097] In some embodiments, if the step in block 405 determines that the light intensity error of all evaluation points 14 is less than a predetermined light intensity error threshold, the method proceeds to block 409. At block 409, the current layout pattern in the lithography model can be set as a first corrected layout pattern. For example, the first corrected layout pattern can be an offset layout pattern. The method can then, for example, output the first corrected layout pattern as an offset layout pattern in block 409.

[0098] According to one or more embodiments, after performing the offset processing described above, the resulting first corrected layout graphic may have excessively sharp corners. In other words, the contour of the first corrected layout graphic after offset processing may contain angles with a radius of curvature smaller than a desired threshold. Therefore, in some embodiments, further processing of the first corrected layout graphic is required to smooth its contour.

[0099] Specifically, Figure 7 A flowchart illustrating a smoothing process for an updated layout graphic according to one or more embodiments is shown. For example, at box 701, each moved first point 13 can be a vertex, and an included angle can be formed by the endpoints 11 of line segments 12 adjacent to the first point 13 on both sides and / or other first points 13.

[0100] In some embodiments, such as in Figure 8 As shown, for a moved point A1, with point A1 as the vertex, the radius of curvature 81 of the angle formed by point A1 and the adjacent moved points 14e and 14f on either side is calculated, and the radius of curvature 82 of the incircle formed by point B1, the adjacent points 14f and 14g is detected. Although this disclosure only discusses embodiments with moved points A1 and B1 as vertices in detail, it is understood that the method 700 according to this disclosure is not limited thereto. For example, each first point 13 of the first revised layout graphic can be used as a vertex to perform smoothing, regardless of whether the first point 13 has been moved.

[0101] Next, the method can proceed to step 703 to calculate the corresponding radius of curvature for the included angle and determine whether the radius of curvature is less than a predetermined radius of curvature threshold. For example, in Figure 8 As shown in the figure, in some embodiments, the radius of curvature 81 of the inscribed circle formed by points 14e, A1, and 14f, and the radius of curvature 82 of the inscribed circle formed by points 14f, B1, and 14g can be calculated by the three-point method.

[0102] When the calculated radius of curvature is less than a predetermined radius of curvature threshold, an unwanted sharp angle is determined at the moved first point 13, and the step proceeds to box 705. For example, when targeting... Figure 8 When smoothing is performed on point B1 shown, it is detected that the radius of curvature 82 of the inscribed circle formed by point B1, adjacent points 14f and 14g is less than a radius of curvature threshold. Since the radius of curvature 82 is less than the predetermined radius of curvature threshold, the position of point B1 needs to be adjusted to smooth the contour of the angle formed by points 14f, B1, and 14g. For example, in some embodiments, it can be calculated using the following formula:

[0103] (6)

[0104] in It can be a pre-set smoothing coefficient, and This could be the calculated radius of curvature. For example, the initial displacement of point B1 in... Figure 8 The distance shown is 84, and the displacement has been adjusted to... Figure 8 The distance is shown as 83.

[0105] Next, a smoothing offset is calculated for the first point 13 where an unwanted sharp angle is determined. Then, the movable first point 13 is moved again in the x and y directions at box 707 based on the obtained smoothing offset. The smoothing method then proceeds to step 709 to output a smoothed and updated layout graphic 15.

[0106] return Figure 7 In some embodiments, the radius of curvature calculated in step 703 is not less than a radius of curvature threshold. For example... Figure 8 As shown in the example, the radius of curvature 81 is greater than a predetermined radius of curvature threshold. Therefore, according to the method of some embodiments of this disclosure, it can be determined that there are no unwanted sharp angles in the layout graphic profile between points 14e, A1, and 14f, and the position of the moved point A1 does not need to be adjusted. In this case, it can be determined that there are no unwanted sharp angles for the corresponding point A1. Then, the method proceeds from box 703 to box 709 to output a smoothed modified layout graphic.

[0107] In some embodiments, method 700 can be performed iteratively, and for each iteration, the predetermined curvature threshold can be the same or different. For example, in some embodiments, the predetermined curvature threshold can gradually increase as the number of iterations increases.

[0108] go through Figure 5 as well as Figure 6 The first stage of the layout graphic offset processing is shown, and after... Figure 7 as well as Figure 8 After the second stage of layout smoothing shown, the displacement adjustment values ​​of the evaluation points 14 for each movable first point 13 and line segment 12 obtained by the curvilinear OPC solver in each iteration are obtained. The movable first point 13 and line segment 12 are moved according to their respective final displacement adjustment values, and the moved first point 13 and line segment 12, as well as the unmoved first point 13 and line segment 12 (if any), can be connected end-to-end in sequence to obtain the updated layout 15 after each iteration. Subsequently, the next iteration can be continued or the iteration can be exited and the updated layout 15 obtained in the last iteration can be output.

[0109] The scope of this disclosure is not limited to performing offset processing and smoothing processing sequentially. For example, it is possible to first perform the process according to... Figure 7 and Figure 8 The smoothing process shown in the graphic is then performed according to... Figure 5 and Figure 6 The layout graphic offset processing is shown. Alternatively, it can be performed separately according to... Figure 5 and Figure 6 The layout graphic offset processing shown, or according to Figure 7 and Figure 8 The layout graphic shown has been smoothed.

[0110] According to embodiments of this disclosure, when determining the positions of all first points 13 and line segments 12 and connecting all first points 13 and line segments 12, the first points 13 can be connected to the endpoints 11 and / or other first points 13 of the line segments 12 by line segments, or by curves determined based on a predetermined method, or by a combination of line segments and curves.

[0111] In a non-limiting embodiment, smoothing may further include constructing a spline curve based on a predetermined radius of curvature threshold and moving the movable first point 13 onto the constructed spline curve. For example, when the movable line segment 12 is restricted to moving only in its normal direction and not rotated, the position of its endpoint 11 and the orientation of the line segment 12 are known. Therefore, a spline curve for placing the moved first point 13 can be constructed based on the position of the endpoint 11 of the line segment 12, the extension direction of the line segment 12, and the predetermined radius of curvature threshold. For example, in a non-limiting embodiment, the spline curve may include a cubic spline curve, a B-spline curve, etc.

[0112] In some embodiments, smoothing can be performed iteratively on each moved first point 13 separately. In other embodiments, smoothing can be performed on multiple first points 13 at once. In still other embodiments, smoothing can be performed on all first points 13 at once.

[0113] The following is for reference. Figure 9 The effects of optical proximity correction using some embodiments of the present disclosure are described. Figure 9 The results of a comparative experiment using, for example, commercial OPC software are shown in the figure. Figure 9 In the example, the parameters of the photolithography model are set as follows: wavelength 193nm, numerical aperture 1.35, light source shape cquad (quadripolar illumination), external sigma 0.95, and internal sigma 0.8. Furthermore, Figure 9 The figure illustrates the optical proximity correction results for a typical metal layer line segment type of photomask pattern, with a critical dimension cd of 45 nm and a minimum spacing sp of 48 nm. From Figure 9 As can be seen, the corrected wafer end patterns 91 and 93 obtained using the method of this disclosure are fuller at the corners and closer to the target layout pattern 10. This indicates that the optical proximity correction method proposed in this disclosure is superior to the wafer end patterns 92 and 94 obtained by the solver based on movable line segments at the corner shrinkage effect. Furthermore, it can be seen that the wafer end pattern 93 corrected using the optical proximity correction method of this disclosure is closer to a perfect circle, while the wafer end pattern 94 obtained using the EPE solver has a more slanted shape. This further demonstrates that the optical proximity correction method according to the embodiments of this disclosure can obtain wafer end patterns closer to the target layout, thus highlighting the superiority of the optical proximity correction method proposed in this disclosure.

[0114] Figure 10 A schematic block diagram of an example device 1000 that can be used to implement embodiments of the present disclosure is shown. Device 1000 can be used to implement... Figure 1The computing device 1000 includes a central processing unit (CPU) 1001, which can perform various appropriate actions and processes according to computer program instructions stored in read-only memory (ROM) 1002 or loaded from storage unit 1008 into random access memory (RAM) 1003. The RAM 1003 may also store various programs and data required for the operation of the device 1000. The CPU 1001, ROM 1002, and RAM 1003 are interconnected via bus 1004. An input / output (I / O) interface 1005 is also connected to bus 1004.

[0115] Multiple components in device 1000 are connected to I / O interface 1005, including: input unit 1006, such as keyboard, mouse, etc.; output unit 1007, such as various types of monitors, speakers, etc.; storage unit 1008, such as disk, optical disk, etc.; and communication unit 1009, such as network card, modem, wireless transceiver, etc. Communication unit 1009 allows device 1000 to exchange information / data with other devices through computer networks such as the Internet and / or various telecommunications networks.

[0116] Processing unit 1001 executes the various methods and processes described above. For example, this disclosure... Figure 5 as well as Figure 6 The first stage of the layout graphic offset processing is shown, and in Figure 7 as well as Figure 8 Any of the second-stage layout graphics smoothing processes shown can be implemented as a computer software program tangibly contained in a machine-readable medium, such as storage unit 1008. In some embodiments, part or all of the computer program can be loaded and / or installed on device 1000 via ROM 1002 and / or communication unit 1009. When the computer program is loaded into RAM 1003 and executed by CPU 1001, one or more steps of any of the layout graphics offset processing and layout graphics smoothing processes described above can be performed. Alternatively, in other embodiments, CPU 1001 can be configured to perform any of the layout graphics offset processing and layout graphics smoothing processes by any other suitable means (e.g., by means of firmware).

[0117] The functions described above in this document can be performed at least in part by one or more hardware logic components. For example, exemplary types of hardware logic components that can be used, without limitation, include: field programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), systems-on-a-chip (SoCs), payload programmable logic devices (CPLDs), and so on.

[0118] The program code used to implement the methods of this disclosure may be written in any combination of one or more programming languages. This program code may be provided to a processor or controller of a general-purpose computer, special-purpose computer, or other programmable data processing apparatus, such that when executed by the processor or controller, the program code causes the functions / operations specified in the flowcharts and / or block diagrams to be implemented. The program code may be executed entirely on a machine, partially on a machine, as a standalone software package partially on a machine and partially on a remote machine, or entirely on a remote machine or server.

[0119] In the context of this disclosure, a machine-readable medium can be a tangible medium that may contain or store a program for use by or in conjunction with an instruction execution system, apparatus, or device. A machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium can be, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination of the foregoing. More specific examples of machine-readable storage media include electrical connections based on one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing.

[0120] Furthermore, although the operations are described in a specific order, this should be understood as requiring that such operations be performed in the specific order shown or in sequential order, or requiring that all illustrated operations be performed to achieve the desired result. In certain environments, multitasking and parallel processing may be advantageous. Similarly, although several specific implementation details are included in the above discussion, these should not be construed as limiting the scope of this disclosure. Certain features described in the context of individual embodiments may also be implemented in combination in a single implementation. Conversely, various features described in the context of a single implementation may also be implemented individually or in any suitable sub-combination in multiple implementations.

[0121] Although the subject matter has been described using language specific to structural features and / or methodological logic, it should be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or actions described above. Rather, the specific features and actions described above are merely illustrative examples of implementing the claims.

Claims

1. An optical proximity correction method, comprising: The outline of the initial layout graphic is cut into multiple line segments; The line segment in the predetermined area of ​​the contour is cut into a plurality of first points; For each of the plurality of line segments and each of the plurality of first points, a corresponding light intensity error is determined, wherein the light intensity error indicates the deviation between the simulated graphic and the target layout graphic; The light intensity error is compared with a first threshold. as well as Move the line segment and the first point that have a light intensity error greater than the first threshold to generate an updated layout pattern with a smaller light intensity error.

2. The method of claim 1, wherein moving the line segment and the first point having a light intensity error greater than the first threshold comprises: The line segment and the first point are offset according to their respective offsets to generate offset line segments and offset points; as well as The offset line segments and the offset points are connected in a predetermined order to generate a first corrected version graphic.

3. The method according to claim 2, further comprising performing a smoothing process on the first revised layout graphic, the smoothing process comprising: An angle is formed between the offset point as the vertex and other points adjacent to the offset point on both sides; Determine the radius of curvature of the offset point at the included angle; The radius of curvature is compared with a second threshold. In response to the radius of curvature being less than the second threshold, the amount of movement of the offset point is reduced so that the radius of curvature of the offset point at the included angle is increased to be not less than the second threshold; The other points include at least one of the following: the offset point that is different from the offset point that is the vertex, the endpoint of the offset line segment, the endpoint of the line segment that is not offset, and the first point that is not offset.

4. The method of claim 1, wherein moving the line segment having an intensity error greater than the first threshold and the first point to generate an updated layout graphic with a smaller intensity error comprises: The line segment and the first point with the light intensity error greater than the first threshold are iteratively moved to generate an updated layout graphic until the light intensity error is less than the first threshold, so that the corresponding updated layout graphic is used as the corrected layout graphic.

5. The method according to claim 1, further comprising: In response to the light intensity error being greater than or equal to the first threshold, the light intensity error is calculated iteratively; as well as The line segment and the first point are iteratively moved based on the light intensity error until the light intensity error is less than the first threshold.

6. The method according to claim 1, wherein determining the corresponding light intensity error for each of the plurality of line segments and each of the plurality of first points comprises: The light intensity error is calculated based on a forward lithography model simulation, wherein the forward lithography model simulation includes simulating the chemical reaction process of the photoresist.

7. The method of claim 2, wherein determining the corresponding light intensity error for each of the plurality of line segments and each of the plurality of first points comprises: Assign a first evaluation point to the midpoint of each line segment to determine the light intensity error; Each of the first points is set as a second evaluation point for determining the light intensity error; as well as The light intensity error at each first evaluation point is determined as the light intensity error of each corresponding line segment, and the light intensity error at each second evaluation point is determined as the light intensity error of each corresponding first point.

8. The method of claim 7, wherein moving the line segment and the first point having a light intensity error greater than the first threshold further comprises: The gradient descent method is used to determine the corresponding second point where the light intensity error is zero for each of the first and second evaluation points; as well as The offset is determined based on the distance between each evaluation point and the second point; as well as The line segment and the first point are moved based on the offset, such that the first evaluation point and the second evaluation point of the moved line segment coincide with the corresponding second point.

9. The method of claim 2, wherein connecting the offset line segment and the offset point in a predetermined order further comprises: Connect the unmoved line segment with the light intensity error less than the first threshold to the first point.

10. The method of claim 3, further comprising: In response to the radius of curvature being greater than or equal to the second threshold, the offset remains unchanged.

11. The method of claim 3, wherein reducing the amount of movement of the offset point comprises: The offset of the offset point is adjusted based on a predetermined smoothing coefficient and the radius of curvature.

12. The method of claim 11, wherein adjusting the movement of the offset point comprises: A spline curve is constructed based on the positions of the endpoints of the line segments adjacent to the offset point and / or other first points, and the second threshold. as well as Move the offset point onto the spline curve.

13. The method according to any one of claims 1 to 12, wherein moving the line segment having a light intensity error greater than the first threshold and the first point comprises: Move the first point in any direction within the plane of the initial layout graphic; as well as The line segment is moved along the normal direction of the line segment in the plane of the initial layout graphic.

14. The method according to claim 13, wherein the preset region is the corner region of the outline of the initial layout graphic.

15. An electronic device comprising: processor; as well as A memory coupled to the processor, the memory having instructions stored therein, the instructions which, when executed by the processor, cause the electronic device to perform actions, the actions including: The outline of the initial layout graphic is cut into multiple line segments; The line segment in the preset area of ​​the contour is cut into a plurality of first points; For each of the plurality of line segments and each of the plurality of first points, a corresponding light intensity error is determined, wherein the light intensity error indicates the deviation between the simulated graphic and the target layout graphic; The light intensity error is compared with a first threshold; and Move the line segment and the first point that have a light intensity error greater than the first threshold to generate an updated layout pattern with a smaller light intensity error.

16. A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the optical proximity correction method as described in any one of claims 1-14.

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