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

Abstract

The present disclosure relates to an optical proximity correction method, an electronic device and a computer readable storage medium. The optical proximity correction method comprises: cutting a contour of an initial layout pattern into a plurality of line segments; cutting a line segment in a preset region of the contour into a plurality of first points; determining a corresponding light intensity error for each of the plurality of line segments and the plurality of first points, wherein the light intensity error indicates a deviation between a simulation pattern and a target layout pattern; comparing the light intensity error with a first threshold; and moving the line segment and the first point having a light intensity error greater than the first threshold to generate an updated layout pattern having a smaller light intensity error. The scheme of the present disclosure embodiment can significantly reduce the shrinkage effect at the preset of the layout pattern while effectively controlling the calculation cost.

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 layout. Figure One 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 the disclosure, an electronic device is provided. The electronic device includes a processor and a memory coupled with the processor, the memory having stored therein instructions that, when executed by the processor, cause the electronic device to perform actions. The actions include cutting an outline of an initial layout pattern into a plurality of line segments; cutting the line segments in a preset region of the outline into a plurality of first points; determining, for each of the plurality of line segments and the plurality of first points, a respective light intensity error, wherein the light intensity error indicates a deviation between a simulated pattern and a target layout pattern; comparing the light intensity error with a first threshold; and moving the line segments and the first points having the light intensity error greater than the first threshold to generate an updated layout pattern having a smaller light intensity error.

[0007] In some embodiments, moving the line segments and the first points having the light intensity error greater than the first threshold to generate the updated layout pattern having the smaller light intensity error includes iteratively moving the line segments and the first points having the light intensity error greater than the first threshold to generate the updated layout pattern until the light intensity error is smaller than the first threshold to take the respective updated layout pattern as a corrected layout pattern.

[0008] In some embodiments, the line segments and the first points are offset according to respective offset amounts to generate offset line segments and offset points; and the offset line segments and the offset points are connected in a predetermined order to generate a first revised layout pattern.

[0009] In some embodiments, further comprising performing a smoothing process on the first revised layout pattern, the smoothing process including: forming an included angle with other points adjacent to the offset point on both sides as a vertex of the offset point; determining a radius of curvature of the offset point at the included angle; comparing the radius of curvature with a second threshold; in response to the radius of curvature being smaller than the second threshold, reducing a movement amount of the offset point to increase the radius of curvature of the offset point at the included angle to be not smaller than the second threshold; wherein the other points include at least one of: offset points different from the offset point as the vertex, end points of the offset line segments, end points of line segments not offset, and first points not offset.

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

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

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

[0013] In some embodiments, moving the line segment and the first point having the light intensity error greater than the first threshold value comprises: determining a respective second point corresponding to each of the first evaluation point and the second evaluation point at which the light intensity error is zero based on a gradient descent method; and determining a corresponding offset based on a 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 evaluation point and the second evaluation point of the moved line segment coincide with the corresponding second point respectively.

[0014] In some embodiments, connecting the offset line segment and the offset point in the predetermined order further comprises connecting the line segment and the first point having the light intensity error less than the first threshold value which are not moved.

[0015] In some embodiments, the offset is kept unchanged in response to the radius of curvature being greater than or equal to a second threshold value.

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

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

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

[0019] In some embodiments, the preset region of the contour of the initial layout graph can be a corner region of the contour of the initial layout graph.

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

[0021] With the scheme of the embodiments of the present disclosure, at least the following beneficial effects can be achieved:

[0022] Break the vertical and horizontal geometric constraints of the optical proximity correction at the corners of the layout pattern, so as to solve the modified layout closer to the target layout, and significantly reduce the shrinkage effect of the layout pattern at the corners;

[0023] The layout modification method based on movable points and movable line segments is fused, which has the dual advantages of high correction accuracy of movable points at preset regions and fast correction speed of movable line segments at other positions.

[0024] By adopting the modified layout smoothing algorithm, the modified layout pattern is more in line with the manufacturability standard.

[0025] It should be understood that the content described in the summary section is not intended to limit or define key or important features of the embodiments of the disclosure, nor to limit the scope of the disclosure. Other features of the disclosure will become apparent from the following description. BRIEF DESCRIPTION OF DRAWINGS

[0026] The above and other features, advantages, and aspects of embodiments of the present disclosure will become more apparent by describing in detail some embodiments thereof with reference to the annexed drawings in which:

[0027] Figure 1 A schematic diagram showing an example environment in which a plurality of embodiments of the present disclosure can be implemented;

[0028] Figure 2 A flowchart illustrating an optical proximity correction method according to some embodiments of the present disclosure;

[0029] Figures 3A-3D A schematic diagram showing layout patterns obtained by performing different steps of an optical proximity correction method according to embodiments of the present disclosure;

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

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

[0032] Figure 6 A flowchart showing the movement of a first point and a line segment based on a gradient descent method according to some embodiments of the present disclosure;

[0033] Figure 7 A flowchart showing a process for smoothing a modified layout pattern according to some embodiments of the present disclosure;

[0034] Figure 8A schematic diagram of a curvature radius based layout pattern adjustment method is shown.

[0035] Figure 9 Optical proximity correction effects are illustrated with some embodiments of the present disclosure.

[0036] Figure 10 A block diagram of a computing device capable of implementing a number of embodiments of the present disclosure is shown. DETAILED DESCRIPTION

[0037] Embodiments of the present disclosure will be described in greater detail below with reference to the accompanying drawings. While certain embodiments of the present disclosure are shown in the drawings, it is understood that the present disclosure can be embodied in various forms and should not be interpreted as being limited to the embodiments set forth herein; rather, these embodiments are provided so that the present disclosure can be more thoroughly and completely understood. It will be appreciated that the drawings of the present disclosure and the embodiments thereof are for illustrative purposes only and are not intended to limit the scope of the present disclosure.

[0038] In the description of embodiments of the present disclosure, the term "includes" and its derivatives are to be construed as open-ended, i.e., as "including, but not limited to." The term "based on" is to be construed as "based at least in part on." The term "one embodiment" or "the embodiment" are to be construed as "at least one embodiment." The terms "first," "second," etc. can refer to different or the same objects. Other explicitly and implicitly recited definitions should be apparent to the skilled person.

[0039] As mentioned previously, OPC techniques mainly modify layout patterns so that the post-lithography wafer end pattern is as close as possible to the target layout pattern. Figure One OPC techniques are mainly divided into conventional OPC techniques and inverse lithography technology (ILT).

[0040] In conventional OPC techniques, in order to modify layout patterns, layout patterns are cut into a series of movable line segments based on certain rules, and evaluation points are placed on the line segments to control the movement of the line segments. Since the OPC problem is a complex nonlinear problem, an analytical solution for layout modification cannot be obtained, so OPC solvers are usually designed using an iterative optimization method. Existing OPC solvers are mostly designed based on edge placement error (EPE) or light intensity error at evaluation points, which directly use measured light intensity signal error values to determine the offset of the movable line segments in the next iteration. However, due to the square topology connection structure between the movable line segments, the conventional OPC method has deficiencies in handling the shrinkage effect at the corners of the layout pattern, thereby causing greater distortion at the corners.

[0041] The so-called shrink effect at the corner of a layout pattern refers to that the wafer end pattern at the corner will produce greater distortion than other positions. The ILT technology pixelizes the layout pattern and optimizes the pixels based on a lithography model, which can remove the square topology constraint of the layout pattern and obtain a relatively full profile at the corner of the layout pattern. However, the ILT technology has a high requirement for computing resources and a low solving speed compared with the traditional OPC solver, and thus is generally not used for global correction of the layout pattern. In order to balance the efficiency of the traditional OPC solver and the correction accuracy of the ILT technology, the curvilinear OPC (which can be referred to as curve OPC) technology is proposed.

[0042] In the curvilinear OPC technology, the layout pattern is cut into a series of closed connections of movable points. The curvilinear mask layout pattern is obtained by moving the movable points instead of the movable line segments. The curvilinear mask layout pattern can solve the shrink effect problem at the corner of the layout pattern. However, the decomposition of the layout pattern into a series of movable points greatly increases the calculation cost.

[0043] In view of the above-mentioned shortcomings of the traditional scheme, there is still a need for an improved scheme.

[0044] According to an embodiment of the present disclosure, an optical proximity correction method is provided. In the method, first, a line segment is cut on the contour of an initial layout pattern to form a first pattern composed of line segments. Then, the line segment at a preset region of the first pattern is cut into a plurality of first points, and each first point and line segment is assigned an evaluation point. Next, the light intensity error corresponding to the first point and the line segment is calculated for each evaluation point. The light intensity error is compared with a first threshold value; and the line segment and the first point having the light intensity error greater than the first threshold value are moved so that the moved line segment and the first point have the light intensity error less than the first threshold value, and thereby a modified layout pattern is formed.

[0045] The method of the embodiment of the present disclosure uses movable points to correct the preset region of the layout pattern and uses movable line segments to correct other positions of the layout pattern, thereby effectively controlling the calculation cost while significantly reducing the shrink effect at the preset region of the layout pattern. In this way, the layout pattern can be quickly modified at low calculation cost, and thus the development cost can be reduced.

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

[0047] Figure 1A schematic diagram illustrating an example environment 100 in which various embodiments of the present disclosure can be implemented is shown. A computing device 102 in the example environment 100 can be any device having computing capability. By way of non-limiting example, the computing device 102 can be any type of stationary, mobile, or portable computing device, including but not limited to a desktop computer, a laptop computer, a notebook computer, a netbook computer, a tablet computer, a multimedia computer, a mobile phone, etc.; all or a portion of the components of the computing device 102 can be distributed in the cloud.

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

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

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

[0051] The offset module 104 and the smoothing module 105 can be configured to generate a corrected layout pattern, e.g., a corrected pattern 120 shown in FIG. 1, based on the initial layout pattern 111, individually or cooperatively. Specifically, the offset module 104 can cut and move points and line segments on the contour of the initial layout pattern 111, and the smoothing module 105 can smooth the contour of the initial layout pattern 111 or an 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, eventually generating the corrected pattern 120 if a threshold condition is satisfied. Figure 1

[0052] It should be appreciated that Figure 1 The number and style of the circuit layouts in the layout pattern 110 shown in FIG. 1 are merely illustrative and not intended to be limiting. In addition,The module partitioning shown in FIG. 1 is merely for illustration and not intended to be limiting. Figure 1

[0053] ​Reference Figure 2 Figure 1 illustrates a general process of an optical proximity correction method 200 according to embodiments of the present disclosure.

[0054] At Figure 2 Block 202, the contour of the initial layout pattern can be cut into a plurality of line segments. In some embodiments, the contour of the initial layout pattern can be cut using conventional methods. For example, in Figure 3A cutting the contour of the initial layout pattern into a plurality of line segments 12 to form a first pattern 300. Specifically, in the first pattern 300 shown in Figure 3A the first pattern 300 shown in

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

[0056] Returning to Figure 2 At block 204, the line segments in the preset region of the contour can be cut into a plurality of first points. In some embodiments, the cutting can be performed using conventional methods. For example, Figure 3B cutting the preset region of the first pattern 300 in Figure 3A the first pattern 300 in Figure 3B Specifically, in the cut layout pattern 301 of the first pattern 300 shown in

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

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

[0059] According to some embodiments of the present disclosure, the first points 13 and the line segments 12 can be configured to modify a minimum correction unit of the initial layout pattern 10.

[0060] Returning to Figure 2 At block 206, a respective 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 a deviation between the simulation pattern and the target layout pattern.

[0061] In some embodiments, the light intensity error can be determined in a conventional manner. In some embodiments, determining a respective light intensity error for each of the plurality of line segments 12 and each of the plurality of first points 13 in the cut-up layout pattern 301 can comprise at least assigning a respective evaluation point 14 for light intensity error measurement to each line segment 12 and each first point 13. For example, in some embodiments, the midpoint of each line segment 12 can be assigned as a first evaluation point, and the first point 13 itself can be assigned as a second evaluation point. Figure 3C An evaluation layout pattern 302 in which each first point 13 and each line segment 12 is assigned with an evaluation point 14 for determining a respective light intensity error is shown in FIG. 3B. According to a non-limiting example, the midpoint of each line segment 12 can be set as a first evaluation point, and the first point 13 itself can be set as a second evaluation point. Herein, for simplicity, the first evaluation point and the second evaluation point are collectively referred to as evaluation points 14 in the subsequent light intensity error determination process.

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

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

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

[0065] Returning to Figure 2At block 208, the light intensity error determined at each evaluation point 14 is compared to a first threshold. For example, the first threshold can be a predetermined light intensity error threshold. In some embodiments, the predetermined light intensity error threshold can be predetermined. In some embodiments, the predetermined light intensity error threshold can be the same for each evaluation point 14.

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

[0067] For example, in the example shown in FIG. 1, the line segment 12 and the first point 13 having the light intensity error greater than the first threshold are moved to generate the updated layout pattern 15 having a smaller light intensity error. Figure 3D For example, in the example shown in FIG. 1, the line segment 12 and the first point 13 having the light intensity error greater than the first threshold are moved to generate the updated layout pattern 15 having a smaller light intensity error.

[0068] According to some embodiments, based on the result of the comparison, the line segment 12 and the first point 13 having the light intensity error greater than the predetermined light intensity error threshold can be moved, and the moved first point 13, the line segment 12, and the first point 13 and the line segment 12 that are not moved (if any) can be connected in order to generate the updated layout pattern 15. Figure 3D It is also shown that only part of the first points 13 and the line segments 12 are moved. This is because the line segments 12 and the first points 13 that already have a light intensity error smaller than the predetermined light intensity error threshold in the initial layout pattern 10 do not need to be moved. According to some embodiments of the present disclosure, each first point 13 and the line segment 12 of the updated layout pattern 15 has a light intensity error smaller than the predetermined light intensity error threshold. According to some embodiments of the present disclosure, in the case that each first point 13 and the line segment 12 of the updated layout pattern 15 does not have a light intensity error completely smaller than the predetermined light intensity error threshold, an iterative process is performed, which is further described below.

[0069] According to some embodiments, moving the line segment 12 and the first point 13 having the light intensity error greater than the first threshold to generate the updated layout pattern 15 having a smaller light intensity error can include iteratively moving the line segment 12 and the first point 13 having the light intensity error greater than the first threshold to generate an updated layout pattern until the light intensity error of all the line segments 12 and the first points 13 is smaller than the first threshold. Then, the corresponding updated layout pattern 15 can be taken as the corrected layout pattern.

[0070] Reference is made below to FIG. 2, which shows a flowchart of a method 200 of iteratively modifying an initial layout pattern 10 based on light intensity error according to non-limiting embodiments of the present disclosure. Figure 4 . Reference is made below to FIG. 2, which shows a flowchart of a method 200 of iteratively modifying an initial layout pattern 10 based on light intensity error according to non-limiting embodiments of the present disclosure. Figure 4 Reference is made below to FIG. 2, which shows a flowchart of a method 200 of iteratively modifying an initial layout pattern 10 based on light intensity error according to non-limiting embodiments of the present disclosure.

[0071] For example, at block 401, the layout pattern assigned with the evaluation points can be input into a lithography model for simulation. According to some embodiments, the light intensity error can be calculated based on the forward lithography model simulation, and wherein the forward lithography model simulation comprises simulating the chemical reaction process of the photoresist. By adding the chemical reaction process of the photoresist into the forward lithography model simulation procedure, more comprehensive simulation results can be obtained.

[0072] According to some embodiments, at block 403, a corresponding light intensity error can be determined for each evaluation point 14, so that the light intensity error relative to the expected light intensity value can be determined. For example, the light intensity error relative to the expected light intensity value can be calculated for each evaluation point 14 in the layout pattern 100 assigned with the evaluation points 14.

[0073] At block 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 of not all evaluation points 14 is less than the predetermined light intensity error threshold, the method 400 proceeds to block 407, and a new offset is calculated again in the curvilinear OPC solver.

[0074] The method of calculating the offset of the first point 13 and the line segment 12 in the curvilinear OPC solver according to the embodiments of the present disclosure will be described more illustratively below with reference to Figure 5

[0075] For example, if the light intensity error calculated for the evaluation point 14 exceeds the predetermined threshold, the light intensity error, the light intensity error change rate, and the like parameters at the evaluation point 14 can be passed to the curvilinear OPC solver. For example, the solver can calculate the offset of the corresponding first point 13 and the line segment 12 in the next iteration according to these parameters, and then generate the initial layout pattern 10 for the next iteration. According to one or more embodiments, the above-mentioned process of forward lithography model simulation and offset calculation can be iteratively performed until the light intensity error at all evaluation points 14 is below the preset threshold.

[0076] For example, Figure 5 The process of calculating the offset of the first point 13 and the line segment 12 in a round of iteration by the curvilinear OPC solver according to the present disclosure is shown. In Figure 5 , the first evaluation point 12a represents the evaluation point assigned to the line segment 12, and the second evaluation point 14a represents the evaluation point assigned to the first point 13. According to some embodiments, the light intensity error at the second evaluation point 14a, whose position is represented as , can be calculated based on the known light intensity distribution map , wherein ​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:

[0077] (1)

[0078] 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.

[0079] In some embodiments, the light intensity change gradient at the second evaluation point 14a It can be represented as:

[0080] (2)

[0081] The aforementioned gradient of light intensity change can be calculated using the following formula via a difference method:

[0082] (3)

[0083] (4)

[0084] In equations (3) and (4), and The second evaluation point 14a is located at and Offset in direction.

[0085] 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). .

[0086] (5)

[0087] For example, the contour point 14c is located on the contour line 17 where the light intensity value is equal to the given light intensity threshold, and the contour line 17 constitutes the wafer end pattern after the current layout pattern is processed by the photolithography model. In the embodiment, since the contour point 14c represents the actual wafer end position, and the second evaluation point 14a is the desired target position, it is necessary to move the second evaluation point 14a along the direction from the contour point 14c to the second evaluation point 14a by the distance 141 from the contour point 14c to the evaluation point 14a in order to reach the expected 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, and the distance 142 from the second evaluation point 14a to the second point 14b is the offset of the first point 13 assigned with the second evaluation point 14a calculated based on the gradient descent method.

[0088] In some examples, for the midpoint 12a of the movable line segment 12, the corresponding contour point 12c can also be found with reference to the equations (1)-(5). For example, the expected target position for 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 moving direction of the movable line segment 12 is limited to the normal direction thereof, and thus it is necessary to calculate the component 122 of the distance from the midpoint 12a of the line segment 12 to the moved midpoint 12b of the line segment in the normal direction of the line segment 12, and the component 122 is the offset of the movable line segment 12.

[0089] Reference will now be made to Figure 6 , Figure 6 A flowchart 600 of a method of moving the movable first points 13 and the movable line segments 12 based on light intensity errors according to one or more embodiments of the present disclosure is shown. For example, after assigning the respective evaluation points 14 (e.g., the first evaluation point 12a and the second evaluation point 14a in Figure 5 , to each first point 13 and each line segment 12, the steps of block 601 are first performed. For example, in block 601, the light intensity error of the light intensity value at each evaluation point 14 with respect to the expected value can be calculated.

[0090] Subsequently, in block 603, the position where the light intensity error with respect to each evaluation point 14 is zero can be calculated based on the gradient descent method. The distance between the calculated position where the light intensity error is zero and each respective evaluation point 14 is the offset of the evaluation point 14, which is a two-dimensional vector, which can be referred to as a two-dimensional initial offset here.

[0091] After obtaining the two-dimensional initial offsets for each evaluation point 14, the steps of block 605 can be performed. For example, at block 605, it is determined for each evaluation point 14 whether it is assigned to a line segment 12. For example, it is determined whether the evaluation point is the first evaluation point 12a or the second evaluation point 14a.

[0092] For the first evaluation point 12a that belongs to the line segment 12, the method proceeds to block 611. At block 611, a component of the two-dimensional initial offset in the normal direction of the line segment 12 can be calculated. The calculated component can be configured as the respective offset of the line segment 12. Then, the method proceeds to block 613 at which the line segment 12 is moved in its normal direction by the respective offset.

[0093] Returning to block 605, for the second evaluation point 14a that is not assigned to a line segment 12, the method proceeds to block 607. For example, at block 607, the movable first points 13 can be moved in the x and y directions, respectively, based on the two-dimensional initial offsets. Subsequently, the moved first points 13 and the moved line segments 12 obtained after performing block 607 and block 613 are represented by blocks 609 and 615, respectively. Next, at block 617, the adjacent moved first points 13, line segments 12 can be sequentially connected end-to-end to form an updated layout pattern. According to non-limiting embodiments, there can be first points 13 and line segments 12 that are not moved. In such a case, the adjacent moved first points 13, line segments 12 and the non-moved first points 13, line segments 12 can be sequentially connected in the respective order to form the updated layout pattern. For example, in Figure 3D Fig. 1 1 is shown to include the moved first points 13, line segments 12 and non-moved first points 13, line segments 12 connected to form the first iteration layout pattern.

[0094] Returning to Figure 4 , after obtaining the offsets for each first point 13 and line segment 12, the method 400 proceeds to block 41 1. At block 41 1, the positions of the line segments 12 and first points 13 having evaluation points 14 with a light intensity error greater than the predetermined light intensity error threshold are adjusted. For example, with the method discussed above based on Figure 5 and Figure 6 , the line segments 12 and first points 13 having evaluation points 14 with a light intensity error greater than the predetermined light intensity error threshold can be moved based on the respective offsets obtained in block 407.

[0095] Subsequently, at block 413, all the line segments 12 and first points 13, whether moved or not, are sequentially connected end-to-end in a predetermined order to form a first iteration layout pattern for processing in a new iteration.

[0096] Subsequently, the method 400 proceeds again to block 403 to calculate the light intensity error for each evaluation point 14 of the first iteration version of the layout pattern from block 413 in a new iteration. In some embodiments, a new light intensity error threshold can be determined for each iteration. For example, the new light intensity error threshold can be determined by a look-up table or by a calculation.

[0097] In some embodiments, the light intensity error threshold can be the same or different for each iteration. For example, in some embodiments, the predetermined light intensity error threshold can be gradually decreased as the number of iterations increases.

[0098] In some embodiments, if the step in block 405 determines that the light intensity error of all evaluation points 14 is less than the 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 the first corrected layout pattern. For example, the first corrected layout pattern can be the offset processed layout pattern. Then, the method can output the first corrected layout pattern as the offset processed layout pattern, for example, in block 409.

[0099] According to one or more embodiments, after performing the offset processing described above, the first corrected layout pattern obtained can have overly sharp corners. In other words, there can be an angle in the profile of the first corrected layout pattern after the offset processing is performed that has a radius of curvature less than a desired threshold. Therefore, in some embodiments, further processing is needed to smooth the profile of the first corrected layout pattern.

[0100] In particular, Figure 7 A flowchart of the smoothing processing performed on the updated layout pattern according to one or more embodiments is shown. For example, at block 701, each moved first point 13 can be taken as a vertex, and an angle can be formed with the end points 11 of the line segments 12 adjacent to the first point 13 on both sides and / or other first points 13.

[0101] In some embodiments, as shown in Figure 8 For the moved point A1, the radius of curvature 81 of the angle formed by the point A1 and the moved points 14e and 14f adjacent to it on both sides is calculated, and the radius of curvature 82 of the inscribed circle formed by the points B1, 14f and 14g adjacent to the point B1 is detected, as shown in

[0102] 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. As shown in Figure 8 In some embodiments, the radius of curvature 81 of the inscribed circle formed by points 14e, Al, 14f and the radius of curvature 82 of the inscribed circle formed by points 14f, Bl, 14g can be calculated by the three-point method.

[0103] When the calculated radius of curvature is less than the predetermined radius of curvature threshold, it is determined that there is an undesirable sharp included angle at the moved first point 13, and the step proceeds to block 705. For example, when performing smoothing processing for point Bl as shown in Figure 8 When performing smoothing processing for point Bl as shown in

[0104] (6)

[0105] wherein may be a predetermined smoothing coefficient, and may be the calculated radius of curvature. For example, the initial displacement for point Bl is shown as distance 84 in Figure 8 and the adjusted displacement is shown as distance 83 in Figure 8

[0106] Next, a smoothing offset is calculated for the first point 13 for which it is determined that there is an undesirable sharp included angle. Then, the movable first point 13 is moved again in the x, y direction respectively based on the obtained smoothing offset at block 707. The smoothing method then proceeds to step 709 to output the smoothed updated layout pattern 15.

[0107] Returning to Figure 7 In some embodiments, the radius of curvature calculated in step 703 is not less than the radius of curvature threshold. As shown in the example in Figure 8 , the radius of curvature 81 is greater than the predetermined radius of curvature threshold, so the method according to some embodiments of the present disclosure can determine that there is no undesirable sharp included angle in the layout pattern profile between points 14e, Al, 14f, and the position of the moved point Al does not need to be adjusted. In this case, it can be determined that there is no undesirable sharp included angle for the corresponding point Al. Then, the method proceeds from block 703 to block 709 to output the smoothed modified layout pattern.

[0108] ​In some embodiments, the method 700 can be iteratively performed, and the predetermined curvature threshold can be the same or different for each iteration. For example, in some embodiments, the predetermined curvature threshold can gradually increase as the number of iterations increases.

[0109] After Figure 5 and Figure 6 the first stage of layout pattern offsetting shown, and after Figure 7 and Figure 8 the second stage of layout pattern smoothing shown, the displacement adjustment values for each movable first point 13 and evaluation point 14 of the line segment 12 derived by the curvilinear OPC solver in each round of iteration solving can be obtained. The movable first points 13 and line segments 12 will be moved according to the respective final displacement adjustment values, and the moved first points 13 and line segments 12, as well as the un-moved first points 13 and line segments 12 (if any) can be sequentially connected end-to-end to obtain the updated layout pattern 15 after each round of iteration. Subsequently, the next round of iteration can be continued or the iteration can be exited and the updated layout pattern 15 obtained in the last iteration can be outputted.

[0110] The scope of the present disclosure is not limited to sequentially performing both the offsetting and the smoothing. For example, the smoothing of the layout pattern according to Figure 7 and Figure 8 may be performed first, and then the offsetting of the layout pattern according to Figure 5 and Figure 6 may be performed. Alternatively, the offsetting of the layout pattern according to Figure 5 and Figure 6 may be performed alone, or the smoothing of the layout pattern according to Figure 7 and Figure 8 may be performed.

[0111] According to embodiments of the present disclosure, when determining the positions of all the first points 13 and line segments 12 and connecting all the first points 13 and line segments 12, the first points 13 can be connected to the end points 11 of the line segments 12 and / or other first points 13 by line segments, by curves determined based on a predetermined manner, or by a combination of line segments and curves.

[0112] In non-limiting embodiments, performing the smoothing process can further include constructing a spline curve based on a predetermined threshold of a radius of curvature, and moving the movable first point 13 to perform on the constructed spline curve. For example, when the movable line segment 12 is restricted to move only in its normal direction and is not rotated, the positions of the end points 11 of the line segment 12 and the direction of the line segment 12 are known. Therefore, a spline curve for placing the moved first point 13 can be constructed based on the positions of the end points 11 of the line segment 12, the direction of the extension of the line segment 12, and the predetermined threshold of the radius of curvature. For example, in non-limiting embodiments, the spline curve can include a cubic spline curve, a B-spline curve, or the like.

[0113] In some embodiments, the smoothing process can be performed iteratively on each moved first point 13 respectively when performing the smoothing process. In other embodiments, the smoothing process can be performed on multiple first points 13 at a time. In yet other embodiments, the smoothing process can be performed on all first points 13 at a time.

[0114] Reference is made below to Figure 9 Effects of optical proximity correction using some embodiments of the present disclosure are described. Figure 9 Results obtained from comparative experiments using, for example, commercial OPC software are shown. In Figure 9 In an example, the parameters of the lithography model are set as: wavelength 193 nm, numerical aperture 1.35, light source shape cquad (quadrupole illumination shape), outer sigma 0.95, and inner sigma 0.8. In addition, Figure 9 Optical proximity correction results for a class of typical metal layer line segment type of mask layout patterns are shown, with a critical dimension cd of 45 nm and a minimum pitch sp of 48 nm. From Figure 9 As can be seen from the figures, the corrected wafer end patterns 91, 93 obtained using the method of the embodiments of the present disclosure are more rounded at the corners and closer to the target layout pattern 10, which demonstrates the advantage of the optical proximity correction method proposed according to the present disclosure over the wafer end patterns 92, 94 obtained using the movable line segment based solver in terms of corner shrinkage. In addition, it can also be seen that the wafer end pattern 93 corrected using the optical proximity correction method according to the present disclosure is closer to a perfect circle, while the wafer end pattern 94 obtained using the EPE solver is more oblique in shape. This further demonstrates that the optical proximity correction method according to the embodiments of the present disclosure can obtain wafer end patterns that are closer to the target layout, thereby highlighting the advantage of the optical proximity correction method according to the present disclosure.

[0115] Figure 10 A schematic block diagram of an example device 1000 that can be used to implement embodiments of the present disclosure is shown. The device 1000 can be used to implement Figure Onecomputing device 102. As shown, the device 1000 includes a central processing unit (CPU) 1001, which can perform various suitable actions and processes in accordance with computer program instructions stored in a read-only memory (ROM) 1002 or computer program instructions loaded from a storage unit 1008 into a random access memory (RAM) 1003. Various programs and data required by the device 1000 to operate can also be stored in the RAM 1003. The CPU 1001, ROM 1002, and RAM 1003 are connected to each other by a bus 1004. An input / output (I / O) interface 1005 is also connected to the bus 1004.

[0116] Various components in the device 1000 are connected to the I / O interface 1005, including an input unit 1006, such as a keyboard, a mouse, etc.; an output unit 1007, such as various types of displays, speakers, etc.; a storage unit 1008, such as a magnetic disk, a magneto-optical disk, etc.; and a communication unit 1009, such as a network card, a modem, a wireless communication transceiver, etc. The communication unit 1009 allows the device 1000 to exchange information / data with other devices over a computer network, such as the Internet, and / or various telecommunication networks.

[0117] The processing unit 1001 performs various methods and processes described above. For example, the present disclosure Figure 5 and Figure 6 The first-stage layout pattern offset processing shown, and any of the Figure 7 and Figure 8 The second-stage layout pattern smoothing processing shown, can be implemented as a computer software program tangibly embodied in a machine-readable medium, such as the storage unit 1008. In some embodiments, part or all of the computer program can be loaded onto and / or installed on the device 1000 via the ROM 1002 and / or the communication unit 1009. When the computer program is loaded onto the RAM 1003 and executed by the CPU 1001, one or more steps of any of the layout pattern offset processing and layout pattern smoothing processing described above can be performed. Alternatively, in other embodiments, the CPU 1001 can be configured to perform any of the layout pattern offset processing and layout pattern smoothing processing by any other suitable means, such as by means of firmware.

[0118] The functionality described herein above can be performed, at least in part, by one or more hardware logic components. For example, and without limitation, example types of hardware logic components that can be used include Field-programmable Gate Arrays (FPGAs), Application-specific Integrated Circuits (ASICs), Application-specific Standard Products (ASSPs), System-on-a-chip systems (SOCs), Complex Programmable Logic Devices (CPLDs), etc.

[0119] Program code for carrying out methods of the present disclosure can be written in any combination of one or more programming languages. The program code can be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the program code, when executed by the processor or controller, causes the machine to perform the functions / acts specified in the flowcharts and / or block diagrams. The program code can be executed entirely on a machine, partially on a machine, partially on a machine and partially on a remote machine or entirely on a remote machine or server.

[0120] In the context of the present disclosure, a machine-readable medium can be a tangible medium that contains or stores program code for use by or in connection with an instruction execution system, apparatus, or device. The machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium can include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the machine-readable storage medium would include one or more lines of a system, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0121] Moreover, while operations can be depicted in a particular, serial order, this should not be understood as requiring or implying that such operations be performed in the particular order shown, or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing can be advantageous. Likewise, while specific implementations are discussed herein, these should not be understood to limit the scope of the disclosure. Certain features that are described in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in subcombination or as separate embodiments. Accordingly, the particular implementation described is merely exemplary in nature and is not intended to suggest any limitation as to the scope of the disclosure.

[0122] Although the subject matter has been described in language specific to structural features and / or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms 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 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. 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, along with the unmoved line segments and the first point having a light intensity error less than the first threshold, are connected in a predetermined order to generate a first corrected pattern 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 offset 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 according to claim 3, further comprising: In response to the radius of curvature being greater than or equal to the second threshold, the offset remains unchanged.

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

11. The method of claim 10, wherein adjusting the offset 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.

12. The method according to any one of claims 1 to 11, 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.

13. The method according to claim 12, wherein the preset region is the corner region of the outline of the initial layout graphic.

14. 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.

15. A computer-readable storage medium having a computer program stored thereon, the program being executed by a processor to implement the optical proximity correction method as described in any one of claims 1-13.

Images