Optical proximity correction method and device, mask preparation method and mask
By identifying and extending the line-end side in semiconductor manufacturing, the edge placement error problem caused by the optical proximity effect in line-end structures is solved, achieving more efficient optical proximity correction, improving pattern fidelity and manufacturing reliability, and reducing computational complexity and time cost.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-27
- Publication Date
- 2026-03-13
AI Technical Summary
In semiconductor manufacturing, the edge placement error (EPE) caused by optical proximity effect in line-end structures is too large, which affects the consistency of device performance and may cause short circuit or open circuit defects. Traditional OPC methods are complex and computationally expensive.
By identifying the line end groups to be processed in the target pattern, extending their sides away from each other by a preset distance, and using this as the initial pattern, photolithography simulation is performed and corrected multiple times until the imaging result is consistent with the target pattern or the deviation is less than the preset value.
It reduces the initial edge placement error at the line ends, avoids the limitations of the minimum spacing rule, improves graphic fidelity and manufacturing reliability, reduces the number of iterations and manual intervention, and improves the efficiency of mask development.
Smart Images
Figure CN121657355A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of semiconductor technology, and more specifically, to an optical proximity correction method, apparatus, method for preparing a photomask, and a photomask. Background Technology
[0002] In semiconductor manufacturing processes, as the feature size of integrated circuits continues to shrink, photolithography faces increasingly severe challenges from optical diffraction and interference effects. To compensate for these optical proximity effects, Optical Proximity Correction (OPC) technology is widely used in the design of photomasks to ensure that the actual photolithographic imaging results are as close as possible to the design target layout.
[0003] Traditional OPC methods typically divide the pattern in the layout into multiple segments and perform independent iterative corrections on each segment based on lithography simulation results. For line-end structures, the conventional approach is to use the port segment at the line end and the end segments on both sides as the initial positions of the original target layout, and correct them separately with the same priority. However, in actual iterations, because the end segments are less affected by the surrounding pattern environment and have shorter correction paths, they often converge to the ideal position more quickly; while the port segments at the line end are more affected by the interference of neighboring patterns and usually need to continue to move outward (away from the line body) multiple times to compensate for the line end retraction effect during the lithography process. This asymmetrical correction behavior can easily lead to the line ends being corrected into a thin, protruding shape, which not only affects pattern fidelity but may also cause manufacturing reliability issues.
[0004] More seriously, when the spacing between two adjacent line ends is too small (e.g., less than the minimum spacing rule specified by the mask, Mask Rule Check, MRC), the port segment cannot freely move outward to the ideal correction position due to MRC constraints, resulting in a significant increase in Edge Placement Error (EPE). This EPE deviation not only reduces the consistency of device performance but may also cause fatal defects such as short circuits or open circuits. Furthermore, to solve the correction problem of such complex line end structures, traditional OPC processes often require the introduction of additional secondary corrections or manual intervention, greatly increasing the complexity and computational time cost of OPC processing and affecting the overall mask development efficiency. Summary of the Invention
[0005] The purpose of this application is to provide an optical proximity correction method, apparatus, mask preparation method, and mask, which can reduce the initial edge placement error at the line end, thereby shortening the movement path of the segment at the line end and avoiding the limitation of the minimum spacing rule.
[0006] The embodiments of this application are implemented as follows: A first aspect of this application provides an optical proximity correction method, comprising: providing a target layout, the target layout including a plurality of line ends with a preset width, two adjacent line ends forming a line end group; identifying a line end group to be processed in the target layout, the line end group to be processed including two line ends to be adjusted with a line end spacing less than a preset spacing, the line end to be adjusted including a horizontal end and side ends connected to both ends of the horizontal end, the line end spacing referring to the vertical distance between the horizontal ends of the two line ends to be adjusted; extending the two side ends of the line ends to be adjusted by a preset distance in a direction away from each other, as an initial layout; performing photolithography simulation based on the initial layout to obtain actual imaging results, and correcting the initial layout multiple times based on the actual imaging results; when the imaging result is the same as the target layout, or the pixel spacing between the imaging result and the target layout is less than a preset value, completing the optical proximity correction to obtain the corrected layout.
[0007] As one possible implementation, the preset distance is less than half of the minimum graphic spacing in the target layout.
[0008] As one possible implementation, identifying a group of line ends to be processed in a target layout includes: identifying each line end in the target layout; taking one of the line ends as a first line end, forming a search area around the first line end; searching for a second line end within the search area, and combining the first line end and the second line end to form a group of line ends to be processed.
[0009] As one possible implementation, a search area is formed around the first line end, including: drawing circles with the two endpoints of the horizontal end of the first line end as centers and a preset distance as the radius; translating the horizontal end of the first line end along a direction perpendicular to the horizontal end and away from the first line end by a preset distance to obtain a horizontal end parallel line; and using the horizontal end, the horizontal end extension line, the two circles, and the area enclosed by the horizontal end parallel line as the search area.
[0010] As one possible implementation, the preset spacing is based on the mask fabrication limit size and the correction space size.
[0011] As one possible implementation, the size of the modified space is inversely proportional to the size of the horizontal end.
[0012] As one possible implementation, the two sides are of the same length and both are greater than the minimum graphic width of the target layout.
[0013] A second aspect of this application provides an optical proximity correction apparatus for performing the aforementioned optical proximity correction method, comprising: an acquisition module for acquiring a target layout; an identification module for identifying a group of line ends to be processed in the target layout, the group of line ends to be processed including two line ends to be adjusted with a line end spacing smaller than a preset spacing, each line end to be adjusted including a horizontal end and two side ends connected to the two ends of the horizontal end, the line end spacing referring to the vertical distance between the horizontal ends of the two line ends to be adjusted; an expansion module for expanding the two side ends of the line ends to be adjusted by a preset distance in a direction away from each other, as an initial layout; and a simulation module for performing photolithography simulation based on the initial layout, obtaining actual imaging results, and performing multiple corrections on the initial layout based on the actual imaging results; when the imaging result is the same as the target layout, or the pixel spacing between the imaging result and the target layout is less than a preset value, optical proximity correction is completed to obtain a corrected layout.
[0014] A third aspect of this application provides a method for preparing a photomask, comprising: preparing a modified pattern obtained by the optical proximity correction method described above; and preparing a photomask using the modified pattern.
[0015] A fourth aspect of the embodiments of this application provides a photomask prepared using the above-described photomask preparation method.
[0016] The beneficial effects of the embodiments of this application include: The optical proximity correction method provided in this application includes: providing a target layout, the target layout including multiple line ends with a preset width, and two adjacent line ends forming a line end group; identifying the line end group to be processed in the target layout, the line end group to be processed including two line ends to be adjusted with a distance between them less than a preset spacing, the line end to be adjusted including a horizontal end and two side ends connected to the two ends of the horizontal end; firstly, identifying the "line end group to be processed" in the target layout with a line end spacing less than a preset threshold, such structures are prone to significant line end retraction due to optical diffraction and proximity effect in advanced photolithography processes, which can lead to excessive edge placement error or even short circuit / open circuit defects; extending the two side ends of the line end to be adjusted by a preset distance in a direction away from each other, as an initial layout, the extended preset distance enhances the optical properties of the local pattern without compressing the spacing between adjacent line ends. By studying stability, the retraction effect is suppressed at its source. The operation of extending the preset distance has a dual advantage: firstly, since the extension direction is along the line extension direction, it does not violate the minimum spacing rule, avoiding the physical constraints faced by direct outward expansion at the horizontal end; secondly, the extended initial layout is closer to the ideal state of photolithography imaging, significantly reducing the initial error in subsequent simulation-correction loops, making the iterative process converge faster. Photolithography simulation is performed based on the initial layout to obtain the actual imaging results, and the initial layout is corrected multiple times based on the actual imaging results to obtain an intermediate layout. When the imaging result is the same as the target layout, or the pixel spacing between the imaging structure and the initial layout is less than a preset value, optical proximity correction is completed, resulting in the corrected layout. When the pixel deviation between the actual imaging result and the target layout is less than a preset tolerance, the correction is considered complete. In summary, this method can reduce the initial edge placement error at the line end, thereby shortening the movement path of the segment at the line end and avoiding the limitations of the minimum spacing rule. Attached Figure Description
[0017] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.
[0018] Figure 1 A flowchart of an optical proximity correction method provided in an embodiment of this application; Figure 2 This is one of the state diagrams for an optical proximity correction method provided in an embodiment of this application; Figure 3 A second state diagram of an optical proximity correction method provided in an embodiment of this application; Figure 4 State diagram three of an optical proximity correction method provided in this application embodiment; Figure 5 A schematic diagram illustrating the distances between graphics in the target layout provided in this application embodiment; Figure 6 This is a schematic diagram of a search area provided in an embodiment of this application.
[0019] Icons: 100 - Line end group to be processed; 110 - Line end to be adjusted; 111 - Horizontal end; 112 - Side end; 121 - First line end; 122 - Second line end. Detailed Implementation
[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. The described embodiments are only some embodiments of this application, not all embodiments. Similar reference numerals and letters in the following drawings indicate similar items. Once an item is defined in one drawing, it does not need to be further defined in other drawings.
[0021] Unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to connections within two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.
[0022] This application provides an optical proximity correction method, such as... Figure 1 As shown, it includes: S100: As Figure 2 As shown, a target layout is provided, which includes multiple line ends with preset widths. Two adjacent line ends form a line end group.
[0023] In this context, a line end refers to a structure consisting of multiple line segments at the end of a graphic. A layout can contain multiple graphics, meaning it includes the line ends corresponding to different graphics. Each line end in a layout has a line end width.
[0024] In this embodiment, the target layout may include multiple line ends with a preset width, and two adjacent line ends constitute a line end group. It should be noted that... Figure 2 Only the two line ends that make up a line end group in the target layout are displayed, that is, only the graphic ends of two adjacent graphics are displayed.
[0025] S200: such as Figure 2As shown, the line end group 100 to be processed in the target layout is identified. The line end group 100 to be processed includes two line ends 110 to be adjusted with a distance between the line ends less than a preset spacing. The line end 110 to be adjusted includes a horizontal end 111 and a side end 112 connected to both ends of the horizontal end 111.
[0026] exist Figure 2 In this context, the distance between two line ends is H1. When H1 is less than a preset spacing, correcting it using existing technology will result in problems such as the MRC limitation mentioned in the background technology. In this embodiment, the two line ends that are less than the preset spacing are designated as line ends 110 to be adjusted, and they are processed in step S300.
[0027] It should be noted that the line end spacing refers to the vertical distance between the horizontal ends 111 of the two line ends 110 to be adjusted. The horizontal ends 111 of the two line ends are parallel, and the vertical distance between the two horizontal ends 111 is the line end spacing.
[0028] S300: such as Figure 3 As shown, the two side ends 112 of the line end 110 to be adjusted are extended by a preset distance in a direction away from each other, as the initial layout.
[0029] The two side ends 112 are extended away from each other by a predetermined distance, increasing the width of the line end. This enhances the stability of the light intensity distribution during photolithography imaging without compressing the spacing. The extension of the side ends 112 also pre-compensates for the line end retraction effect by altering the light field distribution around the line end. According to photolithography principles, the light intensity distribution at the line end is affected by the light fields on both sides of the line end. Extending the side ends 112 away from each other is equivalent to pre-establishing a denser environment on the photoresist, increasing the exposure at the port and thus reducing port retraction.
[0030] By extending the two side ends 112 of the line end 110 to be adjusted by a predetermined distance in a direction away from each other as the initial layout, the line end retraction effect is pre-compensated, reducing the initial edge placement error at the line end and thus shortening the movement path of the segment at the line end. This pre-expansion ensures that the spacing between adjacent line end groups meets the process rules in the initial stage, providing greater adjustment space for subsequent corrections and effectively avoiding the limitations of MRC constraints on port segment correction.
[0031] Secondly, the side-end 112 extension provides a symmetrical correction path, avoiding over-correction of port segments. In traditional OPC, port segments need to be moved outward multiple times, but due to MRC limitations, they cannot be fully corrected. The side-end 112 extension allows for synchronous expansion on both sides of the line end, reducing the need for port segment movement and thus reducing EPE error. This symmetrical correction not only improves pattern fidelity but also enhances manufacturing reliability.
[0032] Finally, the side-end 112 extension increases the spacing between adjacent line ends, ensuring it meets MRC constraints from the initial stage. This provides greater adjustment space for subsequent corrections, avoiding the problem of port segments being unable to move outward due to insufficient spacing. In actual iterations, port segments and side-end segments can be corrected separately with the same priority, improving correction efficiency.
[0033] S400: such as Figure 4 As shown, photolithography simulation is performed based on the initial layout to obtain the actual imaging results, and the initial layout is corrected multiple times based on the actual imaging results.
[0034] Specifically, starting from the initial layout, lithography simulation or actual lithography simulation is performed to obtain the imaging results. The imaging results are compared with the target layout. If there is a deviation (such as the pixel spacing being greater than the preset tolerance), the initial layout is corrected in multiple rounds until the convergence condition is met (the imaging results are consistent with the target, or the error is less than the threshold).
[0035] S500: When the imaging result is the same as the target map, or when the pixel spacing between the imaging result and the target map is less than a preset value, optical proximity correction is completed to obtain the corrected map.
[0036] When the imaging result and the target map meet the convergence condition, optical proximity correction is completed, and the last imaging result is used as the corrected map.
[0037] The extension of this application embodiment ensures that the spacing between adjacent line end groups meets the process rules. In step S300, the two side ends 112 of the line end 110 to be adjusted are extended by a preset distance in a direction away from each other, so that the spacing between adjacent line end groups exceeds the minimum spacing specified by MRC in the initial stage. This provides more adjustment space for subsequent correction and avoids the problem that the port segment cannot move outward due to insufficient spacing.
[0038] Furthermore, this method effectively shortens the travel distance of segments at the line ends, improving correction efficiency. By using the side-end 112 extension as the initial correction, the iterative travel distance of the port segments is reduced, avoiding the elongated shape caused by excessive correction of port segments in traditional OPC. In practical applications, this method can reduce the processing time of the mask data preparation stage from several weeks in traditional methods to even shorter times, significantly improving mask development efficiency.
[0039] Secondly, this method circumvents the limitations of MRC constraints on port segment correction, reducing EPE error. By ensuring the spacing between adjacent line segment groups meets process rules through initial expansion, the port segments have greater adjustment space in subsequent corrections, thus enabling more accurate compensation for line retraction effects. This not only improves pattern fidelity but also reduces the risk of fatal defects such as short circuits or open circuits.
[0040] Finally, this method reduces the need for secondary corrections and manual intervention. Since the initial layout pre-compensates for line-end shrinkage, subsequent correction processes are more automated, reducing the complexity and time cost of manual intervention. This is particularly important in advanced semiconductor manufacturing processes, as the mask development cycle directly impacts chip mass production schedules.
[0041] In summary, the optical proximity correction method of this application can reduce the initial edge placement error at the line end, thereby shortening the movement path of the segment at the line end and avoiding the limitation of the minimum spacing rule.
[0042] The optical proximity correction method provided in this application includes: providing a target layout, the target layout including multiple line ends with a preset width, and two adjacent line ends forming a line end group; identifying a line end group 100 to be processed in the target layout, the line end group 100 including two line ends 110 to be adjusted with a distance between the line ends less than a preset spacing, the line end 110 including a horizontal end 111 and side ends 112 connected to both ends of the horizontal end 111; firstly identifying the "line end group 100 to be processed" in the target layout with a line end spacing less than a preset threshold, such structures are prone to significant line end retraction due to optical diffraction and proximity effect in advanced photolithography processes, leading to excessive edge placement error or even short circuit / open circuit defects; extending the two side ends 112 of the line end 110 to be adjusted by a preset distance in a direction away from each other, as an initial layout, the extended preset distance allows for the adjustment of the line end spacing without compressing the distance between adjacent line ends. Under this premise, the optical stability of the local pattern is enhanced to suppress the shrinkage effect at the source. The operation of extending the preset distance has a dual advantage: on the one hand, since the extension direction is along the line extension direction, it will not violate the minimum spacing rule and avoids the physical constraints faced by directly extending the horizontal end 111; on the other hand, the extended initial pattern is closer to the ideal state of photolithography imaging, which greatly reduces the initial error in the subsequent simulation-correction loop and makes the iteration process converge faster. Photolithography simulation is performed based on the initial pattern to obtain the actual imaging result, and the initial pattern is corrected multiple times based on the actual imaging result to obtain the intermediate pattern. When the imaging result is the same as the target pattern, or the pixel spacing between the imaging structure and the initial pattern is less than the preset value, optical proximity correction is completed to obtain the corrected pattern. When the pixel-level deviation between the actual imaging result and the target pattern is less than the preset tolerance, the correction can be determined to be complete. In summary, this method can reduce the initial edge placement error at the line end, thereby shortening the movement path of the segment at the line end and avoiding the limitation of the minimum spacing rule.
[0043] Optionally, the preset distance W is less than S / 2, where S is the minimum distance between graphics in the target layout, i.e., the minimum graphic spacing.
[0044] During optical proximity correction, when extending the line ends 112 in the target layout, the extension distance W used needs to meet a specific condition: that is, the extension distance W must be less than half of the minimum spacing S between any two graphics in the target layout.
[0045] The preset distance W for the expansion of the side end 112 of the line end 110 to be adjusted is determined based on the aforementioned minimum spacing S. W needs to be less than S / 2. This means that even if both sides expand outwards simultaneously, the distance between the two graphics will not shrink below the minimum spacing rule specified in the process, thus ensuring compliance with design rules and the feasibility of the manufacturing process. Here, the distance between graphics refers to the distance between the edges of two lines, such as... Figure 5 As shown in the middle S.
[0046] As one feasible approach, identifying the line terminal group 100 to be processed in the target layout may include: S210: Identify the ends of lines in the target map.
[0047] Step S210 is used to distinguish and mark all line end positions on the target layout. Line ends typically refer to the ends of metal lines or semiconductor material lines, which are particularly susceptible to proximity effects during photolithography, leading to shape distortion or dimensional changes. In this step, automated algorithms or software tools can be used to scan the entire layout and accurately locate the position and geometric features of each line end.
[0048] S220: Using one of the line ends as the first line end 121, a search area is formed around the first line end 121.
[0049] Once all the wire ends are identified, one is selected as the first wire end 121. Then, a search area of a specific size is defined around this first wire end 121. The size of the search area can be determined based on specific process requirements and minimum spacing rules. The purpose of the search area is to limit the range of subsequent searches for the second wire end 122, thereby ensuring that the distance between the two wire ends is small enough that special processing is required.
[0050] S230: Search for the second line end 122 in the search area. The first line end 121 and the second line end 122 are combined to form the line end group 100 to be processed.
[0051] Within the defined search area, it is searched to see if a second line end 122 exists such that the distance between these two line ends (i.e., the first line end 121 and the second line end 122) is less than a preset threshold. If such a second line end 122 is found, this pair of line ends is identified as a group of line ends to be processed 100. This means that the pair of line ends may encounter problems due to optical proximity effect because they are too close together.
[0052] This effectively identifies the line end group 100 to be processed, improving the correction coverage. Furthermore, by replacing global pairing with local lookup, unnecessary distance calculations are significantly reduced, thereby greatly lowering computational complexity and improving processing efficiency.
[0053] Optional, such as Figure 6 As shown, a search area is formed around the first line end 121, which may include: S221: Draw circles with the two endpoints of the horizontal end 111 of the first line end 121 as the center and the preset spacing L as the radius.
[0054] S222: Shift the horizontal end of the first line end by a preset distance in a direction perpendicular to the horizontal end and away from the first line end to obtain a horizontal end parallel line.
[0055] S223: The search area is defined by the horizontal end 111, the extension line of the horizontal end, the two circles, and the area enclosed by the line parallel to the horizontal end.
[0056] The preset spacing L = M + 2Q, where M is the mask fabrication constraint size and Q is the correction space size.
[0057] Here, M refers to the minimum reliable pattern spacing achievable by the photolithography mask manufacturing process, determined by factors such as equipment resolution and material properties. If the spacing between two patterns is less than M, the mask itself may not be accurately fabricated, or it may suffer severe distortion during exposure. Q is a buffer space reserved for subsequent OPC correction. In the actual correction process, the line ends may need to be finely adjusted outwards (such as extending the side end 112 or moving the edge), and Q ensures that even after correction, the pattern spacing does not violate M. In the embodiments of this application, M can be 40nm.
[0058] Such a search area strictly conforms to the physical shape of the line end and the direction of photolithography, ensuring that all potential interference objects are included in the inspection range and avoiding omission of corner adjacent structures. Using only a rectangular area may miss the line end in the diagonal direction, while the design with rounded ends can completely cover the circular neighborhood near the horizontal end 111, which conforms to the actual physical range of optical action.
[0059] In addition, if no correction space is reserved (Q=0), the identified line end group may fail to converge during correction due to lack of room for movement. This method actively amplifies the risk area by L=M+2Q, giving the OPC system sufficient degrees of freedom in the early stages of correction and significantly improving the convergence success rate.
[0060] Optionally, Q is inversely proportional to the dimension of the transverse end 111.
[0061] Q refers to the correction space dimension, which is the space reserved for subsequent optical proximity correction, while the dimension of the horizontal end 111 is the linewidth. The inverse relationship means that as the size of the horizontal end 111 increases, the required correction space dimension Q decreases accordingly; conversely, if the size of the horizontal end 111 decreases, a larger correction space dimension Q is required. This is because light is more easily scattered when passing through small openings in the mask during photolithography, leading to pattern transfer distortion. Smaller linewidths or feature sizes typically result in more significant optical proximity effects, such as more pronounced diffraction and interference. To compensate for these effects, a larger correction space is needed for smaller feature sizes to ensure that the final pattern can be accurately transferred onto the silicon wafer. Therefore, when the horizontal end 111 dimension is small, a larger Q value is set to provide more degrees of freedom for precise OPC correction.
[0062] As one feasible approach, the two side ends 112 are of equal length and both are greater than the minimum width of the target layout graphic.
[0063] The two side ends 112 are of the same length, that is, the side ends 112 on the left and right sides of the same line end extend from the horizontal end 111 in the direction of the line to the same length. The symmetry ensures that the line end structure is subjected to uniform force / exposure during photolithography imaging, avoiding tilting, twisting or edge placement error offset caused by asymmetry.
[0064] Assuming there's a minimum width specified by the process for all graphics in the target layout, if the side end 112 is too short, the line end will exhibit isolated endpoint characteristics, lacking sufficient support from neighboring graphics. This leads to insufficient exposure energy, excessive edge dissolution during development, and severe line retraction or even breakage. Conversely, when the side end 112 is longer, it effectively creates a sufficiently long reference line segment behind the line end, making the light field distribution in that area closer to a conventional line segment, thereby suppressing the end effect.
[0065] Furthermore, step S300 mentions "extending the side ends 112 in directions away from each other". If the original side ends 112 are too short, they may still not be able to form an effective compensation structure after extension. However, a sufficiently long side end 112 provides a geometric basis and operational space for the extension operation.
[0066] Optionally, the pixel spacing between the imaging result and the target map is less than a preset value, which is 2nm.
[0067] This means that as long as the maximum deviation between the simulated / measured imaging result and the target pattern is ≤2nm, the OPC correction can be considered to have reached the process-acceptable accuracy, and no further iteration is needed. The preset value of 2nm clearly defines the termination condition and avoids invalid iterations. Without a clear convergence criterion, OPC may fall into overcorrection or infinite loops; by setting the 2nm threshold, the system can achieve a balance between accuracy and efficiency and terminate the correction in a timely manner.
[0068] A second aspect of this application provides an optical proximity correction apparatus for performing the aforementioned optical proximity correction method. The apparatus may include: an acquisition module for acquiring a target layout; an identification module for identifying a group of line ends to be processed in the target layout, the group of line ends to be processed including two line ends to be adjusted with a line end spacing smaller than a preset spacing, each line end to be adjusted including a horizontal end and two side ends connected to the horizontal end, the line end spacing referring to the vertical distance between the horizontal ends of the two line ends to be adjusted; an expansion module for expanding the two side ends of the line ends to be adjusted by a preset distance in a direction away from each other, as an initial layout; and a simulation module for performing photolithography simulation based on the initial layout to obtain actual imaging results, and performing multiple corrections on the initial layout based on the actual imaging results; when the imaging result is the same as the target layout, or the pixel spacing between the imaging result and the target layout is less than a preset value, optical proximity correction is completed, and a corrected layout is obtained.
[0069] The above-described device is used to perform the optical proximity correction method provided in the foregoing embodiments. Its implementation principle and technical effect are similar, and will not be described again here.
[0070] These modules can be one or more integrated circuits configured to implement the above methods, such as one or more Application Specific Integrated Circuits (ASICs), one or more microprocessors, or one or more Field Programmable Gate Arrays (FPGAs). Alternatively, when a module is implemented using processing element scheduler code, the processing element can be a general-purpose processor, such as a Central Processing Unit (CPU) or other processor capable of calling program code. Furthermore, these modules can be integrated together as a system-on-a-chip (SOC).
[0071] A third aspect of this application provides a method for preparing a photomask, comprising: fabricating a photomask based on a corrected pattern obtained by the aforementioned optical proximity correction method; and fabricating a photomask using the corrected pattern. Because optical proximity correction has high precision, the quality of the photomask is improved.
[0072] A fourth aspect of the embodiments of this application provides a photomask prepared using the above-described photomask preparation method.
[0073] The above description is merely an optional embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.
[0074] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this application will not describe the various possible combinations separately.
Claims
1. An optical proximity correction method, characterized in that, include: A target layout is provided, which includes multiple line ends with a preset width, and two adjacent line ends constitute a line end group; Identify the line end group to be processed in the target layout. The line end group to be processed includes two line ends to be adjusted with a line end spacing smaller than a preset spacing. The line end to be adjusted includes a horizontal end and side ends connected to both ends of the horizontal end. The line end spacing refers to the vertical distance between the horizontal ends of the two line ends to be adjusted. Extend the two ends of the line to be adjusted by a preset distance in a direction that moves away from each other to form an initial layout. Photolithography simulation is performed based on the initial layout to obtain actual imaging results, and the initial layout is corrected multiple times based on the actual imaging results. When the imaging result is the same as the target map, or when the pixel spacing between the imaging result and the target map is less than a preset value, optical proximity correction is completed to obtain the corrected map.
2. The optical proximity correction method according to claim 1, characterized in that, The preset distance is less than half of the minimum graphic spacing in the target layout.
3. The optical proximity correction method according to claim 1, characterized in that, The process of identifying the line terminal group to be processed in the target layout includes: Identify the ends of each line in the target layout; Using one of the line ends as the first line end, a search area is formed around the first line end; The second line end is searched within the search area, and the first line end and the second line end are combined to form a line end group to be processed.
4. The optical proximity correction method according to claim 3, characterized in that, The process of forming a search area around the first line end includes: Draw circles with the two endpoints of the horizontal end of the first line as centers and the preset spacing as radii. Extend the two endpoints of the horizontal end by a predetermined distance in a direction that moves them away from each other to obtain the horizontal end extension line; The horizontal end of the first line is translated a predetermined distance in a direction perpendicular to the horizontal end and away from the first line end to obtain a horizontal end parallel line. The search area is defined by the horizontal end, the extension line of the horizontal end, the two circles, and the area enclosed by the line parallel to the horizontal end.
5. The optical proximity correction method according to claim 4, characterized in that, The preset spacing is based on the mask manufacturing limit size and the corrected space size.
6. The optical proximity correction method according to claim 5, characterized in that, The size of the correction space is inversely proportional to the size of the horizontal end.
7. The optical proximity correction method according to claim 1, characterized in that, The two side ends are of the same length and both are greater than the minimum graphic width of the target layout.
8. An optical proximity correction device, characterized in that, For performing the optical proximity correction method as described in any one of claims 1-7, comprising: The acquisition module is used to acquire the target map. The identification module is used to identify the line end group to be processed in the target layout. The line end group to be processed includes two line ends to be adjusted with a line end spacing smaller than a preset spacing. The line end to be adjusted includes a horizontal end and a side end connected to both ends of the horizontal end. The line end spacing refers to the vertical distance between the horizontal ends of the two line ends to be adjusted. An extension module is used to extend the two ends of the line to be adjusted by a preset distance in a direction away from each other, as an initial layout; The simulation module is used to perform photolithography simulation based on the initial layout, obtain the actual imaging result, and make multiple corrections to the initial layout based on the actual imaging result; when the imaging result is the same as the target layout, or the pixel spacing between the imaging result and the target layout is less than a preset value, optical proximity correction is completed to obtain the corrected layout.
9. A method for preparing a photomask, characterized in that, include: The corrected layout obtained by the optical proximity correction method according to any one of claims 1-7; A mask is made using the modified layout.
10. A photomask, characterized in that, It is prepared according to the method for preparing the mask according to claim 9.