Edge profile determination method, mask layout correction method, device and electronic equipment

Abstract

This invention discloses an edge contour determination method, a mask pattern correction method, an apparatus, and an electronic device. The edge contour determination method includes obtaining the lithographic intensity value of each grid pixel in an initial simulated lithographic pattern obtained by lithographic simulation of a mask pattern using a lithographic simulation model; determining edge contour points whose lithographic intensity values ​​are equal to a set intensity threshold based on a pre-determined intensity variation trend curve along the edge contour normal direction of the lithographic pattern and the corresponding lithographic intensity value of each grid pixel; and determining the edge contour curve of the initial simulated lithographic pattern based on each edge contour point. In this application, the intensity variation trend curve along the edge contour normal direction of the lithographic pattern is pre-determined, thereby achieving simpler and more accurate and reliable extraction of edge contour points, thus enabling accurate and reliable prediction of the lithographic pattern. When applied to mask pattern correction, this method is beneficial for improving the precision of semiconductor lithography.

Description

Technical Field

[0001] This invention relates to the field of semiconductor lithography technology, and in particular to a method and apparatus for determining the edge contour of lithography simulation, a method and apparatus for correcting lithographic mask patterns, and an electronic device. Background Technology

[0002] In semiconductor photolithography, predicting the lithographic pattern is of paramount importance. During mask exposure, physical and chemical effects such as optical diffraction and photoresist reactions can cause distortions in the exposure pattern. This dictates that the mask pattern cannot directly match the designed target pattern; correction and compensation are necessary to eliminate the distortions caused by optical diffraction and photoresist reactions. Therefore, accurately predicting the lithographic pattern that the mask pattern can form is crucial for mask pattern correction.

[0003] Photolithography simulation models are models that predict photolithography patterns by simulating the photolithography process under a mask pattern. However, due to limitations in computing power, current photolithography simulation models cannot accurately predict the edge contour positions of photolithography patterns. Instead, they need to extract the edge contours based on the fuzzy edge contours roughly determined by the simulation. Not only is the extraction process complex, but the accuracy of the final extracted edge contours is also limited, which restricts the accuracy and reliability of the photolithography pattern prediction results. Summary of the Invention

[0004] The purpose of this invention is to provide a method and apparatus for determining the edge contour of photolithography simulation, a method and apparatus for correcting photolithographic mask patterns, and an electronic device, which can achieve more accurate prediction of photolithographic patterns and help improve the precision of semiconductor photolithography.

[0005] To solve the above technical problems, the present invention provides a method for determining the edge contour in photolithography simulation, comprising:

[0006] Obtain the lithographic intensity value of each grid pixel in the initial simulated lithographic pattern; wherein, the initial simulated lithographic pattern is generated by the lithographic simulation model on the mask layout through lithographic simulation.

[0007] Based on the predetermined intensity variation trend curve in the normal direction of the edge contour of the photolithographic pattern, and the photolithographic intensity value corresponding to each grid pixel, the edge contour point whose photolithographic intensity value is equal to the set intensity threshold is determined.

[0008] Based on each of the described edge contour points, the edge contour curve of the simulated photolithography pattern is determined.

[0009] In an optional embodiment of this application, the process of pre-determining the intensity change trend curve includes:

[0010] The wafer sample is exposed by photolithography using a mask sample to obtain the exposed wafer sample;

[0011] The topography of the exposed area of ​​the exposed wafer sample is scanned to obtain height data samples corresponding to sampling points at different locations in the exposed area;

[0012] Based on multiple location sampling points along the same normal line perpendicular to the edge of the exposure area and corresponding height data samples, an intensity change trend curve that varies with the location sampling points is fitted.

[0013] In one optional embodiment of this application, an intensity variation trend curve is fitted to vary with the position sampling points based on a plurality of position sampling points along the same normal perpendicular to the edge of the exposure area and corresponding height data samples, including:

[0014] The height data samples corresponding to each sampling point on the same normal line are normalized to obtain the lithographic intensity samples corresponding to each sampling point.

[0015] By linearly fitting the sampling points at each location located on the same normal line and the corresponding lithographic intensity sample, an intensity change trend curve as the sampling points at each location are obtained.

[0016] In an optional embodiment of this application, the process of pre-determining the intensity change trend curve includes:

[0017] Multiple wafer samples were pre-exposed using photolithography with different exposure parameters through a mask sample to obtain exposed wafer samples;

[0018] The topography height of the exposed area of ​​each of the exposed wafer samples is scanned to obtain height data samples corresponding to sampling points at different positions in the exposed area of ​​each exposed wafer.

[0019] For each of the exposed wafer samples, an intensity change trend curve sample is obtained by fitting multiple position sampling points along the same normal line perpendicular to the edge of the exposed area and the corresponding height data samples, which vary with the position sampling points.

[0020] Using the exposure parameters corresponding to each intensity change trend curve sample as exposure parameter samples, the intensity change trend curve samples and exposure parameter samples are trained to obtain an intensity change prediction model.

[0021] The intensity change trend curve is determined by performing lithography simulation based on the intensity change prediction model and the lithography simulation model.

[0022] In an optional embodiment of this application, determining edge contour points whose lithographic intensity values ​​are equal to a set intensity threshold based on a predetermined intensity change trend curve and the lithographic intensity values ​​corresponding to each of the grid pixels includes:

[0023] The reference grid pixel is sequentially scanned and identified; wherein the photolithographic intensity value of the reference grid pixel is greater than a set intensity threshold and there are neighboring grid pixels with photolithographic intensity values ​​less than the set intensity threshold in an 8-neighborhood;

[0024] Based on the first lithographic intensity value and the second lithographic intensity value corresponding to the reference grid pixel and the neighboring grid pixel respectively, a first position point with the same lithographic intensity value and the first lithographic intensity value and a second position point with the same lithographic intensity value and the second lithographic intensity value are determined on the intensity change trend curve;

[0025] Using the first center point coordinate value corresponding to the center point of the reference grid pixel and the second center point coordinate value corresponding to the center point of the neighboring grid pixel as the position coordinates of the first position point and the second position point respectively, the intensity change trend curve is converted into an intensity change curve function.

[0026] On the intensity change curve function, the coordinates of the position point where the lithographic intensity value is equal to the set intensity threshold are determined as the coordinates of the edge contour point.

[0027] In an optional embodiment of this application, sequentially scanning and identifying reference grid pixels among each of the grid pixels includes:

[0028] Each of the grid pixels is scanned sequentially to determine whether the photolithography intensity value of the current grid pixel is greater than the set intensity threshold. If not, the next grid pixel is scanned. If so, it is determined whether there are any adjacent grid pixels in the 8-neighborhood of the current grid pixel whose photolithography intensity value is less than the set intensity threshold.

[0029] If there are multiple neighboring grid pixels with lithographic intensity values ​​less than the set intensity threshold within the 8-neighborhood of the current grid pixel, then the current grid pixel is the reference grid pixel, and the neighboring grid pixel with the smallest lithographic intensity value among the neighboring grid pixels is taken as the neighboring grid pixel corresponding to the reference grid pixel.

[0030] A method for correcting a photolithographic mask pattern includes:

[0031] Determine the initial mask layout based on the target layout;

[0032] The photolithography simulation model is used to simulate the photolithography pattern of the mask to generate an initial simulated photolithography pattern.

[0033] According to the edge contour determination method of photolithography simulation as described above, the edge contour of the initial simulated photolithography pattern is extracted to determine the edge contour curve of the simulated exposure pattern corresponding to the initial mask pattern.

[0034] The edge contour curve and the target layout are compared, and the initial mask layout is corrected based on the comparison result until the edge contour curve and the target layout are identical. Figure 1 Thus, the corrected mask pattern is obtained.

[0035] An edge contour determination device for photolithography simulation includes:

[0036] The photolithography simulation module is used to obtain the photolithography intensity value of each grid pixel in the initial simulated photolithography pattern; wherein, the initial simulated photolithography pattern is generated by the photolithography simulation model through photolithography simulation of the mask pattern;

[0037] The edge determination module is used to determine the edge contour points whose lithographic intensity value is equal to a set intensity threshold based on a pre-determined intensity change trend curve and the lithographic intensity value corresponding to each grid pixel point.

[0038] The curve determination module is used to determine the edge contour curve of the simulated photolithography pattern based on each of the edge contour points.

[0039] A photomask pattern correction device, comprising:

[0040] The layout design module is used to determine the initial mask layout based on the target layout;

[0041] The lithography simulation module is used to perform lithography simulation on the mask pattern using a lithography simulation model to generate an initial simulated lithography pattern.

[0042] The contour extraction module is used to extract the edge contour of the initial simulated lithography pattern according to the edge contour determination method of lithography simulation as described in any of the above items, and determine the edge contour curve of the simulated exposure pattern corresponding to the initial mask pattern.

[0043] The comparison correction module is used to compare the edge contour curve with the target layout, and correct the initial mask layout based on the comparison result until the edge contour curve matches the target layout. Figure 1 Thus, the corrected mask pattern is obtained.

[0044] An electronic device, comprising:

[0045] Memory, used to store computer programs;

[0046] A processor for executing the computer program to implement the steps of the edge contour determination method as described in any of the preceding claims and / or the photomask layout correction method as described above.

[0047] The present invention provides a method and apparatus for determining the edge contour in photolithography simulation. The method includes obtaining the photolithography intensity value of each grid pixel in an initial simulated photolithography pattern; wherein the initial simulated photolithography pattern is generated by a photolithography simulation model performing photolithography simulation on a mask layout; determining edge contour points whose photolithography intensity value is equal to a set intensity threshold based on a predetermined intensity variation trend curve in the normal direction of the edge contour of the photolithography pattern and the photolithography intensity value corresponding to each grid pixel; and determining the edge contour curve of the simulated photolithography pattern based on each edge contour point.

[0048] In this application, the intensity variation trend curve corresponding to the lithography intensity in the normal direction of the edge contour of the lithography pattern is predetermined under the lithography conditions simulated by the lithography simulation model. Based on this lithography intensity variation trend curve and combined with the lithography intensity value corresponding to each grid pixel in the initial simulated lithography pattern obtained by simulation, the edge contour point with the lithography intensity value equal to the set intensity threshold can be accurately determined, thereby realizing the accurate and reliable extraction of the edge contour curve. Compared with the current conventional method of calculating the position of the edge contour point with the lithography intensity value equal to the set intensity threshold by assuming that the lithography intensity values ​​change uniformly, the process of determining the edge contour point in this application is simpler and the determined edge contour point is more accurate and reliable, ultimately enabling accurate and reliable prediction of the lithography pattern.

[0049] This application also provides a method and apparatus for correcting a photomask pattern. In this correction method, a more accurate and reliable photomask pattern predicted by the edge contour determination method of the above-mentioned photomask simulation can be obtained, thereby achieving more accurate correction of the photomask pattern and improving the accuracy of semiconductor photolithography based on the photomask pattern.

[0050] This application also provides an electronic device that has the same technical effects as described above. Attached Figure Description

[0051] To more clearly illustrate the technical solutions of the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0052] Figure 1 A schematic diagram of the arrangement of grid pixels in the initial simulated lithography pattern for the lithography simulation model;

[0053] Figure 2 A schematic diagram illustrating the theoretical relationship between lithographic intensity and exposure location points in the conventional determination of edge contour points;

[0054] Figure 3 This is a schematic diagram illustrating a real relationship between lithographic intensity and exposure location points in the edge contour points;

[0055] Figure 4 A flowchart illustrating the edge contour determination method for photolithography simulation provided in this application embodiment;

[0056] Figure 5 A partial cross-sectional schematic diagram of an exposed wafer sample along the normal direction of the exposed area, provided in an embodiment of this application;

[0057] Figure 6 A schematic diagram of the intensity change trend curve provided in the embodiments of this application;

[0058] Figure 7 A schematic flowchart illustrating the method for correcting a photomask layout provided in an embodiment of this application;

[0059] Figure 8 A structural block diagram of the edge contour determination device for photolithography simulation provided in the embodiments of this application;

[0060] Figure 9 This is a structural block diagram of a photomask pattern correction device provided in an embodiment of this application. Detailed Implementation

[0061] To enable those skilled in the art to better understand the present invention, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0062] like Figure 1 As shown, Figure 1 This is a schematic diagram of the arrangement of grid pixels in the initial simulated lithography pattern for the lithography simulation model. In this application, lithography intensity refers to the amount of material removed from the wafer during the lithography process. It is proportional to both the light irradiation intensity sensed on the wafer and the depth of material removed by etching on the wafer. Furthermore, the lithography intensity value is also data representing the magnitude of the lithography intensity.

[0063] In addition, during the photolithography process, this application uses a set intensity threshold as the standard for determining edge contour points. That is to say, when the photolithography intensity is greater than the set intensity threshold, it is considered that the light has caused substantial etching on the wafer surface. Otherwise, it is considered that the light is too weak to cause etching on the wafer surface or that the etching caused is negligible.

[0064] Based on this, the photolithography simulation model simulates the mask layout, and when determining the photolithography intensity at different exposure positions, the exposure area is divided into grids, with each grid region being a grid pixel. For each grid pixel, a value representing the overall photolithography intensity of the area corresponding to that grid pixel can be determined; Figure 1 The grid pixels shown only include those with simulated lithography intensity values ​​close to or greater than the set intensity threshold. Grid pixels with lithography intensity values ​​significantly lower than the threshold are obviously not relevant to the edge contour and are therefore not shown. Furthermore, due to limitations in computing power, the lithography intensity at each exposure location cannot be accurately predicted. Therefore, the area covered by each grid pixel actually corresponds to a relatively large exposure area on the wafer; for example, each grid pixel might correspond to an 18m×18m square area on the wafer. Therefore, using the ring of grid pixels with the lithography intensity closest to the set threshold as the edge contour of the lithography pattern would obviously result in a significant error.

[0065] grid pixels and For example, For grid pixels whose photolithographic intensity value is less than a set intensity threshold, For grid pixels with a photolithographic intensity value greater than a set intensity threshold, it is obvious that edge contour points with a photolithographic intensity equal to the set intensity threshold must be located at... and The line connecting the center points.

[0066] like Figure 2 As shown, in the current conventional method of determining the edge contour of a photolithographic pattern, it is assumed to be determined by... center point to Along the line connecting the center points, the lithographic intensity exhibits a one-dimensional linear uniform variation; therefore, it is first determined that... and The average value of the corresponding photolithography intensity values ​​is used as The center point and The lithographic intensity value at the midpoint between the center points is used to determine the lithographic intensity value at the midpoint and a set intensity threshold (e.g., ...). Figure 2The intensity of the photolithography is compared with the intensity of the photolithography point (T). If the intensity value is greater than the set intensity threshold, the position of the edge contour point at the midpoint can be determined. Between the center points, the position of the center point and... The average value of the lithography intensity is calculated, and the result is used as the midpoint position. The lithography intensity at the midpoint between the two points is calculated, and then the intensity at the new midpoint is compared with a set intensity threshold. This process is repeated, and based on a binary search method, the edge contour points where the lithography intensity equals the set intensity threshold can be finally determined. Place.

[0067] The method described above for finding and determining the accurate edge contour points of the simulated photolithography pattern is not only extremely cumbersome in its calculation process, but also involves actual grid pixels. and Along the line connecting the center points, the change in lithographic intensity is not a uniform one-dimensional linear change; for example, it may be according to... Figure 3 The trend shown is non-uniform, and The location and the actual location of the edge contour points There is a significant deviation between them. In other words, the existing conventional method of extracting edge contour points is not only cumbersome in its calculation process, but also has low accuracy in determining the edge contour points. The accuracy of the edge line of the photolithography pattern determined based on the edge contour points is obviously not high. If the mask pattern is corrected based on the edge line of the photolithography pattern, it is obviously even more difficult to guarantee the accuracy and reliability of the correction result, which leads to the limitation of semiconductor photolithography precision.

[0068] Based on this, this application provides a technical solution that can improve the edge contour prediction accuracy of photolithography patterns and reduce the complexity of edge contour prediction, which is beneficial to improving the precision of semiconductor photolithography.

[0069] Based on the above discussion, such as Figure 4 As shown, in one specific embodiment of this application, the edge contour determination method for photolithography simulation may include:

[0070] S11: Obtain the lithographic intensity value of each grid pixel in the initial simulated lithographic pattern; wherein, the initial simulated lithographic pattern is generated by the lithographic simulation model on the mask pattern.

[0071] The photolithography simulation model in this embodiment is also a model that simulates the mask photolithography process. For example... Figure 1 As shown, based on the simulation of the photomask lithography process using the photolithography simulation model, an initial simulated photolithography pattern can be generated. The photolithography simulation model can predict and determine a photolithography intensity value for each grid pixel (also called a grid pixel region) in the initial simulated photolithography pattern.

[0072] S12: Based on the predetermined intensity variation trend curve in the normal direction of the edge contour of the photolithographic pattern and the photolithographic intensity value corresponding to each grid pixel, determine the edge contour point whose photolithographic intensity value is equal to the set intensity threshold.

[0073] It should be noted that, based on the fundamental characteristics of the photolithography process, under the same photolithography parameters, the trend of photolithography intensity variation along the normal direction of any edge point on the edge contour of the photolithographic pattern is approximately the same. That is to say, in this embodiment, a curve that can more realistically represent the trend of photolithography intensity variation along the normal direction of the edge contour is predetermined, for example... Figure 3 The curve shown is an intensity change trend curve. In this embodiment, the intensity change trend curve is determined based on the material thickness change law of the exposed area after actual exposure of the wafer sample, according to the photolithography removal. That is, it is a curve that can truly characterize the trend of photolithography intensity change. Based on this photolithography intensity change trend curve, and the center point positions of two adjacent grid pixels with photolithography intensities greater than and less than the set intensity threshold respectively, each edge contour point can be accurately determined.

[0074] Furthermore, in this embodiment, the edge contour normal of the photolithographic pattern can be determined based on the photolithographic intensity value corresponding to each grid pixel; such as Figure 1 As shown, grid pixels The photolithography intensity value is greater than the set intensity threshold, while the grid pixels... The photolithography intensity value is greater than the set intensity threshold, which is determined by the grid pixels. Pointing to grid pixels The dashed line with the arrow roughly represents a normal direction of the edge contour; similarly, the grid pixels... The photolithography intensity value is less than the set intensity threshold, while the grid pixels... The photolithography intensity value is greater than the set intensity threshold, which is determined by the grid pixels. Pointing to grid pixels The dashed line with the arrowhead roughly represents the other normal direction of the edge contour.

[0075] S13: Determine the edge contour curve of the simulated photolithography pattern based on each edge contour point.

[0076] After determining each edge contour point in sequence, a linear fit is performed on each edge contour point, and the resulting curve is the edge contour curve.

[0077] Based on the above discussion, in determining the edge contour points in this application, it is not assumed that the edge normal direction changes in a one-dimensional linear uniform manner. Instead, a curve that more closely resembles the trend of photolithography intensity change in the actual exposure process is determined based on the basic laws of the photolithography process. In this embodiment, this curve is used as a reference to determine more accurate and reliable edge contour points. There is no need to repeatedly perform the bisection method to obtain values, which reduces the computational difficulty of edge contour point extraction and improves the accuracy of edge contour points, thereby ensuring the accuracy and reliability of the edge contour curve of the final predicted simulated photolithography pattern.

[0078] In summary, this application predetermines the intensity variation trend curve corresponding to the lithographic intensity in the normal direction of the edge contour of the lithographic pattern under the lithographic conditions simulated by the lithographic simulation model. Based on this lithographic intensity variation trend curve and combined with the lithographic intensity values ​​corresponding to each grid pixel in the initial simulated lithographic pattern obtained from the simulation, the edge contour points whose lithographic intensity values ​​are equal to the set intensity threshold can be accurately determined, thereby achieving accurate and reliable extraction of the edge contour curve. Compared with the current conventional method of calculating the position of the edge contour point whose lithographic intensity value is equal to the set intensity threshold based on the assumption that the lithographic intensity values ​​change uniformly, this application has a simpler calculation process for determining the edge contour points, and the determined edge contour points are more accurate and reliable, ultimately achieving accurate and reliable prediction of the lithographic pattern.

[0079] The process of pre-determining the lithographic intensity in the edge contour normal direction will be described in detail below with specific embodiments.

[0080] In one specific embodiment of this application, the process of pre-determining the intensity change trend curve may include:

[0081] S21: Photolithographic exposure is performed on the wafer sample using a mask sample to obtain an exposed wafer sample;

[0082] S22: Perform a topographic height scan on the exposed area of ​​the exposed wafer sample to obtain height data samples corresponding to sampling points at different locations in the exposed area;

[0083] S23: Based on multiple sampling points at positions along the same normal perpendicular to the edge of the exposure area and the corresponding height data samples, fit the intensity change trend curve as the sampling points change.

[0084] As described above, the photolithography intensity in this application is proportional to the thickness of the material removed by etching on the wafer. Therefore, in this embodiment, by performing actual exposure sampling on the wafer sample and actually scanning and collecting height data samples corresponding to sampling points at different positions on the exposed wafer sample, it is clear that the change trend of the height data samples corresponding to each sampling point along the normal line of the edge of the exposed area is the same as the change trend of the photolithography intensity. Thus, a curve characterizing the change trend of the photolithography intensity can be determined by fitting the height data samples corresponding to each sampling point.

[0085] Further optionally, in order to ensure the accuracy of the fitted intensity change trend curve, in one optional embodiment of this example, the process of fitting and determining the intensity change trend curve of the lithographic intensity change may specifically include:

[0086] S231: Normalize the height data samples corresponding to each sampling point on the same normal line to obtain the lithographic intensity samples corresponding to each sampling point.

[0087] S232: Linearly fit the sampling points at each position on the same normal line with the corresponding photolithographic intensity samples to obtain the intensity change trend curve as the sampling points change.

[0088] like Figure 5 As shown, Figure 5 This is a schematic cross-sectional view of a partial exposure area along the normal direction of an exposed wafer sample provided in this embodiment of the application. Figure 5 In the illustrated embodiment, along the same normal direction of the exposed area, in The height data samples were collected sequentially from 10 sampling points. Therefore, the height data samples corresponding to sampling points at various locations along the same normal line can be normalized using the formula... Normalization is performed to obtain the i-th photolithographic intensity sample. Linear fitting is performed on the lithographic intensity samples corresponding to the location sampling points to determine the intensity change trend curve.

[0089] On the exposed wafer sample, the trend of photolithography intensity variation along the normal direction at any position in the exposed area should be approximately the same. Therefore, when actually fitting and determining the intensity variation trend curve, one can randomly select any sampling point along the normal direction and the corresponding photolithography sample for linear fitting, or select multiple sampling points along the normal direction and the corresponding photolithography samples for linear fitting. Finally, a more reasonable intensity variation trend curve is determined by comprehensively considering the intensity variation trend curves determined separately along each normal direction. This application does not impose specific restrictions on this.

[0090] As shown above, the trend of photolithography intensity variation along the edge contour normal of the exposed area on the exposed wafer is mainly determined by the exposure parameters. Based on this, in another optional embodiment of this application, the process of pre-determining the intensity variation trend curve may further include:

[0091] S31: Pre-expose multiple wafer samples using photolithography under different exposure parameters through mask samples to obtain exposed wafer samples;

[0092] S32: Perform a topographic height scan on the exposure area of ​​each exposed wafer sample to obtain height data samples corresponding to sampling points at different positions in the exposure area of ​​each exposed wafer;

[0093] S33: For each exposed wafer sample, based on multiple sampling points along the same normal perpendicular to the edge of the exposed area and the corresponding height data samples, fit a curve sample of intensity change trend as the sampling points change.

[0094] S34: Using the exposure parameters corresponding to each intensity change trend curve sample as exposure parameter samples, the intensity change trend curve samples and exposure parameter samples are trained to obtain an intensity change prediction model.

[0095] S35: Determine the intensity change trend curve by simulating the exposure parameters based on the intensity change prediction model and the lithography simulation model.

[0096] It is understood that the process of performing photolithography exposure on each wafer sample in this embodiment and obtaining intensity change trend curve samples based on each exposed wafer sample is similar to the process of determining intensity change trend curves in the previous embodiment, and will not be repeated in this embodiment. However, the difference is that each exposed wafer sample in this embodiment is exposed under multiple different exposure parameters. Based on this, this application uses exposure parameter samples and corresponding intensity change trend curve samples as sample data to learn and train an intensity change prediction model that can characterize the correlation between exposure parameters and intensity change trends. Thus, based on the exposure parameters of the photolithography process currently simulated by the photolithography simulation model, the corresponding intensity change trend curve can be directly predicted based on the intensity change prediction model, so there is no need to perform a real exposure process for each exposure parameter, and the intensity change trend curve can still be determined.

[0097] Based on the above embodiments, it should be further explained that, regardless of the sampling method used to determine the intensity variation trend curve in this application, the intensity variation trend curve determined by the height data samples of each sampling point on the exposed wafer sample is only the same as the trend of lithography intensity along the edge contour normal direction in the initial simulated lithography pattern determined by simulation. It is not a one-to-one correspondence between the lithography intensity at each exposure position. Therefore, the intensity variation trend curve referred to in this application is not a curve that can be represented by a definite function, or a curve with a clear one-to-one correspondence between lithography intensity and position points; rather, it only characterizes the trend of lithography intensity changing with the exposure position point. For example, the trend of lithography intensity changing with the exposure position point may be a sine wave, a partially parabolic trend, or other linear relationship, etc. In short, it is sufficient to determine the approximate trend of lithography intensity changing with the exposure position point. Taking the example that the trend of lithography intensity changing with the exposure position point is a sine wave, then it can be used... This represents the trend curve of the intensity change; where, Exposure location point The photolithography intensity value, and This can be a constant parameter that can be predicted based on the photolithography intensity samples in the above embodiments or based on the intensity change prediction model, and can be 0; while These are the amplitude parameter and the proportional parameter, respectively, which are unknown parameters in a predetermined intensity change trend curve.

[0098] Based on this, in an optional embodiment of this application, the process of determining the edge contour points whose lithographic intensity value is equal to a set intensity threshold based on the intensity change trend curve and the lithographic intensity value of the grid pixels may include:

[0099] S121: Scan and identify the reference grid pixel in each grid pixel in sequence; wherein, the lithographic intensity value corresponding to the reference grid pixel is greater than the set intensity threshold and there are neighboring grid pixels with lithographic intensity values ​​less than the set intensity threshold in the 8-neighborhood.

[0100] like Figure 1 As shown, when the grid pixels are scanned... At that time, in grid pixels Within the 3x3 grid centered on the center, the remaining 8 grid pixels are all For each of the 8 neighboring grid pixels, check if there is a grid pixel with a photolithographic intensity lower than a set intensity threshold. If so, then the grid pixel... These can be used as reference grid pixels, and grid pixels with lithographic intensity less than a set intensity threshold within 8 neighborhoods are considered neighboring grid pixels.

[0101] However, it is understandable that for each reference grid pixel, there may be multiple grid pixels in its 8-neighborhood with lithographic intensity less than the set intensity threshold. In this case, the neighboring grid pixel with the smallest lithographic intensity value is taken as the neighboring grid pixel corresponding to the reference grid pixel.

[0102] Furthermore, in practical applications, there may be three consecutive grid pixels within the 8-neighborhood of a reference grid pixel that are less than a set intensity threshold and have the same corresponding lithographic intensity. In this case, the grid pixel located in the middle position among the three grid pixels can be taken as the neighboring grid pixel of the reference grid pixel; for example, when the grid pixel... The lithography intensity is greater than the set intensity threshold, and there are only grid pixels in its 8-neighborhood. , , If the corresponding lithographic intensity is less than the set intensity threshold, and the lithographic intensity of the three grid pixels is the same, then at this time... The reference grid pixels, and It is the neighborhood grid pixels.

[0103] Furthermore, in practical applications, there may be two adjacent grid pixels within the 8-neighborhood of a reference grid pixel that are less than a set intensity threshold and have the same corresponding lithographic intensity. In this case, the non-diagonally adjacent grid pixels of the two grid pixels that are the reference grid pixel can be taken as the neighboring grid pixels of the reference grid pixel. For example, when the grid pixel... The lithography intensity is greater than a set intensity threshold, and the grid pixels in its 8-neighborhood... , The corresponding photolithography intensities are equal and minimum, all less than the set intensity threshold; therefore, at this time... The reference grid pixels, and It is the neighborhood grid pixels.

[0104] In summary, it should be ensured that the line connecting the center point of the reference grid pixel and the center point of the neighboring grid pixel is parallel to the normal direction of the edge contour.

[0105] S122: Based on the first lithographic intensity value and the second lithographic intensity value corresponding to the reference grid pixel and the neighboring grid pixel respectively, determine the first position point where the lithographic intensity value and the first lithographic intensity value are the same, and the second position point where the lithographic intensity value and the second lithographic intensity value are the same on the intensity change trend curve.

[0106] S123: Using the coordinates of the first center point corresponding to the center point of the reference grid pixel and the coordinates of the second center point corresponding to the center point of the neighboring grid pixel as the position coordinates of the first position point and the second position point respectively, the intensity change trend curve is converted into an intensity change curve function.

[0107] S124: On the intensity change curve function, determine the position coordinates of the point where the lithographic intensity value is equal to the set intensity threshold, and use them as the position coordinates of the edge contour point.

[0108] Taking the sinusoidal trend of photolithography intensity variation with exposure location as an example, the following method is used: This represents the trend curve of the intensity change; refer to, for example... Figure 1 and Figure 6 As shown, scanning determines the grid pixels. The photolithography intensity value is greater than the set intensity threshold, and it has adjacent grid pixels. The corresponding photolithography intensity value is less than the set intensity threshold, thus the grid pixels can be... As the reference grid pixel, and the grid pixel Then, as a neighboring grid pixel, the grid pixel is... The coordinates of the first center point and its corresponding lithographic intensity value, as well as the grid pixels. Substituting the coordinates of the second center point and its corresponding lithographic intensity value into the intensity variation trend curve, it is clear that the result can be determined. In Two parameters, therefore Curve function with two known parameters That is, along the grid pixels and grid pixels The intensity change curve function satisfied by the lithography intensity is located in the normal direction of the line connecting the center points. By substituting the set function threshold into this intensity change curve function, the coordinates of the exposure position point where the lithography intensity is equal to the set function threshold can be determined. These coordinates are also the coordinates of the edge contour points.

[0109] Therefore, it can be seen that in this application, only the center point coordinates of two adjacent grid pixels with photolithographic intensities greater than and less than a set intensity threshold, and the photolithographic intensity value are substituted into the intensity change trend curve to determine the edge contour points. The whole calculation process is simple and efficient, without the need for repeated binary search calculations, and the final determined edge contour points are accurate and reliable.

[0110] Based on the above discussion, in this embodiment, the wafer sample is exposed, and the morphological height data after photolithography is collected along the normal direction of the edge contour at the edge position near the exposure area. The morphological height data is used as a height data sample to roughly determine the trend curve of the photolithography intensity changing with the exposure position point in the normal direction of the edge contour. Finally, the definite curve function of the trend of photolithography intensity changing with the exposure position point in each normal direction can be determined. Then, each edge contour point can be found simply and accurately based on the curve function. Finally, an accurate and reliable edge contour curve can be fitted based on each edge contour point.

[0111] Based on the above discussion, this application further provides an embodiment of a method for correcting a photomask layout, such as... Figure 7 As shown, in one specific embodiment of this application, the method for correcting the photolithographic mask pattern may include:

[0112] S41: Determine the initial mask layout based on the target layout;

[0113] S42: Perform photolithography simulation on the mask pattern using a photolithography simulation model to generate an initial simulated photolithography pattern;

[0114] S43: According to the edge contour determination method of photolithography simulation, the edge contour of the initial simulated photolithography pattern is extracted to determine the edge contour curve of the simulated exposure pattern corresponding to the initial mask layout.

[0115] S44: Compare the edge contour curve with the target layout, and correct the initial mask layout based on the comparison results until the edge contour curve matches the target layout. Figure 1 Thus, the corrected mask pattern is obtained.

[0116] It is understood that the edge contour determination method according to photolithography simulation in this embodiment can extract the edge contour of the initial simulated exposure pattern corresponding to the initial mask layout, and obtain a more accurate simulated exposure pattern with a more accurate edge contour curve. That is, the edge contour curve of the simulated exposure pattern is determined according to the edge contour determination method of photolithography simulation in any of the above embodiments.

[0117] In the process of optical proximity correction of photolithographic mask layout, the initial mask layout designed based on the target layout needs to be continuously modified to compensate for the pattern distortion caused by physical and chemical effects such as optical diffraction and photoresist reaction during the photolithography process; and the basis for the modification is the deviation between the exposure pattern of the initial mask layout and the target layout.

[0118] The exposure pattern of the initial mask layout is simulated by a photolithography simulation model to obtain the deviation between the simulated exposure pattern and the target layout. This deviation is the main indicator for measuring the correction of the current initial mask layout. This feedback loop helps the simulated exposure pattern corresponding to the corrected mask layout to gradually approach the target exposure pattern until the deviation between the simulated exposure pattern and the target exposure pattern is reduced to a range acceptable to the process.

[0119] In this embodiment, the edge contour determination method based on the above-mentioned lithography simulation is used to extract the edge contour of the simulated exposure pattern predicted by the lithography simulation model more accurately, that is, to ensure the accuracy and reliability of the lithography pattern predicted by the simulation. Thus, in the process of continuous correction of the initial mask pattern, the deviation between the given exposure pattern and the target pattern is ensured to be more reliable, which also realizes more accurate correction of the lithography mask pattern, thereby improving the accuracy of semiconductor lithography based on the mask pattern.

[0120] The edge contour determination device for photolithography simulation provided in the embodiments of the present invention is described below. The edge contour determination device for photolithography simulation described below and the edge contour determination method for photolithography simulation described above can be referred to in correspondence with each other.

[0121] Figure 8 The structural block diagram of the edge contour determination device for photolithography simulation provided in the embodiments of this application is shown below. Figure 8 The edge contour determination device for photolithography simulation may include:

[0122] The photolithography simulation module 51 is used to obtain the photolithography intensity value of each grid pixel in the initial simulated photolithography pattern; wherein, the initial simulated photolithography pattern is generated by the photolithography simulation model performing photolithography simulation on the mask layout;

[0123] The edge determination module 52 is used to determine the edge contour points whose lithography intensity value is equal to a set intensity threshold based on a pre-determined intensity change trend curve and the lithography intensity value corresponding to each grid pixel point.

[0124] The curve determination module 53 is used to determine the edge contour curve of the simulated photolithography pattern based on each of the edge contour points.

[0125] In an optional embodiment of this application, a first trend module is further included, which is used to perform photolithographic exposure on a wafer sample using a mask sample to obtain an exposed wafer sample; to perform a topographic height scan on the exposed area of ​​the exposed wafer sample to obtain height data samples corresponding to sampling points at different positions in the exposed area; and to fit an intensity change trend curve that varies with the sampling points based on multiple sampling points at the positions along the same normal line perpendicular to the edge of the exposed area and the corresponding height data samples.

[0126] In an optional embodiment of this application, the first trend module is further configured to normalize the height data samples corresponding to each of the sampling points on the same normal line to obtain the lithographic intensity samples corresponding to each of the sampling points; and to linearly fit each of the sampling points on the same normal line and the corresponding lithographic intensity samples to obtain an intensity change trend curve that varies with the sampling points.

[0127] In an optional embodiment of this application, a second trend module is further included, used to pre-expose multiple wafer samples to photolithography using mask samples under different exposure parameters to obtain exposed wafer samples; to perform topographic height scanning on the exposed area of ​​each exposed wafer sample to obtain height data samples corresponding to sampling points at different positions in the exposed area of ​​each exposed wafer; for each exposed wafer sample, to fit an intensity change trend curve sample that varies with the sampling points along the same normal line perpendicular to the edge of the exposed area and the corresponding height data samples; to use the exposure parameters corresponding to each intensity change trend curve sample as exposure parameter samples, to learn and train the intensity change trend curve samples and exposure parameter samples to obtain an intensity change prediction model; and to determine the intensity change trend curve by performing photolithography simulation based on the intensity change prediction model and the photolithography simulation model.

[0128] In an optional embodiment of this application, the edge determination module 402 is specifically used to sequentially scan and identify reference grid pixels among the grid pixels; wherein, the lithographic intensity value of the reference grid pixel is greater than a set intensity threshold and there are neighboring grid pixels with lithographic intensity values ​​less than the set intensity threshold within an 8-neighborhood; based on the first lithographic intensity value and the second lithographic intensity value corresponding to the reference grid pixel and the neighboring grid pixels respectively, a first position point with the same lithographic intensity value as the first lithographic intensity value and a second position point with the same lithographic intensity value as the second lithographic intensity value are determined on the intensity change trend curve; using the coordinate values ​​of the first center point corresponding to the center point of the reference grid pixel and the second center point corresponding to the center point of the neighboring grid pixels as the position coordinates of the first position point and the second position point respectively, the intensity change trend curve is converted into an intensity change curve function; on the intensity change curve function, the position coordinates corresponding to the position point with the lithographic intensity value equal to the set intensity threshold are determined as the position coordinates of the edge contour point.

[0129] In an optional embodiment of this application, the edge determination module 402 is specifically used to sequentially scan each of the grid pixels, determine whether the lithographic intensity value of the current grid pixel is greater than the set intensity threshold, if not, then scan the next grid pixel, if yes, then determine whether there are any adjacent grid pixels with a lithographic intensity value less than the set intensity threshold in the 8-neighborhood of the current grid pixel; if there are multiple adjacent grid pixels with a lithographic intensity value less than the set intensity threshold in the 8-neighborhood of the current grid pixel, then the current grid pixel is the reference grid pixel, and the adjacent grid pixel with the smallest lithographic intensity value among the adjacent grid pixels is taken as the neighboring grid pixel corresponding to the reference grid pixel.

[0130] The edge contour determination device for photolithography simulation in this embodiment is used to implement the aforementioned edge contour determination method for photolithography simulation. Therefore, the specific implementation of the edge contour determination device for photolithography simulation can be found in the embodiment section of the aforementioned edge contour determination method for photolithography simulation. The specific implementation can be referred to the description of the corresponding embodiments, which will not be repeated here.

[0131] like Figure 9 As shown, Figure 9 A structural block diagram of the photomask pattern correction device provided in the embodiments of this application is shown below. Figure 9 The device for correcting the photomask pattern in the image may include:

[0132] Layout design module 61 is used to determine the initial mask layout based on the target layout;

[0133] The lithography simulation module 62 is used to perform lithography simulation on the mask pattern through the lithography simulation model and generate an initial simulated lithography pattern.

[0134] The contour extraction module 63 is used to extract the edge contour of the initial simulated lithography pattern according to the edge contour determination method of lithography simulation as described in any of the above claims, and determine the edge contour curve of the simulated exposure pattern corresponding to the initial mask layout.

[0135] The comparison correction module 64 is used to compare the edge contour curve and the target layout, and correct the initial mask layout according to the comparison result until the edge contour curve and the target layout are consistent. Figure 1 Thus, the corrected mask pattern is obtained.

[0136] The photomask pattern correction device of this embodiment is used to implement the aforementioned photomask pattern correction method. Therefore, the specific implementation of the photomask pattern correction device can be found in the embodiment section of the photomask pattern correction device above. The specific implementation can be referred to the description of the corresponding partial embodiments, and will not be repeated here.

[0137] This application also provides an embodiment of an electronic device, which may include:

[0138] Memory, used to store computer programs;

[0139] A processor for executing the computer program to implement the steps of the edge contour determination method as described in any of the preceding claims and / or the photomask layout correction method as described above.

[0140] The memory in this embodiment may include random access memory (RAM), main memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, register, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art.

[0141] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that the elements inherent in a process, method, article, or apparatus that includes a list of elements are included. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. Additionally, portions of the technical solutions provided in the embodiments of this application that are consistent with the implementation principles of corresponding technical solutions in the prior art have not been described in detail to avoid excessive elaboration.

[0142] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the present invention.

Claims

1. A method for determining the edge contour in photolithography simulation, characterized in that, include: Obtain the lithographic intensity value of each grid pixel in the initial simulated lithographic pattern; wherein, the initial simulated lithographic pattern is generated by the lithographic simulation model on the mask layout through lithographic simulation. Based on the predetermined intensity variation trend curve in the normal direction of the edge contour of the photolithographic pattern, and the photolithographic intensity value corresponding to each grid pixel, the edge contour point whose photolithographic intensity value is equal to the set intensity threshold is determined. Based on each of the aforementioned edge contour points, determine the edge contour curve of the simulated photolithography pattern; The process of pre-determining the intensity change trend curve includes: The wafer sample is exposed by photolithography using a mask sample to obtain the exposed wafer sample; The topography of the exposed area of ​​the exposed wafer sample is scanned to obtain height data samples corresponding to sampling points at different locations in the exposed area; Based on multiple location sampling points along the same normal line perpendicular to the edge of the exposure area and corresponding height data samples, an intensity change trend curve that varies with the location sampling points is fitted.

2. The edge contour determination method for photolithography simulation as described in claim 1, characterized in that, Based on multiple location sampling points along the same normal line perpendicular to the edge of the exposure area and corresponding height data samples, an intensity variation trend curve that varies with the location sampling points is fitted, including: The height data samples corresponding to each sampling point on the same normal line are normalized to obtain the lithographic intensity samples corresponding to each sampling point. By linearly fitting the sampling points at each location located on the same normal line and the corresponding lithographic intensity sample, an intensity change trend curve as the sampling points at each location are obtained.

3. The edge contour determination method for photolithography simulation as described in claim 1, characterized in that, The process of pre-determining the intensity change trend curve includes: Multiple wafer samples were pre-exposed using photolithography with different exposure parameters through a mask sample to obtain exposed wafer samples; The topography height of the exposed area of ​​each of the exposed wafer samples is scanned to obtain height data samples corresponding to sampling points at different positions in the exposed area of ​​each exposed wafer. For each of the exposed wafer samples, an intensity change trend curve sample is obtained by fitting multiple position sampling points along the same normal line perpendicular to the edge of the exposed area and the corresponding height data samples, which vary with the position sampling points. Using the exposure parameters corresponding to each intensity change trend curve sample as exposure parameter samples, the intensity change trend curve samples and exposure parameter samples are trained to obtain an intensity change prediction model. The intensity change trend curve is determined by performing lithography simulation based on the intensity change prediction model and the lithography simulation model.

4. The method for determining the edge contour in photolithography simulation as described in any one of claims 1 to 3, characterized in that, Based on a predetermined intensity change trend curve and the lithographic intensity value corresponding to each grid pixel, edge contour points whose lithographic intensity value equals a set intensity threshold are determined, including: The reference grid pixel is sequentially scanned and identified; wherein the photolithographic intensity value of the reference grid pixel is greater than a set intensity threshold and there are neighboring grid pixels with photolithographic intensity values ​​less than the set intensity threshold in an 8-neighborhood; Based on the first lithographic intensity value and the second lithographic intensity value corresponding to the reference grid pixel and the neighboring grid pixel respectively, a first position point with the same lithographic intensity value and the first lithographic intensity value and a second position point with the same lithographic intensity value and the second lithographic intensity value are determined on the intensity change trend curve; Using the first center point coordinate value corresponding to the center point of the reference grid pixel and the second center point coordinate value corresponding to the center point of the neighboring grid pixel as the position coordinates of the first position point and the second position point respectively, the intensity change trend curve is converted into an intensity change curve function. On the intensity change curve function, the coordinates of the position point where the lithographic intensity value is equal to the set intensity threshold are determined as the coordinates of the edge contour point.

5. The edge contour determination method for photolithography simulation as described in claim 4, characterized in that, The process involves sequentially scanning and identifying the reference grid pixels in each of the grid pixels, including: Each of the grid pixels is scanned sequentially to determine whether the photolithography intensity value of the current grid pixel is greater than the set intensity threshold. If not, the next grid pixel is scanned. If so, it is determined whether there are any adjacent grid pixels in the 8-neighborhood of the current grid pixel whose photolithography intensity value is less than the set intensity threshold. If there are multiple neighboring grid pixels with lithographic intensity values ​​less than the set intensity threshold within the 8-neighborhood of the current grid pixel, then the current grid pixel is the reference grid pixel, and the neighboring grid pixel with the smallest lithographic intensity value among the neighboring grid pixels is taken as the neighboring grid pixel corresponding to the reference grid pixel.

6. A method for correcting a photolithographic mask pattern, characterized in that, include: Determine the initial mask layout based on the target layout; The photolithography simulation model is used to simulate the photolithography pattern of the mask to generate an initial simulated photolithography pattern. According to the edge contour determination method of photolithography simulation as described in any one of claims 1 to 5, the edge contour of the initial simulated photolithography pattern is extracted to determine the edge contour curve of the simulated exposure pattern corresponding to the initial mask pattern. The edge contour curve and the target pattern are compared, and the initial mask pattern is corrected according to the comparison result until the edge contour curve and the target pattern are consistent, thus obtaining the corrected mask pattern.

7. An edge contour determination device for photolithography simulation, characterized in that, include: The photolithography simulation module is used to obtain the photolithography intensity value of each grid pixel in the initial simulated photolithography pattern; wherein, the initial simulated photolithography pattern is generated by the photolithography simulation model through photolithography simulation of the mask pattern; The edge determination module is used to determine the edge contour points whose lithographic intensity value is equal to a set intensity threshold based on a pre-determined intensity change trend curve and the lithographic intensity value corresponding to each grid pixel point. The curve determination module is used to determine the edge contour curve of the simulated photolithography pattern based on each of the edge contour points. It also includes a first trend module, used to perform photolithographic exposure on a wafer sample using a mask sample to obtain an exposed wafer sample; to perform a topographic height scan on the exposed area of ​​the exposed wafer sample to obtain height data samples corresponding to sampling points at different positions in the exposed area; and to fit an intensity change trend curve that varies with the sampling points based on multiple sampling points at the positions along the same normal line perpendicular to the edge of the exposed area and the corresponding height data samples.

8. A photolithographic mask pattern correction device, characterized in that, include: The layout design module is used to determine the initial mask layout based on the target layout; The lithography simulation module is used to perform lithography simulation on the mask pattern using a lithography simulation model to generate an initial simulated lithography pattern. The contour extraction module is used to extract the edge contour of the initial simulated lithography pattern according to the edge contour determination method of lithography simulation as described in any one of claims 1 to 5, and determine the edge contour curve of the simulated exposure pattern corresponding to the initial mask pattern. The comparison correction module is used to compare the edge contour curve with the target layout, and correct the initial mask layout according to the comparison result until the edge contour curve and the target layout are consistent, thereby obtaining the corrected mask layout.

9. An electronic device, characterized in that, include: Memory, used to store computer programs; A processor for executing the computer program to implement the steps of the edge contour determination method for photolithography simulation as described in any one of claims 1 to 5 and / or the photolithographic mask layout correction method as described in claim 6.

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