Contact hole layout correction method based on graphical environment fitting and mask

Abstract

The present disclosure provides a contact hole layout correction method based on pattern environment fitting, comprising: randomly determining at least one pattern region in the contact hole layout; performing optical proximity effect correction on the at least one pattern region based on a super-resolution lithography model, while obtaining actual boundary movement amount of the contact hole pattern in the at least one pattern region; fitting the relationship between the pattern environment characteristics of the contact hole pattern and the actual boundary movement amount in the at least one pattern region, taking minimizing the error between the actual boundary movement amount and the predicted boundary movement amount as the fitting target, to obtain the fitting relationship between the pattern environment of the contact hole pattern and the boundary movement amount; determining the predicted boundary movement amount of the contact hole pattern in the pattern region other than the at least one pattern region in the contact hole layout by using the fitting relationship, correcting the boundary of the corresponding contact hole pattern in the pattern region other than the at least one pattern region based on the predicted boundary movement amount, and outputting the optimized contact hole layout.

Description

Technical Field

[0001] This disclosure relates to the field of integrated circuit technology, specifically to the field of photolithography technology, and particularly to a contact hole layout correction method and mask based on graphics environment fitting. Background Technology

[0002] With the development of integrated circuits, the requirements for lithographic resolution are becoming increasingly stringent, and traditional projection lithography technology is limited by the diffraction limit. Surface plasmons possess unique super-diffractive optical properties. Utilizing these properties to achieve super-resolution lithography can overcome the diffraction limit limitations of traditional optical imaging and focusing resolution, which is of great significance for promoting the development of the integrated circuit industry and advancing micro-nano fabrication technology.

[0003] When a super-resolution lithography system images a contact hole pattern, optical proximity effects (OPE) occur due to light diffraction and interference. Even if the contact hole patterns in the contact hole pattern are the same size, the imaging results will vary greatly because the surrounding pattern environment of each contact hole pattern is different. This difference will affect the performance of the integrated circuit.

[0004] To mitigate the impact of optical proximity effects, several Optical Proximity Correction (OPC) methods have been proposed and adopted in recent years. Rule-based OPC methods correct mask layouts by establishing a rule base, but as lithographic feature sizes decrease, the correction effect becomes limited and the rule base becomes increasingly complex. In recent years, Model-Based OPC (MBOPC) methods have emerged, utilizing a physical model of the lithography imaging process to transform OPC into a mathematical optimization problem, achieving better optimization results. With the evolution of lithography process nodes, the pattern density of contact hole layouts is constantly increasing, leading to a significant increase in the amount of simulation data for MBOPC. In super-resolution lithography, because the lithography imaging model cannot be represented analytically but requires full-wavelength numerical simulation, optimizing the contact hole layout necessitates rasterizing the layout, optimizing each segment individually, and then stitching the optimization results together. This results in excessive time consumption for optimizing the entire chip layout, severely impacting production efficiency. Summary of the Invention

[0005] In view of the above problems, this disclosure provides a contact hole layout correction method based on graphic environment fitting, which is used to at least partially solve the above technical problems.

[0006] According to a first aspect of the present disclosure, a contact hole layout correction method based on graphic environment fitting is provided, comprising: randomly determining at least one graphic region in the contact hole layout; performing optical proximity effect correction on the at least one graphic region based on a super-resolution lithography model, and simultaneously obtaining the actual boundary movement of the contact hole pattern in the at least one graphic region; fitting the relationship between the graphic environment features of the contact hole pattern in the at least one graphic region and the actual boundary movement with minimizing the error between the actual boundary movement and the predicted boundary movement as the fitting objective, and obtaining the fitting relationship between the graphic environment of the contact hole pattern and the boundary movement; using the fitting relationship to determine the predicted boundary movement of the contact hole pattern in the graphic regions other than the at least one graphic region in the contact hole layout, correcting the boundary of the corresponding contact hole pattern in the graphic regions other than the at least one graphic region in the contact hole layout based on the predicted boundary movement, and outputting an optimized contact hole layout.

[0007] According to an embodiment of the present disclosure, randomly determining at least one graphic region in a contact hole layout includes: determining the number and size of graphic regions selected in the contact hole layout; randomly selecting at least one graphic region from the graphic regions in the contact hole layout according to the number and size selected, wherein at least one graphic region at least covers various graphic environments of the contact hole graphic in the contact hole layout, and the size of each graphic region in the at least one graphic region is larger than the range of the contact hole graphic affected by optical influence.

[0008] According to embodiments of this disclosure, optical proximity effect correction is performed on at least one patterned region based on a super-resolution lithography model, and the actual boundary movement of contact hole patterns in at least one patterned region is obtained. This includes: performing gradient iterative optimization on all contact hole patterns in at least one patterned region based on the super-resolution lithography model to obtain optimized contact hole pattern boundary positions; and determining the actual boundary movement of contact hole patterns in at least one patterned region based on the optimized contact hole pattern boundary positions and the unoptimized contact hole pattern boundary positions.

[0009] According to embodiments of this disclosure, with the goal of minimizing the error between the actual boundary movement and the predicted boundary movement, the relationship between the graphic environment features of the contact hole pattern in at least one graphic region and the actual boundary movement is fitted to obtain the fitting relationship between the graphic environment of the contact hole pattern and the boundary movement. This includes: converting the graphic environment of the contact hole pattern into graphic environment features; using the graphic environment feature vector as the independent variable and the actual boundary movement of the contact hole pattern as the dependent variable to obtain the fitting relationship between the graphic environment of the contact hole pattern and the boundary movement, wherein the objective function of the fitting is the sum of the root mean square errors between the actual boundary movement and the predicted boundary movement.

[0010] According to embodiments of this disclosure, fitting is performed using a multilayer perceptron or a deep learning network.

[0011] According to embodiments of this disclosure, converting the graphic environment of a contact hole pattern into graphic environment features includes: setting the graphic environment range of the contact hole pattern based on the center of the contact hole pattern; dividing the range into grid areas with a preset step size; assigning values ​​to each grid based on whether a contact hole pattern exists in each grid within the grid area, thereby converting the graphic environment of the contact hole pattern into graphic environment features.

[0012] According to embodiments of this disclosure, the boundary of the contact hole layout is corrected based on the predicted boundary movement amount in the graphic regions other than the at least one graphic region in the contact hole layout, and an optimized contact hole layout is output. This includes: based on the principle that the movement in the outward normal direction is positive, moving the boundary position of the corresponding contact hole graphic in the graphic regions other than the at least one graphic region in the contact hole layout based on the predicted boundary movement amount, obtaining the corrected contact hole graphic in the graphic regions other than the at least one graphic region, and outputting the corrected contact hole graphic in the at least one graphic region together to obtain the optimized contact hole layout.

[0013] According to embodiments of this disclosure, the super-resolution lithography model includes: a substrate, a metal reflective layer, a photoresist, a metal transmittance layer, an air gap layer, and a mask layer stacked sequentially; or, a substrate, a photoresist layer, an air gap layer, a multilayer film structure, and a mask layer stacked sequentially; or, a substrate, a photoresist layer, a metal transmittance layer, an air gap layer, a multilayer film structure, and a mask layer stacked sequentially; or, a substrate, a metal reflective layer, a photoresist layer, an air gap layer, a multilayer film structure, and a mask layer stacked sequentially; or, a substrate, a metal reflective layer, a photoresist layer, a metal transmittance layer, an air gap layer, a multilayer film structure, and a mask layer stacked sequentially.

[0014] According to embodiments of this disclosure, the shape of the contact hole pattern includes at least one of a circle, an ellipse, a rectangle, and a square.

[0015] According to a second aspect of the present disclosure, a mask is provided, which is prepared based on a modified mask pattern, the modified mask pattern including contact hole patterns, and the modified mask pattern is obtained by modifying the contact hole pattern using the above-described contact hole pattern modification method.

[0016] The contact hole layout correction method and mask based on graphics environment fitting disclosed herein have at least the following technical effects:

[0017] This method randomly selects a portion of the pattern area in the contact hole layout, uses a model-based optical proximity correction method to obtain the actual boundary movement of the contact hole pattern, and uses a fitting method to obtain the fitting relationship between the pattern environment and the actual boundary movement. The predicted boundary movement of the remaining unoptimized patterns is then predicted based on their pattern environment to complete the contact hole layout optimization. This method eliminates the need for rasterization of the entire contact hole layout before optical proximity correction, significantly reducing the area requiring full-wavelength simulation in super-resolution lithography, thereby significantly improving the optimization efficiency of contact hole layouts in super-resolution lithography. Attached Figure Description

[0018] The foregoing contents, as well as other objects, features, and advantages of this disclosure, will become clearer from the following description of embodiments with reference to the accompanying drawings, in which:

[0019] Figure 1 A schematic diagram illustrates a contact hole layout correction method based on graphical environment fitting according to this disclosure;

[0020] Figure 2 A schematic diagram of a super-resolution lithography model structure according to an embodiment of the present disclosure is shown.

[0021] Figure 3 A schematic diagram of a selected graphic region according to an embodiment of the present disclosure is shown.

[0022] Figure 4 An OPC result diagram based on a super-resolution lithography model according to an embodiment of the present disclosure is illustrated schematically.

[0023] Figure 5 The diagram illustrates the variation of the graphing error with the number of iterations according to an embodiment of the present disclosure.

[0024] Figure 6 The diagram schematically illustrates the statistical distribution of the movement of the four boundaries of the contact hole pattern after model-based OPC according to an embodiment of the present disclosure.

[0025] Figure 7 The illustration schematically shows a process of fitting a predicted boundary movement amount after inputting graphical environmental features using a multilayer perceptron according to an embodiment of the present disclosure.

[0026] Figure 8 The diagram schematically illustrates a comparison of graphic errors before and after employing the contact hole layout correction method according to embodiments of the present disclosure.

[0027] Figure 9 The diagram schematically illustrates a comparison of the graphic error between the contact hole layout correction method using embodiments of the present disclosure and the optimized method using average predicted boundary movement. Detailed Implementation

[0028] The embodiments of the present disclosure will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the disclosure. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the present disclosure for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of the present disclosure.

[0029] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of said features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components. All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0030] Figure 1 A schematic diagram illustrates a contact hole layout correction method based on graphical environment fitting according to this disclosure.

[0031] like Figure 1 As shown, the contact hole layout correction method based on graphic environment fitting may include operations S110 to S140.

[0032] In operation S110, at least one graphic area is randomly determined in the contact hole layout.

[0033] In operation S120, optical proximity effect correction is performed on at least one patterned region based on the super-resolution lithography model, and the actual boundary movement of the contact hole pattern in at least one patterned region is obtained.

[0034] In operation S130, with the goal of minimizing the error between the actual boundary movement and the predicted boundary movement, the relationship between the graphic environment features of the contact hole pattern in at least one graphic region and the actual boundary movement is fitted to obtain the fitting relationship between the graphic environment of the contact hole pattern and the boundary movement.

[0035] In operation S140, the predicted boundary movement of the contact hole pattern in the graphic region other than at least one graphic region in the contact hole layout is determined by using the fitting relationship. Based on the predicted boundary movement, the boundary of the corresponding contact hole pattern in the graphic region other than at least one graphic region in the contact hole layout is corrected, and the optimized contact hole layout is output.

[0036] According to embodiments of this disclosure, at least one graphic region may refer to a portion of the graphic regions in all graphic regions of the contact hole layout. The number of graphic regions can be determined based on the characteristics of the distribution of contact hole graphics in the contact hole layout. The more graphic regions selected, the better the fitting result may be obtained when fitting the relationship between graphic environment features and actual boundary movement. However, the computational load required for model-based OPC may be greater. Therefore, the number of graphic regions can be selected according to actual application requirements, and this disclosure does not impose any limitations.

[0037] According to embodiments of this disclosure, since the number of selected pattern regions may be multiple, the selected pattern regions can be optimized one by one using the OPC method based on the super-resolution lithography model to obtain the actual boundary movement of all contact hole patterns within the pattern region.

[0038] According to embodiments of this disclosure, each contact hole pattern can have a corresponding patterning environment and actual boundary movement. The patterning environment characterizes the distribution relationship between each contact hole pattern in at least one patterning region and the contact hole patterns surrounding the contact hole pattern. In super-resolution lithography, the distribution of contact hole patterns around a contact hole pattern may affect the actual boundary movement of that contact hole pattern.

[0039] After obtaining the fitting relationship, the predicted boundary movement of each remaining contact hole pattern in the contact hole layout is obtained by fitting the fitting relationship to each of the remaining contact hole patterns according to their graphic environment characteristics. It should be understood that all remaining contact hole patterns are those that were not used for fitting during the process of obtaining the fitting relationship.

[0040] The method of this disclosure selects a portion of the patterned area from the contact hole layout for model-based OPC, and uses the optimization results to fit the relationship between the patterned environment and the boundary displacement. Based on the fitted relationship between the patterned environment and the boundary displacement, the pattern in the contact hole layout is optimized according to its patterned environment. This significantly improves the optimization efficiency of contact hole layout in super-resolution lithography by eliminating the need for time-consuming full-wave simulation calculations.

[0041] In some embodiments, randomly determining at least one graphic region in the contact hole layout during operation S110 may further include:

[0042] Determine the number and size of the graphic areas selected in the contact hole layout.

[0043] At least one graphic region is randomly selected from the graphic regions in the contact hole layout based on the selected quantity and region size.

[0044] According to embodiments of this disclosure, at least one graphic region can cover various graphic environments of the contact hole pattern in the contact hole layout. On the one hand, the selected graphic region can cover various graphic environments of the contact hole pattern in the layout; on the other hand, too many graphic regions will lead to excessive time consumption for model-based OPC. Simultaneously, the center position and boundary positions of the contact hole patterns contained in each graphic region are recorded.

[0045] The size of the patterned area can be determined based on the super-resolution lithography model, and the area size of each patterned area in at least one patterned area is larger than the range of optical influence on the contact hole pattern.

[0046] Furthermore, the shape of the contact hole pattern can include at least one of the following: circle, ellipse, rectangle, and square. For example, for any square contact hole, the positions of the left, top, right, and bottom boundaries before optimization can be represented as x. left1 y top1 x right1 y bottom1 .

[0047] In some embodiments, the optical proximity effect correction of at least one patterned region based on the super-resolution lithography model in operation S120, while obtaining the actual boundary movement of the contact hole pattern in at least one patterned region, includes:

[0048] Based on the super-resolution lithography model, gradient iterative optimization is performed on all contact hole patterns in at least one pattern region to obtain the optimized contact hole pattern boundary positions.

[0049] Based on the optimized contact hole pattern boundary position and the unoptimized contact hole pattern boundary position, the actual boundary movement of the contact hole pattern in at least one pattern region is determined.

[0050] For example, for any contact hole pattern, the positions of the optimized left, top, right, and bottom boundaries can be represented as x. left2 y top2 x right2 y bottom2 Then the actual boundary movement is (x left2 -x left1 , y top2 -y top1 , x right2 -x right1 , y bottom2 - y bottom1 ).

[0051] In some embodiments, operation S130, with minimizing the error between the actual boundary movement and the predicted boundary movement as the fitting objective, fits the graphic environment of the contact hole pattern in at least one graphic region, and fits the relationship between the graphic environment features of the contact hole pattern in at least one graphic region and the actual boundary movement, obtaining the fitting relationship between the graphic environment of the contact hole pattern and the boundary movement, including:

[0052] Convert the graphic environment of the contact hole pattern into a graphic environment feature.

[0053] Using the feature vector of the graphic environment as the independent variable and the actual boundary movement of the contact hole graphic as the dependent variable, the fitting relationship between the graphic environment of the contact hole graphic and the boundary movement is obtained.

[0054] The feature of the graphical environment can be fitted using a multilayer perceptron or a deep learning network. In this case, the feature of the graphical environment can be a matrix composed of several vectors.

[0055] According to embodiments of this disclosure, the objective function used in iterative optimization can be the pattern error, which can be defined as the sum of the root mean square errors between the predicted boundary movement and the actual boundary movement. The pattern error can be used to measure the fidelity of the lithographic imaging result. Its magnitude is related to parameters such as the number of contact hole patterns and the size of the contact hole patterns. The closer the imaging result pattern is to the target pattern, the smaller the pattern error, and the higher the fidelity of the imaging result.

[0056] Furthermore, in some embodiments, converting the graphical environment into graphical environment features may include:

[0057] The graphic environment range of the contact hole pattern is set based on the center of the contact hole pattern.

[0058] Divide the area into grid zones using a preset step size.

[0059] Each grid is assigned a value based on whether a contact hole pattern exists in each grid within the grid area, thus transforming the graphic environment of the contact hole pattern into graphic environment features.

[0060] For example, when converting the graphic environment of a contact hole pattern into a graphic environment feature for fitting, the range of the graphic environment can be set to R. Only other contact hole patterns whose horizontal and vertical distances from the center of the contact hole pattern are within R are considered. The region with a side length of R is divided into a grid with a certain step size. If a contact hole pattern exists at the corresponding position of the grid, the grid is assigned a value of 1; otherwise, the grid is assigned a value of 0. Using this method, the graphic environment feature x of each contact hole pattern can be obtained. i .

[0061] In some embodiments, the step S140, which corrects the boundary of the corresponding contact hole layout in the graphic region other than the at least one graphic region in the contact hole layout based on the predicted boundary movement, and outputs an optimized contact hole layout, may include:

[0062] Based on the principle that the movement in the outward normal direction is positive, the boundary position of the corresponding contact hole pattern in the graphic region other than at least one graphic region in the contact hole layout is moved according to the predicted boundary movement amount to obtain the corrected contact hole pattern in the graphic region other than at least one graphic region. Together with the corrected contact hole pattern in at least one graphic region, the optimized contact hole layout is output.

[0063] For example, the actual boundary movement obtained by fitting is (x left2 -x left1 , y top2 - y top1 , x right2 -x right1 , y bottom2 - y bottom1 ) in x left2 -x left1 If positive, then the left boundary of the contact hole will be moved x in the outward normal direction. left2 -x left1 The actual boundary movement obtained by fitting is (x left2 -x left1 , y top2 - y top1 , x right2 -x right1 , y bottom2 - y bottom1 ) in y top2 - y top1 If the value is negative, the upper boundary of the contact hole will be moved inwards towards the normal direction |y top2 - y top1 |

[0064] In some embodiments, the super-resolution lithography model can be based on a physical model established from the super-resolution lithography structure. The super-resolution lithography model may include:

[0065] The substrate, metal reflective layer, photoresist, metal transmissive layer, air gap layer, and mask layer are stacked in sequence.

[0066] Alternatively, the substrate, photoresist layer, air gap layer, multilayer film structure, and mask layer are stacked sequentially.

[0067] Alternatively, the substrate, photoresist layer, metal transmission layer, air gap layer, multilayer film structure, and mask layer are stacked in sequence.

[0068] Alternatively, the substrate, metal reflective layer, photoresist layer, air gap layer, multilayer film structure, and mask layer are stacked in sequence.

[0069] Alternatively, the layers can be stacked sequentially as follows: substrate, metal reflective layer, photoresist layer, metal transmissive layer, air spacer layer, multilayer film structure, and mask layer.

[0070] Embodiments of this disclosure also provide a mask, which is prepared based on a modified mask pattern. The modified mask pattern includes contact hole patterns, and the modified mask pattern can be obtained by modifying the contact hole pattern using the contact hole pattern modification method described above. For specific details of the contact hole pattern modification method, please refer to the embodiments section above, which will not be repeated here.

[0071] To more clearly illustrate the contact hole layout correction method based on graphics environment fitting according to the embodiments of this disclosure, specific examples and corresponding data are provided below.

[0072] Figure 2 A schematic diagram of a super-resolution lithography model structure according to an embodiment of the present disclosure is shown.

[0073] like Figure 2 As shown, the super-resolution lithography model in this example may include a substrate, a metal reflective layer, a photoresist layer, a metal transmission layer, an air gap layer, and a mask layer stacked sequentially. The mask layer is set to a thickness of 40 nm, the air gap layer to a thickness of 40 nm, the metal transmission layer to a thickness of 20 nm, the metal reflective layer to a thickness of 30 nm, and the photoresist layer to a thickness of 50 nm.

[0074] Figure 3 A schematic diagram of a selected graphic region according to an embodiment of the present disclosure is shown.

[0075] like Figure 3 As shown, this example randomly selects four pattern regions. These pattern regions are layout areas with a side length of 2 μm, centered on a randomly selected contact hole pattern from the contact hole layout. The period of the contact hole pattern in the contact hole layout is 130 nm, and the contact hole size is 50 nm.

[0076] Figure 4 An OPC result diagram based on a super-resolution lithography model according to an embodiment of the present disclosure is illustrated schematically.

[0077] like Figure 4 As shown, the short dashed line represents the imaging result obtained from simulation before OPC, the long dashed line represents the imaging result corresponding to the mask pattern after OPC, and the solid line represents the target pattern. Figure 4As can be seen, the imaging result of the contact hole pattern after OPC is closer to the target pattern than the imaging result without OPC, that is, model-based OPC has a significant optimization effect on the contact hole pattern.

[0078] Figure 5 The diagram illustrates the variation of the graphing error with the number of iterations according to an embodiment of the present disclosure.

[0079] like Figure 5 As shown, the horizontal axis represents the number of iterations, and the vertical axis represents the image error between the imaging result and the target image. By using OPC based on the super-resolution lithography model to optimize the boundary of the mask image, the image error decreased from 1292 to 400 after 9 iterations of optimization. This indicates that the imaging result corresponding to the mask obtained by the model-based OPC is closer to the target image.

[0080] Figure 6 The diagram schematically illustrates the statistical distribution of the movement of the four boundaries of the contact hole pattern after model-based OPC according to an embodiment of the present disclosure.

[0081] like Figure 6 As shown, after performing model-based OPC on the contact hole patterns within a randomly selected graphic region, the movement of the four boundaries of each contact hole pattern is statistically analyzed, with the outward normal direction of the boundary being positive and the inward direction being negative, in nm. It can be seen that the actual boundary movement of the contact hole patterns in the layout is mostly distributed within the range of -3.5 nm to -1 nm, indicating that all contact hole patterns are reduced to varying degrees after boundary optimization.

[0082] Figure 7 The illustration schematically shows a process of fitting a predicted boundary movement amount after inputting graphical environmental features using a multilayer perceptron according to an embodiment of the present disclosure.

[0083] like Figure 7 As shown, the environmental feature x using the contact hole pattern i As input, the output variable is the predicted boundary movement of the corresponding contact hole pattern. The goal of the fitting model is to reduce the sum of the root mean square errors between the actual boundary movement and the predicted boundary movement. A multilayer perceptron is used as the fitting tool, and the parameters of the hidden layer are set to 100.

[0084] Figure 8 The diagram schematically illustrates a comparison of graphic errors before and after employing the contact hole layout correction method according to embodiments of the present disclosure.

[0085] like Figure 8As shown, after fitting the predicted boundary movement of all patterns in the contact hole layout, the optimized contact hole layout can be output. Ten pattern regions are randomly selected from the optimized contact hole layout, and the optimization effect is verified by comparing the pattern errors of the optimized layout and the layout before optimization. The horizontal axis represents the numbers of the 10 randomly selected pattern regions, the vertical axis represents the pattern error of the pattern region, Pat Sur OPC represents the optimization result using the contact hole layout correction method of this disclosure, and w / o is the result before optimization. It can be seen that the pattern error of the 10 random regions after Pat Sur OPC is significantly smaller than the pattern error before OPC, indicating that Pat Sur OPC can effectively reduce the pattern error.

[0086] Figure 9 The diagram schematically illustrates a comparison of the graphic error between the contact hole layout correction method using embodiments of the present disclosure and the optimized method using average predicted boundary movement.

[0087] like Figure 9 As shown, for Figure 8 The image shows 10 randomly selected graphic regions. Mean Dis OPC represents the result obtained by optimizing the average actual boundary movement of all graphics obtained using the model-based OPC method. The horizontal axis represents the number of the 10 randomly selected graphic regions, and the vertical axis represents the graphic error of the graphic regions. It can be seen that the graphic error of Pat Sur OPC is lower than that of Mean Dis OPC. This indicates that the optimization effect of the contact hole layout correction method disclosed in this paper is better than that of optimization using the average boundary movement, resulting in higher fidelity imaging results.

[0088] The embodiments of this disclosure have been described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of this disclosure. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. The scope of this disclosure is defined by the appended claims and their equivalents. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of this disclosure, and all such substitutions and modifications should fall within the scope of this disclosure.

Claims

1. A contact hole layout correction method based on graphical environment fitting, characterized in that, include: At least one graphic region is randomly selected in the contact hole layout; Based on the super-resolution lithography model, optical proximity effect correction is performed on the at least one patterned region, and the actual boundary movement of the contact hole pattern in the at least one patterned region is obtained. With minimizing the error between the actual boundary movement and the predicted boundary movement as the fitting objective, the relationship between the graphic environment features of the contact hole pattern in the at least one graphic region and the actual boundary movement is fitted to obtain the fitting relationship between the graphic environment of the contact hole pattern and the boundary movement. The predicted boundary movement of the contact hole pattern in the graphic region other than the at least one graphic region in the contact hole layout is determined using the fitting relationship. Based on the predicted boundary movement, the boundary of the corresponding contact hole pattern in the graphic region other than the at least one graphic region in the contact hole layout is corrected, and the optimized contact hole layout is output.

2. The method according to claim 1, characterized in that, The step of randomly determining at least one graphic region in the contact hole layout includes: Determine the number and size of the graphic areas selected in the contact hole layout; At least one graphic region is randomly selected from the contact hole layout according to the selected quantity and region size; Wherein, the at least one graphic region covers at least the various graphic environments of the contact hole graphic in the contact hole layout, and the area size of each graphic region in the at least one graphic region is larger than the range of the contact hole graphic affected by optical influence.

3. The method according to claim 1, characterized in that, The process of correcting the optical proximity effect of at least one patterned region based on a super-resolution lithography model, and simultaneously obtaining the actual boundary movement of the contact hole pattern in the at least one patterned region, includes: Based on the super-resolution lithography model, gradient iterative optimization is performed on all contact hole patterns in the at least one patterned region to obtain the optimized contact hole pattern boundary positions. Based on the optimized contact hole pattern boundary position and the unoptimized contact hole pattern boundary position, the actual boundary movement of the contact hole pattern in the at least one pattern region is determined.

4. The method according to claim 1, characterized in that, The fitting process, which aims to minimize the error between the actual boundary movement and the predicted boundary movement, involves fitting the relationship between the graphic environment features of the contact hole pattern in at least one graphic region and the actual boundary movement to obtain the fitting relationship between the graphic environment of the contact hole pattern and the boundary movement. This includes: The graphic environment of the contact hole pattern is converted into graphic environment features; Using the graphic environment features as independent variables and the actual boundary movement of the contact hole graphic as dependent variables, the fitting relationship between the graphic environment of the contact hole graphic and the boundary movement is obtained. The objective function for fitting is the sum of the mean squared errors between the actual boundary movement and the predicted boundary movement.

5. The method according to claim 4, characterized in that, Fitting can be performed using multilayer perceptrons or deep learning networks.

6. The method according to claim 4, characterized in that, The step of converting the graphic environment of the contact hole pattern into graphic environment features includes: The graphic environment range of the contact hole pattern is set based on the center of the contact hole pattern; The range is divided into grid areas with a preset step size; Each grid in the grid area is assigned a value based on whether a contact hole pattern exists, and the graphic environment of the contact hole pattern is transformed into a graphic environment feature.

7. The method according to claim 1, characterized in that, The step of correcting the boundary of the corresponding contact hole layout in the graphic region other than the at least one graphic region in the contact hole layout based on the predicted boundary movement amount, and outputting the optimized contact hole layout, includes: Based on the principle that the movement in the outward normal direction is positive, the boundary position of the corresponding contact hole pattern in the graphic region other than the at least one graphic region in the contact hole layout is moved based on the predicted boundary movement amount to obtain the corrected contact hole pattern in the graphic region other than the at least one graphic region. The corrected contact hole pattern in the at least one graphic region is output together to obtain the optimized contact hole layout.

8. The method according to any one of claims 1-7, characterized in that, The super-resolution lithography model includes: The substrate, metal reflective layer, photoresist, metal transmissive layer, air gap layer, and mask layer are stacked in sequence. Alternatively, the substrate, photoresist layer, air gap layer, multilayer film structure, and mask layer are stacked sequentially. Alternatively, the substrate, photoresist layer, metal transmission layer, air gap layer, multilayer film structure, and mask layer are stacked in sequence. Alternatively, the substrate, metal reflective layer, photoresist layer, air gap layer, multilayer film structure, and mask layer are stacked in sequence. Alternatively, the layers can be stacked sequentially as follows: substrate, metal reflective layer, photoresist layer, metal transmissive layer, air spacer layer, multilayer film structure, and mask layer.

9. The method according to any one of claims 1-7, characterized in that, The shape of the contact hole pattern includes at least one of the following: circle, ellipse, and rectangle.

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