Method and device for establishing an OPC model, optical proximity correction method and apparatus, storage medium

Abstract

A method and device for establishing an OPC model, an optical proximity correction method and device, and a readable storage medium, the method comprising: forming a semiconductor structure, the semiconductor structure having a patterned photoresist; obtaining a profile of a pattern in the patterned photoresist according to the semiconductor structure; measuring the profile of the pattern in the patterned photoresist to obtain a profile measurement value; and establishing an OPC model according to the profile measurement value. Compared with post-development measurement data obtained by directly measuring the pattern in the patterned photoresist, the technical solution can effectively improve the measurement accuracy, obtain a high-precision profile measurement value, effectively reduce the error of the established OPC model, and improve the establishment efficiency of the OPC model and the correction accuracy of the optical proximity correction method.

Description

Technical Field

[0001] This invention relates to the field of photolithography, and particularly to a method and apparatus for establishing an OPC model, an optical proximity correction method and device, and a storage medium. Background Technology

[0002] In the semiconductor manufacturing process, in order to transfer the circuit pattern of an integrated circuit (IC) onto a semiconductor chip, the circuit pattern of the IC needs to be designed as a mask pattern, and then the mask pattern is transferred from the surface of the mask to the semiconductor chip.

[0003] With the shrinking of integrated circuit feature dimensions (CD) and the limitations of optical exposure tools (OETs) in resolution, optical proximity effect (OPE) easily occurs during the exposure process for pattern transfer of high-density mask patterns, leading to defects in the mask pattern transfer. To address the OPE problem, the industry commonly uses optical proximity correction (OPC), which reduces the deviation of the lithographic pattern obtained by exposure by altering the shape of the original pattern.

[0004] One optical proximity correction method is based on model-based correction. The key to this correction method is to establish an accurate OPC model. However, the OPC models established by existing methods often have large errors. Summary of the Invention

[0005] The problem addressed by this invention is how to reduce the error of the OPC model.

[0006] To address the aforementioned problems, this invention provides a method for establishing an OPC model, comprising: forming a semiconductor structure having a patterned photoresist; obtaining the outline of a pattern in the patterned photoresist based on the semiconductor structure; measuring the outline of the pattern in the patterned photoresist to obtain an outline measurement value; and establishing an OPC model based on the outline measurement value.

[0007] Optionally, the step of obtaining the outline of the pattern in the patterned photoresist according to the semiconductor structure includes: obtaining an image of the patterned photoresist; and extracting the outline of the pattern in the patterned photoresist based on the image of the patterned photoresist.

[0008] Optionally, in the step of obtaining the image of the patterned photoresist, the image of the patterned photoresist is obtained by means of a measurement machine.

[0009] Optionally, in the step of obtaining an image of the patterned photoresist using a measurement instrument, the measurement instrument is a feature-size scanning electron microscope.

[0010] Optionally, in the step of measuring the contour of the pattern in the patterned photoresist to obtain the contour measurement value, the contour of the pattern in the patterned photoresist is measured along a preset direction to obtain the contour measurement value.

[0011] Optionally, in the step of measuring the contour of the pattern in the patterned photoresist along a preset direction to obtain the contour measurement value, the preset direction is consistent with the scanning direction of the feature size scanning electron microscope.

[0012] Optionally, it also includes: after establishing the OPC model based on the contour measurement values, verifying the OPC model.

[0013] Optionally, the step of forming the semiconductor structure includes: providing a photoresist layer; and patterning the photoresist layer to form a patterned photoresist.

[0014] An optical proximity correction method includes: obtaining a design layout; establishing an OPC model, wherein the OPC model is established using the method of the present invention; and using the OPC model to correct the design layout to obtain a fabrication layout.

[0015] Optionally, in the step of obtaining the design layout, the design layout is the design layout of the contact hole layer.

[0016] Accordingly, the present invention also provides an OPC model building apparatus, comprising: a process unit adapted to form a semiconductor structure having a patterned photoresist; a measurement unit adapted to obtain the outline of the pattern in the patterned photoresist based on the semiconductor structure; a measurement unit adapted to measure the outline of the pattern in the patterned photoresist to obtain an outline measurement value; and a modeling unit adapted to build an OPC model based on the outline measurement value.

[0017] Optionally, the measurement unit includes: an imager adapted to obtain an image of the patterned photoresist; and an extractor adapted to extract contours from the image of the patterned photoresist.

[0018] Optionally, the imager is a measurement machine.

[0019] Optionally, the measuring instrument is a feature-size scanning electron microscope.

[0020] Optionally, the measuring unit measures the contour of the pattern in the patterned photoresist along a preset direction to obtain contour measurement values.

[0021] Optionally, the preset direction is consistent with the scanning direction of the feature-size scanning electron microscope.

[0022] Optionally, it may also include a verification unit, which is suitable for verifying the OPC model.

[0023] An optical proximity correction device includes: a creation device adapted to create an OPC model, the creation device being the creation device of the present invention; an acquisition device adapted to acquire a design layout; and a correction device adapted to use the OPC model to correct the design layout to obtain a fabrication layout.

[0024] Optionally, the design layout acquired by the acquisition device is the design layout of the contact hole layer.

[0025] Furthermore, the present invention also provides a storage medium storing a computer program thereon, the computer program being executed by a processor to implement the steps of the establishment method of the present invention.

[0026] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0027] In this invention, after forming a semiconductor structure, the contour of the pattern in the patterned photoresist within the semiconductor structure is obtained. This contour is then measured (gaugeed) to obtain measurement values. Based on these contour measurements, an OPC model is established. Compared to measurement data obtained by directly measuring the pattern in the patterned photoresist, measuring the contour of the pattern in the patterned photoresist effectively avoids interference from edge burrs in the photoresist layer, significantly improving measurement accuracy and obtaining high-precision contour measurements. These high-precision contour measurements provide a solid data foundation for establishing the OPC model, effectively reducing errors in the established OPC model, improving the efficiency of OPC model establishment, and enhancing the accuracy of optical proximity correction methods. Attached Figure Description

[0028] Figure 1 This is a flowchart illustrating an embodiment of the OPC model establishment method of the present invention;

[0029] Figures 2 to 3 It shows Figure 1 The diagram shows the structural schematics of each step in the formation of the semiconductor structure in the embodiment of the OPC model establishment method.

[0030] Figure 4 An image of patterned photoresist obtained in one embodiment of the OPC model establishment method of the present invention is shown;

[0031] Figure 5 It shows Figure 4 The image shown is the outline of the pattern extracted from the patterned photoresist image obtained by the OPC model establishment method embodiment.

[0032] Figure 6 This is a functional block diagram of an embodiment of the optical proximity correction device of the present invention. Detailed Implementation

[0033] As the background technology shows, existing OPC models suffer from large errors. This paper analyzes the reasons for this large error problem by examining the process of establishing an OPC model:

[0034] One OPC model is based on after-development inspection (ADI) measurement data. The specific process is as follows: after the photoresist is exposed and developed to form a pattern, the patterned photoresist is measured using a critical dimension scanning electron microscope (CD-SEM) to obtain the after-development measurement data; and an OPC model is established based on the after-development measurement data.

[0035] However, in patterned photoresists, burrs often appear at the edges of the patterns. These burrs can affect measurement accuracy, leading to a decrease in the accuracy of the measured data after development. This decrease in the accuracy of the measured data after development will deteriorate the accuracy of the OPC model built on this basis, resulting in a larger error in the OPC model. A larger error in the OPC model will not only affect the modeling speed of building the OPC model, but also deteriorate the accuracy of subsequent optical proximity corrections using the model.

[0036] To solve the aforementioned technical problem, the present invention provides a method for establishing an OPC model, comprising:

[0037] A semiconductor structure is formed, the semiconductor structure having a patterned photoresist; based on the semiconductor structure, the outline of the pattern in the patterned photoresist is obtained; the outline of the pattern in the patterned photoresist is measured to obtain the outline measurement value; based on the outline measurement value, an OPC model is established.

[0038] The technical solution of this invention, compared with the measurement data obtained by directly measuring the pattern of the patterned photoresist after development, measures the contour of the pattern in the patterned photoresist. During the measurement process, the interference of burrs at the edge of the pattern in the photoresist layer can be effectively avoided, which can effectively improve the measurement accuracy and obtain high-precision contour measurement values. The high-precision contour measurement values ​​can provide a good data foundation for the establishment of the OPC model, thereby effectively reducing the error of the established OPC model, which is conducive to improving the establishment efficiency of the OPC model and improving the correction accuracy of the optical proximity correction method.

[0039] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0040] refer to Figure 1 The diagram shows a flowchart of an embodiment of the OPC model establishment method of the present invention.

[0041] The method for establishing the OPC model includes:

[0042] Step S110: Form a semiconductor structure having a patterned photoresist; Step S120: Obtain the outline of the pattern in the patterned photoresist based on the patterned photoresist; Step S130: Measure the outline of the pattern in the patterned photoresist to obtain the outline measurement value; Step S140: Establish an OPC model based on the outline measurement value.

[0043] The technical solution of the OPC model establishment method embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

[0044] like Figure 1 As shown, step S110 is first performed to form a semiconductor structure, which has patterned photoresist.

[0045] The OPC model can describe the entire photolithography process, including the optical system, mask, photoresist, and etching process. Some parameters in the OPC model are calibrated by fitting experimental data, so that the calculated structure of the OPC model matches the experimental results. In step S110, forming a semiconductor structure, wherein the patterned photoresist of the semiconductor structure is used to extract the experimental data required to establish the OPC model.

[0046] In some embodiments of the present invention, step S110, the step of forming a semiconductor structure, includes: Figure 2 As shown, photoresist 221 is provided; as Figure 3 As shown, the photoresist is patterned to form patterned photoresist 220.

[0047] like Figure 2 As shown, in some embodiments, in the step of providing photoresist 221, a substrate 210 is provided, on which photoresist 221 is provided. Specifically, the substrate 210 is used to provide mechanical support, and the photoresist 221 is used to provide a process foundation.

[0048] For example, the substrate 210 may be a silicon substrate. In other embodiments of the present invention, the substrate may also be other substrates suitable for conducting OPC model building experiments.

[0049] The photoresist 221 is suitable for transferring patterns to form patterned photoresist. The photoresist 221 can be a photoresist suitable for performing OPC model building experiments. Specifically, the photoresist 221 can be formed on the substrate 210 by spin coating.

[0050] Forming the photoresist 221 (e.g. Figure 2 (As shown) After that, as Figure 3 As shown, the photoresist 221 is patterned to form a patterned photoresist 220.

[0051] Step S110, the step of forming a semiconductor structure further includes: forming a modeling layout, the modeling layout having multiple modeling patterns; fabricating a mask based on the modeling patterns; during the patterning of photoresist 221, exposing and developing the photoresist 221 using the mask, the modeling layout on the mask being transferred to the photoresist 221 to form patterned photoresist 220.

[0052] Specifically, the process of patterning the photoresist 221 can be performed using a method suitable for OPC model building experiments. The patterned photoresist 220 has multiple experimental patterns. The experimental patterns in the patterned photoresist 220 are consistent with the modeling patterns in the modeling layout. The consistency between the experimental patterns and the modeling patterns means that there is a one-to-one correspondence between multiple experimental patterns and multiple modeling patterns.

[0053] It should be noted that the modeling layout refers to the graphics designed in the Design of Experiment (DOE). To ensure the accuracy of the established OPC model, it is necessary to maximize the coverage of the modeling graphics on the designed layout in the modeling layout. For complex design layouts, the more diverse the modeling graphics, the more accurate the established OPC model; however, more diverse modeling graphics will also increase the measurement and modeling time. To ensure the coverage of the modeling graphics, graphics can be directly extracted from the design layout as the modeling graphics during the design experiment. Specifically, graphics that are difficult and complex to lithographically extract are extracted from the design layout as key graphics; similar key graphics are grouped together; representative graphics are extracted from the same category of key graphics as modeling graphics to construct the modeling layout, and then the photomask is made.

[0054] Continue to refer to Figure 1 The method for establishing the OPC model further includes: step S120, obtaining the outline of the pattern in the patterned photoresist based on the patterned photoresist.

[0055] Step S120 is the step of obtaining the outline of the pattern in the patterned photoresist based on the patterned photoresist, that is, obtaining the position and shape of multiple experimental patterns in the patterned photoresist.

[0056] In some embodiments of the present invention, the step of obtaining the outline of the pattern in the patterned photoresist includes: step S121, obtaining an image of the patterned photoresist; and step S122, extracting the outline of the pattern in the patterned photoresist based on the image of the patterned photoresist. Extracting the outline of the pattern from the image of the patterned photoresist can effectively eliminate the influence of edge burrs in the outline of the patterned photoresist, and can effectively improve the accuracy and precision of the data used to establish the OPC model.

[0057] In some embodiments, in step S121, the step of obtaining an image of the patterned photoresist, the image of the patterned photoresist is obtained using a metrology equipment. Specifically, in the step of obtaining the image of the patterned photoresist using a metrology equipment, the metrology equipment is a scanning electron microscope (SEM); for example, the metrology equipment can be a critical dimension scanning electron microscope (CD-SEM). The critical dimension scanning electron microscope has high resolution, and its use can effectively ensure the acquisition of high-precision data.

[0058] In some embodiments, in step S122, the step of extracting the outline of the pattern in the patterned photoresist based on the image of the patterned photoresist, the outline of the pattern in the patterned photoresist can be extracted by a feature-size scanning electron microscope.

[0059] The information output by the feature-dimensional scanning electron microscope includes: line width (critical dimension, CD), SEM image, scan lines, and SEM contour. The SEM contour is the contour of the pattern extracted from the image of the patterned photoresist. Therefore, extracting the contour of the pattern in the patterned photoresist by the feature-dimensional scanning electron microscope means directly using the SEM contour in the information output by the feature-dimensional scanning electron microscope as the contour of the pattern in the patterned photoresist.

[0060] In other embodiments of the present invention, in step S121, the step of obtaining the image of the patterned photoresist can also be performed by scanning electron microscopy; in step S122, the step of extracting the outline of the pattern in the patterned photoresist based on the image of the patterned photoresist can also be performed by image recognition software.

[0061] Specifically, Figure 4 An image of patterned photoresist obtained in one embodiment of the OPC model establishment method of the present invention is shown; Figure 5 It shows Figure 4 The diagram shows the outline of the pattern extracted from the patterned photoresist image obtained in an embodiment of the OPC model establishment method. Among them, Figure 4 Only a portion of the obtained patterned photoresist image is shown. Figure 5 Only a portion of the outline of the extracted graphic is shown, and Figure 4 The area of ​​the part shown is greater than Figure 5 The area of ​​the portion shown.

[0062] Continue to refer to Figure 1 After obtaining the outline of the pattern in the patterned photoresist, the method for establishing the OPC model further includes: step S130, measuring the outline of the pattern in the patterned photoresist to obtain the outline measurement value.

[0063] Step S130: The contour of the pattern in the patterned photoresist is measured (gauge) to obtain contour measurement values ​​for obtaining experimental data required to establish the OPC model.

[0064] The contour measurements used to build the OPC model are obtained by measuring the contour of the extracted graphic. This avoids data shift caused by inconsistent measurement methods and measurement errors caused by poor patterned photoresist profiles. Moreover, obtaining the contour measurements by measuring the contour of the extracted graphic can effectively reduce invalid data in the obtained data, and can even eliminate the step of cleaning invalid data, which can effectively reduce modeling time and improve modeling efficiency.

[0065] Specifically, in step S130, which involves measuring the contour of the pattern in the patterned photoresist using a gauge to obtain contour measurement values, a gauge tool can be used. Using a gauge tool to measure the contour of the pattern in the patterned photoresist is advantageous because the gauge tool is powerful; in addition to obtaining the contour measurement values, it can also extract other information about the contour, thus supplementing the limitations of the single data set in the contour measurement values.

[0066] The contour measurement value can be at least one of the following: line width (critical dimension, CD), spacing, pitch, length, and extension of the contour corresponding to the experimental graphic. For example, ... Figure 3 As shown, the line width, line spacing, and pitch of the experimental pattern in the patterned photoresist 220 are illustrated.

[0067] Step S130, measuring the contour of the pattern in the patterned photoresist to obtain contour measurement values, includes: setting measurement positions, measuring the contour of the pattern at the measurement positions, and obtaining the corresponding contour measurement values. The contour measurement values ​​are related to the required OPC model, and the setting of the measurement positions is determined based on the required OPC model; that is, the number and specific locations of the measurement positions are determined based on the required OPC model.

[0068] For example, in the step of setting measurement locations, the specific number and location of the measurement locations can be referred to the existing OPC model establishment method, which will not be repeated here.

[0069] In some embodiments of the present invention, in the step of measuring the contour of the pattern in the patterned photoresist to obtain the contour measurement value, the contour of the pattern in the patterned photoresist is measured along a preset direction to obtain the contour measurement value.

[0070] In some embodiments, in step S121, the step of obtaining an image of the patterned photoresist, the image of the patterned photoresist is obtained using a feature-size scanning electron microscope; in step S122, the step of extracting the outline of the pattern in the patterned photoresist based on the image of the patterned photoresist, the outline of the pattern in the patterned photoresist is extracted using a feature-size scanning electron microscope. That is, in step S120, the step of obtaining the outline of the pattern in the patterned photoresist based on the patterned photoresist, the patterned photoresist is scanned using a feature-size scanning electron microscope to obtain the outline of the pattern in the patterned photoresist; therefore, in the step of measuring the outline of the pattern in the patterned photoresist along a preset direction to obtain the outline measurement value, the preset direction is consistent with the scanning direction of the feature-size scanning electron microscope.

[0071] Measuring the contour of the pattern in the patterned photoresist along a preset direction, i.e., performing a one-dimensional measurement of the contour of the pattern in the patterned photoresist, can effectively ensure the accuracy of the obtained measurement data; especially when the patterned photoresist is scanned by a feature-size scanning electron microscope, the scanning results of the feature-size scanning electron microscope along the scanning direction have high precision and accuracy, which can better ensure the accuracy and precision of the obtained measurement data.

[0072] Continue to refer to Figure 1 After obtaining the contour measurement value, the method for establishing the OPC model further includes: step S140, establishing the OPC model based on the contour measurement value.

[0073] While rigorous OPC models offer high accuracy, they also require significant computational power. Completing a chip-level OPC model within the market-required timeframe is extremely challenging and demands substantial computing resources. Therefore, to balance the conflict between computational power and OPC model accuracy requirements, a semi-empirical simplified OPC model is used in the modeling process. The simplified OPC model replaces the complex processes of the precise model with simplified empirical formulas. These formulas include multiple parameters, which can be obtained by fitting contour measurements, ultimately ensuring that the computational structure of the simplified lithography model matches experimental results.

[0074] It should be noted that the contour measurement value is obtained by measuring the contour of the extracted pattern. During the contour measurement process, it is not affected by the morphology of the photoresist. There is very little or no invalid data in the contour measurement value. In some embodiments, after measuring the contour of the pattern in the patterned photoresist in step S130 and obtaining the contour measurement value, step S140 can be directly executed to establish the OPC model based on the contour measurement value. There is no need to remove invalid data in the obtained contour measurement value, that is, there is no need to clean the data, which can effectively reduce the modeling time and improve the modeling efficiency.

[0075] Moreover, the contour measurement value is obtained by measuring the contour of the patterned photoresist. During the measurement process, the interference of burrs on the edge of the pattern in the photoresist layer can be effectively avoided, which can effectively improve the measurement accuracy and obtain a high-precision contour measurement value. In step S140, in the step of establishing the OPC model based on the contour measurement value, a higher precision contour measurement value is used. When establishing the OPC model, the model error is smaller, the modeling speed is higher, and the modeling accuracy is better.

[0076] Specifically, step S140, the step of establishing an OPC model based on the contour measurement values, includes: obtaining an initial OPC model, the initial OPC model having multiple parameters to be fitted; performing fitting calculations based on the contour measurement values ​​to obtain the values ​​of the parameters to be fitted; and establishing the OPC model based on the values ​​of the parameters to be fitted and the initial OPC model.

[0077] It should be noted that, as Figure 1 As shown, in some embodiments of the present invention, the method for establishing the OPC model further includes: after establishing the OPC model based on the contour measurement values, performing step S150 to verify the OPC model.

[0078] Step S150, the step of verifying the OPC model, can discover software bugs, design errors, and may also discover potential hotspots.

[0079] In some embodiments of the present invention, step S150, the step of verifying the OPC model, includes: obtaining a verification layout; performing optical proximity correction on the verification layout based on the established OPC model to obtain a corrected layout; forming a semiconductor structure based on the verification layout, the semiconductor structure including patterned photoresist; obtaining an image of the patterned photoresist; and comparing the image of the patterned photoresist and the corrected layout to verify the OPC model.

[0080] In other embodiments, the step of establishing an OPC model based on the contour measurement values ​​includes: establishing the OPC model based on a portion of the contour measurement values; and verifying the OPC model by: performing optical proximity correction on the modeled layout based on the established OPC model to obtain a corrected layout; measuring the corrected layout based on the remaining contour measurement values ​​to obtain corrected measurement values, wherein the corrected measurement values ​​correspond one-to-one with the remaining contour measurement values, and the remaining contour measurement values ​​are contour measurement values ​​not used in the process of establishing the OPC model; and comparing the corrected measurement values ​​with the corresponding contour measurement values ​​to verify the OPC model.

[0081] Accordingly, the present invention also provides an optical proximity correction method.

[0082] The optical proximity correction method includes: obtaining a design layout; establishing an OPC model, wherein the OPC model is established by the method of the present invention; and using the OPC model to correct the design layout to obtain a fabrication layout.

[0083] Specifically, the steps to obtain the design layout include: obtaining a GDS (Geometry Summary Data) file of the design layout. The GDS file is used to define the three-dimensional structure and electrical characteristics of the chip, and it contains geometric data related to the chip's structure, shape, and hierarchy. For example, in the step of obtaining the design layout, the design layout is the design layout of the contact hole layer, i.e., obtaining the GDS file of the contact hole layer's design layout.

[0084] In the step of establishing the OPC model, the OPC model is established using the method of this invention. Specific technical solutions for establishing the OPC model can be found in the embodiments of the aforementioned OPC model establishment method, and will not be repeated here.

[0085] Subsequently, the design layout is modified based on the OPC model to obtain the chip fabrication layout.

[0086] The method of this invention involves measuring the contour of the pattern in the photoresist and then establishing an OPC model based on the contour measurement values. The established OPC model has higher precision and accuracy. Therefore, corrections based on the higher precision and accuracy of the OPC model can effectively improve the accuracy and precision of the obtained wafer fabrication layout. In particular, in the design layout of the contact hole layer, the density of the contact hole pattern is relatively high. Using the OPC model of this invention to correct the design layout of the contact hole layer effectively improves the precision and accuracy of the correction, which is conducive to the formation of high-quality contact hole layers and high-quality contact hole structures.

[0087] Accordingly, the present invention also provides an apparatus for establishing an OPC model.

[0088] The device for establishing the OPC model includes:

[0089] Process unit 310, the process unit 310 being adapted to form a semiconductor structure having a patterned photoresist;

[0090] Measurement unit 320 is adapted to obtain the outline of the pattern in the patterned photoresist based on the semiconductor structure;

[0091] Measurement unit 330 is adapted to measure the contour of the patterned photoresist image to obtain contour measurement values;

[0092] Modeling unit 340 is adapted to establish an OPC model based on the contour measurement values.

[0093] In some embodiments of the present invention, the OPC model building apparatus is adapted to perform the steps of the OPC model building method of the present invention. Specific technical solutions for the OPC model building apparatus can be found in the aforementioned embodiments of the OPC model building method.

[0094] The technical solution of the embodiment of the OPC model building device of the present invention will be described in detail below with reference to the accompanying drawings.

[0095] The process unit 310 forms a semiconductor structure having patterned photoresist.

[0096] The OPC model can describe the entire photolithography process, including the optical system, mask, photoresist, and etching process. Some parameters in the OPC model are calibrated by fitting experimental data, so that the calculated structure of the OPC model matches the experimental results. The patterned photoresist of the semiconductor structure formed by the process unit 310 is used to extract the experimental data needed to establish the OPC model.

[0097] In some embodiments of the present invention, the process unit 310 may be a semiconductor manufacturing system that includes the entire photolithography process, including an optical system, a mask, a photoresist, and an etching process. In other embodiments of the present invention, the process unit may also be a control device connected to the semiconductor manufacturing system.

[0098] like Figure 3 As shown, in the semiconductor structure, the semiconductor structure has a patterned photoresist 220, which is a material layer that has been exposed and developed to form a pattern. The patterned photoresist 220 has multiple experimental patterns. The experimental patterns in the patterned photoresist 220 are consistent with the modeling patterns in the modeling layout. The consistency between the experimental patterns and the modeling patterns means that there is a one-to-one correspondence between multiple experimental patterns and multiple modeling patterns.

[0099] It should be noted that the modeling layout refers to the graphics designed in the Design of Experiment (DOE). To ensure the accuracy of the established OPC model, it is necessary to maximize the coverage of the modeling graphics on the designed layout in the modeling layout. For complex design layouts, the more diverse the modeling graphics, the more accurate the established OPC model; however, more diverse modeling graphics will also increase the measurement and modeling time. To ensure the coverage of the modeling graphics, graphics can be directly extracted from the design layout as the modeling graphics during the design experiment. Specifically, graphics that are difficult and complex to lithographically extract are extracted from the design layout as key graphics; similar key graphics are grouped together; representative graphics are extracted from the same category of key graphics as modeling graphics to construct the modeling layout, and then the photomask is made.

[0100] Continue to refer to Figure 1 The measurement unit 320 obtains the outline of the pattern in the patterned photoresist based on the patterned photoresist.

[0101] The measurement unit 320 obtains the position and shape of multiple experimental patterns in the patterned photoresist.

[0102] In some embodiments of the present invention, the measurement unit 320 includes: an imager 321 adapted to acquire an image of the patterned photoresist; and an extractor 322 adapted to extract contours from the image of the patterned photoresist. The extractor 322 extracts the contours of the pattern from the image of the patterned photoresist acquired by the imager 321, effectively eliminating the influence of edge burrs in the patterned photoresist and effectively improving the accuracy and precision of the data used to establish the OPC model.

[0103] In some embodiments, at least the imager 321 is a measurement stage. For example, the measurement stage may be a scanning electron microscope (CD-SEM); for instance, a critical dimension scanning electron microscope (CD-SEM). The critical dimension scanning electron microscope has high resolution, and its use effectively ensures the acquisition of high-precision data.

[0104] In some embodiments, the extractor 322 is also a feature-size scanning electron microscope that extracts the outline of the pattern in the patterned photoresist, that is, the measurement unit 320 may include a feature-size scanning electron microscope.

[0105] The information output by the feature-dimensional scanning electron microscope includes: line width (critical dimension, CD), SEM image, scan lines, and SEM contour. The SEM contour is the contour of the pattern extracted from the image of the patterned photoresist. Therefore, extracting the contour of the pattern in the patterned photoresist by the feature-dimensional scanning electron microscope means directly using the SEM contour in the information output by the feature-dimensional scanning electron microscope as the contour of the pattern in the patterned photoresist.

[0106] In other embodiments of the present invention, the imager may also be a scanning electron microscope; the extractor may also be other software or hardware capable of image recognition to extract the outline of the pattern in the patterned photoresist.

[0107] Specifically, Figure 4 An image of patterned photoresist obtained in one embodiment of the OPC model building apparatus of the present invention is shown; Figure 5 It shows Figure 4 The diagram shows the outline of the pattern extracted from the patterned photoresist image obtained by the OPC model building apparatus embodiment. Among them, Figure 4 Only a portion of the obtained patterned photoresist image is shown. Figure 5 Only a portion of the outline of the extracted graphic is shown, and Figure 4 The area of ​​the part shown is greater than Figure 5 The area of ​​the portion shown.

[0108] Continue to refer to Figure 1 The measurement unit 330 measures the outline of the pattern in the patterned photoresist to obtain the outline measurement value.

[0109] The contour measurement values ​​obtained by the measurement unit 330 are used to obtain the experimental data required to establish the OPC model.

[0110] The contour measurement values ​​used to build the OPC model are obtained by the measurement unit 330 measuring the contour of the extracted graphic. This avoids data shift caused by inconsistent measurement methods and measurement errors caused by poor patterned photoresist profiles. Moreover, the contour measurement values ​​obtained by the measurement unit 330 measuring the contour of the extracted graphic can effectively reduce invalid data in the obtained data and can even eliminate the step of cleaning invalid data, which can effectively reduce modeling time and improve modeling efficiency.

[0111] Specifically, the measurement unit 330 can be a Gauge-based tool that measures the contour of the graphic obtained by the measurement unit 320 to obtain contour measurement values. The measurement unit 330 is a Gauge-based tool; due to the powerful functionality of Gauge, in addition to obtaining the contour measurement values, the measurement unit 330 can also extract other information about the graphic's contour to supplement the limited data of the contour measurement values.

[0112] The contour measurement value can be at least one of the following: line width (critical dimension, CD), spacing, pitch, length, and extension of the contour corresponding to the experimental graphic. For example, ... Figure 3 As shown, the line width, line spacing, and pitch of the experimental pattern in the patterned photoresist 220 are illustrated.

[0113] The measurement unit 330 can set measurement positions and measure the contour of the graphic at the measurement positions to obtain the corresponding contour measurement values. The contour measurement values ​​are related to the required OPC model, and the setting of the measurement positions is determined based on the required OPC model; that is, the number and specific locations of the measurement positions are determined based on the required OPC model.

[0114] For example, the specific number and location of the measurement positions set by the measurement unit 330 can be referred to the existing OPC model establishment method, and will not be repeated here.

[0115] In some embodiments of the present invention, the measuring unit 330 measures the contour of the pattern in the patterned photoresist along a preset direction to obtain contour measurement values.

[0116] In some embodiments, the measurement unit 320 is a feature-size scanning electron microscope to obtain an image of the patterned photoresist and extract the outline of the pattern in the patterned photoresist. That is, the feature-size scanning electron microscope scans the patterned photoresist to obtain the outline of the pattern in the patterned photoresist; therefore, the preset direction is consistent with the scanning direction of the feature-size scanning electron microscope.

[0117] Measuring the contour of the pattern in the patterned photoresist along a preset direction, i.e., performing a one-dimensional measurement of the contour of the pattern in the patterned photoresist, can effectively ensure the accuracy of the obtained measurement data; especially when the patterned photoresist is scanned by a feature-size scanning electron microscope, the scanning results of the feature-size scanning electron microscope along the scanning direction have high precision and accuracy, which can better ensure the accuracy and precision of the obtained measurement data.

[0118] Continue to refer to Figure 1 The modeling unit 340 establishes an OPC model based on the contour measurement values.

[0119] While rigorous OPC models offer high accuracy, they also require significant computational power. Completing a chip-level OPC model within the market-required timeframe is extremely challenging and demands substantial computing resources. Therefore, to balance the conflict between computational power and OPC model accuracy requirements, the modeling unit 340 establishes a semi-empirical simplified OPC model. This simplified OPC model replaces the complex processes of the precise model with simplified empirical formulas. These formulas include multiple parameters, which can be obtained by fitting contour measurements, ultimately ensuring that the computational structure of the simplified lithography model matches experimental results.

[0120] It should be noted that the contour measurement value is obtained by measuring the contour of the extracted graphic. During the contour measurement process, it will not be affected by the photoresist morphology. There is very little or no invalid data in the contour measurement value. In some embodiments, the OPC model building device does not need to set up a cleaning unit and does not need to clean the data, which can effectively reduce the modeling time and improve the modeling efficiency.

[0121] Moreover, the contour measurement value is obtained by measuring the contour of the patterned photoresist. During the measurement process, the interference of burrs on the edge of the pattern in the photoresist layer can be effectively avoided, which can effectively improve the measurement accuracy and obtain high-precision contour measurement values. The modeling unit 340 uses higher precision contour measurement values, resulting in smaller model errors, higher modeling speed, and better modeling accuracy when establishing the OPC model.

[0122] Specifically, the modeling unit 340 is equipped with an initial OPC model, which has multiple parameters to be fitted. Based on the contour measurement values, the modeling unit 340 performs fitting calculations to obtain the values ​​of the parameters to be fitted. Based on the values ​​of the parameters to be fitted and combined with the initial OPC model, the modeling unit 340 establishes the OPC model.

[0123] It should be noted that, in some embodiments of the present invention, the OPC model building apparatus further includes a verification unit 350, which is adapted to verify the OPC model.

[0124] The verification unit 350 can detect software bugs, design errors, and may also detect potential hotspots.

[0125] In some embodiments of the present invention, after obtaining the verification layout, based on the established OPC model, the verification unit 350 performs optical proximity correction on the verification layout to obtain a corrected layout; based on the verification layout, the verification unit 350 forms a semiconductor structure, the semiconductor structure including patterned photoresist; the verification unit 350 also obtains an image of the patterned photoresist; the verification unit 350 compares the image of the patterned photoresist and the corrected layout to verify the OPC model.

[0126] In other embodiments, the modeling unit establishes the OPC model based on a portion of the contour measurement values; the verification unit performs optical proximity correction on the modeled layout based on the established OPC model to obtain a corrected layout; the verification unit measures the corrected layout based on the remaining contour measurement values ​​to obtain corrected measurement values, which correspond one-to-one with the contour measurement values ​​of the remaining portion, wherein the contour measurement values ​​of the remaining portion are contour measurement values ​​not used in the process of establishing the OPC model; the verification unit compares the corrected measurement values ​​with the corresponding contour measurement values ​​to verify the OPC model.

[0127] Accordingly, the present invention also provides an optical proximity correction device.

[0128] The optical proximity correction device includes: an acquisition device 420, which is adapted to acquire a design layout; a creation device 410, which is adapted to create an OPC model, and the creation device 410 is the creation device of the present invention; and a correction device 430, which is adapted to use the OPC model to correct the design layout to obtain a fabrication layout.

[0129] Specifically, the acquisition device 420 obtains a GDS (Geometry Summary Data) file of the design layout. The GDS file defines the three-dimensional structure and electrical characteristics of the chip, and contains geometric data regarding the chip's structure, shape, and hierarchy. For example, the design layout obtained by the acquisition device 420 is a design layout of the contact hole layer, i.e., it obtains a GDS file of the contact hole layer design layout.

[0130] The establishment device 410 is the establishment device of the present invention. The specific technical solution of the establishment device 410 can be referred to the aforementioned embodiment of the OPC model establishment device, and will not be repeated here.

[0131] The correction device 430 corrects the design layout based on the OPC model to obtain the chip fabrication layout.

[0132] The device 410 of this invention measures the contour of the pattern in the photoresist and then establishes an OPC model based on the contour measurement value. The established OPC model has higher precision and accuracy. Therefore, based on the correction of the higher precision and accuracy OPC model, the correction device 430 can effectively improve the accuracy and precision of the obtained wafer layout. In particular, in the design layout of the contact hole layer, the density of the contact hole pattern is relatively high. Using the OPC model of this invention, the correction device 430 corrects the design layout of the contact hole layer, effectively improving the precision and accuracy of the correction, which is conducive to the formation of a high-quality contact hole layer and a high-quality contact hole structure.

[0133] Furthermore, the present invention also provides a readable storage medium having a computer program stored thereon, the computer program being executed by a processor to implement the steps of the OPC model establishment method of the present invention.

[0134] The computer program stored on the readable storage medium is executed by a processor to implement the steps of the OPC model establishment method of the present invention. Specific technical solutions for the readable storage medium can be found in the aforementioned embodiments of the OPC model establishment method, and will not be repeated here.

[0135] In summary, after forming the semiconductor structure, the contour of the pattern in the patterned photoresist within the semiconductor structure is obtained. This contour is then measured (gaugeed) to obtain its measurement value. Based on these contour measurements, an OPC model is established. Compared to post-development measurement data obtained by directly measuring the pattern in the patterned photoresist, measuring the contour of the pattern in the patterned photoresist effectively avoids interference from edge burrs in the photoresist layer, significantly improving measurement accuracy and obtaining high-precision contour measurements. These high-precision contour measurements provide a solid data foundation for establishing the OPC model, effectively reducing errors in the established OPC model, improving the efficiency of OPC model establishment, and enhancing the correction accuracy of the optical proximity correction method.

[0136] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A method for establishing an OPC model, characterized in that, include: A semiconductor structure is formed, the semiconductor structure having a patterned photoresist; The step of obtaining the outline of the pattern in the patterned photoresist based on the semiconductor structure includes: obtaining an image of the patterned photoresist; and extracting the outline of the pattern in the patterned photoresist based on the image of the patterned photoresist. The contour of the pattern in the patterned photoresist is measured to obtain the contour measurement value in order to eliminate the interference of edge burrs in the patterned photoresist. An OPC model is established based on the contour measurements.

2. The method for establishing as described in claim 1, characterized in that, In the step of obtaining the image of the patterned photoresist, the image of the patterned photoresist is obtained by means of a measurement machine.

3. The method for establishing as described in claim 2, characterized in that, In the step of obtaining an image of the patterned photoresist using a measuring instrument, the measuring instrument is a scanning electron microscope.

4. The method for establishing as described in claim 3, characterized in that, In the step of obtaining an image of the patterned photoresist using a measurement instrument, the measurement instrument is a feature-size scanning electron microscope.

5. The method for establishing as described in claim 1, characterized in that, In the step of measuring the contour of the pattern in the patterned photoresist to obtain the contour measurement value, the contour of the pattern in the patterned photoresist is measured along a preset direction to obtain the contour measurement value.

6. The method for establishing as described in claim 4 or 5, characterized in that, In the step of measuring the contour of the pattern in the patterned photoresist along a preset direction to obtain the contour measurement value, the preset direction is consistent with the measurement direction of the feature size scanning electron microscope.

7. The method for establishing as described in claim 1, characterized in that, Also includes: After establishing the OPC model based on the contour measurements, the OPC model is then validated.

8. The method for establishing as described in claim 1, characterized in that, The steps involved in forming a semiconductor structure include: Provide photoresist layer; The photoresist layer is patterned to form a patterned photoresist.

9. An optical proximity correction method, characterized in that, include: Obtain the design map; An OPC model is established, wherein the OPC model is established by the method described in any one of claims 1 to 8. The design layout is modified using the OPC model to obtain the chip fabrication layout.

10. The optical proximity correction method as described in claim 9, characterized in that, In the step of obtaining the design layout, the design layout is the design layout of the contact hole layer.

11. An apparatus for establishing an OPC model, characterized in that, include: A process unit suitable for forming a semiconductor structure having a patterned photoresist; A measurement unit, adapted to obtain the outline of a pattern in the patterned photoresist based on the semiconductor structure, the measurement unit comprising: an imager adapted to obtain an image of the patterned photoresist; and an extractor adapted to extract the outline from the image of the patterned photoresist. A measurement unit is provided, which is adapted to measure the contour of the pattern in the patterned photoresist and obtain contour measurement values ​​to eliminate the interference of edge burrs in the patterned photoresist. A modeling unit, which is adapted to establish an OPC model based on the contour measurement values.

12. The apparatus for establishing as claimed in claim 11, characterized in that, At least the imager is a measurement instrument.

13. The apparatus for establishing as claimed in claim 12, characterized in that, The measuring instrument is a scanning electron microscope.

14. The apparatus for establishing as claimed in claim 13, characterized in that, The measuring instrument is a feature-size scanning electron microscope.

15. The apparatus for establishing as claimed in claim 11, characterized in that, The measuring unit measures the contour of the pattern in the patterned photoresist along a preset direction to obtain contour measurement values.

16. The apparatus for establishing as claimed in claim 14 or 15, characterized in that, The preset orientation is consistent with the measurement orientation of the feature size scanning electron microscope.

17. The apparatus for establishing as claimed in claim 11, characterized in that, Also includes: A verification unit, which is suitable for verifying the OPC model.

18. An optical proximity correction device, characterized in that, include: A setup apparatus, suitable for setting up an OPC model, as described in any one of claims 11 to 17; Acquisition device, the acquisition device being adapted to acquire design layout; A correction device is suitable for using the OPC model to correct the design layout to obtain a chip fabrication layout.

19. The optical proximity correction device as claimed in claim 18, characterized in that, The design layout acquired by the acquisition device is the design layout of the contact hole layer.

20. A storage medium having a computer program stored thereon, characterized in that, The computer program is executed by a processor to implement the steps of the method according to any one of claims 1 to 8.

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