CN119002167A - OPC model establishing method and device, optical proximity correction method and device and storage medium - Google Patents
OPC model establishing method and device, optical proximity correction method and device and storage medium Download PDFInfo
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- CN119002167A CN119002167A CN202411230603.0A CN202411230603A CN119002167A CN 119002167 A CN119002167 A CN 119002167A CN 202411230603 A CN202411230603 A CN 202411230603A CN 119002167 A CN119002167 A CN 119002167A
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F1/00—Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles therefor; Containers specially adapted therefor; Preparation thereof
- G03F1/36—Masks having proximity correction features; Preparation thereof, e.g. optical proximity correction [OPC] design processes
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/70—Microphotolithographic exposure; Apparatus therefor
- G03F7/70425—Imaging strategies, e.g. for increasing throughput or resolution, printing product fields larger than the image field or compensating lithography- or non-lithography errors, e.g. proximity correction, mix-and-match, stitching or double patterning
- G03F7/70433—Layout for increasing efficiency or for compensating imaging errors, e.g. layout of exposure fields for reducing focus errors; Use of mask features for increasing efficiency or for compensating imaging errors
- G03F7/70441—Optical proximity correction [OPC]
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Abstract
一种OPC模型的建立方法及装置、光学临近修正方法和设备、可读存储介质，所述建立方法包括：形成半导体结构，所述半导体结构具有图形化光刻胶；根据所述半导体结构，获得所述图形化光刻胶中图形的轮廓；对所述图形化光刻胶中图形的轮廓进行测量，获得轮廓测量值；根据所述轮廓测量值，建立OPC模型。与直接对图形化光刻胶的图形进行量测而获得的显影后量测数据相比，本发明技术方案，能够有效提高测量精度，获得高精度的轮廓测量值，从而能够有效减小所建立OPC模型的误差，有利于提高OPC模型的建立效率，有利于提高光学临近修正方法的修正精度。
A method and device for establishing an OPC model, an optical proximity correction method and device, and a readable storage medium, wherein the establishment method includes: forming a semiconductor structure, wherein the semiconductor structure has a patterned photoresist; obtaining the contour of the pattern in the patterned photoresist according to the semiconductor structure; measuring the contour of the pattern in the patterned photoresist to obtain a contour measurement value; and establishing an OPC model according to the contour measurement value. Compared with the post-development measurement data obtained by directly measuring the pattern of the patterned photoresist, the technical solution of the present invention can effectively improve the measurement accuracy and obtain a high-precision contour measurement value, thereby effectively reducing the error of the established OPC model, which is beneficial to improving the establishment efficiency of the OPC model and the correction accuracy of the optical proximity correction method.
Description
Technical Field
The present invention relates to the field of photolithography, and in particular, to a method and apparatus for creating an OPC model, an optical proximity correction method and apparatus, and a storage medium.
Background
In the semiconductor manufacturing process, in order to transfer the circuit pattern of the integrated circuit (INTEGRATED CIRCUIT, IC) onto the semiconductor chip, the circuit pattern of the integrated circuit is designed as a mask pattern, and then the mask pattern is transferred from the mask surface to the semiconductor chip.
With the shrinking of the feature size (Critical Dimension, CD) of the integrated circuit and the influence of the Resolution Limit (Resolution Limit) of the exposure tool (Optical Exposure Tool, OET), optical proximity effects (Optical Proximity Effect, OPE) are easily generated when performing an exposure process for pattern transfer on the mask pattern arranged at high density, so that defects occur in the mask pattern transfer. One approach currently in common use in the industry to address the problem of optical proximity effects is optical proximity correction (Optical Proximity Correction, OPC), which reduces the deviation of the lithographic pattern obtained by exposure by changing the shape of the original layout pattern.
An optical proximity correction method is based on model development correction, and the key of the correction method is to establish an accurate OPC model, but the OPC model established by the existing method often has the problem of large error (error).
Disclosure of Invention
The problem to be solved by the invention is how to reduce the error of the OPC model.
In order to solve the above problems, the present invention provides a method for establishing an OPC model, including: forming a semiconductor structure, wherein the semiconductor structure is provided with a patterned photoresist; obtaining the outline of the graph in the graphical photoresist according to the semiconductor structure; measuring the outline of the graph in the graphical photoresist to obtain an outline measurement value; and establishing an OPC model according to the profile measurement value.
Optionally, the step of obtaining the profile 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 graph in the graphical photoresist according to the image of the graphical photoresist.
Optionally, in the step of obtaining the image of the patterned photoresist, the image of the patterned photoresist is obtained by a measuring machine.
Optionally, in the step of obtaining the image of the patterned photoresist by a measurement machine, the measurement machine is a feature size scanning electron microscope.
Optionally, in the step of measuring the profile of the pattern in the patterned photoresist to obtain the profile measurement value, measuring the profile of the pattern in the patterned photoresist along a preset direction to obtain the profile measurement value.
Optionally, measuring the outline of the pattern in the patterned photoresist along a preset direction, and in the step of obtaining the outline measurement value, the preset direction is consistent with the scanning direction of the feature size scanning electron microscope.
Optionally, the method further comprises: and establishing an OPC model according to the profile measured value, and then verifying the OPC model.
Optionally, the step of forming the semiconductor structure includes: providing a photoresist layer; and patterning the photoresist layer to form patterned photoresist.
An optical proximity correction method, comprising: obtaining a design layout; an OPC model is built, and the OPC model is built for the building method of the invention; and correcting the design layout by using the OPC model to obtain a flow sheet layout.
Optionally, in the step of obtaining the design layout, the design layout is a design layout of a contact hole layer.
Correspondingly, the invention also provides a device for establishing the OPC model, which comprises the following steps: a process unit adapted to form a semiconductor structure having a patterned photoresist; the measuring unit is suitable for obtaining the outline of the graph in the graphical photoresist according to the semiconductor structure; the measuring unit is suitable for measuring the outline of the graph in the graphical photoresist to obtain an outline measuring value; and the modeling unit is suitable for establishing an OPC model according to the profile measured value.
Optionally, the measuring unit includes: an imager adapted to obtain an image of the patterned photoresist; an extractor adapted to extract contours in an image of the patterned photoresist.
Optionally, the imager is a measurement machine.
Optionally, the measuring machine is a feature size scanning electron microscope.
Optionally, the measuring unit measures the outline of the pattern in the patterned photoresist along a preset direction to obtain a profile measurement value.
Optionally, the preset direction is consistent with a scanning direction of the feature size scanning electron microscope.
Optionally, the method further comprises: and the verification unit is suitable for verifying the OPC model.
An optical proximity correction apparatus comprising: a build device adapted to build an OPC model, the build device being a build device of the present invention; the acquisition device is suitable for acquiring the design layout; and the correcting device is suitable for correcting the design layout by utilizing the OPC model to obtain the flow sheet layout.
Optionally, the design layout obtained by the obtaining device is a design layout of a contact hole layer.
Furthermore, the present invention provides a storage medium having stored thereon a computer program to be executed by a processor for carrying out the steps of the inventive setup method.
Compared with the prior art, the technical scheme of the invention has the following advantages:
In the technical scheme of the invention, after a semiconductor structure is formed, the outline (content) of a pattern in the patterned photoresist in the semiconductor structure is obtained, so that the outline of the obtained pattern is measured (Gauge) to obtain a measured value of the outline; and then, according to the number profile measurement values, an OPC model is established. Compared with post-development measurement data obtained by directly measuring the pattern of the patterned photoresist, the method has the advantages that the outline of the pattern in the patterned photoresist is measured, interference of pattern edge burrs in the photoresist layer can be effectively avoided in the measuring process, the measuring precision can be effectively improved, and a high-precision outline measurement value can be obtained; the high-precision profile measurement value can provide a good data basis for the establishment of the OPC model, so that the error of the established OPC model can be effectively reduced, the establishment efficiency of the OPC model can be improved, and the correction precision of the optical proximity correction method can be improved.
Drawings
FIG. 1 is a flow chart of an embodiment of an OPC model building method of the present invention;
FIGS. 2 to 3 are schematic structural views showing various steps in the process of forming a semiconductor structure in the embodiment of the OPC model building method shown in FIG. 1;
FIG. 4 illustrates an image of a patterned photoresist obtained in an embodiment of the OPC model creation method of the present invention;
FIG. 5 illustrates an outline of a pattern extracted from an image of a patterned photoresist obtained by the embodiment of the OPC model creation method shown in FIG. 4;
FIG. 6 is a functional block diagram of an embodiment of an optical proximity correction device of the present invention.
Detailed Description
As known from the background art, the OPC model in the prior art has the problem of large error. The cause of the big error problem is analyzed by combining the establishment process of an OPC model:
An OPC model is built based on post-development (after develop inspection, ADI) metrology data, which is specifically: after exposing and developing the photoresist to pattern, measuring the patterned photoresist by a characteristic dimension scanning electron microscope (critical dimension scanning electron microscope, CD-SEM) to obtain measured data after development; and establishing an OPC model based on the post-development measurement data.
However, in the patterned photoresist, burrs often occur on the edges of the pattern, and the burrs on the edges of the pattern easily affect the measurement accuracy, so that the measurement accuracy of measured developed measurement data is reduced; the reduction of the accuracy of the measured data after development can deteriorate the accuracy of an OPC model established based on the accuracy, so that the error of the OPC model is larger; the larger error of the OPC model can affect the modeling speed of establishing the OPC model, and the correction accuracy of the optical proximity correction by using the OPC model later can be deteriorated.
In order to solve the technical problem, the invention provides a method for establishing an OPC model, which comprises the following steps:
Forming a semiconductor structure, wherein the semiconductor structure is provided with a patterned photoresist; obtaining the outline of the graph in the graphical photoresist according to the semiconductor structure; measuring the outline of the graph in the graphical photoresist to obtain an outline 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 of the patterned photoresist, the technical scheme of the invention measures the outline of the pattern in the patterned photoresist, can effectively avoid the interference of the edge burrs of the pattern in the photoresist layer in the measurement process, can effectively improve the measurement precision and obtain a high-precision outline measurement value; the high-precision profile measurement value can provide a good data basis for the establishment of the OPC model, so that the error of the established OPC model can be effectively reduced, the establishment efficiency of the OPC model can be improved, and the correction precision of the optical proximity correction method can be improved.
In order that the above objects, features and advantages of the invention will be readily understood, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings.
Referring to FIG. 1, a flow chart of an embodiment of the OPC model building method of the present invention is shown.
The OPC model building method comprises the following steps:
step S110, forming a semiconductor structure, wherein the semiconductor structure is provided with patterned photoresist; step S120, according to the patterned photoresist, obtaining the outline of the pattern in the patterned photoresist; step S130, measuring the outline of the graph in the graphical photoresist to obtain an outline measurement value; and step S140, establishing an OPC model according to the profile measurement value.
The following describes in detail the technical scheme of the embodiment of the OPC model building method according to the present invention with reference to the accompanying drawings.
As shown in fig. 1, step S110 is first performed to form a semiconductor structure having a patterned photoresist.
The OPC model may describe the entire lithography process including the optical system, mask, photoresist, etching process. Some parameters in the OPC model are calibrated through experimental data fitting, and finally the calculation structure of the OPC model is matched with an experimental result; in step S110, a semiconductor structure is formed, where the patterned photoresist of the semiconductor structure is used to extract experimental data required for building an OPC model.
In some embodiments of the present invention, step S110, the step of forming the semiconductor structure includes: as shown in fig. 2, a photoresist 221 is provided; as shown in fig. 3, the photoresist is patterned to form a patterned photoresist 220.
In the step of providing the photoresist 221, a substrate 210 is provided, the photoresist 221 being provided on the substrate 210, as shown in fig. 2. Specifically, the substrate 210 is used to provide mechanical support and the photoresist 221 is used to provide a process basis.
The substrate 210 may be a silicon substrate, for example. In other embodiments of the present invention, the substrate may be other substrates suitable for performing OPC modeling experiments.
The photoresist 221 is adapted to transfer a pattern to form a patterned photoresist. The photoresist 221 may be a photoresist suitable for performing OPC modeling experiments. Specifically, the photoresist 221 may be formed on the substrate 210 by spin coating.
After forming the photoresist 221 (shown in fig. 2), the photoresist 221 is patterned to form a patterned photoresist 220, as shown in fig. 3.
In step S110, the step of forming the semiconductor structure further includes: forming a modeling layout, wherein the modeling layout is provided with a plurality of modeling graphs; manufacturing a mask plate based on the modeling graph; in the process of patterning the photoresist 221, the photoresist 221 is exposed and developed by using the mask, and the modeling layout on the mask is transferred to the photoresist 221 to form the patterned photoresist 220.
Specifically, the process of patterning the photoresist 221 may be performed by a method suitable for performing an OPC model building experiment. Patterned photoresist 220 has a plurality of experimental patterns. The experimental pattern in the patterned photoresist 220 is consistent with the modeling pattern in the modeling layout. The consistency of the experimental graph and the modeling graph means that a plurality of experimental graphs and a plurality of modeling graphs are in one-to-one correspondence.
The modeling layout is a graph designed in a design experiment (design of experiment, DOE). In order to ensure the precision of the built OPC model, the coverage capability of modeling graphics in the modeling layout to the designed layout needs to be improved as much as possible; for complex design layout, the more diversified the modeling graphics are, the more accurate the built OPC model is; the more diverse the modeling patterns, however, the correspondingly increased measurement and modeling time. In order to ensure the coverage capability of the modeling graph, the graph can be directly extracted from the design layout as the modeling graph in the design experiment process. Specifically, extracting graphics with difficult photoetching and complex photoetching from a design layout as key graphics; similar key patterns fall into one category; and extracting representative graphs from the key graphs of the same class as modeling graphs to construct the modeling layout, thereby manufacturing the mask plate.
With continued reference to fig. 1, the method for establishing the OPC model further includes: and step S120, according to the patterned photoresist, obtaining the outline of the pattern in the patterned photoresist.
Step S120, according to the patterned photoresist, obtaining the outline of the pattern in the patterned photoresist, that is, obtaining the positions and shapes of a plurality of experimental patterns in the patterned photoresist.
In some embodiments of the present invention, the step of obtaining the profile of the pattern in the patterned photoresist according to the patterned photoresist includes: step S121, obtaining an image of the patterned photoresist; step S122, extracting the outline of the graph in the patterned photoresist according to the image of the patterned photoresist. The outline of the graph is extracted from the image of the graphical photoresist, so that the influence of outline edge burrs in the graphical photoresist can be effectively eliminated, and the precision and accuracy of data used for establishing the OPC model can be effectively improved.
In some embodiments, in step S121, in the step of obtaining the image of the patterned photoresist, the image of the patterned photoresist is obtained by a measurement machine. Specifically, in the step of obtaining the image of the patterned photoresist by a measuring machine, the measuring machine is a scanning electron microscope (scanning electron microscope, SEM); for example, the metrology tool may be a feature size scanning electron microscope (critical dimension scanning electron microscope, CD-SEM). The feature size scanning electron microscope has higher resolution, and the use of the feature size scanning electron microscope can effectively ensure the acquisition of high-precision data.
In some embodiments, in step S122, in the step of extracting the outline of the pattern in the patterned photoresist according to the image of the patterned photoresist, the outline of the pattern in the patterned photoresist may be extracted by a feature size scanning electron microscope.
The information output by the feature size scanning electron microscope includes: line width (critical dimension, CD), SEM image, scan line, SEM profile, wherein SEM profile is the profile of the pattern extracted from the image of the patterned photoresist, so that the profile of the pattern in the patterned photoresist is extracted by a feature size scanning electron microscope, i.e. the SEM profile in the information output by the feature size scanning electron microscope is directly adopted as the profile of the pattern in the patterned photoresist.
In other embodiments of the present invention, in step S121, in the step of obtaining the image of the patterned photoresist, the image of the patterned photoresist may also be obtained by a scanning electron microscope; step S122, in the step of extracting the outline of the pattern in the patterned photoresist according to the image of the patterned photoresist, the outline of the pattern in the patterned photoresist may also be extracted by image recognition software.
Specifically, fig. 4 shows an image of a patterned photoresist obtained in an embodiment of the OPC model building method of the present invention; FIG. 5 illustrates an outline of a pattern extracted from an image of the patterned photoresist obtained by the embodiment of the OPC model building method shown in FIG. 4. Wherein fig. 4 shows only a portion of the obtained image of the patterned photoresist, fig. 5 shows only a portion of the outline of the extracted pattern, and the area of the portion shown in fig. 4 is larger than that of the portion shown in fig. 5.
With continued reference to fig. 1, after obtaining the outline of the pattern in the patterned photoresist, the method for establishing the OPC model further includes: step S130, measuring (gauge) the profile of the pattern in the patterned photoresist to obtain a profile measurement value.
Step S130, measuring (gauge) the outline of the pattern in the patterned photoresist to obtain an outline measurement value for obtaining experimental data required for establishing an OPC model.
The profile measurement value used for establishing the OPC model is obtained by measuring the profile of the extracted pattern, so that data floating (shift) caused by inconsistent measurement methods can be avoided, and measurement errors caused by poor patterned photoresist morphology (profile) can be avoided; and the contour measurement value is obtained by measuring the contour of the extracted graph, so that invalid data in the obtained data can be effectively reduced, and even the step of clearing (Clean) invalid data can be omitted, the modeling time can be effectively reduced, and the modeling efficiency can be improved.
Specifically, in step S130, the profile of the pattern in the patterned photoresist is measured (Gauge), and in the step of obtaining the profile measurement value, the Gauge tool may be used to measure the profile of the pattern in the patterned photoresist in step S130, so as to obtain the profile measurement value. And measuring the outline of the pattern in the patterned photoresist by using a Gauge tool, and extracting other information of the outline of the pattern besides the outline measured value due to the powerful function of the Gauge tool so as to supplement the data singleness of the outline measured value.
The profile measurement value may be at least one of a line width (critical dimension, CD), a line pitch (spacing), a pitch (pitch), a length (length), and an extension distance (extension) of a profile corresponding to the experimental pattern. By way of example, as shown in fig. 3, the line widths, line distances, and pitches of experimental patterns in the patterned photoresist 220 are shown.
Step S130, measuring (gauge) the profile of the pattern in the patterned photoresist, and obtaining a profile measurement value includes: and setting a measuring position, and measuring the outline of the graph at the measuring position to obtain a corresponding outline measuring value. Wherein the profile measurement value is related to the required build OPC model, the setting of the measurement positions is determined based on the required build OPC model, i.e. the number of measurement positions and the specific position are determined based on the required build OPC model.
For example, in the step of setting the measurement positions, the specific number and specific positions of the set measurement positions may refer to the existing method for establishing the OPC model, which is not described herein.
In some embodiments of the present invention, in the step of measuring the profile of the pattern in the patterned photoresist to obtain the profile measurement value, the profile of the pattern in the patterned photoresist is measured along a preset direction to obtain the profile measurement value.
In some embodiments, in step S121, in the step of obtaining the image of the patterned photoresist, the image of the patterned photoresist is obtained by a feature size scanning electron microscope; step S122, in the step of extracting the outline of the pattern in the patterned photoresist according to the image of the patterned photoresist, the outline of the pattern in the patterned photoresist is extracted by a feature size scanning electron microscope, that is, step S120, in the step of obtaining the outline of the pattern in the patterned photoresist according to the patterned photoresist, the patterned photoresist is scanned by a feature size scanning electron microscope, so as to obtain the outline of the pattern in the patterned photoresist; therefore, the outline of the pattern in the patterned photoresist is measured along a preset direction, and in the step of obtaining the outline measurement value, the preset direction is consistent with the scanning direction of the feature size scanning electron microscope.
Measuring the outline of the graph in the patterned photoresist along a preset direction, namely, one-dimensional measuring the outline of the graph in the patterned photoresist, so that the accuracy of the obtained measurement data can be effectively ensured; particularly, under the condition that the patterned photoresist is scanned by the characteristic dimension scanning electron microscope, the scanning result of the characteristic dimension scanning electron microscope is high in precision and accuracy along the scanning direction, and the accuracy and the precision of the obtained measurement data can be better ensured.
With continued reference to fig. 1, after obtaining the profile measurement value, the method for establishing the OPC model further includes: and step S140, establishing an OPC model according to the profile measurement value.
Although the strict OPC model has high precision, the calculation capability requirement for establishing the OPC model is high, the establishment of the chip-level OPC model is completed within the time required by the market, the difficulty is high, and the calculation force requirement is high. Therefore, in order to balance the conflict between the calculation force requirement and the OPC model precision requirement, in the step of establishing the OPC model, a simplified OPC model with half experience is established. The simplified OPC model is a model formed by replacing a complex process in an accurate model with some simplified empirical formulas, wherein the empirical formulas comprise a plurality of parameters, the parameters in the empirical formulas can be obtained based on contour measurement value fitting, and finally, the calculation structure of the simplified OPC model is matched with an experimental result.
It should be noted that, the profile measurement value is obtained by measuring the profile of the extracted pattern, the profile measurement value is not interfered by the photoresist morphology in the process of measuring the profile measurement value, and the invalid data in the profile measurement value is little, even none, in some embodiments, step S130 measures the profile of the pattern in the patterned photoresist, after the profile measurement value is obtained, step S140 can be directly executed, and an OPC model is built according to the profile measurement value, so that the invalid data in the obtained profile measurement value does not need to be cleared, that is, the data does not need to be cleaned, the modeling time can be effectively reduced, and the modeling efficiency is improved.
The profile measurement value is obtained by measuring the profile of the pattern of the patterned photoresist, so that interference of pattern edge burrs in the photoresist layer can be effectively avoided in the measurement process, the measurement precision can be effectively improved, and the high-precision profile measurement value can be obtained; and step 140, in the step of establishing the OPC model according to the profile measurement value, the profile measurement value with higher precision is adopted, and when the OPC model is established, the model error is smaller, the modeling speed is higher, and the modeling accuracy is better.
Specifically, in step S140, the step of establishing an OPC model according to the profile measurement value includes: obtaining an initial OPC model, wherein the initial OPC model is provided with a plurality of parameters to be fitted; fitting calculation is carried out according to the profile measured value, and the numerical value of the parameter to be fitted is obtained; and according to the numerical value of the parameter to be fitted, combining the initial OPC model, and establishing the OPC model.
It should be noted that, as shown in fig. 1, in some embodiments of the present invention, the method for establishing an OPC model further includes: and after establishing an OPC model according to the profile measurement value, executing step S150, and verifying the OPC model.
In step S150, a step of verifying the OPC model may find software defects (software bug) and design defects (design error), and may find possible bad points (hotspot).
In some embodiments of the present invention, step S150, the step of verifying the OPC model includes: obtaining a verification layout; based on the established OPC model, performing optical proximity correction on the verification layout to obtain a corrected layout; forming a semiconductor structure based on the verification layout, wherein the semiconductor structure comprises graphical photoresist; obtaining an image of the patterned photoresist; and comparing the image of the graphical photoresist with the corrected layout to verify the OPC model.
In other embodiments, in the step of establishing an OPC model according to the profile measurement values, the OPC model is established according to the profile measurement values of the partial number; the step of verifying the OPC model comprises: performing optical proximity correction on the modeling layout based on the established OPC model to obtain a corrected layout; measuring the corrected layout according to the profile measured value of the remaining part to obtain a corrected measured value, wherein the corrected measured value corresponds to the profile measured value of the remaining part one by one, and the profile measured value of the remaining part is an unused profile measured value in the process of establishing the OPC model; and comparing the corrected measured value with the corresponding profile measured value to verify the OPC model.
Correspondingly, the invention also provides an optical proximity correction method.
The optical proximity correction method comprises the following steps: obtaining a design layout; an OPC model is built, and the OPC model is built by the building method; and correcting the design layout by using the OPC model to obtain a flow sheet layout.
Specifically, the step of obtaining the design layout includes: and obtaining GDS (Geometry Summary Data) files of the design layout. The GDS file is used for defining the three-dimensional structure and electrical characteristics of the chip, and the GDS file contains geometric data about the chip structure, shape and hierarchical structure. In the step of obtaining the design layout, the design layout is a design layout of the contact hole layer, that is, the GDS file of the design layout of the contact hole layer is obtained.
In the step of establishing an OPC model, the OPC model is established for the establishment method of the invention. For the specific technical scheme of the step of establishing the OPC model, reference may be made to the foregoing embodiment of the method for establishing the OPC model, and the disclosure is not repeated herein.
And then, correcting the design layout based on the OPC model to obtain a flow sheet layout.
The building method of the invention is to build an OPC model based on the contour measurement value after measuring the contour of the graph in the photoresist; the built OPC model has higher precision and higher accuracy, so that the accuracy and precision of the obtained flow sheet layout can be effectively improved based on the correction of the OPC model with higher precision and higher accuracy; particularly, in the design layout of the contact hole layer, the density of the contact hole pattern is relatively high, and the OPC model is utilized to correct the design layout of the contact hole layer, so that the correction precision and accuracy are effectively improved, and the formation of a high-quality contact hole layer and a high-quality contact hole structure is facilitated.
Correspondingly, the invention also provides a device for establishing the OPC model.
The OPC model building device comprises:
A process unit 310, the process unit 310 being adapted to form a semiconductor structure having a patterned photoresist;
A measurement unit 320, wherein the measurement unit 320 is adapted to obtain a profile of a pattern in the patterned photoresist according to the semiconductor structure;
A measurement unit 330, wherein the measurement unit 330 is suitable for measuring the outline of the image of the patterned photoresist to obtain an outline measurement value;
a modeling unit 340, said modeling unit 340 being adapted to build an OPC model based on said profile measurement values.
In some embodiments of the present invention, the OPC model creation means is adapted to perform the steps of the OPC model creation method of the present invention. The specific technical scheme of the OPC model building device may refer to the foregoing embodiment of the OPC model building method.
The following describes in detail the technical scheme of the embodiment of the OPC model building apparatus of the present invention with reference to the accompanying drawings.
The process unit 310 forms a semiconductor structure having a patterned photoresist.
The OPC model may describe the entire lithography process including the optical system, mask, photoresist, etching process. Some parameters in the OPC model are calibrated through experimental data fitting, and finally the calculation structure of the OPC model is matched with an experimental result; the patterned photoresist of the semiconductor structure formed by the process unit 310 is used to extract experimental data required for establishing an OPC model.
In some embodiments of the present invention, the process unit 310 may be a semiconductor manufacturing system for the entire photolithography process including an optical system, a mask, a photoresist, and an etching process. In other embodiments of the invention, the process unit may also be a control device coupled to the semiconductor manufacturing system.
As shown in fig. 3, in the semiconductor structure, the patterned photoresist 220 is a patterned material layer that is exposed and developed. The patterned photoresist 220 has a plurality of experimental patterns. The experimental pattern in the patterned photoresist 220 is consistent with the modeling pattern in the modeling layout. The consistency of the experimental graph and the modeling graph means that a plurality of experimental graphs and a plurality of modeling graphs are in one-to-one correspondence.
The modeling layout is a graph designed in a design experiment (design of experiment, DOE). In order to ensure the precision of the built OPC model, the coverage capability of modeling graphics in the modeling layout to the designed layout needs to be improved as much as possible; for complex design layout, the more diversified the modeling graphics are, the more accurate the built OPC model is; the more diverse the modeling patterns, however, the correspondingly increased measurement and modeling time. In order to ensure the coverage capability of the modeling graph, the graph can be directly extracted from the design layout as the modeling graph in the design experiment process. Specifically, extracting graphics with difficult photoetching and complex photoetching from a design layout as key graphics; similar key patterns fall into one category; and extracting representative graphs from the key graphs of the same class as modeling graphs to construct the modeling layout, thereby manufacturing the mask plate.
With continued reference to fig. 1, the measurement unit 320 obtains a profile of a pattern in the patterned photoresist according to the patterned photoresist.
The measurement unit 320 obtains the positions and shapes of the plurality of experimental patterns in the patterned photoresist.
In some embodiments of the present invention, the measurement unit 320 includes: an imager 321, said imager 321 adapted to obtain an image of said patterned photoresist; an extractor 322, said extractor 322 being adapted to extract contours in an image of said patterned photoresist. The extractor 322 extracts the outline of the graph from the image of the patterned photoresist obtained by the imager 321, so that the influence of the outline edge burr in the patterned photoresist can be effectively eliminated, and the precision and accuracy of the data used for establishing the OPC model can be effectively improved.
In some embodiments, at least the imager 321 is a metrology tool. Illustratively, the metrology tool may be a scanning electron microscope (scanning electron microscope, CD-SEM); for example, a feature size scanning electron microscope (critical dimension scanning electron microscope, CD-SEM). The feature size scanning electron microscope has higher resolution, and the use of the feature size scanning electron microscope can effectively ensure the acquisition of high-precision data.
In some embodiments, the extractor 322 is also a feature size scanning electron microscope for extracting the outline of the pattern in the patterned photoresist, i.e. the measuring unit 320 may include: feature size scanning electron microscopy.
The information output by the feature size scanning electron microscope includes: line width (critical dimension, CD), SEM image, scan line, SEM profile, wherein SEM profile is the profile of the pattern extracted from the image of the patterned photoresist, so that the profile of the pattern in the patterned photoresist is extracted by a feature size scanning electron microscope, i.e. the SEM profile in the information output by the feature size scanning electron microscope is directly adopted as the profile of the pattern in the patterned photoresist.
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 that can implement image recognition to extract the contours of the patterns in the patterned photoresist.
Specifically, fig. 4 shows an image of a patterned photoresist obtained in an embodiment of the OPC model creation apparatus of the present invention; fig. 5 shows an outline of a pattern extracted from an image of the patterned photoresist obtained by the embodiment of the OPC modeling apparatus shown in fig. 4. Wherein fig. 4 shows only a portion of the obtained image of the patterned photoresist, fig. 5 shows only a portion of the outline of the extracted pattern, and the area of the portion shown in fig. 4 is larger than that of the portion shown in fig. 5.
With continued reference to fig. 1, the measurement unit 330 measures (gauge) the profile of the pattern in the patterned photoresist to obtain a profile measurement value.
The profile measurement values obtained by the measurement unit 330 are used to obtain experimental data required for establishing an OPC model.
The profile measurement value used for establishing the OPC model is obtained by measuring the profile of the extracted pattern by the measurement unit 330, so that data floating (shift) caused by inconsistent measurement methods can be avoided, and measurement errors caused by poor patterned photoresist morphology (profile) can be avoided; and the measurement unit 330 measures the contour of the extracted graph to obtain the contour measurement value, which can effectively reduce invalid data in the obtained data, and can even omit the step of clearing (Clean) invalid data, thereby effectively reducing modeling time and improving modeling efficiency.
Specifically, the measuring unit 330 may be a Gauge-based tool for measuring the profile of the graph obtained by the measuring unit 320 to obtain a profile measurement value. The measuring unit 330 is a Gauge-based tool, and since Gauge is powerful, the measuring unit 330 can extract other information of the profile of the graph in addition to the profile measurement value, so as to supplement the data singleness of the profile measurement value.
The profile measurement value may be at least one of a line width (critical dimension, CD), a line pitch (spacing), a pitch (pitch), a length (length), and an extension distance (extension) of a profile corresponding to the experimental pattern. By way of example, as shown in fig. 3, the line widths, line distances, and pitches of experimental patterns in the patterned photoresist 220 are shown.
The measuring unit 330 may set a measuring position, and measure the profile of the pattern at the measuring position to obtain a corresponding profile measurement value. Wherein the profile measurement value is related to the required build OPC model, the setting of the measurement positions is determined based on the required build OPC model, i.e. the number of measurement positions and the specific position are determined based on the required build OPC model.
For example, the specific number and specific positions of the measurement positions set by the measurement unit 330 may refer to a method for establishing an existing OPC model, which is not described herein.
In some embodiments of the present invention, the measurement unit 330 measures the profile of the pattern in the patterned photoresist along a preset direction to obtain a profile measurement value.
In some embodiments, the measurement unit 320 is a feature size scanning electron microscope to obtain an image of the patterned photoresist and extract a profile of a pattern in the patterned photoresist, that is, the feature size scanning electron microscope scans the patterned photoresist to obtain a profile of a pattern in the patterned photoresist; thus, the predetermined direction coincides with the scanning direction of the feature size scanning electron microscope.
Measuring the outline of the graph in the patterned photoresist along a preset direction, namely, one-dimensional measuring the outline of the graph in the patterned photoresist, so that the accuracy of the obtained measurement data can be effectively ensured; particularly, under the condition that the patterned photoresist is scanned by the characteristic dimension scanning electron microscope, the scanning result of the characteristic dimension scanning electron microscope is high in precision and accuracy along the scanning direction, and the accuracy and the precision of the obtained measurement data can be better ensured.
With continued reference to FIG. 1, the modeling unit 340 builds an OPC model based on the profile measurements.
Although the strict OPC model has high precision, the calculation capability requirement for establishing the OPC model is high, the establishment of the chip-level OPC model is completed within the time required by the market, the difficulty is high, and the calculation force requirement is high. Thus, in order to balance the conflict between the computational force requirements and the OPC model accuracy requirements, the modeling unit 340 builds a simplified OPC model that is semi-empirical. The simplified OPC model is a model formed by replacing a complex process in an accurate model with some simplified empirical formulas, wherein the empirical formulas comprise a plurality of parameters, the parameters in the empirical formulas can be obtained based on contour measurement value fitting, and finally, the calculation structure of the simplified OPC model is matched with an experimental result.
It should be noted that, the profile measurement value is obtained by measuring the profile of the extracted pattern, the profile measurement value is not interfered by the photoresist morphology in the measurement process, and the profile measurement value has few or even no invalid data, in some embodiments, the device for establishing the OPC model does not need to set a cleaning unit, does not need to clean the data, can effectively reduce the modeling time, and improves the modeling efficiency.
The profile measurement value is obtained by measuring the profile of the pattern of the patterned photoresist, so that interference of pattern edge burrs in the photoresist layer can be effectively avoided in the measurement process, the measurement precision can be effectively improved, and the high-precision profile measurement value can be obtained; the modeling unit 340 uses the profile measurement value with higher precision, and when the OPC model is built, the model error is smaller, the modeling speed is higher, and the modeling accuracy is better.
Specifically, an initial OPC model is disposed in the modeling unit 340, where the initial OPC model has a plurality of parameters to be fitted; according to the profile measurement value, the modeling unit 340 performs fitting calculation to obtain a value of the parameter to be fitted; the modeling unit 340 establishes the OPC model in combination with the initial OPC model according to the values of the parameters to be fitted.
It should be noted that, in some embodiments of the present invention, the device for establishing an OPC model further includes: a verification unit 350, said verification unit 350 being adapted to verify said OPC model.
The verification unit 350 may find software bugs (software bugs), design bugs (design bugs), and possibly also dead spots (hotspots).
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 including a 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 with the corrected layout to verify the OPC model.
In other embodiments, the modeling unit establishes the OPC model according to a partial number of profile measurement values; the verification unit performs optical proximity correction on the modeling layout based on the established OPC model to obtain a corrected layout; according to the profile measured value of the remaining part, the verification unit measures the corrected layout to obtain corrected measured values, wherein the corrected measured values correspond to the profile measured values of the remaining part one by one, and the profile measured values of the remaining part are the profile measured values which are not used in the process of establishing the OPC model; the verification unit compares the corrected measurement values with the corresponding profile measurement values to verify the OPC model.
Correspondingly, the invention also provides optical proximity correction equipment.
The optical proximity correction apparatus includes: an obtaining means 420, said obtaining means 420 being adapted to obtain a design layout; a build device 410, said build device 410 being adapted to build an OPC model, said build device 410 being a build device of the present invention; and the correction device 430 is suitable for correcting the design layout by using the OPC model to obtain a flow sheet layout.
Specifically, the obtaining device 420 obtains GDS (Geometry Summary Data) files of the design layout. The GDS file is used for defining the three-dimensional structure and electrical characteristics of the chip, and the GDS file contains geometric data about the chip structure, shape and hierarchical structure. For example, the design layout obtained by the obtaining device 420 is a design layout of a contact hole layer, that is, a GDS file of the design layout of the contact hole layer is obtained.
The establishing device 410 is an establishing device of the present invention, and the specific technical scheme of the establishing device 410 may refer to the foregoing embodiment of the establishing device of the OPC model, which is not described herein.
The correction device 430 corrects the design layout based on the OPC model to obtain a flow sheet layout.
The invention setting up device 410 is to set up an OPC model based on the contour measurement value after measuring the contour of the graph in the photoresist; the accuracy of the built OPC model is higher, so that the accuracy and the precision of the obtained flow sheet layout can be effectively improved by the correction device 430 based on the correction of the OPC model with higher accuracy and higher precision; particularly, in the design layout of the contact hole layer, the density of the contact hole pattern is relatively high, and by utilizing the OPC model, the correction device 430 corrects the design layout of the contact hole layer, thereby effectively improving the correction precision and accuracy and being beneficial to the formation of high-quality contact hole layers and high-quality contact hole structures.
Furthermore, the present invention provides a readable storage medium having stored thereon a computer program for execution by a processor for performing the steps of the inventive OPC model building method.
The computer program stored on the readable storage medium is executed by a processor to implement the steps of the OPC model building method of the present invention. For a specific technical solution of the readable storage medium, reference may be made to the foregoing embodiment of the OPC model building method, and the disclosure is not repeated herein.
In summary, after forming a semiconductor structure, obtaining a Contour (Contour) of a pattern in a patterned photoresist in the semiconductor structure, thereby measuring (Gauge) the Contour of the obtained pattern to obtain a measured value of the Contour; and then, according to the number profile measurement values, an OPC model is established. Compared with post-development measurement data obtained by directly measuring the pattern of the patterned photoresist, the method has the advantages that the outline of the pattern in the patterned photoresist is measured, interference of pattern edge burrs in the photoresist layer can be effectively avoided in the measuring process, the measuring precision can be effectively improved, and a high-precision outline measurement value can be obtained; the high-precision profile measurement value can provide a good data basis for the establishment of the OPC model, so that the error of the established OPC model can be effectively reduced, the establishment efficiency of the OPC model can be improved, and the correction precision of the optical proximity correction method can be improved.
Although the present invention is disclosed above, the present invention is not limited thereto. Various changes and modifications may be made by one skilled in the art without departing from the spirit and scope of the invention, and the scope of the invention should be assessed accordingly to that of the appended claims.
Claims (22)
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