CN115712227A

CN115712227A - Optical proximity effect correction method and device based on evanescent wave field strong attenuation characteristic modulation mode

Info

Publication number: CN115712227A
Application number: CN202211370699.1A
Authority: CN
Inventors: 韩丹丹; 韦亚一; 邓森
Original assignee: Institute of Microelectronics of CAS
Current assignee: Institute of Microelectronics of CAS
Priority date: 2022-11-03
Filing date: 2022-11-03
Publication date: 2023-02-24

Abstract

The application discloses a modulated optical proximity effect correction method and device based on evanescent wave field strong attenuation characteristics, and relates to the technical field of photoetching resolution enhancement. The method comprises the following steps: determining the effective action range of the near-field optical proximity effect on the target graph by modeling and analyzing the field intensity attenuation characteristic of the evanescent wave in the photoresist; taking the target pattern as an input image of surface plasma photoetching, and determining the accuracy of the target exposure pattern in the photoresist corresponding to the target pattern under a preset exposure condition and the target compensation exposure dose; determining an area needing compensation modulation on a target graph, and performing compensation correction on the near-field optical proximity effect based on the target compensation exposure dose within an effective action range to obtain a corrected correction graph; and taking the correction pattern as an input image, and comparing the contour of the correction exposure pattern extracted from the photoresist under the preset exposure condition to determine the accuracy of the correction exposure pattern and the cost function curve data.

Description

Optical proximity effect correction method and device based on evanescent wave field strong attenuation characteristic modulation mode

Technical Field

The application relates to the technical field of photoetching resolution enhancement, in particular to a modulated optical proximity effect correction method and device based on evanescent wave field strong attenuation characteristics.

Background

The photolithography technique is one of the key techniques in the process of manufacturing very large scale integrated circuits, and as the integration of chips is continuously increased and the feature size is continuously reduced, the requirements on the photolithography resolution and the quality of the exposed patterns are also higher and higher. The surface plasma lithography (plasma lithography) technology is a next-generation lithography technology with great development prospect, and provides an important method and a technical approach for developing a high-resolution, low-cost, high-efficiency and large-area nano lithography technology because the surface plasma lithography (plasma lithography) technology has the advantages of breaking through the resolution diffraction limit existing in the traditional optical lithography and needing no physical mask.

At present, experiments verify that the surface plasma lithography technology can meet the requirement of the micro-nano manufacturing field on the resolution of 14 nanometers (nm) and the following technical nodes, but with the further reduction of the feature size of an integrated circuit, the Near-field optical proximity effect (Near-field OPE) also becomes more serious, so that the resolution of an exposure pattern is greatly reduced, the distortion phenomenon of the final exposure pattern in a photoresist is sharply increased, the physical performance and the electrical performance of a manufactured nanometer device are deviated, the function and the yield of the product are further influenced, and the practical applicability of the surface plasma lithography technology is severely limited. Therefore, to meet the high performance requirements for the size and quality of nanostructured devices in integrated circuits, near-field OPE has become an important issue to be solved in surface plasma lithography.

In order to further improve the exposure performance of the surface plasma lithography technology and solve the problem of the effect of near-field OPE phenomenon on the quality of an exposed pattern in a photoresist, researchers have proposed various Resolution Enhancement Technologies (RET), which mainly include Optical proximity correction (Optical proximity correction) technology, off-axis illumination (OAI) technology, phase Shifting Mask (PSM) technology, sub-Resolution auxiliary pattern (SRAF) technology, and the like.

Although these resolution enhancement techniques can improve the quality of the exposed pattern in the photoresist to some extent, they have various problems such as long time, complicated operation, low accuracy, or high price. In addition, as the number of nodes of the nano lithography process is continuously reduced, the target pattern and the density are continuously improved, and a complex 2D pattern becomes a main type in the nano process layout, and by adopting these conventional resolution enhancement techniques, it is difficult to obtain a good exposure pattern on a silicon wafer by using a surface plasma lithography system under the condition of guaranteeing high resolution, so a method for improving the imaging resolution and the fidelity of the exposure pattern of the surface plasma lithography system is urgently needed.

Disclosure of Invention

The application aims to provide a modulation type optical proximity effect correction method and device based on evanescent wave field intensity attenuation characteristics, so as to solve the problems of low imaging resolution and low exposure pattern fidelity of the existing surface plasma lithography system.

In a first aspect, the present application provides a method for optical proximity correction based on modulation of evanescent wave field attenuation characteristics, the method comprising:

carrying out modeling analysis on three-dimensional field intensity distribution data reaching the surface of the photoresist in surface plasma photoetching, and determining a point spread function;

analyzing an exposure pattern of a two-dimensional pattern formed in the photoresist based on the point spread function, and determining a corresponding relation between the field intensity attenuation characteristic of the evanescent wave and the quality of the exposure pattern;

based on the corresponding relation between the field intensity attenuation characteristic and the quality of the exposure pattern, determining the effective action range of the near-field optical proximity effect on the target pattern by carrying out modeling analysis on the field intensity attenuation characteristic of the evanescent wave in the photoresist;

taking the target pattern as an input image of the surface plasma photoetching, and determining the accuracy of the target exposure pattern in the photoresist and the target compensation exposure dose corresponding to the target pattern under a preset exposure condition;

determining an area needing compensation modulation on the target graph, and performing compensation correction on the near-field optical proximity effect based on the target compensation exposure dose within the effective action range to obtain a corrected graph;

and taking the corrected graph as an input image, and comparing the contour of the corrected exposure graph extracted from the photoresist under the preset exposure condition to determine the accuracy of the corrected exposure graph and cost function curve data.

By adopting the technical scheme, the method for correcting the optical proximity effect based on the evanescent wave field strong attenuation characteristic modulation type provided by the embodiment of the application can be used for carrying out modeling analysis on three-dimensional field intensity distribution data reaching the surface of the photoresist in surface plasma lithography and determining a point spread function; analyzing an exposure pattern of a two-dimensional pattern formed in the photoresist based on the point spread function, and determining a corresponding relation between the field intensity attenuation characteristic of evanescent waves and the quality of the exposure pattern; based on the corresponding relation between the field intensity attenuation characteristic and the quality of the exposure pattern, determining the effective action range of the near-field optical proximity effect on the target pattern by carrying out modeling analysis on the field intensity attenuation characteristic of the evanescent wave in the photoresist; taking the target pattern as an input image of the surface plasma photoetching, and determining the accuracy of the target exposure pattern in the photoresist and the target compensation exposure dose corresponding to the target pattern under a preset exposure condition; determining an area needing compensation modulation on the target graph, and performing compensation correction on the near-field optical proximity effect based on the target compensation exposure dose within the effective action range to obtain a corrected graph; and taking the corrected graph as an input image, and comparing the contour of the corrected exposure graph extracted from the photoresist under the preset exposure condition to determine the accuracy of the corrected exposure graph and cost function curve data. The optimization method is an experimental verification model established based on the photoetching imaging model and the photoresist imaging model, so that the influence of the near-field optical proximity effect on the quality of an exposed graph in each process step in the surface plasma photoetching process can be reflected really, the remarkable effect of the surface evanescent wave attenuation characteristic specific to the surface plasma photoetching in the generation of the near-field optical proximity effect can be further verified, a feasible solution is provided for reducing the characteristic dimension error and improving the uniformity of the quality of the exposed graph, the optimization method has strong practical applicability, the calibration precision of the quality of the exposed graph can be effectively improved, the simulation complexity is effectively reduced, the calculation efficiency is improved, the practical applicability is very strong, and the optimization method has very important significance for further developing the research on the surface plasma photoetching system with low cost, large area and high exposure quality.

In a possible implementation manner, the analyzing, based on the point spread function, an exposure pattern of a two-dimensional pattern formed in the photoresist to determine a corresponding relationship between a field intensity attenuation characteristic of an evanescent wave and quality of the exposure pattern includes:

establishing a photoetching imaging model and a photoresist imaging model of the surface plasma photoetching;

determining a corresponding relation between exposure dose and exposure time based on the point spread function;

determining an exposure pattern of a two-dimensional pattern formed in the photoresist based on the corresponding relationship between the exposure dose and the exposure time;

and determining the corresponding relation between the field intensity attenuation characteristic of the evanescent wave and the quality of the exposure pattern based on the photoetching imaging model and the photoresist imaging model and combining the exposure pattern of the two-dimensional pattern.

In a possible implementation manner, the determining, by using the target pattern as an input image of the surface plasma lithography, the accuracy of a target exposure pattern in the photoresist and a target compensation exposure dose corresponding to the target pattern under a preset exposure condition includes:

taking the target pattern as an input image of the surface plasma photoetching, and extracting the outline of the target exposure pattern in the photoresist under a preset exposure condition;

determining an error value between the target pattern and the contour of the target exposure pattern, determining an accuracy of the target exposure pattern and a target compensation exposure dose based on the error value.

In one possible implementation, the corresponding relationship between the field intensity attenuation characteristic and the quality of the exposure pattern is that the optical proximity effect has the field intensity attenuation characteristic, and the quality of the exposure pattern varies with the field intensity attenuation characteristic.

In a possible implementation manner, the determining, based on the correspondence between the field intensity attenuation characteristic and the quality of the exposure pattern, an effective action range of the near-field optical proximity effect on the target pattern by performing modeling analysis on the field intensity attenuation characteristic of the evanescent wave in the photoresist includes:

based on the corresponding relation between the field intensity attenuation characteristic and the quality of the exposure pattern, determining the field intensity attenuation characteristic corresponding to the evanescent wave in the near field range to carry out quantitative analysis, and determining the corresponding relation between the space frequency in the photoresist and the near field intensity attenuation length;

and determining the effective action range of the near-field optical proximity effect on the target pattern based on the corresponding relation between the space frequency in the photoresist and the near-field intensity attenuation length.

In a possible implementation manner, the determining a region on the target pattern that needs to be compensated and modulated, and performing compensation correction on the near-field optical proximity effect based on the target compensation exposure dose within the effective action range to obtain a corrected correction pattern includes:

and determining an area needing compensation modulation on the target graph in a point-line-surface mode, and performing compensation correction on the near-field optical proximity effect by adopting a gradient descent algorithm in the effective action range to obtain the corrected graph.

In a possible implementation manner, the correspondence between the exposure dose and the exposure time includes:

wherein the psf represents the point spread function; said N is _exp Represents the total number of pixels, said B _n (x _i ,y _j ) A two-bit valued pixelized matrix representing the target graphic; said I _psf (x-x _i ,y-y _j ) Representing the optical field intensity distribution of the surface of the photoresist; said t is _n Denotes the exposure time, said D _arb (x, y) represents the exposure dose.

In one possible implementation manner, the correspondence between the spatial frequency in the photoresist and the attenuation length of the near field strength includes:

wherein, k is _z (z) represents the spatial frequency within the photoresist, and β (z) represents the near field strength decay length.

In one possible implementation, the establishing a photolithography imaging model and a photoresist imaging model of the surface plasma lithography includes:

acquiring the three-dimensional field intensity distribution data of the surface of the photoresist;

and establishing the photoetching imaging model and the photoresist imaging model based on the three-dimensional field intensity distribution data.

In a second aspect, the present application further provides an optical proximity correction apparatus based on evanescent wave field attenuation characteristic modulation, the apparatus is used to implement any one of the optical proximity correction methods based on evanescent wave field attenuation characteristic modulation described in the first aspect, the apparatus includes:

the first determining module is used for carrying out modeling analysis on three-dimensional field intensity distribution data reaching the surface of the photoresist in surface plasma photoetching and determining a point spread function;

the second determination module is used for analyzing an exposure pattern of a two-dimensional pattern formed in the photoresist based on the point spread function and determining the corresponding relation between the field intensity attenuation characteristic of the evanescent wave and the quality of the exposure pattern;

the third determination module is used for determining the effective action range of the near-field optical proximity effect on the target graph by carrying out modeling analysis on the field intensity attenuation characteristic of the evanescent wave in the photoresist based on the corresponding relation between the field intensity attenuation characteristic and the quality of the exposure graph;

a fourth determining module, configured to determine, using the target pattern as an input image of the surface plasma lithography, accuracy of a target exposure pattern in the photoresist corresponding to the target pattern under a preset exposure condition and a target compensation exposure dose;

a fifth determining module, configured to determine an area that needs compensation modulation on the target pattern, and perform compensation correction on the near-field optical proximity effect based on the target compensation exposure dose within the effective action range to obtain a corrected pattern;

and the sixth determining module is used for taking the corrected graph as an input image, comparing the contour of the corrected exposure graph extracted from the photoresist under the preset exposure condition, and determining the accuracy of the corrected exposure graph and cost function curve data.

In one possible implementation manner, the second determining module includes:

establishing a submodule for establishing a photoetching imaging model and a photoresist imaging model of the surface plasma photoetching;

the first determining submodule is used for determining the corresponding relation between the exposure dose and the exposure time based on the point spread function;

the second determining submodule is used for determining an exposure pattern of a two-dimensional pattern formed in the photoresist based on the corresponding relation between the exposure dose and the exposure time;

and the third determining submodule is used for determining the corresponding relation between the field intensity attenuation characteristic of the evanescent wave and the quality of the exposure pattern by combining the exposure pattern of the two-dimensional pattern based on the photoetching imaging model and the photoresist imaging model.

In one possible implementation manner, the fourth determining module includes:

the extraction submodule is used for taking the target pattern as an input image of the surface plasma photoetching and extracting the outline of the target exposure pattern in the photoresist under the preset exposure condition;

a fourth determining submodule for determining an error value between the target pattern and the contour of the target exposure pattern, and determining an accuracy of the target exposure pattern and a target compensation exposure dose based on the error value.

In one possible implementation manner, the third determining module includes:

a fifth determining submodule, configured to determine, based on a correspondence between the field intensity attenuation characteristic and the quality of the exposure pattern, that the field intensity attenuation characteristic corresponds to an evanescent wave in a near field range, perform quantitative analysis, and determine a correspondence between a spatial frequency in the photoresist and a near field intensity attenuation length;

and the sixth determining submodule is used for determining the effective action range of the near-field optical proximity effect on the target graph based on the corresponding relation between the space frequency in the photoresist and the near-field intensity attenuation length.

In one possible implementation manner, the fifth determining module includes:

and the seventh determining submodule is used for determining an area which needs to be subjected to compensation modulation on the target graph in a point-line-surface mode, and performing compensation correction on the near-field optical proximity effect by adopting a gradient descent algorithm in the effective action range to obtain the corrected correction graph.

In one possible implementation, the establishing sub-module includes:

the acquisition unit is used for acquiring the three-dimensional field intensity distribution data of the surface of the photoresist;

and the establishing unit is used for establishing the photoetching imaging model and the photoresist imaging model based on the three-dimensional field intensity distribution data.

The beneficial effects of the evanescent wave field strong attenuation characteristic modulation-based optical proximity effect correction apparatus provided in the second aspect are the same as those of the evanescent wave field strong attenuation characteristic modulation-based optical proximity effect correction method described in the first aspect or any one of the possible implementation manners of the first aspect, and are not described herein again.

Drawings

The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the application and together with the description serve to explain the application and not to limit the application. In the drawings:

fig. 1 shows a schematic flowchart of a modulated optical proximity correction method based on evanescent wave field strong attenuation characteristics according to an embodiment of the present application;

FIG. 2 is a schematic flow chart of another modulated optical proximity correction method based on evanescent wave field strong attenuation characteristics according to an embodiment of the present application;

FIG. 3 is a graph illustrating a near-field optical proximity effect at the center of a surface plasmon lithography technique according to an embodiment of the present application;

FIG. 4 is a diagram illustrating an effect of a near-field optical proximity effect on an exposed pattern quality according to an embodiment of the present disclosure;

FIG. 5 is a schematic diagram showing a target pattern and a comparison between the target pattern and a target exposure pattern in a photoresist obtained under a preset exposure condition according to an embodiment of the present application;

FIG. 6 is a schematic diagram illustrating an exposure dose compensation map provided by an embodiment of the present application;

FIG. 7 is a schematic diagram illustrating a comparison between a calibration pattern and a final exposure pattern obtained from the calibration pattern and an original pattern in a photoresist according to an embodiment of the present application;

fig. 8 shows a schematic structural diagram of an optical proximity correction apparatus modulated based on evanescent wave field strong attenuation characteristics according to an embodiment of the present application.

Detailed Description

In the embodiments of the present application, terms such as "first" and "second" are used to distinguish the same or similar items having substantially the same function and action. For example, the first threshold and the second threshold are only used for distinguishing different thresholds, and the sequence order of the thresholds is not limited. Those skilled in the art will appreciate that the terms "first," "second," and the like do not denote any order or importance, but rather the terms "first," "second," and the like do not denote any order or importance.

It is noted that, in the present application, words such as "exemplary" or "for example" are used to mean exemplary, illustrative, or descriptive. Any embodiment or design described herein as "exemplary" or "e.g.," is not necessarily to be construed as preferred or advantageous over other embodiments or designs. Rather, use of the word "exemplary" or "such as" is intended to present concepts related in a concrete fashion.

In the present application, "at least one" means one or more, "a plurality" means two or more. "and/or" describes the association relationship of the associated objects, meaning that there may be three relationships, e.g., a and/or B, which may mean: a exists alone, A and B exist simultaneously, and B exists alone, wherein A and B can be singular or plural. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship. "at least one of the following" or similar expressions refer to any combination of these items, including any combination of the singular or plural items. For example, at least one (one) of a, b, or c, may represent: a, b, c, a and b combination, a and c combination, b and c combination, or a, b and c combination, wherein a, b and c can be single or multiple.

At present, experiments verify that the surface plasma lithography technology can meet the requirement of the micro-nano manufacturing field on the resolution of 14 nanometers (nm) and the following technical node resolution, but with the further reduction of the feature size of an integrated circuit, the Near-field optical proximity effect (Near-field OPE) becomes more serious, so that the resolution of an exposure pattern is greatly reduced, the distortion phenomenon of the final exposure pattern in a photoresist is also sharply increased, the physical performance and the electrical property of the manufactured nanometer device have deviation, the function and the yield of the product are further influenced, and the practical applicability of the surface plasma lithography technology is severely limited. Therefore, to meet the high performance requirements for the size and quality of nanostructured devices in integrated circuits, near-field OPE has become an important issue to be solved in surface plasma lithography.

In order to further improve the exposure performance of the surface plasma lithography technology and solve the problem of the effect of near-field OPE phenomenon on the quality of an exposed pattern in a photoresist, researchers have proposed various Resolution Enhancement Technologies (RET), which mainly include an Optical Proximity Correction (OPC) technology, an Off-axis illumination (OAI) technology, a Phase Shifting Mask (PSM) technology, a Sub-Resolution auxiliary pattern (SRAF) technology, and the like.

Although these resolution enhancement techniques can improve the quality of the exposed pattern in the photoresist to some extent, they have various problems such as long time, complicated operation, low accuracy, or high price. In addition, with the continuous reduction of nano lithography technology nodes, the target pattern and density are continuously improved, complex 2D patterns have become the main type in nano process layouts, and by adopting the traditional resolution enhancement technology, a good exposure pattern on a silicon wafer is difficult to obtain by using a surface plasma lithography system under the condition of guaranteeing high resolution.

Therefore, it is necessary to develop a deep research on the generation mechanism and the physical calculation of near-field OPE in the surface plasma lithography system, so as to provide a solution to the problem accurately and efficiently, so as to achieve the purpose of further improving the imaging resolution and the exposure pattern fidelity of the surface plasma lithography system, and further meet the requirement of the integrated circuit process technology node on the surface plasma lithography imaging accuracy.

The current traditional optimization method for correcting the optical proximity effect of the two-dimensional image based on the pixels belongs to a 'rule-based' optical proximity effect correction method. The specific content is that after the imaging result of the Aerial image (initial image) after convolution between the Point Spread Function (PSF) of surface plasma photoetching and the binary image of the target pattern is quantitatively analyzed, the geometric error existing between the imaging contour of the Aerial image and the target pattern is found out, and a method for randomly modifying the geometric distribution of the original target pattern is provided, so that the problems of pattern distortion such as corner rounding, line width deviation, line end shortening and the like of an exposure pattern in photoresist are solved.

However, because the method is a 'rule-based' optical proximity effect correction method established based on the imaging characteristics of the space image after exposure of the target pattern and the geometric information of the local environment of the space image, although the method is easy to implement, the method can only correct the pattern distortion problem existing in the local area of the imaging result, and the method is difficult to implement global pattern correction along with the continuous increase of the complexity and the density of the target pattern. More importantly, because the quality of the exposed pattern in the final photoresist is also affected by the development time in the development process and the chemical reaction between the developing solution and the photoresist, and only by the optical proximity effect correction method based on the aerial image imaging result, the error between the exposed pattern in the final photoresist and the target pattern still exists after correction, and therefore, the accuracy of the method still needs to be improved.

In order to solve the problems, the method disclosed by the application discloses the generation mechanism of near-field OPE from the physical source, the influence of complex attenuation characteristics and field distribution asymmetry of Evanescent waves (Evanescent waves) on the edge feature size of an exposure pattern by quantitatively representing the special near-field enhancement effect of surface plasma lithography, and provides an optical proximity effect correction optimization method based on an Evanescent wave field strong attenuation characteristic modulation mode by jointly optimizing exposure dose and a target pattern from the mathematical relationship between lithography parameters and indexes representing the fidelity of the lithography pattern.

Fig. 1 shows a schematic flowchart of an optical proximity correction method based on evanescent wave field strong attenuation characteristic modulation provided by an embodiment of the present application, and as shown in fig. 1, the optical proximity correction method based on evanescent wave field strong attenuation characteristic modulation includes:

step 101: and carrying out modeling analysis on three-dimensional field intensity distribution data reaching the surface of the photoresist in surface plasma photoetching to determine a point spread function.

Step 102: and analyzing an exposure pattern of a two-dimensional pattern formed in the photoresist based on the point spread function, and determining the corresponding relation between the field intensity attenuation characteristic of the evanescent wave and the quality of the exposure pattern.

In the application, a photoetching imaging model and a photoresist imaging model of the surface plasma photoetching can be established; determining a corresponding relation between exposure dose and exposure time based on the point spread function; determining an exposure pattern of a two-dimensional pattern formed in the photoresist based on the corresponding relationship between the exposure dose and the exposure time; and determining the corresponding relation between the field intensity attenuation characteristic of the evanescent wave and the quality of the exposure pattern based on the photoetching imaging model and the photoresist imaging model and combining the exposure pattern of the two-dimensional pattern.

Wherein, the corresponding relation between the field intensity attenuation characteristic and the quality of the exposure pattern is that the optical proximity effect has the field intensity attenuation characteristic, and the quality of the exposure pattern changes along with the field intensity attenuation characteristic.

Step 103: and determining the effective action range of the near-field optical proximity effect on the target pattern by carrying out modeling analysis on the field intensity attenuation characteristic of the evanescent wave in the photoresist based on the corresponding relation between the field intensity attenuation characteristic and the quality of the exposure pattern.

In the application, the field intensity attenuation characteristic corresponding to the evanescent wave in the near field range can be determined for quantitative analysis based on the corresponding relation between the field intensity attenuation characteristic and the quality of the exposure pattern, and the corresponding relation between the space frequency in the photoresist and the near field intensity attenuation length can be determined; and determining the effective action range of the near-field optical proximity effect on the target pattern based on the corresponding relation between the space frequency in the photoresist and the near-field intensity attenuation length.

Step 104: and taking the target pattern as an input image of the surface plasma photoetching, and determining the accuracy of the target exposure pattern in the photoresist and the target compensation exposure dose corresponding to the target pattern under the preset exposure condition.

In the application, the target pattern may be used as an input image for the surface plasma lithography, and the profile of the target exposure pattern in the photoresist is extracted under a preset exposure condition; determining an error value between the target pattern and the profile of the target exposure pattern, and determining an accuracy of the target exposure pattern and a target compensation exposure dose based on the error value.

Step 105: and determining an area needing compensation modulation on the target graph, and performing compensation correction on the near-field optical proximity effect based on the target compensation exposure dose in the effective action range to obtain a corrected graph.

In the application, the region on the target pattern, which needs to be compensated and modulated, may be determined in a point-line-plane manner, and the near-field optical proximity effect is compensated and corrected by using a gradient descent algorithm within the effective action range, so as to obtain the corrected correction pattern.

Step 106: and taking the corrected graph as an input image, comparing the outlines of the corrected exposure graphs extracted from the photoresist under the preset exposure condition, and determining the accuracy of the corrected exposure graphs and cost function curve data.

In summary, modeling analysis can be performed on three-dimensional field intensity distribution data reaching the surface of the photoresist in surface plasma lithography, and a point spread function is determined; analyzing an exposure pattern of a two-dimensional pattern formed in the photoresist based on the point spread function, and determining a corresponding relation between the field intensity attenuation characteristic of the evanescent wave and the quality of the exposure pattern; based on the corresponding relation between the field intensity attenuation characteristic and the quality of the exposure pattern, determining the effective action range of the near-field optical proximity effect on the target pattern by carrying out modeling analysis on the field intensity attenuation characteristic of the evanescent wave in the photoresist; taking the target pattern as an input image of the surface plasma photoetching, and determining the accuracy of the target exposure pattern in the photoresist and the target compensation exposure dose corresponding to the target pattern under a preset exposure condition; determining an area which needs to be subjected to compensation modulation on the target graph, and performing compensation correction on the near-field optical proximity effect based on the target compensation exposure dose in the effective action range to obtain a corrected graph; and taking the corrected graph as an input image, comparing the outlines of the corrected exposure graphs extracted from the photoresist under the preset exposure condition, and determining the accuracy of the corrected exposure graphs and cost function curve data. The optimization method is an experimental verification model established based on the photoetching imaging model and the photoresist imaging model, so that the influence of the near-field optical proximity effect on the quality of an exposed graph in each process step in the surface plasma photoetching process can be reflected really, the remarkable effect of the surface evanescent wave attenuation characteristic specific to the surface plasma photoetching in the generation of the near-field optical proximity effect can be further verified, a feasible solution is provided for reducing the characteristic dimension error and improving the uniformity of the quality of the exposed graph, the optimization method has strong practical applicability, the calibration precision of the quality of the exposed graph can be effectively improved, the simulation complexity is effectively reduced, the calculation efficiency is improved, the practical applicability is very strong, and the optimization method has very important significance for further developing the research on the surface plasma photoetching system with low cost, large area and high exposure quality.

Fig. 2 is a schematic flowchart of another optical proximity correction method based on modulation of evanescent wave field strong attenuation characteristic according to an embodiment of the present application, where as shown in fig. 2, the optical proximity correction method based on modulation of evanescent wave field strong attenuation characteristic includes:

step 201: and carrying out modeling analysis on three-dimensional field intensity distribution data reaching the surface of the photoresist in surface plasma photoetching, and determining a point spread function.

In the application, the three-dimensional field intensity distribution finally reaching the surface of the photoresist after passing through the nano butterfly-junction aperture structure of the focusing element in the surface plasma lithography can be modeled and analyzed, and the three-dimensional field intensity distribution is used as a Point Spread Function (PSF) of a surface plasma lithography system.

Step 202: and analyzing an exposure pattern of a two-dimensional pattern formed in the photoresist based on the point spread function, and determining the corresponding relation between the field intensity attenuation characteristic of the evanescent wave and the quality of the exposure pattern.

In the application, a generation mechanism of a near-field optical proximity effect (near-field OPE) can be revealed by establishing a surface plasma photoetching imaging model and a photoresist imaging model and analyzing a final exposure pattern of a complex two-dimensional pattern in a photoresist.

Specifically, the step 202 is implemented by the following steps:

substep A1: and establishing a photoetching imaging model and a photoresist imaging model of the surface plasma photoetching.

The implementation process of the sub-step A1 may include: acquiring the three-dimensional field intensity distribution data of the surface of the photoresist; and establishing the photoetching imaging model and the photoresist imaging model based on the three-dimensional field intensity distribution data.

Substep A2: and determining the corresponding relation between the exposure dose and the exposure time based on the point spread function.

When a surface plasma lithography system performs exposure of any pattern, the exposure dose distribution required by the final exposure pattern in the photoresist is determined by the convolution relationship of the exposure dose modulation mapping between the Point Spread Function (PSF), the exposure time and the two-bit value pixelization matrix of the target pattern, that is, the corresponding relationship between the exposure dose and the exposure time, wherein the corresponding relationship between the exposure dose and the exposure time comprises:

Substep A3: and determining an exposure pattern of the two-dimensional pattern formed in the photoresist based on the corresponding relation between the exposure dose and the exposure time.

In the present application, an exposure pattern can be obtained only when the exposure dose in the photoresist reaches above the critical dose (Threshold dose) of the photoresist.

Fig. 3 is a graph illustrating a near-field Optical proximity effect at the center of a surface plasmon lithography technology provided in an embodiment of the present application, as shown in fig. 3, a vertical axis represents an irradiation dose (Exposure dose), which, after a Background effect (Background effect) is added, results in a change of a feature size from W to W ± Δ, and further, the Optical proximity effect (Optical proximity effect) can be regarded as a Background effect (Background effect) capable of affecting an Exposure dose, thereby affecting the feature size W of a target pattern.

Substep A4: and determining the corresponding relation between the field intensity attenuation characteristic of the evanescent wave and the quality of the exposure pattern based on the photoetching imaging model and the photoresist imaging model and combining the exposure pattern of the two-dimensional pattern.

The corresponding relation between the field intensity attenuation characteristic and the quality of the exposure pattern is that the optical proximity effect has the field intensity attenuation characteristic, and the quality of the exposure pattern changes along with the field intensity attenuation characteristic.

Fig. 4 is a schematic diagram illustrating an influence of a near-field optical proximity effect on quality of an exposure Pattern provided in an embodiment of the present application, as shown in fig. 4, scanning (Scanning) is performed based on an Isointensity contour Point Spread Function (PSF), and exposing a Target Pattern (Target Pattern) to obtain an exposure Pattern (Pattern profile) of a two-dimensional Pattern formed in a photoresist, and further, analyzing a Cross-section of the exposure Pattern (Cross-section of the Pattern profile), a longitudinal axis of which represents a Dose (Dose), wherein when an exposure Dose in the photoresist reaches above a critical Dose (Threshold Dose) of the photoresist, the exposure Pattern can be obtained, and the Point Spread Function (PSF) of surface plasmon lithography has a relatively complex field intensity distribution and field intensity attenuation characteristic, and receives an influence of geometric characteristics of a nano butterfly-junction aperture structure, and the distribution of the point spread function also has an asymmetric line on a plane, and the influence of the point spread function also has a relatively complex field intensity distribution and field intensity attenuation characteristic, so that the influence of the edge and the edge line width of the exposure Pattern also has a relatively complex field intensity attenuation characteristic, and the influence of the edge line width of the exposure Pattern is not symmetric, such as a reduction problem of a line width of the exposure Pattern. It can thus be determined that the optical proximity effect has the field intensity attenuation characteristic, and the quality of the exposure pattern varies with the field intensity attenuation characteristic.

Step 203: and determining the field intensity attenuation characteristic corresponding to the evanescent wave in the near field range for quantitative analysis based on the corresponding relation between the field intensity attenuation characteristic and the quality of the exposure pattern, and determining the corresponding relation between the space frequency in the photoresist and the near field intensity attenuation length.

In the application, the field intensity attenuation characteristic of evanescent waves in the photoresist can be modeled and analyzed to determine the effective action range of the near-field optical proximity effect on a target graph, the Point Spread Function (PSF) of surface plasma lithography determines the field intensity distribution in the photoresist, the PSF mainly consists of the evanescent waves in the near-field range, the high-frequency energy carried by the evanescent waves can be rapidly lost due to the near-field attenuation characteristic of the evanescent waves, the high-frequency loss conditions of the frequency spectrum after being filtered by an exposure system are different due to different characteristic sizes and different proximity effects generated under the graphs, the lost high-frequency imaging information is different, and the exposed graphs have different optical proximity distortions. Therefore, the near-field attenuation characteristic of the evanescent wave can be quantitatively analyzed, and the relation that high-frequency information is attenuated along with the exposure depth can be established. According to an exposure model of a near-field lithography system, the following relationship exists between spatial frequency (kz) in the photoresist and near-field intensity decay length (decap length, β (z)):

Therefore, the physical mechanism of the near-field optical proximity effect existing in the surface plasma photoetching system can be determined to be mainly generated by loss of high-frequency information carried by the near-field attenuation characteristic that evanescent waves in photoresist are rapidly attenuated along with increase of the exposure depth.

It should be noted that the physical mechanism is completely different from the loss of high frequency information caused by diffraction limit or physical characteristics of the exposure element/structure in the conventional optical lithography system, and the discovery of the physical mechanism can provide theoretical support for providing an optical proximity effect correction method that fundamentally and effectively improves the quality of the exposed pattern.

Step 204: and determining the effective action range of the near-field optical proximity effect on the target pattern based on the corresponding relation between the space frequency in the photoresist and the near-field intensity attenuation length.

Step 205: and taking the target pattern as an input image of the surface plasma photoetching, and extracting the outline of the target exposure pattern in the photoresist under a preset exposure condition.

The preset exposure condition is also the optimal exposure condition, and the specific numerical value of the preset exposure condition is not limited in the embodiment of the application and can be adjusted according to the actual application scene.

Fig. 5 shows a schematic diagram of a Target Pattern and a comparison between the Target Pattern and the Target Pattern in the photoresist obtained under a preset exposure condition according to the embodiment of the present application, where fig. 5 (a) shows the Target Pattern, and fig. 5 (b) shows a profile of the Target Pattern (Pattern profile) formed in the photoresist under an optimal exposure condition by exposing the Target Pattern (Target Pattern).

Step 206: determining an error value between the target pattern and the contour of the target exposure pattern, determining an accuracy of the target exposure pattern and a target compensation exposure dose based on the error value.

In the present application, with reference to fig. 5, the error value between the profile of the target exposure pattern and the target pattern may be compared, the accuracy of the final exposure pattern, that is, the target exposure pattern, may be calculated, a compensation map that needs exposure dose modulation may be obtained, and the target compensation exposure dose may be determined through the compensation map.

Fig. 6 is a schematic diagram of an exposure dose compensation map provided by an embodiment of the present application, and as shown in fig. 6, a compensated exposure dose corresponding to each position requiring exposure compensation can be determined according to the exposure dose compensation map.

Step 207: and determining an area needing compensation modulation on the target graph, and performing compensation correction on the near-field optical proximity effect based on the target compensation exposure dose in the effective action range to obtain a corrected graph.

Step 208: and taking the corrected graph as an input image, comparing the outlines of the corrected exposure graphs extracted from the photoresist under the preset exposure condition, and determining the accuracy of the corrected exposure graphs and cost function curve data.

In the method, the correction graph can be used as an input image, the contour of the final exposure graph in the photoresist obtained under the optimal exposure condition is compared with the original target graph, and the accuracy and the cost function curve of the final exposure graph are calculated. Therefore, compared with other optical proximity effect correction optimization methods, the optical proximity effect correction optimization method provided by the application is more suitable for being applied to processing of complex two-dimensional patterns and large-area exposure patterns, and the practical applicability of the surface plasma lithography process is further improved.

Fig. 7 shows a schematic diagram comparing a corrected Pattern and a final exposure Pattern obtained from the corrected Pattern in a photoresist with an original Pattern, for example, fig. 7 (a) shows the corrected Pattern, and fig. 7 (b) shows a schematic diagram of a Target Pattern (Target Pattern), that is, the original Pattern, and a Target exposure Pattern (Pattern profile) formed in the photoresist under an optimal exposure condition, that is, the profile of the final exposure Pattern.

The application aims to provide an optical proximity effect correction optimization method which can quantitatively analyze physical sources generated by near-field optical proximity effects in a surface plasma photoetching process and accurately correct the physical sources. The influence of the field intensity distribution of a point spread function and the attenuation characteristic thereof on the quality of an exposure pattern in the photoresist is quantitatively analyzed by establishing a three-dimensional photoetching imaging model and a photoresist imaging model of surface plasma photoetching, and the physical source generated by the near-field optical proximity effect is revealed to be mainly generated due to the fact that evanescent waves are continuously increased along the exposure depth in the photoresist to cause the high-frequency information to be rapidly lost. And providing a calculation formula of attenuation length which changes along with the exposure depth, and quantitatively analyzing the influence range of the field intensity attenuation characteristic of the evanescent wave on the target graph, and providing an optical proximity effect correction optimization method based on the exposure dose compensation principle on the basis.

In summary, the method for correcting the optical proximity effect based on the modulation type of the evanescent wave field strong attenuation characteristic provided by the embodiment of the present application can perform modeling analysis on three-dimensional field intensity distribution data reaching the surface of the photoresist in surface plasma lithography, and determine a point spread function; analyzing an exposure pattern of a two-dimensional pattern formed in the photoresist based on the point spread function, and determining a corresponding relation between the field intensity attenuation characteristic of the evanescent wave and the quality of the exposure pattern; based on the corresponding relation between the field intensity attenuation characteristic and the quality of the exposure pattern, determining the effective action range of the near-field optical proximity effect on the target pattern by carrying out modeling analysis on the field intensity attenuation characteristic of the evanescent wave in the photoresist; taking the target pattern as an input image of the surface plasma photoetching, and determining the accuracy of the target exposure pattern in the photoresist and the target compensation exposure dose corresponding to the target pattern under a preset exposure condition; determining an area needing compensation modulation on the target graph, and performing compensation correction on the near-field optical proximity effect based on the target compensation exposure dose within the effective action range to obtain a corrected graph; and taking the corrected graph as an input image, comparing the outlines of the corrected exposure graphs extracted from the photoresist under the preset exposure condition, and determining the accuracy of the corrected exposure graphs and cost function curve data. The optimization method is an experimental verification model established based on the photoetching imaging model and the photoresist imaging model, so that the influence of the near-field optical proximity effect on the quality of an exposed graph in each process step in the surface plasma photoetching process can be reflected really, the remarkable effect of the surface evanescent wave attenuation characteristic specific to the surface plasma photoetching in the generation of the near-field optical proximity effect can be further verified, a feasible solution is provided for reducing the characteristic dimension error and improving the uniformity of the quality of the exposed graph, the optimization method has strong practical applicability, the calibration precision of the quality of the exposed graph can be effectively improved, the simulation complexity is effectively reduced, the calculation efficiency is improved, the practical applicability is very strong, and the optimization method has very important significance for further developing the research on the surface plasma photoetching system with low cost, large area and high exposure quality.

Fig. 8 shows a schematic structural diagram of an optical proximity correction apparatus based on evanescent wave field strong attenuation characteristic modulation provided in an embodiment of the present application, for implementing any one of the optical proximity correction methods based on evanescent wave field strong attenuation characteristic modulation described in the present application, as shown in fig. 8, the optical proximity correction apparatus 300 based on evanescent wave field strong attenuation characteristic modulation includes:

the first determining module 301 is configured to perform modeling analysis on three-dimensional field intensity distribution data reaching the surface of a photoresist in surface plasma lithography, and determine a point spread function;

a second determining module 302, configured to analyze an exposure pattern of a two-dimensional pattern formed in the photoresist based on the point spread function, and determine a correspondence between field intensity attenuation characteristics of an evanescent wave and quality of the exposure pattern;

a third determining module 303, configured to determine an effective acting range of the near-field optical proximity effect on the target pattern by performing modeling analysis on the field attenuation characteristic of the evanescent wave in the photoresist based on the correspondence between the field attenuation characteristic and the quality of the exposure pattern;

a fourth determining module 304, configured to determine, by using the target pattern as an input image of the surface plasma lithography, accuracy of a target exposure pattern in the photoresist corresponding to the target pattern under a preset exposure condition and a target compensation exposure dose;

a fifth determining module 305, configured to determine an area that needs to be compensated and modulated on the target pattern, and perform compensation and correction on the near field optical proximity effect based on the target compensation exposure dose within the effective acting range, so as to obtain a corrected pattern;

a sixth determining module 306, configured to use the corrected pattern as an input image, and compare the profile of the corrected exposure pattern extracted from the photoresist under the preset exposure condition, so as to determine the accuracy of the corrected exposure pattern and the cost function curve data.

In one possible implementation manner, the second determining module includes:

In one possible implementation manner, the fourth determining module includes:

In one possible implementation manner, the third determining module includes:

In one possible implementation manner, the fifth determining module includes:

wherein the psf represents the point spread function; said N is _exp Represents the total number of pixels, said B _n (x _i ,y _j ) A two-bit valued pixelized matrix representing the target graphic; said I _psf (x-x _i ,y-y _j ) Representing the optical field intensity distribution of the surface of the photoresist; the above-mentionedt _n Denotes the exposure time, said D _arb (x, y) represents the exposure dose.

In one possible implementation, the establishing sub-module includes:

The optical proximity effect correction device based on the evanescent wave field strong attenuation characteristic modulation type can be used for carrying out modeling analysis on three-dimensional field intensity distribution data reaching the surface of a photoresist in surface plasma photoetching and determining a point spread function; analyzing an exposure pattern of a two-dimensional pattern formed in the photoresist based on the point spread function, and determining a corresponding relation between the field intensity attenuation characteristic of the evanescent wave and the quality of the exposure pattern; based on the corresponding relation between the field intensity attenuation characteristic and the quality of the exposure pattern, determining the effective action range of the near-field optical proximity effect on the target pattern by carrying out modeling analysis on the field intensity attenuation characteristic of the evanescent wave in the photoresist; taking the target pattern as an input image of the surface plasma photoetching, and determining the accuracy of the target exposure pattern in the photoresist and the target compensation exposure dose corresponding to the target pattern under a preset exposure condition; determining an area needing compensation modulation on the target graph, and performing compensation correction on the near-field optical proximity effect based on the target compensation exposure dose within the effective action range to obtain a corrected graph; and taking the corrected graph as an input image, comparing the outlines of the corrected exposure graphs extracted from the photoresist under the preset exposure condition, and determining the accuracy of the corrected exposure graphs and cost function curve data. The optimization method is an experimental verification model established based on the photoetching imaging model and the photoresist imaging model, so that the influence of the near-field optical proximity effect on the quality of an exposed graph in each process step in the surface plasma photoetching process can be reflected really, the remarkable effect of the surface evanescent wave attenuation characteristic specific to the surface plasma photoetching in the generation of the near-field optical proximity effect can be further verified, a feasible solution is provided for reducing the characteristic dimension error and improving the uniformity of the quality of the exposed graph, the optimization method has strong practical applicability, the calibration precision of the quality of the exposed graph can be effectively improved, the simulation complexity is effectively reduced, the calculation efficiency is improved, the practical applicability is very strong, and the optimization method has very important significance for further developing the research on the surface plasma photoetching system with low cost, large area and high exposure quality.

The optical proximity effect correction device based on the evanescent wave field strong attenuation characteristic modulation type provided by the application can realize the optical proximity effect correction method based on the evanescent wave field strong attenuation characteristic modulation type shown in any one of fig. 1 to fig. 7, and is not described herein again in order to avoid repetition.

While the present application has been described in connection with various embodiments, other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed application, from a review of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the word "a" or "an" does not exclude a plurality. A single processor or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Although the present application has been described in conjunction with specific features and embodiments thereof, it will be evident that various modifications and combinations can be made thereto without departing from the spirit and scope of the application. Accordingly, the specification and figures are merely exemplary of the present application as defined in the appended claims and are intended to cover any and all modifications, variations, combinations, or equivalents within the scope of the present application. It will be apparent to those skilled in the art that various changes and modifications may be made in the present application without departing from the spirit and scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include such modifications and variations.

Claims

1. A method for correcting optical proximity effect based on evanescent wave field strong attenuation characteristic modulation mode is characterized by comprising the following steps:

and taking the corrected graph as an input image, comparing the outlines of the corrected exposure graphs extracted from the photoresist under the preset exposure condition, and determining the accuracy of the corrected exposure graphs and cost function curve data.

2. The method as claimed in claim 1, wherein the analyzing the exposure pattern of the two-dimensional pattern formed in the photoresist based on the point spread function to determine the corresponding relationship between the field intensity attenuation characteristic of the evanescent wave and the quality of the exposure pattern comprises:

and determining the corresponding relation between the field intensity attenuation characteristic of the evanescent wave and the quality of the exposure pattern by combining the exposure pattern of the two-dimensional pattern based on the photoetching imaging model and the photoresist imaging model.

3. The method of claim 1, wherein determining the accuracy of the target exposure pattern in the photoresist and the target compensation exposure dose corresponding to the target pattern under a preset exposure condition using the target pattern as an input image of the surface plasma lithography comprises:

4. The method of claim 1, wherein said field strength attenuation characteristic and exposure pattern quality are related such that said optical proximity effect has said field strength attenuation characteristic, and said exposure pattern quality varies with said field strength attenuation characteristic.

5. The method as claimed in claim 4, wherein the determining the effective action range of the near-field optical proximity effect on the target pattern by performing modeling analysis on the field attenuation characteristic of the evanescent wave in the photoresist based on the corresponding relationship between the field attenuation characteristic and the quality of the exposure pattern comprises:

determining the field intensity attenuation characteristic corresponding to the evanescent wave in the near field range for quantitative analysis based on the corresponding relation between the field intensity attenuation characteristic and the quality of the exposure pattern, and determining the corresponding relation between the space frequency in the photoresist and the near field intensity attenuation length;

6. The method of claim 1, wherein the determining the region of the target pattern that needs compensation modulation, and performing compensation correction on the near-field optical proximity effect based on the target compensation exposure dose within the effective action range to obtain a corrected correction pattern comprises:

7. The method of claim 2, wherein said exposure dose to exposure time correspondence comprises:

wherein the psf represents the point spread functionCounting; said N is _exp Represents the total number of pixels, said B _n (x _i ,y _j ) A two-bit valued pixelized matrix representing the target graphic; said I _psf (x-x _i ,y-y _j ) Representing the optical field intensity distribution of the surface of the photoresist; said t is _n Denotes the exposure time, said D _arb (x, y) represents the exposure dose.

8. The method of claim 5, wherein the mapping of spatial frequency within the photoresist to near field strength decay length comprises:

9. The method of claim 2, wherein said creating a lithography imaging model and a photoresist imaging model of said surface plasma lithography comprises:

10. An optical proximity correction device based on evanescent wave field strong attenuation characteristic modulation mode, which is used for realizing the optical proximity correction method based on evanescent wave field strong attenuation characteristic modulation mode as claimed in any one of claims 1 to 9, and the device comprises:

and the sixth determining module is used for taking the corrected graph as an input image, comparing the outlines of the corrected exposure graphs extracted from the photoresist under the preset exposure condition, and determining the accuracy of the corrected exposure graphs and cost function curve data.