Lithography simulation model construction method and related equipment

Abstract

The invention provides a photoetching simulation model construction method and related equipment, and the construction method comprises the steps: obtaining a design drawing, splitting the design drawing into at least two mask patterns, and enabling the at least two mask patterns to be overlapped in a connection region; constructing a corresponding optical model for each mask pattern, wherein the optical model is used for describing the light field distribution of the corresponding mask pattern in the photoetching process; according to the connection relation of the at least two mask patterns, combining the corresponding optical models to obtain an optical synthesis model; and constructing a photoresist model based on the optical synthesis model, wherein the photoresist model is used for describing the forming process of a photoresist pattern. According to the construction method, the optical model is constructed for each mask pattern to describe the overall influence of each mask pattern on the exposure and development area of the photoresist during exposure, so that the purpose of simulating the exposure process under a double exposure process is achieved, the accuracy of the simulation result of the optical synthesis model is improved, and the defect risk in chip manufacturing is further reduced.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor manufacturing technologies, and in particular, to a method for constructing a lithography simulation model, a computer program product, a computer-readable storage medium, and a computer device. Background Art

[0002] In the manufacturing of a system on chip (SoC), when the chip area exceeds the single-exposure limit of a lithography machine (26 mm × 33 mm), a double-exposure process (LLE, Litho-Litho-Etch) needs to be adopted. This process performs two exposures on a single layer of photoresist using two sets of special masks, and forms a target pattern by the superposition of light intensities. The special mask is composed of a light-transmitting quartz substrate, an exposure area composed of a light-shielding material (Cr and MoSi), and a light-shielding layer (Cr) in the non-exposure area outside. The purpose is to avoid the interference of stray light during the two exposures. However, in the existing lithography simulation models, the modeling of the aerial image (AI) and the resist image (RI) is usually based on the single-exposure process. Especially in the modeling of the aerial image, the tone type of the mask is composed of the polygon tone type of the exposure area and the filedtone type of the field area, and does not include the non-exposure area outside the mask, so the non-linear superposition effect of the light intensities of the two exposures in the double-exposure process is not considered, and the influence of the mask polarity difference on the development kinetics is ignored. As a result, the key parameters of the double-exposure process (such as the exposure dose and the alignment accuracy of the special mask) are difficult to accurately optimize through simulation, increasing the defect risk in chip manufacturing. Summary of the Invention

[0003] In view of the above problems, the present invention is proposed to provide a method for constructing a lithography simulation model, a computer program product, a computer-readable storage medium, and a computer device that overcome the above problems or at least partially solve the above problems.

[0004] An object of the present invention is to solve the problem that the existing lithography simulation model is not applicable to the double-exposure process, so as to achieve the purpose of simulating the exposure process under the double-exposure process.

[0005] Specifically, the present invention provides a method for constructing a lithography simulation model, including:

[0006] Obtaining a design drawing and splitting the design drawing into at least two mask drawings, and at least two of the mask drawings overlap in a connection area;

[0007] Constructing a corresponding optical model for each of the mask drawings, where the optical model is used to describe the light field distribution of the corresponding mask drawing in the lithography process;

[0008] Merge the corresponding optical models according to the connection relationships of at least two of the mask patterns to obtain an optically synthesized model;

[0009] Construct a photoresist model based on the optically synthesized model, where the photoresist model is used to describe the formation process of a photoresist pattern.

[0010] Optionally, the step of constructing the optical model for the mask pattern includes:

[0011] Generate exposure-type polarity parameters for each of the mask patterns, where the exposure-type polarity parameters include: pattern parameters and field parameters, or pattern parameters, field parameters, and light-shielding parameters; where the pattern parameters are used to characterize the light transmittance of the pattern region in the mask pattern, the field parameters are used to characterize the light transmittance of the blank region in the mask pattern, and the light-shielding parameters are used to characterize the light-blocking rate of the light-blocking region outside the mask pattern;

[0012] Construct the optical model corresponding to each of the exposure-type polarity parameters.

[0013] Optionally, the step of constructing the optical model for the mask pattern further includes:

[0014] Generate light-blocking-type polarity parameters for at least one of the mask patterns, where the light-blocking-type polarity parameters are composed of the light-shielding parameters and the field parameters;

[0015] Construct the optical model corresponding to each of the light-blocking-type polarity parameters, denoted as the light-blocking-type optical model; and,

[0016] The step of merging the optical models includes:

[0017] Merge the light-blocking-type optical model corresponding to at least one of at least two of the mask patterns and the exposure-type optical model corresponding to the others to obtain the optically synthesized model, denoted as the light-blocking-type optically synthesized model; where the exposure-type optical model is the optical model corresponding to the exposure-type polarity parameters of each of the mask patterns; and,

[0018] The step of constructing the photoresist model includes:

[0019] Construct the photoresist model based on the light-blocking-type optically synthesized model, denoted as the light-blocking-type photoresist model; the light-blocking-type photoresist model is at least used to describe the formation process of at least one boundary pattern in the connection region on the photoresist.

[0020] Optionally, the step of obtaining the light-blocking-type optically synthesized model includes:

[0021] When the patterns of at least two of the mask patterns are the same, merge the light-shielding optical model corresponding to one of the same-patterned ones and the exposure optical model corresponding to the others to obtain one light-shielding optical composite model; and,

[0022] The step of constructing the light-shielding photoresist model includes:

[0023] Construct one light-shielding photoresist model based on one light-shielding optical composite model, and one light-shielding photoresist model is at least used to describe the formation process of all boundary patterns of all the same mask patterns in the connection area on the photoresist.

[0024] Optionally, constructing a photoresist model based on the optical composite model includes:

[0025] Construct the multiple-exposure area of the photoresist model based on the optical composite model, and the multiple-exposure area corresponds to the connection area of at least two mask patterns;

[0026] Construct at least one single-exposure area of the photoresist model based on at least one of the optical models, and each single-exposure area corresponds to an independent area of one mask pattern, and the independent area is located outside the connection area.

[0027] Optionally, when the patterns of at least two mask patterns are the same, after constructing the corresponding optical model for each mask pattern, it further includes:

[0028] Construct the single-exposure area of the photoresist model based on the optical model corresponding to one of at least two mask patterns with the same pattern, and the single-exposure area corresponds to the independent areas of all the same-patterned ones, and the independent areas are located outside the connection area.

[0029] Optionally, when the design drawing is split into at least three mask patterns, the connection areas of any two of the mask patterns overlap, or at least three of them overlap in the same connection area.

[0030] According to another aspect of the present invention, there is also provided a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the steps of the above-mentioned photolithography simulation model construction method are implemented.

[0031] According to still another aspect of the present invention, there is also provided a computer program product, including a computer program, and when the computer program is executed by a processor, the steps of the above-mentioned photolithography simulation model construction method are implemented.

[0032] According to another aspect of the present invention, there is also provided a computer device, including a memory, a processor, and a computer program stored on the memory, wherein the processor executes the computer program to implement the steps of the above-mentioned lithography simulation model construction method.

[0033] The lithography simulation model construction method of the present invention constructs an optical model for each mask pattern to describe the overall influence of each mask pattern on the exposure and development area of the photoresist during exposure, achieving the purpose of simulating the exposure process under double exposure process, improving the accuracy of the simulation results of the optical synthesis model, and further reducing the defect risk in chip manufacturing.

[0034] Those skilled in the art will become more apparent about the above and other objects, advantages, and features of the present invention according to the following detailed description of specific embodiments of the present invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Some specific embodiments of the present invention will be described in detail hereinafter with reference to the accompanying drawings in an exemplary but not restrictive manner. The same reference numerals in the drawings denote the same or similar components or parts. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings:

[0036] Figure 1 is a flowchart of the construction method according to an embodiment of the present invention;

[0037] Figure 2 is a flowchart of constructing an exposure-type optical model of the construction method according to an embodiment of the present invention;

[0038] Figure 3 is a flowchart of constructing an exposure-type optical model of the construction method according to another embodiment of the present invention;

[0039] Figure 4 is a flowchart of constructing a light-blocking-type optical model of the construction method according to an embodiment of the present invention;

[0040] Figure 5 is a flowchart of constructing a single-exposure area of the construction method according to an embodiment of the present invention;

[0041] Figure 6 is a flowchart of constructing a photoresist mask model of the construction method according to an embodiment of the present invention;

[0042] Figure 7 is a flowchart of constructing a multiple-exposure area and a single-exposure area of the construction method according to an embodiment of the present invention;

[0043] Figure 8Schematic front view of a customized mask according to a construction method of an embodiment of the present invention;

[0044] Figure 9 Schematic cross-sectional view of a customized mask according to a construction method of an embodiment of the present invention;

[0045] Figure 10 Schematic flowchart of forming an exposure and development area according to a construction method of an embodiment of the present invention;

[0046] Figure 11 Schematic frame diagram of an exposure and development area according to a construction method of an embodiment of the present invention;

[0047] Figure 12 Schematic flowchart of forming an exposure and development area according to a construction method of another embodiment of the present invention;

[0048] Figure 13 Schematic flowchart of forming an exposure and development area according to a construction method of still another embodiment of the present invention;

[0049] Figure 14 Schematic diagram of a computer program product according to an embodiment of the present invention;

[0050] Figure 15 Schematic diagram of a computer-readable storage medium according to an embodiment of the present invention; and

[0051] Figure 16 Schematic diagram of a computer device according to an embodiment of the present invention. Detailed implementation manners

[0052] An object of the present invention is to solve the problem that the existing lithography simulation model is not applicable to the double-exposure process, so as to improve the accuracy of simulating the exposure process under the double-exposure process. As Figure 1 shown, the lithography simulation model construction method of the present invention generally may include:

[0053] S100, obtaining a design drawing and splitting the design drawing into at least two mask drawings, and the at least two mask drawings overlap in a connection area;

[0054] S200, respectively constructing corresponding optical models for each mask drawing, and the optical models are used to describe the light field distribution of the corresponding mask drawing in the lithography process;

[0055] S300, merging the corresponding optical models according to the connection relationship of the at least two mask drawings to obtain an optical synthesis model;

[0056] S400, constructing a photoresist model based on the optical synthesis model, and the photoresist model is used to describe the formation process of the photoresist pattern.

[0057] A System on Chip (SoC) is also known as a "system on a chip". It is a system or product formed by combining multiple integrated circuits with specific functions on a single chip, which includes a complete hardware system and the embedded software it carries. The System on Chip will simultaneously include the content of "integrated circuits" and "chips", such as the design of integrated circuits, system integration, chip design, production, packaging, testing, etc. The System on Chip emphasizes more on being a whole. That is to say, on a single chip, the function of an electronic system can be completed, while this system often required one or more circuit boards, as well as various electronic devices, chips, and interconnections on the board to cooperate to achieve in the past.

[0058] The System on Chip generally has the following characteristics:

[0059] First, more supporting circuits are integrated on a single chip, saving the area of the integrated circuit and thus the cost. Second, on-chip interconnection enables the information transmission between devices that were originally distributed on the circuit board to be concentrated in the same chip, greatly improving the signal transmission speed. Third, due to the integration of many different functional modules, the area of a single chip is relatively large, even larger than the exposure size limit of current mainstream lithography machines (such as 26mm × 33mm).

[0060] Due to the relatively large area of a single chip, the Litho-Litho-Etch (LLE) process is often introduced during the manufacturing of the System on Chip. The Litho-Litho-Etch process usually involves performing two exposures on the wafer covered with photoresist. These two exposures are carried out on the same layer of photoresist, but two different special masks are used. The superposition of the light intensities of the two exposures generates the required pattern on the photoresist. After the two exposures, the photoresist on the wafer needs to be baked and developed. After development, the wafer also needs to be etched to generate the required pattern on the wafer. The overall manufacturing process flow of this chip can be abbreviated as: photoresist coating - exposure 1 - exposure 2 - development - etching.

[0061] Please refer to Figures 8 - 9, a customized reticle 400 generally includes an exposure area 410 and a light-shielding area 420 (also known as a non-exposure area). The exposure area 410 is usually composed of a graphic area 411 (polygon) and a blank area 412 (field) with different light transmittance. The graphic area 411 is used to form a graphic polarity (polygon tone type) of light during exposure and affects the light intensity distribution projected onto the photoresist. The blank area 412 forms a field polarity (field tone type) and affects the light intensity distribution projected onto the photoresist. According to different mask processes, the graphic area 411 and the blank area 412 can have different light-transmitting properties. Taking the positive mask process as an example, the graphic area 411 can be fully transparent (light transmittance close to 1), and the blank area 412 can be semi-transparent (for example, the light transmittance is between 0.06 - 0.28) or opaque (light transmittance close to 0). The light-shielding area 420 is arranged on the outer periphery of the exposure area 410, and a strong light-shielding layer made of an opaque (light transmittance close to 0) material is usually set to greatly reduce the light passing through the light-shielding area 420 during exposure and reduce its influence on the photoresist. However, the light-shielding area 420 cannot completely avoid light passing through. During exposure, it will form a light-shielding polarity (block tone type) of light and affect the light intensity distribution projected onto the photoresist.

[0062] Taking the example of using two customized reticles, during exposure, the exposure area of the first customized reticle can be mapped to the first exposure and development partition on the photoresist, and the exposure area of the second customized reticle can be mapped to the second exposure and development partition on the photoresist. The combination of the first exposure and development partition and the second exposure and development partition can constitute the complete exposure and development area of the photoresist. However, in actual use, due to reasons such as diffraction, interference, and scattering, the light near the edge of the exposure area of the first customized reticle may enter some areas of the second exposure and development partition outside the first exposure and development partition of the photoresist, and the light near the edge of the exposure area of the second customized reticle may also enter some areas of the first exposure and development partition outside the second exposure and development partition of the photoresist. In addition, the light in the light-shielding area of the first customized reticle will be projected onto the second exposure and development partition, and the light in the light-shielding area of the second customized reticle will be projected onto the first exposure and development partition.

[0063] For the above reasons, if the lithography simulation model only simulates the exposure result of the first customized reticle on the first exposure and development partition and only simulates the exposure result of the second customized reticle on the second exposure and development partition, it will miss the overall influence of the two exposures on the entire exposure and development area of the photoresist, resulting in poor simulation accuracy.

[0064] In this embodiment, the mask pattern may be the design layout of a special mask plate. The mask pattern may also include an exposure area (which may include a pattern area and a blank area) and a light-shielding area. According to the size and / or shape of the exposure and development area of the photoresist corresponding to the chip-level system in the design drawing, it can be split into multiple mask patterns, and the exposure area of each mask pattern corresponds to an exposure and development sub-area of the exposure and development area of the photoresist.

[0065] In this embodiment, there is an overlapping connection area between the exposure areas of any two adjacent mask patterns. That is to say, there is also an overlapping area between the two exposure and development sub-areas of the photoresist corresponding to the exposure areas of the two mask patterns. This area is called the multiple exposure area (LLE area, Litho-Litho-Etch area). The connection area is used to ensure that the pattern areas of the two mask patterns can be highly consistent and coherent within the multiple exposure area. The independent area in the exposure and development area of the photoresist other than the multiple exposure area can be called the single exposure area (SE area, Single Expose area).

[0066] Please refer to Figure 10 , Figure 10 FIG. shows the exposure and development area 700 formed by mapping two mask patterns, namely the left mask pattern 500 and the right mask pattern 600, on the photoresist. The exposure and development area 700 can be divided into three areas: the left single exposure area 710, the multiple exposure area 720, and the right single exposure area 730. Among them, the exposure area 510 of the left mask pattern is mapped to the left single exposure area 710 and the multiple exposure area 720, and the exposure area 610 of the right mask pattern is mapped to the multiple exposure area 720 and the right single exposure area 730. The light-shielding area 520 on the right side of the left mask pattern can be mapped to the right single exposure area 730, and the light-shielding area 620 on the left side of the right mask pattern can be mapped to the left single exposure area 710. The exposure area 510 of the left mask pattern may include the pattern area 511 of the left mask pattern and the blank area 512 of the left mask pattern. The exposure area 610 of the right mask pattern may include the pattern area 611 of the right mask pattern and the blank area 612 of the right mask pattern.

[0067] In this embodiment, after splitting the design drawing into multiple mask patterns, an optical model can be constructed for each mask pattern. Specifically, for each mask pattern, a pattern polarity model and a field region polarity model can be obtained respectively according to the distribution of its graphic region and blank region, light transmission performance, mask film thickness, mask etching angle, etc. Then, exposure simulation is performed simultaneously according to the pattern polarity model and the field region polarity model (the light rays of different polarity models of the same mask pattern are coherent and need to be simulated simultaneously) to predict the light field distribution (such as light intensity distribution) in the exposed and developed region of the photoresist for this mask pattern. Exemplarily, an aerial image of the exposed and developed region of a photoresist can be obtained for each mask pattern through the optical model.

[0068] It should be understood that generally, the light transmission performance of the light-blocking region of the mask pattern is weak, and its influence on the light field distribution in the exposed and developed region of the photoresist can be ignored during rough modeling and simulation. However, in the case of fine modeling and simulation, a light-blocking polarity model also needs to be obtained according to the distribution, light transmission performance, mask film thickness, mask etching angle, etc. of the light-blocking region of the mask pattern. Then, exposure simulation is performed simultaneously according to the pattern polarity model, the field region polarity model, and the light-blocking polarity model to predict the light field distribution in the exposed and developed region of the photoresist for this mask pattern.

[0069] After obtaining multiple aerial images of the exposed and developed regions of the photoresist through optical model simulation for all mask patterns respectively, the aerial images need to be combined to predict the final pattern in the exposed and developed region of the photoresist. During exposure, the mask patterns are performed sequentially, and only one mask pattern is being exposed at the same time. Therefore, the exposure of each mask pattern is incoherent light with the exposure of other mask patterns. Based on this, the optical synthesis model can simply add the simulation results of the optical models of each mask pattern, that is, add multiple aerial images, to obtain the final aerial image of the exposed and developed region of the photoresist.

[0070] After obtaining the final aerial image, a photoresist model can be established. The photoresist model can simulate the physical and chemical reactions generated by the photoresist under the influence of the final aerial image according to various process parameters, and then simulate the baking process and the developing process, and finally output the pattern obtained after developing the exposed and developed region of the photoresist. Exemplarily, the photoresist model obtains a resist image (RI) after performing developing simulation on the exposed and developed region.

[0071] The construction method of the present invention realizes the purpose of simulating the exposure process under the double-exposure process by constructing an optical model for each mask pattern to describe the overall influence of each mask pattern on the exposed and developed region of the photoresist during exposure, improves the accuracy of the simulation results of the optical synthesis model, and further reduces the defect risk in chip manufacturing.

[0072] It should be noted that the construction method of the present invention is not limited to simulating the exposure and development of a chip-level system, and can also be applied to chips using a double-exposure process (such as a single chip with a large area), and chips using an X / Y bipolar illumination exposure process (DDL, Double-Dipole-Litho), etc. Those skilled in the art can make appropriate adjustments based on the inventive concept of the present invention.

[0073] In some embodiments of the construction method of the present invention, as Figure 7 shown, constructing a photoresist model based on an optical synthesis model includes:

[0074] S411, constructing a multiple-exposure area of the photoresist model based on the optical synthesis model, where the multiple-exposure area corresponds to the connection area of at least two mask patterns;

[0075] S413, constructing at least one single-exposure area of the photoresist model based on at least one optical model, where each single-exposure area corresponds to an independent area of a mask pattern, and the independent area is located outside the connection area.

[0076] The multiple-exposure area is the area on the photoresist mapped by the exposure areas of at least two mask patterns. When simulating the multiple-exposure area, it is necessary to construct an optical model for the exposure area of each mask pattern involved respectively, then merge the optical models to form an optical synthesis model, and then construct a photoresist model for the multiple-exposure area based on the optical synthesis model to realize the simulation of the multiple-exposure area of the photoresist.

[0077] The single-exposure area is an independent area on the photoresist mapped only by the exposure area of one mask pattern. When simulating the multiple-exposure area, it is necessary to construct an optical model for the exposure area of the mask pattern involved respectively, and it may also be necessary to construct an optical model for the light-blocking area of other mask patterns mapped to this area, then merge the optical models to form an optical synthesis model, and then construct a photoresist model for the single-exposure area based on the optical synthesis model to realize the simulation of the single-exposure area of the photoresist.

[0078] In some embodiments of the construction method of the present invention, as Figure 2 shown, the steps of constructing an optical model for a mask pattern include:

[0079] S211, generating an exposure-type polarity parameter for each mask pattern respectively, where the exposure-type polarity parameter includes: a pattern parameter, a field parameter, and a light-blocking parameter; among them, the pattern parameter is used to characterize the light transmittance of the pattern area in the mask pattern, the field parameter is used to characterize the light transmittance of the blank area in the mask pattern, and the light-blocking parameter is used to characterize the light-blocking rate of the light-blocking area outside the mask pattern;

[0080] S213. Construct an optical model corresponding to each exposure type polarity parameter, denoted as the exposure type optical model.

[0081] In this embodiment, the optical model can simulate the light field distribution of each mask pattern in the exposure and development region of the photoresist based on three models to obtain the corresponding exposure type optical model. The three models are the pattern polarity model, the field region polarity model, and the light-shielding polarity model. Among them, the pattern polarity model can be constructed based on the pattern parameters at various locations in the pattern region of the mask pattern and is used to describe the pattern polarity. The field region polarity model can be constructed based on the field region parameters at various locations in the blank region of the mask pattern and is used to describe the field region polarity. The light-shielding polarity model can be constructed based on the light-shielding parameters at various locations in the light-shielding region of the mask pattern and is used to describe the light-shielding polarity.

[0082] By performing exposure simulation according to the pattern polarity, the field region polarity, and the light-shielding polarity simultaneously, the exposure type optical model can accurately predict the light field distribution of the mask pattern in the exposure and development region of the photoresist, improving the accuracy rate of the simulation results.

[0083] In some embodiments of the construction method of the present invention, as Figure 3 shown, the steps of constructing an optical model for a mask pattern include:

[0084] S221. Generate exposure type polarity parameters for each mask pattern respectively. The exposure type polarity parameters include: pattern parameters and field region parameters.

[0085] S223. Construct an exposure type optical model corresponding to each exposure type polarity parameter, denoted as the exposure type optical model.

[0086] In this embodiment, the optical model can simulate the light field distribution of each mask pattern in the exposure and development region of the photoresist based on the pattern polarity model and the field region polarity model to obtain the corresponding exposure type optical model. When the light-blocking rate in the light-shielding region of the mask pattern is relatively high, the influence of the light transmitted through the light-shielding region on the overall light field distribution in the exposure and development region of the photoresist is relatively low. When this influence is within an acceptable range, the light-shielding polarity model can be not constructed, and only the pattern polarity model and the field region polarity model are used to simulate the light field distribution of each mask pattern in the exposure and development region of the photoresist. In this way, computing resources can be saved and the simulation efficiency can be improved without significantly reducing the simulation accuracy rate.

[0087] In some embodiments of the construction method of the present invention, as Figure 4 shown, the steps of constructing an optical model for a mask pattern further include:

[0088] S231. Generate light-shielding type polarity parameters for at least one mask pattern. The light-shielding type polarity parameters are composed of light-shielding parameters and field region parameters.

[0089] S233. Construct an optical model corresponding to each light-shielding type polarity parameter, denoted as the light-shielding type optical model. And,

[0090] The steps of combining the optical models include:

[0091] S311. Combine the light-shielding type optical model corresponding to at least one of at least two mask patterns with the exposure type optical models corresponding to the others to obtain an optically synthesized model, denoted as the light-shielding type optically synthesized model. Wherein the exposure type optical model is an optical model corresponding to the exposure type polarity parameter of each mask pattern. And,

[0092] The steps of constructing the photoresist model include:

[0093] S313. Construct a photoresist model based on the light-shielding type optically synthesized model, denoted as the light-shielding type photoresist model. The light-shielding type photoresist model is at least used to describe the formation process of at least one boundary pattern in the connection area on the photoresist.

[0094] In this embodiment, the optical model can simulate the light field distribution in at least part of the exposure and development area of the photoresist for each mask pattern based on the field area polarity model and the light-shielding polarity model to obtain the corresponding exposure type optical model.

[0095] Please refer to Figure 11 , Figure 11 In Figure 10 On this basis, further divide the left single exposure area 710 into a left single exposure sub-area 711 and a left critical sub-area 712. The left critical sub-area 712 is within the left single exposure area 710 and is close to the multiple exposure area 720. And divide the right single exposure area 730 into a right single exposure sub-area 731 and a right critical sub-area 732. The right critical sub-area 732 is within the right single exposure area 730 and is close to the multiple exposure area 720. Wherein the widths W of the left critical sub-area 712 and the right critical sub-area 732 can generally be set to be more than 1 μm.

[0096] In this embodiment, to prevent interference, the exposure area of the right mask pattern near the left critical partition usually does not have a pattern area, but only a blank area. Therefore, when constructing a light-blocking optical synthesis model for the light field distribution of the left critical partition through two mask patterns, an exposure-type optical model based on the pattern parameters and field parameters of the exposure area can be constructed for the left mask pattern first to obtain the first optical spatial image of the left critical partition. Then, a light-blocking optical model based on the light-blocking parameters of the light-blocking area and the field parameters of the exposure area can be constructed for the right mask pattern to obtain the second optical spatial image of the left critical partition. Then, the first optical spatial image of the left critical partition and the second optical spatial image of the left critical partition are merged to obtain the final optical spatial image of the light-blocking optical synthesis model of the left critical partition. Finally, a light-blocking photoresist model is constructed based on the light-blocking optical synthesis model, and the final developed pattern of the photoresist is obtained.

[0097] In this embodiment, the exposure-type optical model for the left critical partition only involves two polarities (pattern polarity and field polarity), and the light-blocking optical model for the left critical partition also only involves two polarities (field polarity and light-blocking polarity). Compared with using three polarities simultaneously, it can save computing resources and improve simulation efficiency without significantly reducing the simulation accuracy of the left critical partition.

[0098] In this embodiment, the processing method for the simulation of the right critical partition can be referred to that of the left critical partition and will not be elaborated here.

[0099] It should be noted that when it is necessary to further improve the simulation accuracy of the left critical partition, its optical model can be constructed as an exposure-type optical model based on pattern parameters, field parameters, and light-blocking parameters, and the exposure-type optical model and the light-blocking optical model can be merged.

[0100] In some embodiments of the construction method of the present invention, the steps of obtaining the light-blocking optical synthesis model include:

[0101] When the patterns of at least two mask patterns are the same, the light-blocking optical model corresponding to one of the same patterns and the exposure-type optical model corresponding to the others are merged to obtain a light-blocking optical synthesis model.

[0102] The steps of constructing the light-blocking photoresist model include:

[0103] Construct a light-blocking photoresist model based on a light-blocking optical synthesis model. A light-blocking photoresist model is at least used to describe the formation process of all boundary patterns of all the same mask patterns in the connection area on the photoresist.

[0104] Please continue to refer to Figure 11 , when the areas near the two boundaries in the connection area of the two mask patterns ( Figure 11When the patterns or exposure process conditions of the boundary graphics of the left critical partition 712 and the right critical partition 732 are the same, the same light-shielding optical model can be used to simulate the two boundary graphics, and then they are respectively merged with their respective exposure optical models to obtain their respective light-shielding optical synthesis models. Then, according to their respective light-shielding optical synthesis models, the light-shielding photoresist models of the two boundary graphics are obtained. Specifically, when performing optical simulation on the left critical partition 712, an exposure optical model can be constructed for the left mask pattern, and a light-shielding optical model can be constructed for the right mask pattern, and then the two are merged to form a light-shielding optical synthesis model. When performing optical simulation on the right critical partition 732, another exposure optical model can be constructed for the right mask pattern, and then the light-shielding optical model constructed during the optical simulation of the left critical partition 712 in the previous step can be directly used, and the two are merged to form a light-shielding optical synthesis model. In this way, computing resources can be saved and the simulation efficiency can be improved.

[0105] In some embodiments of the construction method of the present invention, when constructing an optical synthesis model for a partial area in the single-exposure area that is far from the multi-exposure area, an exposure optical model and an optical model based on light-shielding parameters can be respectively constructed.

[0106] Please continue to refer to Figure 11 , a partial area in the left single-exposure area 710 that is far from the multi-exposure area can be the left single-exposure partition 711 (for example, the distance between the left single-exposure partition 711 and the multi-exposure area 720 is greater than or equal to 1 μm). When constructing an optical synthesis model for the left single-exposure partition 711, an exposure optical model based on the graphic parameters of the exposure area and the field parameters can be first constructed for the left mask pattern to obtain the first optical spatial image of the single-exposure partition. Then, an optical model based on the light-shielding parameters of the light-shielding area can be constructed for the right mask pattern to obtain the second optical spatial image of the single-exposure partition. Finally, the first optical spatial image and the second optical spatial image of the single-exposure partition are merged to obtain the final optical spatial image of the optical synthesis model of the single-exposure partition 711. Compared with using three polarities simultaneously, this embodiment can save computing resources and improve simulation efficiency without significantly reducing the simulation accuracy of the single-exposure partition 711.

[0107] In some embodiments of the construction method of the present invention, as Figure 5 shown, when the patterns of at least two mask patterns are the same, after constructing corresponding optical models for each mask pattern, it further includes:

[0108] S241, based on the optical model corresponding to one of the at least two mask patterns with the same pattern, constructing the single-exposure area of the photoresist model, where the single-exposure area corresponds to the independent areas of all those with the same pattern, and the independent areas are located outside the connection area.

[0109] Please continue to refer to Figure 11 , when the patterns or exposure process conditions of the graphic areas of the mask patterns corresponding to the left single-exposure area 710 and the right single-exposure area 730 are the same, and when the influence of the light in the light-shielding area on the photoresist is within an acceptable range, an optical model based on the light-shielding polarity model may not be constructed. Instead, an optical model can be constructed for the left single-exposure area 710 and the right single-exposure area 730 based on the graphic polarity model with the same parameters. In this way, computing resources can be saved and the simulation efficiency can be improved.

[0110] In some embodiments of the construction method of the present invention, in the case where the design drawing is split into at least three mask patterns, the connection areas of any two of the mask patterns overlap, or at least three of them overlap in the same connection area.

[0111] The construction method of the present invention can be applied to the case of double-exposure processes based on three or more mask patterns. Please refer to Figure 12 , Figure 12 schematically shows that four first mask patterns 800 are sequentially and overlappingly placed from left to right, so as to map and form an exposure and development area with a relatively large area. Please refer to Figure 13 , Figure 13 schematically shows that four second mask patterns 900 are overlappingly placed in pairs, so as to map and form an exposure and development area with a relatively large area. Those skilled in the art can make appropriate adjustments based on the inventive concept of the present invention, and details will not be elaborated here.

[0112] The flowchart provided in this embodiment is not intended to indicate that the operations of the method will be executed in any specific order, or that all operations of the method are included in every case. In addition, the method may include additional operations. Within the scope of the technical idea provided by the method in this embodiment, additional changes can be made to the above method.

[0113] It should be understood that in some embodiments, each part can be implemented by hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system.

[0114] The embodiments of the present invention also provide a computer program product 10, a computer-readable storage medium 20, and a computer device 30. Figure 14 is a schematic diagram of a computer program product 10 according to an embodiment of the present invention, Figure 15 is a schematic diagram of a computer-readable storage medium 20 according to an embodiment of the present invention, Figure 16It is a schematic diagram of a computer device 30 according to an embodiment of the present invention. The computer program product 10 includes a computer program 11, and when the computer program 11 is executed by a processor 32, it implements the steps of any one of the above construction methods. The computer-readable storage medium 20 stores the above computer program 11, and when the computer program 11 is executed by the processor 32, it implements the steps of the construction method of any one of the above embodiments. The computer device 30 may include a memory 31, a processor 32, and a computer program 11 stored on the memory 31 and running on the processor 32.

[0115] The computer program 11 for performing the operations of the present invention may be assembly instructions, instruction set architecture (InstructionSet Architecture, abbreviated as ISA) instructions, machine instructions, machine-related instructions, microcode, firmware instructions, status setting data, configuration data of an integrated circuit, or source code or object code written in any combination of one or more programming languages and procedural programming languages. The computer program 11 may be executed entirely on the user's computer, partially on the user's computer, executed as an independent software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the latter case, the remote computer may be connected to the user's computer through any type of network (including a local area network (Local Area Network, abbreviated as LAN) or a wide area network (Wide Area Network, abbreviated as WAN)), or may be connected to an external computer (for example, using an Internet service provider through the Internet). In some embodiments, in order to perform various aspects of the present invention, an electronic circuit including, for example, a programmable logic circuit, a field-programmable gate array (Field-Programmable Gate Array, abbreviated as FPGA), or a programmable logic array (ProgrammableLogic Array, abbreviated as PLA) may execute computer-readable program instructions by using the status information of the computer-readable program instructions to personalize the electronic circuit.

[0116] For the description of this embodiment, the computer program product 10 is a related product including the computer program 11.

[0117] For the description of this embodiment, the computer-readable storage medium 20 is a tangible device capable of retaining and storing the computer program 11, which can be any device that can contain, store, communicate, propagate, or transmit the computer program 11 for use by or in connection with an instruction execution system, apparatus, or device. More specific examples (non-exhaustive list) of the computer-readable storage medium 20 include the following: portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), static random access memory (SRAM), portable compact disc read-only memory (CD-ROM), digital versatile disc (DVD), memory stick, floppy disk, mechanically encoded device, and any suitable combination of the above.

[0118] The computer device 30 can be, for example, a server, a desktop computer, a laptop computer, a tablet computer, or a smartphone. In some examples, the computer device 30 can be a cloud computing node. The computer device 30 can be described in the general context of computer system-executable instructions, such as program modules, executed by a computer system. Generally, program modules can include routines, programs, object programs, components, logic, data structures, etc. that perform specific tasks or implement specific abstract data types. The computer device 30 can be implemented in a distributed cloud computing environment where tasks are executed by remote processing devices linked through a communication network. In the distributed cloud computing environment, program modules can be located on local or remote computing system storage media including storage devices.

[0119] The computer device 30 can include a processor 32 adapted to execute stored instructions and a memory 31 that provides temporary storage space for the operation of the instructions during operation. The processor 32 can be a single-core processor, a multi-core processor, a computing cluster, or any other number of other configurations. The memory 31 can include random access memory (RAM), read-only memory, flash memory, or any other suitable storage system.

[0120] The computer device 30 can also include a network adapter / interface and an input / output (I / O) interface. The I / O interface allows data to be input and output with external devices that can be connected to the computer device. The network adapter / interface can provide communication between the computer device and a network, which is typically shown as a communication network.

[0121] At this point, those skilled in the art should recognize that although numerous exemplary embodiments of the present invention have been shown and described in detail herein, many other variations or modifications consistent with the principles of the present invention can still be directly determined or derived from the disclosure of the present invention without departing from the spirit and scope of the present invention. Therefore, the scope of the present invention should be understood and construed to cover all such other variations or modifications.

Claims

1. A method for constructing a lithography simulation model, characterized in that: include: Acquire a design drawing, and split the design drawing into at least two mask images, wherein at least two of the mask images overlap in a connection area; Constructing a corresponding optical model for each of the mask images respectively, wherein the optical model is used to describe the light field distribution of the corresponding mask image in the photolithography process; According to the connection relationship between at least two of the mask images, the corresponding optical models are merged to obtain an optical synthesis model; A photoresist model is constructed based on the optical synthesis model, and the photoresist model is used to describe the formation process of the photoresist pattern.

2. The method according to claim 1, characterized in that The step of constructing the optical model for the mask image comprises: Generate exposure polarity parameters for each mask image respectively, the exposure polarity parameters including: pattern parameters and field parameters, or pattern parameters, field parameters and shading parameters; wherein the pattern parameters are used to characterize the transmittance of the pattern area in the mask image, the field parameters are used to characterize the transmittance of the blank area in the mask image, and the shading parameters are used to characterize the light blocking rate of the shading area outside the mask image; The optical model corresponding to each of the exposure type polarity parameters is constructed.

3. The method according to claim 2, characterized in that The step of constructing the optical model for the mask image further includes: Generating a light-shielding polarity parameter for at least one of the mask images, wherein the light-shielding polarity parameter is composed of the light-shielding parameter and the field region parameter; Constructing the optical model corresponding to each of the light-shielding polarity parameters, recorded as a light-shielding optical model; and, The step of merging the optical models comprises: The shading type optical model corresponding to at least one of at least two mask images and the exposure type optical model corresponding to the other ones are combined to obtain the optical synthesis model, which is recorded as the shading type optical synthesis model; wherein the exposure type optical model is the optical model corresponding to the exposure type polarity parameter of each mask image; and, The steps of constructing the photoresist model include: The photoresist model is constructed based on the light-shielding optical synthesis model and is recorded as a light-shielding photoresist model; the light-shielding photoresist model is at least used to describe the formation process of at least one boundary figure of the connection area on the photoresist.

4. The method according to claim 3, characterized in that The steps of obtaining the light-shielding optical synthesis model include: In the case where the patterns of at least two of the mask images are the same, the light-shielding optical model corresponding to one of the same patterns and the exposure optical model corresponding to the other are combined to obtain a light-shielding optical composite model; and The steps of constructing the light-shielding photoresist model include: A light-shielding photoresist model is constructed based on the light-shielding optical synthesis model, and the light-shielding photoresist model is at least used to describe the formation process of all boundary graphics of all the same mask images in the connection area on the photoresist.

5. The method according to claim 1, characterized in that Constructing a photoresist model based on the optical synthesis model includes: Constructing a multiple exposure region of the photoresist model based on the optical synthesis model, wherein the multiple exposure region corresponds to a connection region of at least two mask images; At least one single exposure region of the photoresist model is constructed based on at least one of the optical models, each of the single exposure regions corresponds to an independent region of the mask image, and the independent region is located outside the connection region.

6. The method according to claim 1, characterized in that In the case where the patterns of at least two of the mask images are the same, after constructing a corresponding optical model for each of the mask images, the method further includes: Based on the optical model corresponding to one of at least two mask images with the same pattern, a single exposure area of ​​the photoresist model is constructed, wherein the single exposure area corresponds to an independent area of ​​all the mask images with the same pattern, and the independent area is located outside the connection area.

7. The method according to claim 1, characterized in that When the design drawing is split into at least three mask images, connection regions of two of the mask images overlap, or at least three of the mask images overlap in the same connection region.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

9. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

10. A computer device, characterized in that: The method comprises a memory, a processor and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of the method according to any one of claims 1 to 7.

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