Negative Tone Development Photoresist Model Optimization Method

Abstract

The present invention relates to the field of semiconductor technology, and more particularly to a method for optimizing a negative tone developing photoresist model. The method comprises the steps of: obtaining an initial negative tone developing photoresist model; constructing a distribution function S based on the acid concentration in the photoresist where the light field is distributed, based on the light field distribution in the initial negative tone developing photoresist model and the acid concentration in the photoresist; constructing a concentration distribution function D of a developing solution using the distribution function S based on the acid concentration in the photoresist; constructing a developing solution concentration diffusion calculation formula R based on the developing solution concentration distribution function D to calculate the diffusion results of developing solutions of different concentrations; simulating the developing process using the developing solution concentration diffusion calculation formula R to obtain a developed simulated negative tone developing photoresist shape; and comparing relevant data between the simulated negative tone developing photoresist shape and a preset shape.

Description

Technology Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a method for optimizing a negative tone development photoresist model. Background Technology

[0002] Photolithography is the most important manufacturing process in modern large-scale integrated circuit manufacturing, serving as a crucial means of transferring the design geometry of an integrated circuit on a mask onto a silicon wafer using a lithography machine. In this manufacturing process, as feature sizes are progressively reduced, the manufacturing window also becomes smaller; however, since the entire photolithography process must be precisely controlled, the demand for computational lithography accuracy increases. Accurately computing the lithography model can theoretically explore ways to increase photolithography resolution and the manufacturing window, thereby suggesting the optimization of process parameters.

[0003] In current technical solutions, relatively advanced photoresist technologies have all utilized negative tone development. Although photoresists used in negative tone development possess good adhesion and blocking properties and offer fast photosensitivity, deformation and expansion occur during development. Consequently, the thermal shrinkage effect in negative tone development is more intense compared to positive tone development; this thermal shrinkage causes the distribution of the developing solution to differ from the light field distribution during the process, thereby reducing modeling accuracy. Furthermore, regarding chips, the maximum size of a single chip can be 32mm x 26mm, where the minimum geometric line width is only 10nm and the domain file of a single lithography layer can reach hundreds of GBs; thus, modeling speed is also a critical technical indicator. However, existing methods for optimizing negative tone development photoresist models struggle to consider both accuracy and speed simultaneously. The problem to be solved

[0004] To solve the problem that existing negative tone development photoresist model optimization methods find it difficult to consider both accuracy and speed, the present invention provides a negative tone development photoresist model optimization method. means of solving the problem

[0005] The solution to the technical problem of the present invention provides a method for optimizing a negative tone development photoresist model, comprising the following steps:

[0006] Step of acquiring an initial negative tone development photoresist model;

[0007] A step of constructing a distribution function S based on the acid concentration in the photoresist in which the light field is distributed, based on the light field distribution in the initial negative tone development photoresist model and the acid concentration in the photoresist;

[0008] A step of constructing a concentration distribution function D of a developing solution using a distribution function S based on acid concentration in the photoresist;

[0009] A step for calculating the diffusion results of developer solutions of different concentrations by constructing a developer solution concentration diffusion calculation formula R based on the developer solution concentration distribution function D;

[0010] A step of simulating the development process using the developer solution concentration diffusion calculation formula R to obtain a developed simulated negative tone developed photoresist shape;

[0011] It includes a step of comparing relevant data between a simulated negative tone development photoresist shape and a preset shape, and if it satisfies the preset standard, using the simulated negative tone development photoresist shape as the official negative tone development photoresist shape.

[0012] Preferably, the step of constructing a distribution function S based on the acid concentration in the photoresist in which the light field is distributed, based on the light field distribution in the initial negative tone development photoresist model and the acid concentration in the photoresist, specifically includes the following steps:

[0013] A step of obtaining light field distribution data based on the position of mask shape pixel points from an initial negative tone development photoresist model, and constructing a light field distribution function E(x, y) related to position information based on pixel points using the obtained light field distribution data, wherein E is a function related to (x, y) and (x, y) is pixel point position information;

[0014] The method includes the step of constructing an acid concentration distribution function S(x, y) in the photoresist based on a light field distribution function E(x, y), wherein the acid concentration distribution function S(x, y) in the photoresist is a related function of the light field distribution function E(x, y) S(x, y)=F(E(x, y)).

[0015] Preferably, the expression of the acid concentration distribution function in the photoresist is However, here G is the concentration of the photogenerator, and the expression for the immediate consumption rate of the photogenerator concentration is However, here c represents the exposure rate constant and t represents time.

[0016] Preferably, the step of constructing the concentration distribution function D of the developing solution using the distribution function S based on the acid concentration among the photoresists specifically includes the following steps:

[0017] A step of determining the consumption ratio of the developing solution and the acid in the photoresist by the chemical reaction equation between the acid in the photoresist and the developing solution;

[0018] It includes the step of constructing the concentration distribution function D(x, y)=F(S(x, y)) of the developer solution based on the ratio of acid and developer solution consumption in the photoresist.

[0019] Preferably, the expression of the concentration distribution function of the developing solution is However, here represents the crosslinking reaction rate constant, and t represents time.

[0020] Preferably, prior to the step of constructing the developer solution concentration diffusion calculation formula R based on the concentration distribution function D of the developer solution and calculating the diffusion results of developer solutions of different concentrations, the method further includes the following steps:

[0021] Step of constructing expression D1 for the concentration diffusion direction of the developing solution;

[0022] It further includes the step of constructing the expression D2 for the concentration diffusion intensity of the developing solution.

[0023] The expression for the direction of concentration diffusion of the developing solution is And, the expression for the concentration diffusion intensity of the developing solution is am.

[0024] Preferably, the step of constructing a developer solution concentration diffusion calculation formula R based on the concentration distribution function D of the developer solution and calculating the diffusion results of developer solutions of different concentrations specifically includes the following steps:

[0025] The method includes the step of obtaining the concentration diffusion direction and intensity of the developer solution within each unit area using the concentration diffusion direction expression D1 and the diffusion intensity expression D2 of the developer solution, and calculating and obtaining the diffusion result of the developer solution within each unit area based on the concentration distribution function D of the developer solution; and subsequently, constructing the developer solution concentration diffusion calculation formula R(x, y) based on the concentration diffusion direction expression D1 and the diffusion intensity expression D2 of the developer solution, accumulating the diffusion result of the developer solution within each unit area, and diffusing the simulation developer solution.

[0026] Preferably, the formula for calculating the total diffusion result is R(x, y)= And, the formula for calculating the total diffusion result R(x, y)= is constructed by calculus, where m belongs to positive integer constants.

[0027] Preferably, include the following steps further:

[0028] The elements for comparing the developed simulation negative tone developed photoresist shape with the preset shape further include the step of including the square mean size of the preset key size and / or the grid error size. Effects of the invention

[0029] Compared to the prior art, the negative tone development photoresist model optimization method of the present invention has the following advantages:

[0030] 1. The negative tone development photoresist model optimization method of the present invention is a negative tone development simulation method calculated based on the density distribution of the development solution. First, a function S related to the distribution function of the acid concentration in the photoresist is constructed based on relevant data of the light field distribution in the initial negative tone development photoresist model; subsequently, during the development process, the development solution chemically reacts with the acid in the photoresist, and since a certain amount of the development solution consumes a corresponding proportion of acid according to the chemical reaction equation, it can be assumed that the concentration consumption of the development solution is directly proportional to the concentration consumption of the acid in the photoresist. Based on this, the concentration distribution function D of the development solution can be rapidly constructed and obtained; Concentration distribution data of the developer solution can be obtained through the developer solution concentration distribution function D. Since diffusion effects occur due to differences in concentration between developer solutions distributed within different regions, the developer solution concentration diffusion calculation formula R can be constructed based on the developer solution concentration distribution function D; as the development process involves a chemical reaction between the photoresist and the developer solution, changes in the developer solution concentration are directly related to the photoresist image. In negative tone development, since the part of the photoresist that reacts with the developer solution is deferred, we can determine which region of the photoresist the reaction occurred based on changes in the developer solution concentration, and we can also determine the photoresist image after the reaction; therefore, by accurately controlling the changes in the developer solution concentration distribution during the simulation development process, we can ensure that the simulated photoresist changes accurately during the development process, thereby obtaining a developed high-precision negative tone developed photoresist shape; This method allows for the simultaneous consideration of modeling speed and accuracy, ensuring accuracy while enabling the modeling speed and forward phenomena to be in harmony.

[0031] 2. In the present invention, the light field distribution function E is constructed based on acquired light field distribution data, and the acid concentration distribution function S in the photoresist is constructed based on the light field distribution function E. Therefore, if the light field distribution function E is a function related to (x, y), the acid concentration distribution function S in the photoresist is also a function related to (x, y). This design is convenient for unifying variables, and is advantageous for reducing the amount of computation during optimization by simply performing calculations, thereby improving computation speed; furthermore, the light field distribution data in the present invention is acquired based on the position of the pixel points of the mask shape, and thus has high accuracy.

[0032] 3. Since the acid in the photoresist of the present invention is generated as the photogenerative agent decomposes, the expression of the acid concentration distribution function in the photoresist is And, since the photogenerator decomposes and generates acid as it is irradiated with light, the immediate consumption rate of the photogenerator concentration can be related to the exposure rate constant c and the light field distribution function E.

[0033] 4. The concentration distribution function D of the developing solution in the present invention is constructed based on the ratio of acid consumption in the developing solution and the photoresist, and is a function related to (x, y). This design is convenient for unifying variables, and is advantageous for reducing the amount of computation when optimizing by simply performing calculations, thereby improving the computation speed.

[0034] 5. According to the first point above, during the development process, the developing solution chemically reacts with the acid in the photoresist, and since a certain amount of the developing solution consumes a corresponding proportion of acid according to the chemical reaction equation, it can be assumed that the concentration consumption of the developing solution is directly proportional to the concentration consumption of the acid in the photoresist; therefore, within the concentration distribution function of the developed solution, the immediate consumption rate of the concentration of the photogenerator Immediate consumption rate of developing solution related to height After using, the crosslinking reaction rate constant By this, the concentration distribution function of the developing solution is denoted as D and is associated with the acid concentration distribution function S in the photoresist.

[0035] 6. In the present invention, since the concentration of the developing solution differs between different locations, an intense diffusion effect occurs, so that the developing solution in an area of ​​relatively high concentration can diffuse into an area of ​​relatively low concentration, and furthermore, if the concentration is greater than a certain intensity, the diffusion effect can be enhanced; the technical solution of the present application is, first of all, an expression of the concentration diffusion direction of the developing solution. Expression for the concentration diffusion intensity of the developing solution After constructing it, the concentration diffusion calculation formula R of the developing solution was constructed based on calculus mapping, allowing the total sum of the reaction to be calculated effectively and quickly, and significantly improving the speed and accuracy of the modeling.

[0036] 7. In the present invention, the expression for the concentration diffusion direction of the developing solution and expression for the concentration diffusion intensity of the developing solution All of these are expressions related to (x, y), and since the variables are unified, it is convenient for calculations, which can further reduce the amount of calculations when modeling and improve the speed of calculations.

[0037] 8. In the present invention, the concentration diffusion calculation formula R of the developing solution accumulates the diffusion of concentration based on calculus, so there is no need to perform pure random superposition calculations, which further reduces the amount of computation during modeling and improves the overall computation speed.

[0038] 9. In the present invention, expression for the concentration diffusion direction of the developing solution Through this, the development status can be monitored, so the expression for the concentration diffusion direction of the developing solution When the setting value changes to this value, it indicates that the developer solution concentration distribution has already entered a steady state and therefore no further diffusion occurs.

[0039] 10. The comparison element in the present invention includes the square mean size of a preset key size and / or the grid error size, and by comparing comprehensively, it can effectively prevent situations in which comparison errors occur. Brief explanation of the drawing

[0040] In order to explain the technical solution means in the embodiments of the present invention more clearly, the drawings to be used in the description of the embodiments or prior art below have been briefly introduced. It is obvious that the drawings in the description below are merely some embodiments of the present invention, and a person skilled in the art may obtain other drawings from these drawings under the premise of not striving to create an inventive step. FIG. 1 is a block diagram of a negative tone development photoresist model optimization method provided in the first embodiment of the present invention. FIG. 2 is a light field distribution of a selected photoresist region in the negative tone development photoresist model optimization method provided in the first embodiment of the present invention. Figure 3 is a light field distribution diagram after the development solution has been fully diffused into the selected photoresist area in the negative tone development photoresist model optimization method provided in the first embodiment of the present invention. FIG. 4 is a light field distribution diagram of another photoresist region selected in the negative tone development photoresist model optimization method provided in the first embodiment of the present invention. FIG. 5 is a light field distribution diagram after the development solution has been fully diffused into another photoresist region selected in the negative tone development photoresist model optimization method provided in the first embodiment of the present invention. Specific details for implementing the invention

[0041] To more clearly understand the purpose, technical solution, and advantages of the present invention, the present invention will be described in further detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are merely for interpreting the present invention and are not intended to limit the present invention.

[0042] The terms “vertical,” “horizontal,” “left,” “right,” “top,” “bottom,” “top-left,” “top-right,” “bottom-left,” “bottom-right,” and similar expressions used in this text are for illustrative purposes only.

[0043] Combining FIGS. 1 to 5, the first embodiment of the present invention provides a method for optimizing a negative tone development photoresist model,

[0044] Step (S1): A step of acquiring an initial negative tone development photoresist model;

[0045] Step (S2): A step of constructing a distribution function S based on the acid concentration in the photoresist in which the light field is distributed, based on the light field distribution in the initial negative tone development photoresist model and the acid concentration in the photoresist;

[0046] Step (S3): A step of constructing a concentration distribution function D of a developing solution using a distribution function S based on acid concentration in the photoresist;

[0047] Step (S4): A step for calculating the diffusion results of developer solutions of different concentrations by constructing a developer solution concentration diffusion calculation formula R based on the developer solution concentration distribution function D;

[0048] Step (S5): A step of simulating the development process using the development solution concentration diffusion calculation formula R to obtain a developed simulated negative tone developed photoresist shape;

[0049] Step (S6): Includes a step of comparing relevant data between a simulated negative tone developing photoresist shape and a preset shape, and if the preset standard is satisfied, using the simulated negative tone developing photoresist shape as the official negative tone developing photoresist shape.

[0050] It is understandable that the negative tone development photoresist model optimization method of the present invention is a negative tone development imitation method calculated based on the density distribution of the developing solution, wherein first, a function S related to the distribution function of the acid concentration in the photoresist is constructed based on relevant data of the light field distribution in the initial negative tone development photoresist model; subsequently, during the development process, the developing solution chemically reacts with the acid in the photoresist, and since a certain amount of the developing solution consumes a corresponding proportion of acid according to the chemical reaction equation, it can be assumed that the concentration consumption of the developing solution is directly proportional to the concentration consumption of the acid in the photoresist, and based on this, the concentration distribution function D of the developing solution can be rapidly constructed and obtained; Concentration distribution data of the developer solution can be obtained through the developer solution concentration distribution function D. Since diffusion effects occur due to differences in concentration between developer solutions distributed within different regions, the developer solution concentration diffusion calculation formula R is constructed based on the developer solution concentration distribution function D; during the development process, since the photoresist chemically reacts with the developer solution, changes in the developer solution concentration are directly related to the photoresist image. In negative tone development, since the part of the photoresist that reacts with the developer solution is deferred, we can determine which region of the photoresist the reaction occurred based on the change in the developer solution concentration, and we can also determine the photoresist image after the reaction; therefore, by accurately controlling the change in the developer solution concentration distribution during the simulation development process, we can ensure that the simulated photoresist changes accurately during the development process, thereby obtaining a developed high-precision negative tone developed photoresist shape; This method allows for the simultaneous consideration of modeling speed and accuracy, ensuring accuracy while enabling the modeling speed and forward phenomena to be in harmony.

[0051] Furthermore, step (S1) specifically includes the following steps:

[0052] Step (S11): A step of selecting at least one partial region of the photoresist as a target region and generating a mask image of a predetermined size;

[0053] Specifically, in this embodiment, a mask image with a pixel size of 512*512 is generated; it can be understood that the pixel size of the mask image can be adjusted according to actual demand.

[0054] Step (S12): Includes the step of constructing an initial negative tone development photoresist model from a generated mask image of a planned size using an existing modeling method.

[0055] Furthermore, step (S2) specifically includes the following steps:

[0056] Step (S21): A step of obtaining light field distribution data based on the position of mask shape pixel points from an initial negative tone development photoresist model, and constructing a light field distribution function E(x, y) related to position information based on pixel points using the obtained light field distribution data, wherein E is a function related to (x, y) and (x, y) is pixel point position information;

[0057] Specifically, the light field distribution function is the result of a statistical distribution function of different light intensities caused by factors such as projection, reflection, or refraction at different locations. It is understandable that since different optical models have different light field distributions, the light field distribution function E(x, y) constructed by different optical models is also different.

[0058] Step (S22): Constructing an acid concentration distribution function S(x, y) in the photoresist based on a light field distribution function E(x, y), wherein the acid concentration distribution function S(x, y) in the photoresist is a related function S(x, y) of the light field distribution function E(x, y) = F(E(x, y)).

[0059] It is understandable that the light field distribution function E in the present invention is constructed based on acquired light field distribution data, and the acid concentration distribution function S in the photoresist is constructed based on the light field distribution function E. Therefore, if the light field distribution function E is a function related to (x, y), the acid concentration distribution function S in the photoresist is also a function related to (x, y). This design is convenient for unifying variables, and is advantageous for reducing the amount of computation during optimization by simply performing calculations, thereby improving computation speed; furthermore, the light field distribution data in the present invention is acquired based on the position of the pixel points of the mask shape, and thus has high accuracy.

[0060] Furthermore, the expression for the acid concentration distribution function in the photoresist is However, here G is the concentration of the photogenerator, and the expression for the immediate consumption rate of the photogenerator concentration is However, here c represents the exposure rate constant and t represents time.

[0061] What is understandable is, in mathematics, Since G is a derivation for t, G is the concentration of the photogenerator, and t represents time, as can be seen according to the derived definition, is the immediate consumption rate of the concentration of the photogenerative agent.

[0062] It is understandable that, since the acid in the photoresist of the present invention is generated as the photogenerative agent decomposes, the expression of the acid concentration distribution function in the photoresist is And, since the photogenerator decomposes and generates acid as it is irradiated with light, the immediate consumption rate of the photogenerator concentration can be related to the exposure rate constant c and the light field distribution function E.

[0063] Photogenerators are compounds capable of generating specific acids by decomposing under radiation such as light, radiation, or plasma, and the generated acids can cause acid-sensitive resins to undergo decomposition or cross-linking reactions.

[0064] Furthermore, step (S3) specifically includes the following steps:

[0065] Step (S31): A step of determining the consumption ratio of the developing solution and the acid in the photoresist by the chemical reaction equation between the acid in the photoresist and the developing solution;

[0066] It is understandable that during the development process, the developer solution chemically reacts with the acid in the photoresist, and since a certain amount of the developer solution consumes a corresponding proportion of acid according to the chemical reaction equation, it can be assumed that the consumption of the developer solution concentration is directly proportional to the consumption of the acid concentration in the photoresist; therefore, the proportion of consumption of the developer solution and the acid in the photoresist can be determined by the chemical reaction equation between the developer solution and the acid in the photoresist.

[0067] Step (S32): Includes the step of constructing a concentration distribution function D(x, y)=F(S(x, y)) of the developer solution based on the ratio of acid in the photoresist to the consumption of the developer solution.

[0068] Furthermore, the expression for the concentration distribution function of the developing solution is However, here represents the crosslinking reaction rate constant, and t represents time.

[0069] As mentioned above, during the development process, the developing solution chemically reacts with the acid in the photoresist, and since a certain amount of the developing solution consumes a corresponding proportion of acid according to the chemical reaction equation, it can be assumed that the concentration consumption of the developing solution is directly proportional to the concentration consumption of the acid in the photoresist; therefore, within the established concentration distribution function of the developing solution, the immediate consumption rate of the concentration of the photogenerator Immediate consumption rate of developing solution related to height After using, the crosslinking reaction rate constant By this, the concentration distribution function of the developing solution is denoted as D and is associated with the acid concentration distribution function S in the photoresist.

[0070] Furthermore, step (S4) specifically includes the following steps:

[0071] Step (S31): A step of constructing the expression D1 for the concentration diffusion direction of the developing solution;

[0072] Step (S32): Includes the step of constructing the expression D2 for the concentration diffusion intensity of the developing solution.

[0073] It is understandable that, in the present invention, since the concentration of the developing solution differs between different locations, an intense diffusion effect occurs, so that the developing solution in an area of ​​relatively high concentration can diffuse to an area of ​​relatively low concentration, and furthermore, if the concentration is greater than a certain intensity, the diffusion effect can be enhanced; the technical solution of the present application is, first of all, an expression of the concentration diffusion direction of the developing solution. Expression for the concentration diffusion intensity of the developing solution After constructing it, the concentration diffusion calculation formula R of the developing solution was constructed based on calculus mapping, allowing the total sum of the reaction to be calculated effectively and quickly, and significantly improving the speed and accuracy of the modeling.

[0074] Furthermore, the expression for the direction of concentration diffusion of the developing solution is And, the expression for the concentration diffusion intensity of the developing solution is is. In the present invention, the expression for the concentration diffusion direction of the developing solution and expression for the concentration diffusion intensity of the developing solution All of these are expressions related to (x, y), and since the variables are unified, it is convenient for calculations, which can further reduce the amount of calculations when modeling and improve the speed of calculations.

[0075] Furthermore, step (S4) specifically includes the following steps:

[0076] The method includes the step of obtaining the concentration diffusion direction and intensity of the developer solution within each unit area using the concentration diffusion direction expression D1 and the diffusion intensity expression D2 of the developer solution, and calculating and obtaining the diffusion result of the developer solution within each unit area based on the concentration distribution function D of the developer solution; and subsequently, constructing the developer solution concentration diffusion calculation formula R(x, y) based on the concentration diffusion direction expression D1 and the diffusion intensity expression D2 of the developer solution, accumulating the diffusion result of the developer solution within each unit area, and diffusing the simulation developer solution.

[0077] It is understandable that the developer solution concentration diffusion calculation formula R can accumulate the diffusion results of the developer solution within each unit area of ​​this selected region to obtain the total diffusion result of the developer solution, and by optimizing the existing Computational Lithography model based on the calculated total diffusion result of the developer solution, a single high-accuracy negative tone development photoresist model can be obtained. This method allows for the simultaneous consideration of modeling speed and accuracy, thereby guaranteeing accuracy while ensuring that modeling speed and forward development are harmonized; furthermore, since the developer solution concentration diffusion calculation formula R accumulates the diffusion of concentration based on calculus, there is no need to perform pure random superposition calculations, which further reduces the amount of computation during modeling and improves the overall computation speed.

[0078] Furthermore, the formula for calculating the total diffusion result is R(x, y)= and m belongs to the positive integer constants.

[0079] What is understandable is that the total diffusion result calculation formula R(x, y)= It is constructed based on calculus mapping, which allows for rapid simulation of the diffusion of the developing solution, thereby obtaining the total diffusion result of the developing solution.

[0080] Furthermore, in step (S5), the change in the concentration distribution of the developing solution during the simulation development process can be accurately controlled so that the simulation photoresist changes accurately during the development process, thereby obtaining a developed high-precision negative tone developed photoresist shape.

[0081] Furthermore, expression for the direction of concentration diffusion of the developing solution When the setting value changes to this level, that is, when there is no difference in concentration, it indicates that the concentration distribution of the developing solution has already entered a steady state and therefore no further diffusion occurs.

[0082] Furthermore, in step (S6), if the result of comparing the related data between the negative tone developing photoresist shape and the preset shape does not satisfy the preset standard, this high-precision photoresist shape is continuously optimized until the preset standard is reached. It is understandable that the specific preset standard can be self-set according to the type of data compared.

[0083] Specifically, in this embodiment, the preset shape in step (S6) is a model design; the comparison of data related to the developed high-precision negative tone developed photoresist shape and the preset shape includes a comparison of variation / error of the key size, and the method of comparing variation / error of the key size includes comparing the square mean size of the key size; in addition, comparing the gap error of the key size; it is understandable that the smaller the square mean size of the key size and the gap error, the better. In other embodiments, other comparison factors may be added when comparing.

[0084] It is understandable that, in the present invention, when comparing the developed high-precision negative tone developed photoresist shape with a preset shape, if the preset standard cannot be satisfied, this modeling result is continuously optimized, which is advantageous for ensuring the accuracy of the negative tone developed photoresist model; and.

[0085] Specifically, in this embodiment, the preset standard includes determining whether the squared mean of the optimized model is less than 2; in other embodiments, this standard may be other values ​​greater or smaller than this.

[0086] Furthermore, continuing to optimize this model involves further optimizing formulas such as S(x, y) and D(x, y).

[0087] Combining FIGS. 2 to 5, FIG. 2 shows a light field distribution within an initially selected photoresist region, FIG. 3 shows a light field distribution after the development effect has been applied to the photoresist according to different developer solution densities, and different grayscale color blocks indicate different light field intensities, and as can be clearly seen through a comparison of FIG. 2 and FIG. 3, after the developer solution has diffused, a very large change has already occurred in the image; similarly, FIG. 4 and FIG. 5 represent another set of contrasts, including a light field distribution within an initially selected photoresist region ( FIG. 4) and a light field distribution after the development effect has been applied to the photoresist according to different developer solution densities ( FIG. 5); Although existing negative tone developing photoresist models cannot simulate changes in this part of FIGS. 2 to 3 or FIGS. 4 to 5, the negative tone developing photoresist model optimization method of the present application can optimize this, so that the developing process is simulated by the developing solution concentration diffusion calculation formula R, and the change in the concentration distribution of the developing solution during the simulated developing process is accurately made so that the simulated photoresist changes accurately during the developing process, thereby obtaining a developed high-precision negative tone developing photoresist shape.

[0088] Compared to the prior art, the negative tone development photoresist model optimization method of the present invention has the following advantages:

[0089] 1. The negative tone development photoresist model optimization method of the present invention is a method for mimicking negative tone development calculated based on the density distribution of the development solution. First, a function S related to the distribution function of the acid concentration in the photoresist is constructed based on relevant data of the light field distribution in the initial negative tone development photoresist model; subsequently, during the development process, the development solution chemically reacts with the acid in the photoresist, and since a certain amount of the development solution consumes a corresponding proportion of acid according to the chemical reaction equation, it can be assumed that the concentration consumption of the development solution is directly proportional to the concentration consumption of the acid in the photoresist. Based on this, the concentration distribution function D of the development solution can be rapidly constructed and obtained; and concentration distribution data of the development solution can be obtained through the concentration distribution function D of the development solution. Since a diffusion effect occurs as the concentrations of the development solution distributed within different regions differ, a development solution concentration diffusion calculation formula R is constructed again based on the concentration distribution function D of the development solution; During the development process, since the photoresist chemically reacts with the developer solution, changes in the developer solution concentration are directly related to the photoresist image. In negative tone development, however, because the parts of the photoresist that react with the developer solution are deferred, we can determine which regions of the photoresist the reaction occurred based on changes in the developer solution concentration, and we can also determine the photoresist image after the reaction. Therefore, by accurately controlling the changes in the developer solution concentration distribution during the simulation development process, we can ensure that the simulated photoresist changes accurately during the process, thereby obtaining a high-precision developed negative tone photoresist shape. This method allows for the simultaneous consideration of modeling speed and accuracy, ensuring accuracy while enabling the modeling speed and forward development to be in harmony.

[0090] 2. In the present invention, the light field distribution function E is constructed based on acquired light field distribution data, and the acid concentration distribution function S in the photoresist is constructed based on the light field distribution function E. Therefore, if the light field distribution function E is a function related to (x, y), the acid concentration distribution function S in the photoresist is also a function related to (x, y). This design is convenient for unifying variables, and is advantageous for reducing the amount of computation during optimization by simply performing calculations, thereby improving computation speed; furthermore, the light field distribution data in the present invention is acquired based on the position of the pixel points of the mask shape, and thus has high accuracy.

[0091] 3. Since the acid in the photoresist of the present invention is generated as the photogenerative agent decomposes, the expression of the acid concentration distribution function in the photoresist is And, since the photogenerator decomposes and generates acid as it is irradiated with light, the immediate consumption rate of the photogenerator concentration can be related to the exposure rate constant c and the light field distribution function E.

[0092] 4. The concentration distribution function D of the developing solution in the present invention is constructed based on the ratio of acid consumption in the developing solution and the photoresist, and is a function related to (x, y). This design is convenient for unifying variables, and is advantageous for reducing the amount of computation when optimizing by simply performing calculations, thereby improving the computation speed.

[0093] 5. According to the first point above, during the development process, the developing solution chemically reacts with the acid in the photoresist, and since a certain amount of the developing solution consumes a corresponding proportion of acid according to the chemical reaction equation, it can be assumed that the concentration consumption of the developing solution is directly proportional to the concentration consumption of the acid in the photoresist; therefore, within the concentration distribution function of the developed solution, the immediate consumption rate of the concentration of the photogenerator Immediate consumption rate of developing solution related to height After using, the crosslinking reaction rate constant By this, the concentration distribution function of the developing solution is denoted as D and is associated with the acid concentration distribution function S in the photoresist.

[0094] 6. In the present invention, since the concentration of the developing solution differs between different locations, an intense diffusion effect occurs, so that the developing solution in an area of ​​relatively high concentration can diffuse into an area of ​​relatively low concentration, and furthermore, if the concentration is greater than a certain intensity, the diffusion effect can be enhanced; the technical solution of the present application is, first of all, an expression of the concentration diffusion direction of the developing solution. Expression for the concentration diffusion intensity of the developing solution After constructing it, the concentration diffusion calculation formula R of the developing solution was constructed based on calculus mapping, allowing the total sum of the reaction to be calculated effectively and quickly, and significantly improving the speed and accuracy of the modeling.

[0095] 7. In the present invention, the expression for the concentration diffusion direction of the developing solution and expression for the concentration diffusion intensity of the developing solution All of these are expressions related to (x, y), and since the variables are unified, it is convenient for calculations, which can further reduce the amount of calculations when modeling and improve the speed of calculations.

[0096] 8. In the present invention, the concentration diffusion calculation formula R of the developing solution accumulates the diffusion of concentration based on calculus, so there is no need to perform pure random superposition calculations, which further reduces the amount of computation during modeling and improves the overall computation speed.

[0097] 9. In the present invention, expression for the concentration diffusion direction of the developing solution Through this, the development status can be monitored, so the expression for the concentration diffusion direction of the developing solution When the setting value changes to this value, it indicates that the developer solution concentration distribution has already entered a steady state and therefore no further diffusion occurs.

[0098] 10. The comparison element in the present invention includes the square mean size of a preset key size and / or the grid error size, and by comparing comprehensively, it can effectively prevent situations in which comparison errors occur.

[0099] The negative tone development photoresist model optimization method disclosed in the embodiments of the present invention has been introduced in detail above. In the text, the principles and embodiments of the present invention have been described by applying specific examples. The description of the embodiments above is merely intended to facilitate understanding of the method and core concept of the present invention; furthermore, those skilled in the art can make modifications within the specific embodiments and scope of application based on the concept of the present invention. Therefore, the contents of this specification should not be understood as a limitation to the present invention, and any modifications, equivalent substitutions, and improvements made within the principles of the present invention will all be included within the scope of protection of the present invention.

Claims

Claim 1 A step of obtaining an initial negative tone developing photoresist model; a step of constructing a distribution function S based on the acid concentration in the photoresist where the light field is distributed, based on the light field distribution in the initial negative tone developing photoresist model and the acid concentration in the photoresist; a step of constructing a concentration distribution function D of the developing solution using the distribution function S based on the acid concentration in the photoresist; a step of constructing a developing solution concentration diffusion calculation formula R based on the developing solution concentration distribution function D to calculate the diffusion results of the developing solution at different concentrations; a step of simulating the developing process using the developing solution concentration diffusion calculation formula R to obtain a developed simulated negative tone developing photoresist shape; The method includes a step of comparing relevant data between a simulated negative tone developing photoresist shape and a preset shape, and if the preset standard is satisfied, using the simulated negative tone developing photoresist shape as the official negative tone developing photoresist shape; and the step of constructing a distribution function S based on the acid concentration in the photoresist where the light field is distributed, based on the light field distribution in the initial negative tone developing photoresist model and the acid concentration in the photoresist, specifically includes the following steps: obtaining light field distribution data based on the position of the mask shape pixel point from the initial negative tone developing photoresist model, and constructing a light field distribution function E(x, y) related to the position information based on the pixel point using the obtained light field distribution data, wherein E is a function related to (x, y) and (x, y) is pixel point position information; A method for optimizing a negative tone developing photoresist model, characterized by constructing an acid concentration distribution function S(x, y) in the photoresist based on a light field distribution function E(x, y), wherein the acid concentration distribution function S(x, y) in the photoresist includes the step of S(x, y) = F(E(x, y)), which is a related function of the light field distribution function E(x, y). Claim 2 delete Claim 3 In claim 1, the expression of the acid concentration distribution function in the photoresist is However, here G is the concentration of the photogenerator, and the expression for the immediate consumption rate of the photogenerator concentration is A negative tone development photoresist model optimization method characterized in that, wherein c represents an exposure rate constant and t represents time. Claim 4 A method for optimizing a negative tone developing photoresist model according to claim 1, wherein the step of constructing a concentration distribution function D of a developing solution based on an acid concentration in the photoresist specifically includes the following steps: a step of determining the consumption ratio of the developing solution and the acid in the photoresist by a chemical reaction equation between the acid in the photoresist and the developing solution; and a step of constructing a concentration distribution function D(x, y)=F(S(x, y)) of the developing solution by the consumption ratio of the acid in the photoresist and the developing solution. Claim 5 In Clause 4, the expression of the concentration distribution function of the developing solution is However, here A negative tone development photoresist model optimization method characterized by θ representing the crosslinking reaction rate constant and t representing time. Claim 6 A method for optimizing a negative tone developing photoresist model according to claim 1, wherein, prior to the step of calculating the diffusion results of developing solutions of different concentrations by constructing a developing solution concentration diffusion calculation formula R based on the concentration distribution function D of the developing solution, the method further comprises the following steps: constructing a developing solution concentration diffusion direction expression D1; and constructing a developing solution concentration diffusion intensity expression D2. Claim 7 In Clause 6, the expression for the concentration diffusion direction of the developing solution is And, the expression for the concentration diffusion intensity of the developing solution is A negative tone development photoresist model optimization method characterized by. Claim 8 In claim 7, the step of constructing a developer solution concentration diffusion calculation formula R based on the developer solution concentration distribution function D and calculating the diffusion results of developer solutions of different concentrations specifically includes the following steps: obtaining the concentration diffusion direction and intensity of the developer solution within each unit area based on the developer solution concentration diffusion direction expression D1 and the diffusion intensity expression D2, and calculating and obtaining the diffusion results of the developer solution within each unit area based on the developer solution concentration distribution function D; subsequently, constructing a developer solution concentration diffusion calculation formula R(x, y) based on the developer solution concentration diffusion direction expression D1 and the diffusion intensity expression D2, accumulating the diffusion results of the developer solution within each unit area, and diffusing the simulation developer solution, characterized by a method for optimizing a negative tone developing photoresist model. Claim 9 In Clause 8, the formula for calculating the total diffusion result is R(x, y)= And, the formula for calculating the total diffusion result R(x, y)= A negative tone phenomenon photoresist model optimization method characterized by being constructed by calculus mapping, wherein m belongs to a positive integer constant. Claim 10 A method for optimizing a negative tone developed photoresist model according to claim 7, characterized in that when comparing a developed high-precision negative tone developed photoresist shape with a preset shape, the comparison factor includes the square mean size of the preset key size and the grid error size. Claim 11 A method for optimizing a negative tone developing photoresist model according to claim 10, characterized in that a preset standard includes determining whether the square mean of the optimized model is less than 2, wherein the standard may be any other value greater or smaller than this. Claim 12 A method for optimizing a negative tone developing photoresist model, characterized in that, in claim 5, the immediate consumption rate of the developing solution is used within the concentration distribution function of the developed solution. Claim 13 A method for optimizing a negative tone developing photoresist model according to claim 12, characterized by associating the acid concentration distribution function S in the photoresist with the concentration distribution function D of the developing solution by the crosslinking reaction rate constant.

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