Method for rapidly screening photoresist by using molecular simulation

Abstract

The invention provides a method for rapidly screening photoresist by using molecular simulation. The method comprises the following steps: drawing a molecular structure of the photoresist to be screened; obtaining an optimized molecular structure and charge distribution by using a quantum chemistry method according to the molecular structure; based on the optimized molecular structure, constructing a photoresist force field parameter structure file, and substituting the charge distribution into the force field parameter structure file; constructing a molecular dynamics model based on the force field parameter structure file; performing molecular dynamics calculation according to the molecular dynamics model to obtain three parameters, namely Young modulus, a contact angle between the photoresist and the developing solution and surface tension of the developing solution; and substituting the three parameters into a two-dimensional elastic beam bending model to obtain a three-dimensional curved surface diagram about the width of the photoresist pattern line, the height of the photoresist pattern and the interval parameter of the photoresist pattern, and determining the patterning capability of the pattern space size of the photoresist. According to the invention, the preliminary quantitative screening of the photoresist can be rapidly completed under the condition of not carrying out an experiment.

Description

Technical Field

[0001] The invention relates to the technical field of molecular simulation, and in particular to a method for rapidly screening photoresists using molecular simulation. Background Art

[0002] Currently, the screening of photoresists refers to screening photoresists by adjusting the patterning parameters of the photoresists. However, the existing screening methods require the use of special exposure tools and already prepared photoresists. The experimental conditions are harsh and the screening cycle is long.

[0003] In addition, the existing photoresist simulation work is a simulation of the photolithography process, including numerical simulation of the macroscopic photoresist distribution and simulation of the diffusion mechanism of the internal photoacid generator (PAG) in the photoresist. However, it does not link the patterning ability of the photoresist with the properties of the photoresist, nor does it apply the advantages of the convenience of simulation to photoresist screening.

[0004] Therefore, it is necessary to propose a method for rapid screening of photoresists to overcome the shortcomings of the existing photoresist screening process, such as high cost, harsh experimental conditions, and long screening cycle. Summary of the invention

[0005] In view of the defects in the prior art, the object of the present invention is to provide a method for rapidly screening photoresists using molecular simulation.

[0006] According to one aspect of the present invention, there is provided a method for rapidly screening photoresists using molecular simulation, comprising:

[0007] Draw the molecular structure of the photoresist to be screened;

[0008] According to the molecular structure, using quantum chemical methods to obtain an optimized molecular structure and charge distribution;

[0009] Based on the optimized molecular structure, construct a photoresist force field parameter structure file, and substitute the charge distribution into the force field parameter structure file;

[0010] Based on the force field parameter structure file, a molecular dynamics model is constructed;

[0011] Performing molecular dynamics calculations according to the molecular dynamics model to obtain three parameters: Young's modulus, contact angles of the photoresist and the developer, and surface tension of the developer;

[0012] Substituting the three parameters into the two-dimensional elastic beam bending model, a three-dimensional surface diagram of the width of the photoresist pattern line, the height of the photoresist pattern and the spacing parameters of the photoresist pattern is obtained to determine the patterning capability of the photoresist pattern space size.

[0013] Optionally, based on the molecular structure, quantum chemical methods are used to obtain optimized molecular structure and charge distribution, including: using density functional theory to perform structural optimization for photoresist molecules with no more than a preset number of atoms, and using a semi-empirical method to perform structural optimization for photoresist molecules with more than a preset number of atoms, wherein the preset number of atoms is determined according to the type of photoresist to be screened.

[0014] Optionally, according to the molecular structure, an optimized molecular structure and charge distribution are obtained using a quantum chemical method, including: using a quantum chemical calculation method based on functionals and basis sets to calculate the charge distribution.

[0015] Optionally, based on the optimized molecular structure, constructing a photoresist force field parameter structure file includes: using a molecular dynamics force field to model the optimized molecular structure.

[0016] Optionally, based on the force field parameter structure file, a molecular dynamics model is constructed, wherein: the model system for calculating the Young's modulus of the photoresist has 10,000 to several hundred thousand atoms.

[0017] Optionally, molecular dynamics calculations are performed based on a molecular dynamics model to obtain three parameters: Young's modulus, contact angles of the photoresist and the developer, and surface tension of the developer, wherein: in the calculation of Young's modulus, the polymer-based photoresist is stretched to apply strain to the simulation system.

[0018] Optionally, molecular dynamics calculations are performed according to the molecular dynamics model to obtain three parameters: Young's modulus, contact angles of photoresist and developer, and surface tension of developer, wherein: in the calculation of Young's modulus, strain is applied to the simulation system by compression of the molecular glass photoresist system.

[0019] Optionally, based on the force field parameter structure file, a molecular dynamics model is constructed, wherein: the contact angle model of the photoresist and the developer is a layered model, the upper layer is a spherical model of the developer, and the lower layer is the photoresist with its periodicity cancelled after sufficient relaxation.

[0020] Optionally, molecular dynamics calculations are performed according to the molecular dynamics model to obtain three parameters: Young's modulus, contact angles of the photoresist and the developer, and surface tension of the developer, wherein: in the calculation of the contact angle of the photoresist and the developer, the lower layer of photoresist is first relaxed to obtain a rough surface of the photoresist, and then the contact angle is simulated.

[0021] Optionally, based on the force field parameter structure file, a molecular dynamics model is constructed, wherein: a model for calculating the surface tension of the developer is to add two vacuum layers above and below a box filled with developer to construct two liquid-vacuum layer interfaces.

[0022] Compared with the prior art, the present invention has at least one of the following beneficial effects:

[0023] The present invention adopts a method combining molecular simulation and numerical simulation, and can obtain various properties of a photoresist to be screened within one day at the fastest, and screen out the photoresist that can form a stable pattern, so that the preliminary quantitative screening of the photoresist can be quickly completed without conducting experiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0025] Figure 1 A schematic diagram of a process for rapidly screening photoresists using molecular simulation in an embodiment of the present invention;

[0026] Figure 2 The molecular structure diagram of EUV molecular glass photoresist CR1-2Boc in an embodiment of the present invention;

[0027] Figure 3 The optimized structure and charge information in the embodiment of the present invention;

[0028] Figure 4 Schematic diagram of three models in an embodiment of the present invention;

[0029] Figure 5 is a schematic diagram of a two-dimensional elastic beam bending model in an embodiment of the present invention;

[0030] Figure 6 It is a three-dimensional surface diagram of the spatial dimensions of the photoresist pattern in an embodiment of the present invention. DETAILED DESCRIPTION

[0031] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several variations and improvements may be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0032] Reference Figure 1 , is a schematic flow chart of a method for rapid screening of photoresists using molecular simulation provided by an embodiment of the present invention, the method comprising:

[0033] S1. Draw the molecular structure of the photoresist to be screened; specifically, use existing software to draw the molecular structure of the photoresist to be screened, wherein the photoresist to be screened may be an existing determined structure or a structure that has been designed but not yet synthesized;

[0034] S2. Based on the molecular structure, the optimized molecular structure and charge distribution are obtained using quantum chemical methods. The molecules after structural optimization are more consistent with the actual structure, making the subsequent molecular dynamics simulation and photoresist screening results more accurate. Charge is an important information in molecular dynamics, which will directly affect the accuracy of simulating non-bonded interactions and have an important impact on the simulation results. Whether the molecular structure and charge information are accurate directly affects the molecular dynamics simulation results.

[0035] S3. Based on the optimized molecular structure, a photoresist force field parameter structure file is constructed, and the charge distribution is substituted into the force field parameter structure file; the force field parameter structure file contains a more reasonable optimized molecular structure and the atomic charges under the structure. Molecular dynamics simulation based on this file can improve the accuracy of the results.

[0036] S4. Construct a molecular dynamics model based on the force field parameter structure file;

[0037] S5. Perform molecular dynamics calculations according to a molecular dynamics model to obtain three parameters: Young's modulus, contact angles of the photoresist and the developer, and surface tension of the developer;

[0038] S6. Substitute the three parameters into the two-dimensional elastic beam bending model to obtain a three-dimensional surface graph of the width of the photoresist pattern line (i.e., the key dimension of the photoresist pattern), the photoresist pattern height, and the photoresist pattern spacing parameters to determine the patterning capability of the photoresist pattern space size.

[0039] In order to overcome the shortcomings of the existing photoresist screening process, such as high cost, harsh experimental conditions and long screening cycle, the embodiment of the present invention provides a molecular simulation screening method, which combines the means of quantum chemistry and molecular dynamics, combines the mechanical properties of photoresist and the photoresist patterning parameters, and quickly screens the photoresist based on the photoresist patterning ability. The various properties of the photoresist to be screened can be obtained within one day at the fastest, and the photoresist that can form a stable pattern can be screened, so that the preliminary quantitative screening of the photoresist can be quickly completed without conducting experiments.

[0040] For optimizing the photoresist molecular structure, the molecular structure drawn out in step S1 is imported into Gaussian software for calculation, in some embodiments, in step S2, for the photoresist molecule not more than the preset atomic number, the density functional method is adopted to carry out structural optimization, for the photoresist molecule greater than the preset atomic number, the semi-empirical method is used to carry out structural optimization, the preset atomic number is related to the element composition and structural complexity of the photoresist molecule, and illustratively, the preset atomic number can be 200, which is specifically determined according to the type of the photoresist to be screened. Based on suitable functional and basis set, the calculation method of quantum chemistry is used to calculate the charge distribution. Here, the selection of functional and basis set is according to the system to be calculated, and B3LYP is selected for the system structure optimization of the main group element composition, and the situation that the dispersion effect seriously affects the system conformation can be corrected by DFT-D3 (BJ), if it is a large-scale significant conjugated system, wB97XD or M06-2X is used, and the functional basis set for structural optimization and calculating charge distribution here is consistent.

[0041] In some embodiments, based on the optimized molecular structure, a photoresist force field parameter structure file is constructed, including: using molecular dynamics force fields such as oplsaa force field and gaff force field to model the optimized molecular structure, obtaining a force field parameter structure file for molecular dynamics calculation, and substituting the charge distribution calculated in step S2 into the force field parameter structure file.

[0042] The force field parameter structure file obtained in step S3 is used in molecular dynamics calculations, and a molecular dynamics model of three parameters to be calculated is first constructed. In some embodiments, in step S3, the model system for calculating the Young's modulus of the photoresist is in 10,000 to hundreds of thousands of atoms. This system can reduce the amount of calculation while ensuring the accuracy of the simulation calculation, improve the calculation efficiency, and save the cycle of photoresist screening. The contact angle model of the photoresist and the developer is a layered model, the upper layer is a spherical model of the developer, and the lower layer is a photoresist with periodicity cancelled after sufficient relaxation. The selection of the developer needs to be consistent with actual production, the positive photoresist adopts a positive developer, and the negative photoresist adopts a negative developer. At the same time, the surface tension of the developer must be calculated. The molecular dynamics method for calculating the surface tension of the liquid requires that the model has two interfaces, and the model for calculating the surface tension of the developer is to add two vacuum layers up and down in a box full of developer to construct the interface of two liquid phase-vacuum layers.

[0043] The three models constructed in step S4 are run with molecular dynamics to obtain results, which are Young's modulus, contact angles of photoresist and developer, and surface tension of developer. The developer calculated here is matched with the photoresist. In some embodiments, in step S5, in the calculation of Young's modulus, different methods are used to calculate Young's modulus for different types of photoresists. In the calculation of Young's modulus, a stretching method is used to apply strain to the simulation system for polymer-based photoresists. Polymer-based photoresists are polymer materials, and the stretching method can ensure the accuracy of the results. The compression method is used to apply strain to the simulation system for the molecular glass photoresist system. Small molecule systems do not have chain entanglements like polymer materials. The stretching method will cause gaps in the system and affect the simulation results. Therefore, the stretching method is used for polymer-based photoresists, and the compression method is used for molecular glass photoresists to ensure the accuracy of the simulation.

[0044] In some embodiments, in step S5, in the calculation of the contact angle between the photoresist and the developer, a step-by-step calculation method is used, firstly relaxing the lower layer of photoresist to obtain a rough surface of the photoresist, and then simulating the contact angle to make the simulation result more accurate.

[0045] The calculated contact angle results of the photoresist and the developer include those greater than 90 degrees and those less than 90 degrees. For photoresists with contact angles greater than 90 degrees, they are considered to be highly hydrophobic and will not have pattern collapse problems during the photolithography process. For photoresists with contact angles less than 90 degrees, they are considered to have the risk of pattern collapse and can be further screened using a two-dimensional beam bending model to select photoresists that can form stable patterns.

[0046] The embodiment of the present invention uses a combination of material properties calculated by a molecular simulation method and a two-dimensional elastic beam bending model to predict the ability of photoresist patterning. Step S6 constructs a mathematical model for the two-dimensional elastic beam bending model, and the model is a relationship equation about six parameters, which are Young's modulus, contact angle between photoresist and developer, surface tension of developer, key size of photoresist pattern, height of photoresist pattern, and spacing of photoresist pattern, wherein the key size of photoresist pattern is the width of photoresist pattern line, and the three parameters obtained in step S5 are substituted into the two-dimensional elastic beam bending model with six parameters, and a three-dimensional surface diagram is drawn for the remaining three parameters, namely the width of photoresist pattern line, height of photoresist pattern, and spacing of photoresist pattern, thereby obtaining the patterning ability of the spatial size of the photoresist pattern.

[0047] The three-dimensional surface graph obtained in step S6 can be used to judge the patterning capability of the photoresist, wherein the larger the range of the surface graph, the more stable the pattern formed by the photoresist. In this surface graph, the three spatial parameters are defined as the common photoresist pattern size range. The larger the range contained in the surface graph within this specified range, the more selectable spatial sizes of the photoresist pattern that can be formed by the photoresist, and the more stable the formed photoresist pattern. During screening, according to the required patterning specifications, the method of the embodiment of the present invention can be used to quickly screen photoresists that meet the requirements.

[0048] The method for quickly screening photoresists using molecular simulation provided by the above-mentioned embodiment of the present invention first draws the molecular structure of the photoresist to be screened, and uses quantum chemistry methods to obtain its reasonable molecular structure and charge distribution. On this basis, a force field parameter file of the photoresist is constructed, and the file is used for molecular dynamics simulation. The Young's modulus of the photoresist, the contact angle between the photoresist and the developer, and the surface tension of the developer are calculated by the molecular dynamics method. These three parameters are substituted into the two-dimensional elastic beam bending model to obtain a three-dimensional surface graph of the three parameters of the photoresist pattern. The larger the range of the surface graph, the more stable the pattern formed by the photoresist. Photoresists that do not contain the desired spatial size can be screened out, thereby quickly screening out photoresists that can form stable patterns without conducting experiments.

[0049] In a specific embodiment, for an EUV molecular glass photoresist CR1-2Boc with a certain structure, the molecular structure formula is drawn using ChemDraw software, such as Figure 2 As shown, the molecular structure formula is imported into Chem3D software to obtain a three-dimensional structure, and is saved as a file recognizable by Gaussian software, such as a mol file.

[0050] Will Figure 2 The mol file of the structure is imported into Gaussian software and converted into a gjf file that can be calculated. The functional and basis set are modified to B3LYP / 6-31G, and quantum chemical calculations are performed to obtain the results. Based on the results, an optimized and reasonable three-dimensional structure is obtained. The optimized structure continues to be charged calculated, and the chelpg method is used to obtain the charge of each atom in the optimized structure.

[0051] Figure 3 The left picture in the middle is the optimized structure, and the right picture is the charge information of the optimized structure. Based on the optimized molecular structure information, the oplsaa force field is matched, and the calculated charge information replaces the atomic charge in the oplsaa force field to obtain the force field parameter file for molecular dynamics.

[0052] Will Figure 3 The force field parameter file obtained in is used to construct Figure 4 The three models in Figure 4 (a), (b), and (c) are the models for calculating the Young's modulus of the photoresist, the contact angle model between the photoresist and the developer, and the model for the surface tension of the developer, respectively.

[0053] Molecular dynamics calculations were performed on these three models, and the simulation results showed that the Young's modulus was 11.79 GPa, the contact angle was 77°, and the surface tension of the TMAH developer was 55 mN / m.

[0054] Will Figure 4 Substitute the calculation results into the two-dimensional elastic beam bending model. Figure 5 . Figure 5 The first model diagram on the left shows the spatial parameters of the photoresist. H represents the height of the photoresist pattern, W is the width of the photoresist pattern line, d is the spatial interval of the photoresist pattern, and D is the depth of the photoresist pattern. The middle model diagram shows a schematic diagram of the photoresist filled with developer. In the figure, θ is the contact angle between the developer and the photoresist. The model diagram on the right is a schematic diagram of the pattern collapse of the photoresist. In the figure, δmax is the displacement at the top of the photoresist pattern. The formula of the two-dimensional elastic beam bending model is:

[0055]

[0056] A python script is written based on the model formula, and the three-dimensional surface diagram of the spatial size of the photoresist pattern is obtained through the script. Figure 6 . Figure 6 The middle ordinate is the thickness of the photoresist pattern, and the two coordinates of the plane are the width of the photoresist pattern lines and the interval of the photoresist pattern. From the figure, we can intuitively observe the size of the spatial size of the pattern that can be formed by this type of photoresist and screen this type of photoresist.

[0057] The above-mentioned embodiment of the present invention uses a method combining molecular simulation and numerical simulation, which makes up for the shortcomings of the existing screening method that the experimental conditions are required and the experimental conditions are harsh. Because the means of simulation calculation are adopted, the preliminary quantitative screening of photoresists can be quickly completed without conducting experiments. The entire process can obtain various properties of photoresists and screen out photoresists that can form stable patterns within one day at the fastest. The embodiment of the present invention can achieve the preliminary quantitative screening of a large number of photoresists in a short time when only computing resources are available, thereby quickly screening out photoresists that can form highly stable patterns.

[0058] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various modifications or variations within the scope of the claims, which does not affect the essence of the present invention. The above preferred features can be used in any combination without conflicting with each other.

Claims

1. A method for rapidly screening photoresists using molecular simulation, characterized in that, it includes: drawing the molecular structure of the photoresist to be screened; obtaining the optimized molecular structure and charge distribution using quantum chemical methods based on the molecular structure; constructing a photoresist force field parameter structure file based on the optimized molecular structure, and substituting the charge distribution into the force field parameter structure file; constructing a molecular dynamics model based on the force field parameter structure file; performing molecular dynamics calculations according to the molecular dynamics model to obtain three parameters: Young's modulus, the contact angle between the photoresist and the developer, and the surface tension of the developer; substituting the three parameters into a two-dimensional elastic beam bending model to obtain a three-dimensional surface plot of the width, height, and spacing parameters of the photoresist pattern lines, and determining the patterning ability of the pattern space size of the photoresist.

2. The method for rapidly screening photoresists using molecular simulation according to claim 1, characterized in that, obtaining the optimized molecular structure and charge distribution using quantum chemical methods based on the molecular structure, including: using density functional theory method for structure optimization for photoresist molecules with no more than a preset number of atoms, and using semi-empirical methods for structure optimization for photoresist molecules with more than the preset number of atoms, where the preset number of atoms is determined according to the type of the photoresist to be screened.

3. The method for rapidly screening photoresists using molecular simulation according to claim 1, characterized in that, obtaining the optimized molecular structure and charge distribution using quantum chemical methods based on the molecular structure, including: calculating the charge distribution using the calculation methods of quantum chemistry based on functionals and basis sets.

4. The method for rapidly screening photoresists using molecular simulation according to claim 1, characterized in that, constructing a photoresist force field parameter structure file based on the optimized molecular structure, including: using a molecular dynamics force field to model the optimized molecular structure.

5. The method for rapidly screening photoresists using molecular simulation according to claim 1, characterized in that, constructing a molecular dynamics model based on the force field parameter structure file, where: the model system for calculating Young's modulus of the photoresist has from ten thousand to several hundred thousand atoms.

6. The method for rapidly screening photoresists using molecular simulation according to claim 5, characterized in that, performing molecular dynamics calculations according to the molecular dynamics model to obtain three parameters: Young's modulus, the contact angle between the photoresist and the developer, and the surface tension of the developer, where: in the calculation of Young's modulus, a stretching method is used to apply strain to the simulation system for polymer-based photoresists.

7. The method for rapidly screening photoresists using molecular simulation according to claim 5, characterized in that, performing molecular dynamics calculations according to the molecular dynamics model to obtain three parameters: Young's modulus, the contact angle between the photoresist and the developer, and the surface tension of the developer, where: in the calculation of Young's modulus, a compression method is used to apply strain to the simulation system for molecular glass photoresist systems.

8. The method for rapidly screening photoresists using molecular simulation according to claim 1, characterized in that, Based on the force field parameter structure file, a molecular dynamics model is constructed, where: the contact angle model of the photoresist and the developer is a layered model, with the upper layer being the spherical model of the developer and the lower layer being the photoresist after sufficient relaxation and without periodicity.

9. The method for rapidly screening photoresists using molecular simulation according to claim 8, characterized in that, molecular dynamics calculations are performed according to the molecular dynamics model to obtain three parameters: Young's modulus, the contact angle between the photoresist and the developer, and the surface tension of the developer. Among them: in the calculation of the contact angle between the photoresist and the developer, the rough surface of the photoresist is first relaxed for the lower layer photoresist, and then the contact angle simulation is carried out.

10. The method for rapidly screening photoresists using molecular simulation according to claim 1, characterized in that, Based on the force field parameter structure file, a molecular dynamics model is constructed, where: the model for calculating the surface tension of the developer is to add two vacuum layers above and below the box filled with the developer to construct two liquid-vacuum layer interfaces.

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