Modeling methods

Abstract

The application provides a modeling method, which comprises the following steps: obtaining a data source, wherein the data source comprises mask-related initial parameters, GDS data and Gauge data; pre-setting the mask-related initial parameters and setting machine-related parameters; performing optimization calculation on the mask-related initial parameters to obtain mask optimization parameters and generating point light intensity and Gauge critical dimensions; optimizing the mask optimization parameters, the point light intensity and the Gauge critical dimensions by using a simulated annealing algorithm; outputting a complex graphic contour; and performing graphic overlay processing on the obtained complex graphic contour and a picture collected by a line width scanner to evaluate whether the graphic contours of the two are consistent. The application solves the problem of long tapeout cycle and mask delivery cycle of existing products.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing technology, and in particular to a modeling method. Background Technology

[0002] With the development of advanced process technologies, the lithography process window is becoming increasingly smaller. In particular, yield losses caused by the optical proximity effect have become a key factor restricting lithography processes. At advanced process nodes, the commonly used modeling method for OPC (Optical Proximity Correction) is still a combination of pure optical models and process model data to compensate and correct the photomask. Specifically, the pure optical model used in current lithography exposure processes is fully described by the Hopkins equation, while the process model is based on experimentally measuring key dimensional data on actual silicon wafers and then performing trend fitting to predict lithography processes in advance.

[0003] Strictly speaking, the lithography imaging simulation problem is actually a projection imaging problem of partially coherent light in an imaging system with aberrations. At advanced process nodes, it is difficult to systematically calibrate the OPC model using existing pure optical models combined with process data simulation methods. Although a relatively accurate model can be obtained through regression search, the process of regressing to find the optimal solution is lengthy and requires repeated correction of the model's accuracy, increasing the tapeout cycle and mask delivery cycle. Summary of the Invention

[0004] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a modeling method to solve the problems of long tapeout cycles and long delivery cycles of existing products.

[0005] To achieve the above and other related objectives, the present invention provides a modeling method, the method comprising:

[0006] Obtain the data source, which includes initial parameters related to the photomask, GDS data, and Gauge data;

[0007] The initial parameters related to the photomask are preset, and the relevant parameters of the machine tool are set.

[0008] The initial parameters related to the photomask are optimized to obtain optimized photomask parameters, and the point light intensity and Gauge key dimensions are generated.

[0009] The simulated annealing algorithm was used to optimize the photomask parameters, the point light intensity, and the key dimensions of the Gauge.

[0010] Output the complex graphic outline, and perform graphic overlay processing on the obtained complex graphic outline and the image acquired by the line width scanner to evaluate whether the graphic outlines of the two match.

[0011] Optionally, the initial parameters related to the photomask include: photomask material, reflection coefficient, refractive index, photomask curvature, and linear offset of the photomask pattern.

[0012] Optionally, when optimizing the initial parameters of the photomask to obtain the optimized parameters, it is necessary to set the optimization range of the initial parameters of the photomask and the step size of each calculation step.

[0013] Optionally, the relevant parameters of the machine include baking temperature and exposure step size.

[0014] Optionally, the method for generating point light intensity includes: calculating the light intensity at each Gauge point in the GDS map and outputting the result.

[0015] Optionally, the method for generating Gauge key dimensions includes: obtaining key dimensions by simulating the light intensity on each Gauge using an optimization method.

[0016] Optionally, the method for optimizing the photomask optimization parameters, the point light intensity, and the Gauge key dimensions using a simulated annealing algorithm includes:

[0017] Set optimization space;

[0018] Set the initial solution for optimization;

[0019] Define the objective function.

[0020] Optionally, the setting optimization space refers to setting an optimized range of values ​​for the focusing accuracy parameters, focusing position parameters, photomask optimization parameters, thermal diffusion effect parameters in photoresist effect, rounded corner passivation effect parameters, line end shortening effect parameters, photoresist reflection coefficient parameters, refractive index parameters, and photoresist thickness parameters of the lithography machine.

[0021] Optionally, the initial solution for optimization refers to setting initial values ​​for the following parameters of the lithography machine: focusing accuracy parameter, focusing position parameter, photomask optimization parameter, thermal diffusion effect parameter in photoresist effect, rounded corner passivation effect parameter, line end shortening effect parameter, reflectance coefficient parameter, refractive index parameter, and photoresist thickness parameter.

[0022] Optionally, the objective function should make the initial solution optimal both locally and globally.

[0023] Optionally, the GDS data is obtained by reading a GDS file, and the GDS file is a layout file.

[0024] Optionally, the Gauge data is obtained by reading in a Gauge file, which is used to calculate the light intensity at the coordinate positions of the map recorded in the map.

[0025] As described above, the modeling method of the present invention can significantly shorten the time for the OPC model to search for the optimal solution, and shorten the product tapeout cycle and the delivery cycle of the photomask. Attached Figure Description

[0026] Figure 1 The flowchart shown is a modeling method of the present invention.

[0027] Figure 2 The figure shown is an experimental result obtained by the method provided in this invention. Detailed Implementation

[0028] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0029] Please see Figures 1 to 2 It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Although the illustrations only show components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation, the shape, quantity and proportion of each component in the actual implementation can be arbitrarily changed, and the layout of the components may also be more complex.

[0030] like Figure 1 As shown, this embodiment provides a modeling method, the method including:

[0031] Obtain the data source, which includes initial parameters related to the photomask, GDS data, and Gauge data;

[0032] The initial parameters related to the photomask are preset, and the relevant parameters of the machine tool are set.

[0033] The initial parameters related to the photomask are optimized to obtain optimized photomask parameters, and the point light intensity and Gauge key dimensions are generated.

[0034] The simulated annealing algorithm was used to optimize the photomask parameters, the point light intensity, and the key dimensions of the Gauge.

[0035] Output the complex graphic outline, and perform graphic overlay processing on the obtained complex graphic outline and the image acquired by the line width scanner to evaluate whether the graphic outlines of the two match.

[0036] Specifically, the initial parameters related to the photomask include: photomask material, reflection coefficient, refractive index, photomask curvature, and linear offset of the photomask pattern.

[0037] Specifically, when optimizing the initial parameters of the photomask to obtain the optimized parameters, it is necessary to set the optimization range of the initial parameters and the step size of each calculation step.

[0038] Specifically, the relevant parameters of the machine include baking temperature and exposure step size.

[0039] Specifically, the method for generating point light intensity includes: calculating the light intensity at each Gauge point in the GDS map and outputting the results.

[0040] Specifically, the method for generating Gauge key dimensions includes: obtaining key dimensions by simulating the light intensity on each Gauge using an optimization method.

[0041] Specifically, the method for optimizing the photomask optimization parameters, the point light intensity, and the Gauge key dimensions using the simulated annealing algorithm includes: setting an optimization space; setting an initial solution for optimization; and setting an objective function.

[0042] Specifically, the optimization space refers to the set optimization range for the focusing accuracy parameters, focusing position parameters, photomask optimization parameters, thermal diffusion effect parameters in photoresist effect, rounded corner passivation effect parameters, line end shortening effect parameters, photoresist reflection coefficient parameters, refractive index parameters, and photoresist thickness parameters of the lithography machine.

[0043] Specifically, the initial solution for optimization refers to setting initial values ​​for the following parameters of the lithography machine: focusing accuracy parameters, focusing position parameters, photomask optimization parameters, thermal diffusion effect parameters in photoresist effect, rounded corner passivation effect parameters, line end shortening effect parameters, photoresist reflection coefficient parameters, refractive index parameters, and photoresist thickness parameters.

[0044] Specifically, the objective function should make the initial solution optimal both locally and globally.

[0045] Specifically, the GDS data is obtained by reading in a GDS file, and the GDS file is a layout file.

[0046] Specifically, the Gauge data is obtained by reading in a Gauge file, which is used to calculate the light intensity at the coordinate positions recorded in the layout.

[0047] like Figure 2 As shown, in this embodiment, by monitoring the graphic contours of eight locations prone to weak points, it was found that the complex graphic OPC modeling method using the layout contours adopted in this embodiment (such as...) Figure 2 Compared with the OPC model established by conventional modeling methods (shown in red), the model method established in this embodiment is significantly superior to the traditional OPC modeling method. The red graph can clearly predict the bridging phenomenon on the actual wafer. The key dimension values ​​simulated by the method provided in this embodiment are shown in the table below.

[0048]

[0049] In summary, the modeling method of this invention can significantly shorten the time for searching for the optimal solution in the OPC model, and reduce the product tapeout cycle and photomask delivery cycle. Therefore, this invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0050] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A modeling method, characterized in that, The method includes: The data source is obtained, which includes initial parameters related to the photomask, GDS data, and Gauge data. The Gauge data is obtained by reading in a Gauge file, which is used to calculate the light intensity at the coordinate positions recorded in the layout. The initial parameters related to the photomask are preset, and the relevant parameters of the machine tool are set. The initial parameters related to the photomask are optimized to obtain optimized photomask parameters, and the point light intensity and Gauge key dimensions are generated. The method for generating the Gauge key dimensions includes: obtaining the key dimensions by simulating the light intensity on each Gauge through an optimization method. The simulated annealing algorithm was used to optimize the photomask parameters, the point light intensity, and the key dimensions of the Gauge. Output the complex graphic outline, and perform graphic overlay processing on the obtained complex graphic outline and the image acquired by the line width scanner to evaluate whether the graphic outlines of the two match.

2. The modeling method according to claim 1, characterized in that, The initial parameters related to the photomask include: photomask material, reflection coefficient, refractive index, photomask curvature, and linear offset of the photomask pattern.

3. The modeling method according to claim 2, characterized in that, When optimizing the initial parameters of the photomask to obtain the optimized parameters, it is necessary to set the optimization range of the initial parameters and the step size of each calculation step.

4. The modeling method according to claim 1, characterized in that, The relevant parameters of the machine include baking temperature and exposure step size.

5. The modeling method according to claim 1, characterized in that, The method for generating point light intensity includes: calculating the light intensity at each Gauge point in the GDS map and outputting the result.

6. The modeling method according to claim 1, characterized in that, The method for optimizing the photomask parameters, the point light intensity, and the Gauge key dimensions using simulated annealing includes: Set optimization space; Set the initial solution for optimization; Define the objective function.

7. The modeling method according to claim 6, characterized in that, The optimization space refers to the set optimization range for parameters such as focusing accuracy, focusing position, photomask optimization, thermal diffusion effect, rounded corner passivation, line shortening, reflectance, refractive index, and thickness of the photoresist.

8. The modeling method according to claim 6, characterized in that, The initial solution for optimization refers to setting initial values ​​for the following parameters of the lithography machine: focusing accuracy parameter, focusing position parameter, photomask optimization parameter, thermal diffusion effect parameter in photoresist effect, rounded corner passivation effect parameter, line end shortening effect parameter, photoresist reflection coefficient parameter, refractive index parameter, and photoresist thickness parameter.

9. The modeling method according to claim 6, characterized in that, The objective function is to make the initial solution optimal both locally and globally.

10. The modeling method according to claim 1, characterized in that, The GDS data is obtained by reading in a GDS file, and the GDS file is a layout file.

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