Optical key dimension measurement method, device, storage medium and equipment

Abstract

In an optical critical dimension measurement method, device, storage medium and equipment provided in this specification, in the field of semiconductor manufacturing, a physical model of a micro-nano structure to be measured is constructed, and the dielectric constant is Fourier expanded in the periodic distribution direction of the grating area in the physical model. The screening range is determined according to the energy of the central order in the Fourier decomposition matrix of the dielectric constant, and the order whose energy falls into the screening range in the Fourier decomposition matrix is ​​determined to obtain a target order distribution matrix, and the optical critical dimensions are determined by rigorous coupled wave analysis based on the components corresponding to each order in the target order distribution matrix in the Fourier decomposition matrix and the boundary conditions of the physical model. The screening range is determined based on the energy of the central order of the Fourier decomposition matrix of the dielectric constant, and the orders that have a greater impact on the calculation results of the rigorous coupled wave analysis are screened out according to the screening range, thereby ensuring the accuracy of the optical critical dimensions of the micro-nano structure to be measured and improving efficiency.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor manufacturing, and in particular to an optical critical dimension measurement method, device, storage medium and equipment. Background Art

[0002] In the field of semiconductor manufacturing, a key step to ensure product performance is to accurately measure the size of micro-nano structures (such as gratings), and optical critical dimension (OCD) measurement technology is an important means to determine the size of micro-nano structures.

[0003] At present, in OCD measurement, Rigorous Coupled-Wave Analysis (RCWA) can obtain a simulated spectrum by analyzing the diffraction effect of micro-nanostructures on electromagnetic waves, and the size of the micro-nanostructure can be analyzed based on the simulated spectrum. However, RCWA contains a large number of calculation processes and requires a lot of computing resources, which makes the efficiency of analyzing the size of the micro-nanostructure low.

[0004] Based on this, this specification provides an optical critical dimension measurement method, device, storage medium and equipment. Summary of the invention

[0005] This specification provides an optical key dimension measurement method, device, storage medium and equipment to partially solve the above-mentioned problems existing in the prior art.

[0006] This manual adopts the following technical solutions:

[0007] This specification provides an optical key dimension measurement method, the method comprising:

[0008] Construct a physical model based on the structural information of the micro-nano structure to be tested;

[0009] In the periodic distribution direction of the grating region in the physical model, Fourier expansion is performed on the dielectric constant of the grating region to obtain a Fourier decomposition matrix;

[0010] Determining a screening range according to the energy of the central order in the Fourier decomposition matrix;

[0011] According to the energy of each order in the Fourier decomposition matrix, determine the order whose energy falls within the screening range, and determine the target order distribution matrix according to each screened order;

[0012] According to the Fourier decomposition matrix, the components corresponding to each order in the target order distribution matrix are determined, and according to the components corresponding to each order and the boundary conditions in the physical model, the optical critical dimensions of the micro-nano structure to be measured are determined through rigorous coupled wave analysis.

[0013] Optionally, the step of determining the screening range according to the energy of the central order in the Fourier decomposition matrix specifically includes:

[0014] The product of the energy of the central order in the Fourier decomposition matrix and a preset ratio is used as a screening threshold;

[0015] The range greater than the screening threshold is used as the screening range.

[0016] Optionally, the ratio is within 1 / 1000 and 1 / 100.

[0017] Optionally, when the grating region of the micro-nano structure to be measured is a non-rectangular surface, the method further includes:

[0018] The grating region is discretized in layers in the normal direction of the upper and lower boundaries of the grating region.

[0019] Optionally, the step of performing Fourier expansion on the dielectric constant of the grating region in the periodic distribution direction of the grating region in the physical model to obtain a Fourier decomposition matrix; and determining the screening range according to the energy of the central order in the Fourier decomposition matrix specifically includes:

[0020] For each layer of the grating region, the dielectric constant of the layer is expanded in the periodic distribution direction of the grating region to obtain the Fourier decomposition matrix of the layer;

[0021] The screening range of the layer is determined according to the energy of the central order in the Fourier decomposition matrix of the layer.

[0022] Optionally, the step of determining the orders whose energies fall within the screening range according to the energies of each order in the Fourier decomposition matrix, and determining the target order distribution matrix according to each screened order specifically includes:

[0023] According to the energy of each order in the Fourier decomposition matrix of the layer, determining the order whose energy falls within the screening range of the layer as the target order of the layer;

[0024] According to the target order of each layer, the target order distribution matrix of the physical model is determined.

[0025] Optionally, the step of determining the target order distribution matrix of the physical model according to the target order of each layer specifically includes:

[0026] Determine the union of the target orders of each layer;

[0027] According to the union, a target order distribution matrix is ​​determined.

[0028] Optionally, the method further includes:

[0029] The energy of each order in the Fourier decomposition matrix is ​​determined according to the period in the periodic distribution direction of the grating region and the dielectric constant.

[0030] Optionally, the step of determining the optical critical dimensions of the micro-nanostructure to be measured by rigorous coupled wave analysis according to the components corresponding to each order and the boundary conditions in the physical model specifically includes:

[0031] Determining a simulated spectrum of the physical model through rigorous coupled wave analysis according to the components corresponding to each order and the boundary conditions in the physical model;

[0032] Determining the actual spectrum of the micro-nanostructure to be measured;

[0033] Determining the similarity between the actual spectrum and the simulated spectrum, and judging whether the similarity reaches a preset similarity threshold;

[0034] If yes, determining the optical critical dimension of the micro-nano structure to be measured according to the structural information;

[0035] If not, the structural information is adjusted, and the physical model is adjusted according to the adjusted structural information; and the simulated spectrum of the adjusted physical model is re-determined.

[0036] Optionally, the method further includes:

[0037] Determining structural information of multiple micro-nano structures to be measured according to a preset parameter range;

[0038] For each micro-nano structure to be tested, a physical model is constructed according to the structural information of the micro-nano structure to be tested;

[0039] In the periodic distribution direction of the grating region in the physical model, Fourier expansion is performed on the dielectric constant of the grating region to obtain the Fourier decomposition matrix of the micro-nano structure to be measured;

[0040] Determining a screening range according to the energy of the central order in the Fourier decomposition matrix;

[0041] According to the energy of each order in the Fourier decomposition matrix, determine the order whose energy falls within the screening range, and determine the target order distribution matrix according to each screened order;

[0042] Determine the components corresponding to each order in the target order distribution matrix corresponding to the micro-nanostructure to be measured according to the Fourier decomposition matrix of the micro-nanostructure to be measured, and determine the simulated spectrum of the micro-nanostructure to be measured by rigorous coupled wave analysis according to the components corresponding to each order and the boundary conditions in the physical model;

[0043] A spectral library is constructed based on the simulated spectra of each micro-nanostructure to be tested.

[0044] Optionally, the step of determining the optical critical dimensions of the micro-nanostructure to be measured by rigorous coupled wave analysis specifically includes:

[0045] Determining the actual spectrum of the micro-nanostructure to be measured;

[0046] For each simulated spectrum in the spectrum library, determine the similarity between the simulated spectrum and the actual spectrum, and when the similarity reaches a preset similarity threshold, use the simulated spectrum as a matching spectrum of the micro-nano structure to be measured;

[0047] The optical critical dimension of the micro-nano structure to be measured is determined according to the structural information corresponding to the matching spectrum.

[0048] This specification provides an optical critical dimension measuring device, comprising:

[0049] A model building module is used to build a physical model based on the structural information of the micro-nano structure to be measured;

[0050] A Fourier expansion module, used for performing Fourier expansion on the dielectric constant of the grating region in the periodic distribution direction of the grating region in the physical model to obtain a Fourier decomposition matrix;

[0051] A range determination module, used to determine the screening range according to the energy of the central order in the Fourier decomposition matrix;

[0052] An order screening module, used to determine the orders whose energy falls within the screening range according to the energy of each order in the Fourier decomposition matrix, and determine the target order distribution matrix according to each screened order;

[0053] The size determination module is used to determine the components corresponding to each order in the target order distribution matrix according to the Fourier decomposition matrix, and determine the optical critical dimensions of the micro-nano structure to be measured through rigorous coupled wave analysis according to the components corresponding to each order and the boundary conditions in the physical model.

[0054] This specification provides a computer-readable storage medium, wherein the storage medium stores a computer program, and when the computer program is executed by a processor, an optical critical dimension measurement method is implemented.

[0055] This specification provides an electronic device corresponding to an optical critical dimension measurement method, the electronic device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor implements a method when executing the program.

[0056] At least one of the above-mentioned technical solutions adopted in the present specification can achieve the following beneficial effects: in an optical critical dimension measurement method provided in the present specification, first, a physical model is constructed according to the structural information of the micro-nano structure to be measured, and the dielectric constant of the grating area is Fourier expanded in the periodic distribution direction of the grating area in the physical model to obtain a Fourier decomposition matrix; secondly, a screening range is determined according to the energy of the central order in the Fourier decomposition matrix, and the order whose energy falls within the screening range is determined according to the energy of each order in the Fourier decomposition matrix; finally, a target order distribution matrix is ​​determined according to each screened order, and components corresponding to each order in the target order distribution matrix are determined based on the Fourier decomposition matrix, and the optical critical dimensions of the micro-nano structure to be measured are determined through rigorous coupled wave analysis according to the components corresponding to each screened order and the boundary conditions of the physical model.

[0057] It can be seen from the above method that the screening range is determined based on the energy of the central order in the Fourier decomposition matrix of the dielectric constant, and based on the screening range, the orders that have a greater impact on the calculation results of the rigorous coupled wave analysis are screened out, thereby improving the calculation efficiency while ensuring the accuracy of the optical key dimensions of the micro-nano structure to be measured determined by rigorous coupled wave analysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] The drawings described herein are used to provide a further understanding of this specification and constitute a part of this specification. The illustrative embodiments and descriptions of this specification are used to explain this specification and do not constitute an improper limitation on this specification. In the drawings:

[0059] Figure 1 A schematic diagram of a process of measuring an optical critical dimension provided in this specification;

[0060] Figure 2 A schematic diagram of a one-dimensional grating physical model provided in this specification;

[0061] Figure 3 A schematic diagram of determining optical critical dimensions based on iterative optimization provided in this specification;

[0062] Figure 4 A schematic diagram of the layered discretization of the non-rectangular surface grating area provided in this specification;

[0063] Figure 5A schematic diagram of determining optical critical dimensions based on library matching provided in this specification;

[0064] Figure 6 A schematic diagram of an optical critical dimension measurement device provided in this specification;

[0065] Figure 7 A schematic diagram of the structure of an electronic device corresponding to an optical key dimension measurement method provided in this specification. DETAILED DESCRIPTION

[0066] In order to make the purpose, technical solutions and advantages of this specification more clear, the technical solutions of this specification will be clearly and completely described below in combination with the specific embodiments of this specification and the corresponding drawings. Obviously, the described embodiments are only part of the embodiments of this specification, not all of them. Based on the embodiments in this specification, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this specification.

[0067] The process of executing an optical key dimension measurement method in this specification involves data processing. Therefore, in the embodiments of this specification, the process of the optical key dimension measurement method can be executed by a server. Of course, this specification does not limit the device that executes the process of the optical key dimension measurement method, for example, a personal computer and a mobile terminal. For the convenience of description, the following description is based on the server as the execution subject.

[0068] The technical solutions provided by the embodiments of this specification are described in detail below in conjunction with the accompanying drawings.

[0069] Figure 1 The flowchart of an optical key dimension measurement method provided in this specification includes the following steps:

[0070] S100: constructing a physical model according to the structural information of the micro-nano structure to be measured.

[0071] In one or more embodiments of the present specification, in order to determine the Fourier decomposition matrix corresponding to the dielectric constant of the grating region in the micro-nano structure to be measured in the subsequent steps, in this step, the server needs to first construct a physical model based on the structural information of the micro-nano structure to be measured.

[0072] Specifically, the server can configure the structural information of the micro-nano structure to be tested, and then build a physical model of the micro-nano structure to be tested based on the structural information. When configuring the structural information of the micro-nano structure to be tested, the structural information of the initial design of the micro-nano structure to be tested can be referred to. The structural information includes several structural parameters, such as the grating period, the geometric shape of the grating (the width and height corresponding to the grating protrusions and grating grooves, respectively), and the grating material properties (refractive index). The physical model is a three-dimensional model constructed based on the structural parameters in the structural information.

[0073] like Figure 2 As shown, a physical model of a micro-nano structure to be measured provided in this specification is provided. The grating area in the physical model is a one-dimensional grating. If the height of the one-dimensional grating is d, then the upper area of ​​the grating area (the area where z<0) is the incident-reflection area, and the lower area of ​​the grating area (the area where z>d) is called the transmission area. The incident-reflection area and the transmission area are generally uniform medium distribution areas.

[0074] S102: Performing Fourier expansion on the dielectric constant of the grating region in the periodic distribution direction of the grating region in the physical model to obtain a Fourier decomposition matrix.

[0075] In one or more embodiments of the present specification, RCWA is a deterministic differential solution method. In order to deal with the fluctuation problem in the grating area, it is necessary to use Floquet's theorem to expand the periodic dielectric constant into a Fourier series, and convert the partial differential equation into a set of ordinary differential equations for solving. The degree of influence of each order in the Fourier decomposition matrix of the periodic dielectric constant on the calculation result of RCWA is different, so the orders in the Fourier decomposition matrix can be screened to screen out the orders with a large degree of influence on the calculation result, thereby avoiding the calculation workload of "the orders with a small degree of influence on the calculation result in RCWA". Therefore, in order to determine the screening range for screening the orders in the Fourier decomposition matrix in the subsequent steps, in this step, the server can Fourier expand the dielectric constant of the grating area in the periodic distribution direction of the grating area in the physical model based on the physical model determined in step S100 to obtain the Fourier decomposition matrix.

[0076] Specifically, the server may perform Fourier expansion on the dielectric constant of the grating region in the periodic distribution direction of the grating region in the physical model based on the physical model of step S100, thereby obtaining a Fourier decomposition matrix. The periodic distribution direction is the extension direction of the periodic repeating unit in the grating region. Figure 2 For example, a one-dimensional grating is usually a structure that is repeatedly arranged along a specific direction on a two-dimensional plane, that is, the direction of the repeated arrangement is the direction of the periodic distribution. Figure 2In the figure, the one-dimensional grating is repeatedly arranged in the X direction, that is, the periodic distribution direction is in the X direction.

[0077] It should be noted that the maximum order of Fourier expansion is not limited in this specification and can be set according to actual needs. Alternatively, the maximum order can be set based on the computational efficiency required in actual applications. Specifically, in engineering applications, the maximum order is mainly limited by the software and hardware resources available for calculation or the timeliness and efficiency required by the engineering.

[0078] Alternatively, the maximum order in RCWA can be determined by a convergence test, that is, by gradually increasing the maximum order of Fourier expansion and observing the changes in the RCWA calculation results, the maximum order when the gradually increasing order no longer significantly changes the RCWA calculation results is used as the maximum order for Fourier expansion of the grating area. Alternatively, the maximum order can be determined based on the limitation of computing resources.

[0079] S104: Determine a screening range according to the energy of the central order in the Fourier decomposition matrix.

[0080] In one or more embodiments of the present specification, in order to screen each order in subsequent steps and determine the target order distribution matrix, in this step, the server needs to determine the screening range based on the energy of the central order in the Fourier decomposition matrix determined in step S102.

[0081] Specifically, the server can determine the screening range according to the energy of the central order in the Fourier decomposition matrix. As follows:

[0082] The product of the energy of the central order in the Fourier decomposition matrix and the preset ratio is used as the screening threshold, and the range greater than the screening threshold is used as the screening range. Among them, the ratio is within 1 / 1000 and 1 / 100, that is, the ratio is from 1 / 1000 to 1 / 100. Moreover, in the embodiment of the present specification, the value range of the ratio is 1 / 1000~1 / 100, and the boundary value of the value range can also be selected as the preset ratio. In this specification, there is no restriction on determining the energy corresponding to each order in the Fourier decomposition matrix. In one or more embodiments of the present specification, the server can determine the energy of each order in the Fourier decomposition matrix based on the period of the grating area in the periodic distribution direction and the dielectric constant. The calculation formula is as follows:

[0083]

[0084] in, is the Fourier decomposition matrix The energy of the order, and are the orders in the x and y directions respectively, is the distribution function of the dielectric constant of the grating area in the xy direction, and are the grating periods in the x and y directions, and are the wave numbers in the x and y directions, is an imaginary unit, and the energy of the central order is .

[0085] It should be noted that the central order (fundamental frequency order) represents the fundamental frequency response of the micro-nanostructure to be measured, and the energy of the central order reflects the basic response information of the micro-nanostructure to the incident light. Therefore, based on the energy of the central order, the screening range is determined, so that in the subsequent steps, the orders of energy in the Fourier decomposition matrix within the screening range can be screened out to reduce the calculation load.

[0086] S106: Determine the orders whose energies fall within the screening range according to the energies of each order in the Fourier decomposition matrix, and determine the target order distribution matrix according to each screened order.

[0087] In one or more embodiments of the present specification, in step S104, a screening range is determined based on the energy of the central order in the Fourier decomposition matrix. In this step, the server may screen out orders whose energy falls within the screening range from each order in the Fourier decomposition matrix based on the screening range determined in step S104, and determine the target order distribution matrix based on the screened orders.

[0088] Specifically, the server may determine the orders whose energies fall within the screening range according to the energies of each order in the Fourier decomposition matrix determined in step S102, and determine the target order distribution matrix based on each screened order.

[0089] It should be noted that the screening range determined in step S104 is a range greater than the "screening threshold determined based on the energy of the central order". That is, in this step, from the orders of the Fourier decomposition matrix, the orders within the screening range are screened out, that is, the orders with high energy and higher than the screening threshold are screened out. Then, in the subsequent steps, the RCWA calculation can be performed based on the screened orders, so as to ensure that the RCWA calculation process focuses on screening out the orders that have a great impact on the calculation results, thereby reducing the calculation burden of RCWA and improving efficiency on the basis of ensuring the calculation accuracy.

[0090] S108: Determine the components corresponding to each order in the target order distribution matrix according to the Fourier decomposition matrix, and determine the optical critical dimensions of the micro-nanostructure to be measured through rigorous coupled wave analysis according to the components corresponding to each order and the boundary conditions in the physical model.

[0091] In one or more embodiments of the present specification, the server may determine the Fourier components corresponding to each order in the target order distribution matrix in step S106 from the Fourier decomposition matrix determined in step S102, and then determine the optical critical dimensions of the micro-nanostructure to be measured through rigorous coupled wave analysis based on the components corresponding to each order and the boundary conditions in the physical model.

[0092] Specifically, the server can determine the components corresponding to each order in the target order distribution matrix based on the Fourier decomposition matrix, and determine the optical critical dimensions of the micro-nanostructure to be measured through rigorous coupled wave analysis based on the components corresponding to each order and the boundary conditions in the physical model. Among them, rigorous coupled wave analysis can transform the problem of solving partial differential equations into the problem of solving eigenvalues ​​and eigenvectors of ordinary differential equations by Fourier expansion of the electromagnetic field and dielectric constant of the grating area.

[0093] The specific method of determining the optical critical dimensions of the micro-nano structure to be measured, such as iterative optimization, is not limited in this specification. Based on iterative optimization, the optical critical dimensions of the micro-nano structure to be measured are determined, such as Figure 3 As shown, specifically including:

[0094] First, the server can determine the optical critical dimensions of the micro-nano structure to be measured through rigorous coupled wave analysis according to the components corresponding to each order in the target order distribution matrix and the boundary conditions in the physical model. Secondly, the server can determine the actual spectrum of the micro-nano structure to be measured by measuring the micro-nano structure to be measured. Finally, the server can determine the similarity between the actual spectrum and the simulated spectrum, and determine the optical critical dimensions based on the relationship between the preset similarity threshold and the similarity. Among them, when the similarity reaches the preset similarity threshold, the structural information is used as the optical critical dimensions of the micro-nano structure to be measured. When the similarity does not reach the preset similarity threshold, the structural information needs to be adjusted, and based on the adjusted structural information, the physical model and the simulated spectrum of the adjusted physical model are re-determined, and then the similarity between the simulated spectrum of the adjusted physical model and the actual spectrum is judged again until the similarity reaches the preset similarity threshold.

[0095] It should be noted that the structural information may be adjusted according to an optimization algorithm (such as a nonlinear least squares optimization algorithm) until the similarity between the simulated spectrum corresponding to the structural information and the actual spectrum reaches a preset similarity threshold.

[0096] In the above method, a physical model is constructed based on the structural information of the configuration of the micro-nano structure to be measured, and then before the optical critical dimensions are determined by RCWA, a screening range can be determined based on the energy of the central order in the Fourier decomposition matrix corresponding to the dielectric constant, and then based on the screening range, the order in the Fourier decomposition matrix that has a great impact on the accuracy of "determining the optical critical dimensions by RCWA" is screened, thereby obtaining a target order distribution matrix. Then, when determining the optical critical dimensions based on RCWA, the components corresponding to each order in the target order distribution matrix can be determined from the Fourier decomposition matrix, and then the optical critical dimensions of the micro-nano structure to be measured are determined by rigorous coupled wave analysis in combination with the boundary conditions of the grating area and the upper and lower boundaries. In other words, when the maximum order of the Fourier expansion of the dielectric constant is determined, the amount of calculation can be reduced by screening the order, or when the computing resources are determined, the Fourier expansion of the dielectric constant can be achieved with a higher maximum order by screening the order, thereby improving the accuracy of RCWA.

[0097] For example, assuming that the maximum order of Fourier expansion is 32, the number of normal Fourier orders is 6225. When the ratio is 1 / 100, the screening range is determined based on the ratio and the energy of the central order in the Fourier decomposition matrix, and the number of orders screened out based on the screening range is 185. Based on the calculation characteristics of RCWA, an acceleration of about 520 times can be achieved. When the ratio is 1 / 200, the screening range is determined based on the ratio and the energy of the central order in the Fourier decomposition matrix, and the number of orders screened out based on the screening range is 453. Based on the calculation characteristics of RCWA, an acceleration of about 87 times can be achieved.

[0098] It should be noted that in the process of micro-nano structure processing, due to various process limitations, processing errors such as uneven etching and inconsistent deposition thickness will occur. These processing errors cause the structural information of the micro-nano structure to be tested to deviate from the designed structural information. Therefore, RCWA, as a simulation tool, can determine whether the actual manufactured structural information is consistent with the expected structural information by simulating the physical model. When there is a mismatch, the optical critical dimensions (actual manufactured structural information) of the micro-nano structure to be tested can be explored by continuously adjusting the structural information configured on the physical model, or by directly matching with the determined simulated spectra through library matching, so that the structural information of the matched spectrum is used as the optical critical dimensions of the micro-nano structure to be tested.

[0099] In addition, when the grating area of ​​the micro-nano structure to be measured is a non-rectangular surface, this specification also provides a method of discretizing the non-rectangular surface grating area in layers, and then determining the target order corresponding to each layer for each layer, and then determining the content of the target order distribution matrix based on the target order of each layer, as follows:

[0100] In one or more embodiments of the present specification, first, the server may discretize the grating area in layers in the normal direction of the upper and lower boundaries of the grating area. Figure 4 As shown, it is a schematic diagram of layered discretization when the geometric morphology of the grating area provided in this specification is a trapezoid, wherein the upper boundary of the grating area refers to the boundary with the incident-reflection area, and the lower boundary of the grating area refers to the boundary with the transmission area.

[0101] Secondly, the server can expand the dielectric constant of each layer of the grating area in the periodic distribution direction of the grating area to obtain the Fourier decomposition matrix of the layer, and then determine the screening range of the layer according to the energy of the central order in the Fourier decomposition matrix of the layer, and based on the screening range of the layer, screen the orders in the Fourier decomposition matrix of the layer to obtain the target order of the layer. For details, refer to the above steps S104 to S106 to determine the screening range and the content of the screening order.

[0102] Finally, the server can determine the target order distribution matrix of the non-rectangular surface-shaped micro-nanostructure to be tested according to the target orders screened out in each layer.

[0103] It should be noted that, since the continuity of the boundary conditions applied between layers needs to be determined in RCWA, the purpose of determining the target order distribution matrix is ​​to ensure that the orders of each layer in the grating area are the same. However, the specific method of determining the target order distribution matrix based on the target orders screened out from each layer is not limited in this specification. In one or more embodiments of this specification, the server may determine the union of the target orders of each layer, and determine the target order distribution matrix based on the union.

[0104] It should be noted that the purpose of mentioning the screening range in step S106 is to allow the RCWA calculation process to focus on the orders with high energy and above the screening threshold, that is, the orders that have a great impact on the calculation results. Then, when the grating region is a non-rectangular surface, for each layer of the grating region, the screening range of the layer is determined, and the target order of the layer is screened out based on the screening range of the layer, and the target order that has a great impact on the RCWA calculation result of the layer is screened out only from the dimension of the layer. Therefore, the degree of influence of each target order on the overall RCWA calculation result can be evaluated from the overall structure of the grating region, so as to further screen each target order and improve the calculation efficiency of the overall RCWA. In one or more embodiments of the present specification, the server takes the target order as the first order, and for each first order, if the order to be selected is at least the target order of the layer in the preset number of grating regions, the first order is taken as the second order, and the target order distribution matrix is ​​determined according to each second order. For example, if the grating area is divided into 9 layers and the preset number is 3, when the first order is the target order of the middle layer of the 3 grating areas, the first order is used as the second order.

[0105] In the above, by evaluating the influence of each target order on the overall RCWA calculation results, the second order with a large influence on the overall RCWA calculation results can be screened out, avoiding the calculation of orders with a small influence on the overall RCWA calculation results, and improving the calculation efficiency. That is, under the condition of limited computing resources, RCWA can focus on the calculation of the second order first, and the maximum order selected can be increased. When the maximum order is fixed, the calculation process of RCWA focusing on the second order can shorten the calculation time while ensuring the calculation accuracy.

[0106] In addition, this specification also provides content on determining the optical critical dimensions of the micro-nanostructure to be measured based on library matching, such as Figure 5 As shown, specifically including:

[0107] In one or more embodiments of the present specification, first, the server can determine the actual spectrum of the micro-nano structure to be measured by measuring the micro-nano structure to be measured. Secondly, the server can determine the similarity between the simulated spectrum and the actual spectrum for each simulated spectrum in the pre-constructed spectral library, and determine whether the similarity reaches a preset similarity threshold, and when it reaches it, the simulated spectrum is used as the matching spectrum of the micro-nano structure to be measured. Finally, the structural information corresponding to the matching spectrum is used as the optical critical dimension of the micro-nano structure to be measured. Among them, if there are multiple matching spectra, the structural information corresponding to a matching spectrum can be randomly selected as the optical critical dimension of the micro-nano structure to be measured, or the structural information corresponding to the matching spectrum with the highest similarity can be selected as the optical critical dimension of the micro-nano structure to be measured, that is, the specific method of determining the optical critical dimension according to the structural information corresponding to the matching spectrum is not limited in this specification, and can be set according to actual needs.

[0108] The process of constructing the spectral library is as follows:

[0109] The server can determine the structural information of multiple micro-nano structures to be tested according to a preset parameter range, and for each micro-nano structure to be tested, construct a physical model of the micro-nano structure to be tested according to the structural information of the micro-nano structure to be tested. In the periodic distribution direction of the grating area in the physical model, the dielectric constant of the grating area is Fourier expanded to obtain the Fourier decomposition matrix of the micro-nano structure to be tested, and then the screening range is determined according to the energy of the central order in the Fourier decomposition matrix. According to the energy of each order in the Fourier decomposition matrix, the order whose energy falls into the screening range is determined, and the target order distribution matrix is ​​determined according to each screened order. According to the Fourier decomposition matrix of the micro-nano structure to be tested, the components corresponding to each order in the target order distribution matrix corresponding to the micro-nano structure to be tested are determined, and according to the components corresponding to each order and the boundary conditions in the physical model, the simulated spectrum of the micro-nano structure to be tested is determined by rigorous coupled wave analysis. According to the simulated spectra of each micro-nano structure to be tested, a spectrum library is constructed.

[0110] Among them, the parameter range includes the parameter range corresponding to each parameter in the structural information. In this specification, "determining the structural information of multiple micro-nano structures to be measured according to the preset parameter range" means determining the various structural information that may correspond to the micro-nano structure to be measured within a certain parameter range, so as to obtain a certain number of simulated spectra to match the actual spectrum of the micro-nano structure to be measured. The process of determining the simulated spectrum specifically refers to steps S100 to S108.

[0111] The above is an optical critical dimension measurement method provided in one or more embodiments of this specification. Based on the same idea, this specification also provides a corresponding optical critical dimension measurement device, such as Figure 6 shown.

[0112] A model building module 500 builds a physical model according to the structural information of the micro-nano structure to be measured;

[0113] A Fourier expansion module 501 performs Fourier expansion on the dielectric constant of the grating region in the periodic distribution direction of the grating region in the physical model to obtain a Fourier decomposition matrix;

[0114] A range determination module 502 determines a screening range according to the energy of the central order in the Fourier decomposition matrix;

[0115] An order screening module 503 determines the orders whose energies fall within the screening range according to the energies of each order in the Fourier decomposition matrix, and determines a target order distribution matrix according to each screened order;

[0116] The size determination module 504 determines the components corresponding to each order in the target order distribution matrix according to the Fourier decomposition matrix, and determines the optical critical dimensions of the micro-nano structure to be measured through rigorous coupled wave analysis according to the components corresponding to each order and the boundary conditions in the physical model.

[0117] Optionally, the range determination module 502 is specifically used to use the product of the energy of the central order in the Fourier decomposition matrix and a preset ratio as a screening threshold; and use a range greater than the screening threshold as a screening range, and the ratio is within 1 / 1000 and 1 / 100.

[0118] Optionally, the device may further include a layering module 505, which is specifically used to discretize the grating region in layers in the normal direction of the upper and lower boundaries of the grating region when the grating region of the micro-nano structure to be measured is a non-rectangular surface.

[0119] Optionally, the range determination module 502 can also be used to expand the dielectric constant of each layer of the grating area in the periodic distribution direction of the grating area to obtain the Fourier decomposition matrix of the layer; and determine the screening range of the layer based on the energy of the central order in the Fourier decomposition matrix of the layer.

[0120] Optionally, the order screening module 503 can also be used to determine the order whose energy falls within the screening range of the layer according to the energy of each order in the Fourier decomposition matrix of the layer, as the target order of the layer; and determine the target order distribution matrix of the physical model according to the target orders of each layer.

[0121] Optionally, the order screening module 503 may also be used to determine a union of target orders of each layer; and determine a target order distribution matrix based on the union.

[0122] Optionally, the order screening module 503 may also be used to determine the energy of each order in the Fourier decomposition matrix according to the period in the direction of the periodic distribution of the grating region and the dielectric constant.

[0123] Optionally, the size determination module 504 is specifically used to determine the simulated spectrum of the physical model through rigorous coupled wave analysis according to the components corresponding to the orders and the boundary conditions in the physical model; determine the actual spectrum of the micro-nano structure to be measured; determine the similarity between the actual spectrum and the simulated spectrum, and judge whether the similarity reaches a preset similarity threshold; if so, determine the optical critical dimensions of the micro-nano structure to be measured according to the structural information; if not, adjust the structural information, and adjust the physical model according to the adjusted structural information; and re-determine the simulated spectrum of the adjusted physical model.

[0124] Optionally, the device further includes a spectral library construction module 506, which is specifically used to determine the structural information of multiple micro-nano structures to be measured according to a preset parameter range; for each micro-nano structure to be measured, a physical model is constructed according to the structural information of the micro-nano structure to be measured; in the periodic distribution direction of the grating area in the physical model, the dielectric constant of the grating area is Fourier expanded to obtain the Fourier decomposition matrix of the micro-nano structure to be measured; according to the energy of the central order in the Fourier decomposition matrix, a screening range is determined; according to the energy of each order in the Fourier decomposition matrix, the order whose energy falls within the screening range is determined, and according to each screened order, a target order distribution matrix is ​​determined; according to the Fourier decomposition matrix of the micro-nano structure to be measured, the components corresponding to each order in the target order distribution matrix corresponding to the micro-nano structure to be measured are determined, and according to the components corresponding to each order and the boundary conditions in the physical model, the simulated spectrum of the micro-nano structure to be measured is determined through rigorous coupled wave analysis; according to the simulated spectra of each micro-nano structure to be measured, a spectral library is constructed.

[0125] Optionally, the size determination module 504 is specifically used to determine the actual spectrum of the micro-nano structure to be measured; for each simulated spectrum in the spectral library, determine the similarity between the simulated spectrum and the actual spectrum, and when the similarity reaches a preset similarity threshold, use the simulated spectrum as the matching spectrum of the micro-nano structure to be measured; and determine the optical critical dimension of the micro-nano structure to be measured based on the structural information corresponding to the matching spectrum.

[0126] This specification also provides a computer-readable storage medium, which stores a computer program, which can be used to execute the above Figure 1 An optical critical dimension measurement method is provided.

[0127] This manual also provides Figure 7The schematic structure diagram of the electronic device shown in FIG. Figure 7 As shown in the figure, at the hardware level, the device includes a processor, an internal bus, a network interface, a memory, and a non-volatile memory, and may also include other hardware required for the business. The processor reads the corresponding computer program from the non-volatile memory into the memory and then runs it to achieve the above Figure 1 Of course, in addition to the software implementation, this specification does not exclude other implementations, such as logic devices or a combination of software and hardware, etc., that is, the execution subject of the following processing flow is not limited to each logic unit, but can also be hardware or logic devices.

[0128] In the 1990s, it was very clear whether the improvement of a technology was hardware improvement (for example, improvement of the circuit structure of diodes, transistors, switches, etc.) or software improvement (improvement of the method flow). However, with the development of technology, many improvements of the method flow today can be regarded as direct improvements of the hardware circuit structure. Designers almost always obtain the corresponding hardware circuit structure by programming the improved method flow into the hardware circuit. Therefore, it cannot be said that the improvement of a method flow cannot be implemented with hardware entity modules. For example, a programmable logic device (PLD) (such as a field programmable gate array (FPGA)) is such an integrated circuit whose logical function is determined by the user's programming of the device. Designers can "integrate" a digital system on a PLD by programming it themselves, without having to ask chip manufacturers to design and make dedicated integrated circuit chips. Moreover, nowadays, instead of manually making integrated circuit chips, this kind of programming is mostly implemented by "logic compiler" software, which is similar to the software compiler used when developing and writing programs, and the original code before compilation must also be written in a specific programming language, which is called hardware description language (HDL). There is not only one kind of HDL, but many kinds, such as ABEL (Advanced Boolean Expression Language), AHDL (Altera Hardware Description Language), Confluence, CUPL (Cornell University Programming Language), HDCal, JHDL (Java Hardware Description Language), Lava, Lola, MyHDL, PALASM, RHDL (Ruby Hardware Description Language), etc. The most commonly used ones are VHDL (Very-High-Speed ​​Integrated Circuit Hardware Description Language) and Verilog. Those skilled in the art should also know that it is only necessary to program the method flow slightly in the above-mentioned hardware description languages ​​and program it into the integrated circuit, and then it is easy to obtain the hardware circuit that implements the logic method flow.

[0129] The controller may be implemented in any suitable manner, for example, the controller may take the form of a microprocessor or processor and a computer-readable medium storing a computer-readable program code (e.g., software or firmware) executable by the (micro)processor, a logic gate, a switch, an application-specific integrated circuit (ASIC), a programmable logic controller, and an embedded microcontroller, examples of which include but are not limited to the following microcontrollers: ARC 625D, Atmel AT91SAM, Microchip PIC18F26K20, and Silicone Labs C8051F320, and the memory controller may also be implemented as part of the control logic of the memory. It is also known to those skilled in the art that, in addition to implementing the controller in a purely computer-readable program code manner, the controller may be implemented in the form of a logic gate, a switch, an application-specific integrated circuit, a programmable logic controller, and an embedded microcontroller by logically programming the method steps. Therefore, such a controller may be considered as a hardware component, and the devices for implementing various functions included therein may also be considered as structures within the hardware component. Or even, the devices for implementing various functions may be considered as both software modules for implementing the method and structures within the hardware component.

[0130] The systems, devices, modules or units described in the above embodiments may be implemented by computer chips or entities, or by products with certain functions. A typical implementation device is a computer. Specifically, the computer may be, for example, a personal computer, a laptop computer, a cellular phone, a camera phone, a smart phone, a personal digital assistant, a media player, a navigation device, an email device, a game console, a tablet computer, a wearable device, or a combination of any of these devices.

[0131] For the convenience of description, the above device is described in various units according to their functions. Of course, when implementing this specification, the functions of each unit can be implemented in the same or multiple software and / or hardware.

[0132] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0133] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0134] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0135] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0136] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0137] The memory may include non-permanent storage in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0138] Computer readable media include permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. Information can be computer readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer readable media does not include temporary computer readable media (transitory media), such as modulated data signals and carrier waves.

[0139] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0140] This specification may be described in the general context of computer-executable instructions executed by a computer, such as program modules. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform specific tasks or implement specific abstract data types. This specification may also be practiced in distributed computing environments where tasks are performed by remote processing devices connected through a communication network. In a distributed computing environment, program modules may be located in local and remote computer storage media, including storage devices.

[0141] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0142] The above description is only an embodiment of the present specification and is not intended to limit the present specification. For those skilled in the art, the present specification may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present specification shall be included in the scope of the claims of the present specification.

Claims

1. An optical critical dimension measurement method, characterized in that: include: Construct a physical model based on the structural information of the micro-nano structure to be tested; In the periodic distribution direction of the grating region in the physical model, Fourier expansion is performed on the dielectric constant of the grating region to obtain a Fourier decomposition matrix; The product of the energy of the central order in the Fourier decomposition matrix and a preset ratio is used as a screening threshold, and a range greater than the screening threshold is used as a screening range, wherein the central order is 0th order; According to the energy of each order in the Fourier decomposition matrix, determine the order whose energy falls within the screening range, and determine the target order distribution matrix according to each screened order; According to the Fourier decomposition matrix, the components corresponding to each order in the target order distribution matrix are determined, and according to the components corresponding to each order and the boundary conditions in the physical model, the optical critical dimensions of the micro-nano structure to be measured are determined through rigorous coupled wave analysis.

2. The method according to claim 1, characterized in that The ratio is within 1 / 1000 and 1 / 100.

3. The method according to claim 1, characterized in that When the grating region of the micro-nano structure to be measured is a non-rectangular surface, the method further includes: The grating region is discretized in layers in the normal direction of the upper and lower boundaries of the grating region.

4. The method according to claim 3, characterized in that The step of performing Fourier expansion on the dielectric constant of the grating region in the periodic distribution direction of the grating region in the physical model to obtain a Fourier decomposition matrix; and determining the screening range according to the energy of the central order in the Fourier decomposition matrix specifically includes: For each layer of the grating region, the dielectric constant of the layer is expanded in the periodic distribution direction of the grating region to obtain the Fourier decomposition matrix of the layer; The screening range of the layer is determined according to the energy of the central order in the Fourier decomposition matrix of the layer.

5. The method according to claim 4, characterized in that The step of determining the order whose energy falls within the screening range according to the energy of each order in the Fourier decomposition matrix, and determining the target order distribution matrix according to each screened order, specifically includes: According to the energy of each order in the Fourier decomposition matrix of the layer, determining the order whose energy falls within the screening range of the layer as the target order of the layer; According to the target order of each layer, the target order distribution matrix of the physical model is determined.

6. The method according to claim 5, characterized in that The step of determining the target order distribution matrix of the physical model according to the target order of each layer specifically includes: Determine the union of the target orders of each layer; According to the union, a target order distribution matrix is ​​determined.

7. The method according to claim 1, characterized in that The method further comprises: The energy of each order in the Fourier decomposition matrix is ​​determined according to the period in the periodic distribution direction of the grating region and the dielectric constant.

8. The method according to claim 1, characterized in that The step of determining the optical critical dimensions of the micro-nanostructure to be measured by rigorous coupled wave analysis according to the components corresponding to each order and the boundary conditions in the physical model specifically includes: Determining a simulated spectrum of the physical model through rigorous coupled wave analysis according to the components corresponding to each order and the boundary conditions in the physical model; Determining the actual spectrum of the micro-nanostructure to be measured; Determining the similarity between the actual spectrum and the simulated spectrum, and judging whether the similarity reaches a preset similarity threshold; If yes, determining the optical critical dimension of the micro-nano structure to be measured according to the structural information; If not, the structural information is adjusted, and the physical model is adjusted according to the adjusted structural information; and the simulated spectrum of the adjusted physical model is re-determined.

9. The method according to claim 1, characterized in that The method further comprises: Determining structural information of multiple micro-nano structures to be measured according to a preset parameter range; For each micro-nano structure to be tested, a physical model is constructed according to the structural information of the micro-nano structure to be tested; In the periodic distribution direction of the grating region in the physical model, Fourier expansion is performed on the dielectric constant of the grating region to obtain the Fourier decomposition matrix of the micro-nano structure to be measured; Determining a screening range according to the energy of the central order in the Fourier decomposition matrix; According to the energy of each order in the Fourier decomposition matrix, determine the order whose energy falls within the screening range, and determine the target order distribution matrix according to each screened order; Determine the components corresponding to each order in the target order distribution matrix corresponding to the micro-nanostructure to be measured according to the Fourier decomposition matrix of the micro-nanostructure to be measured, and determine the simulated spectrum of the micro-nanostructure to be measured by rigorous coupled wave analysis according to the components corresponding to each order and the boundary conditions in the physical model; A spectral library is constructed based on the simulated spectra of each micro-nanostructure to be tested.

10. The method according to claim 9, characterized in that The step of determining the optical critical dimensions of the micro-nanostructure to be measured by rigorous coupled wave analysis specifically includes: Determining the actual spectrum of the micro-nanostructure to be measured; For each simulated spectrum in the spectrum library, determine the similarity between the simulated spectrum and the actual spectrum, and when the similarity reaches a preset similarity threshold, use the simulated spectrum as a matching spectrum of the micro-nano structure to be measured; The optical critical dimension of the micro-nano structure to be measured is determined according to the structural information corresponding to the matching spectrum.

11. An optical critical dimension measuring device, characterized in that: include: A model building module is used to build a physical model based on the structural information of the micro-nano structure to be measured; A Fourier expansion module, used for performing Fourier expansion on the dielectric constant of the grating region in the periodic distribution direction of the grating region in the physical model to obtain a Fourier decomposition matrix; A range determination module, used to use the product of the energy of the central order in the Fourier decomposition matrix and a preset ratio as a screening threshold, and use a range greater than the screening threshold as a screening range, wherein the central order is 0th order; An order screening module, used to determine the orders whose energy falls within the screening range according to the energy of each order in the Fourier decomposition matrix, and determine the target order distribution matrix according to each screened order; The size determination module is used to determine the components corresponding to each order in the target order distribution matrix according to the Fourier decomposition matrix, and determine the optical critical dimensions of the micro-nano structure to be measured through rigorous coupled wave analysis according to the components corresponding to each order and the boundary conditions in the physical model.

12. A computer-readable storage medium, characterized in that: The storage medium contains a computer program, and when the computer program is executed by a processor, the method described in any one of claims 1 to 10 is implemented.

13. An electronic device, characterized in that: The method comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the method according to any one of claims 1 to 10 is implemented when the processor executes the program.

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