Method for building a theoretical spectral library, measurement method, and electronic device, medium, program product

Abstract

The application discloses a kind of theoretical spectral library library construction method, measurement method and its electronic equipment, medium, program product. Among them, the theoretical spectral library library construction method includes: the geometry modeling of a semiconductor device is carried out, the structure parameters for describing the geometry model and the floating range of the structure parameters are set;The geometry model is divided into multiple main modules, and the structure parameter set of each main module is selected for each main module;For each floating value of each structure parameter in the structure parameter set of the main module, define the module structure set corresponding to each main module to construct a main module structure library;According to the condition corresponding to OCD measurement, the scattering matrix / transmission matrix of each module structure in the main module structure library is calculated respectively, and is saved one by one with the main module, to construct main module database.The application greatly reduces the calculation time by reducing repeated calculation.

Description

Technical Field

[0001] This invention relates to methods for constructing theoretical spectral libraries, methods for measuring key dimensions, and related electronic devices, media, and program products. Background Technology

[0002] With the development of the semiconductor manufacturing industry, the size of semiconductor devices continues to shrink, and device structure designs become increasingly complex. This places more stringent control requirements on semiconductor manufacturing processes, necessitating wafer measurement or inspection after many process steps to achieve high yields. Supplementing measurement channels and modeling techniques to further improve measurement capabilities is essential for this subsequent processing. Typically, optical critical dimension (OCD) measurement is applied to obtain highly accurate and precise information about the geometry and material properties of these structures.

[0003] The basic working principle of OCD measurement technology is as follows: A theoretical spectral library corresponding to the morphological model of the sample is established. Specific theoretical spectra from this library are then used to achieve the best match with the measured spectra obtained by the OCD measurement device, thereby determining the morphological parameters. The measured spectrum is the reflected light signal of a periodically distributed semiconductor device acquired by the OCD measurement device. Although the dielectric distribution characteristics of the sample cannot be directly deduced from the measured spectrum, a model can be established and parameterized based on the sample's dielectric distribution. Then, numerical calculation methods are used to calculate the theoretical spectral library corresponding to different parameter values ​​for this model; that is, simulation calculation is performed on the measured spectra obtained by the OCD measurement device. Finally, specific parameters corresponding to the theoretical spectrum that best matches the measured spectrum are found from the theoretical spectral library and used as parameters characterizing the sample structure and dielectric material properties.

[0004] As semiconductor structures evolve from two-dimensional to three-dimensional, product sizes become smaller and structures more complex, placing increasingly higher demands on measurement. In the measurement of critical dimensions in semiconductor optics, the rigorous coupled-wave analysis (RCWA) method is generally used for theoretical calculations.

[0005] In the RCWA method, a periodic boundary condition is applied along the grating direction, allowing the components of the electromagnetic field in the periodic direction to be expanded into Fourier eigenmodes. In the longitudinal direction perpendicular to the grating surface, the semiconductor device is divided into multiple thin layers, such that the material in each layer is approximately uniformly distributed in the longitudinal direction, making the longitudinal component of the electromagnetic field a simple homogeneous medium propagation mode. During the calculation, the response of each thin layer to the incident electromagnetic field is defined as either a scattering matrix or a transmission matrix. The propagation of the electromagnetic field along the propagation direction is achieved by iterating the scattering / transmission matrix according to the boundary conditions of the electromagnetic field, obtaining the propagation of the incident light throughout the entire structure.

[0006] Therefore, in the RCWA method, computational complexity is related to structural complexity. With advancements in semiconductor technology, semiconductor structures are becoming increasingly complex, with three-dimensional structures and finer structural partitioning leading to a dramatic increase in the computation time required for RCWA. Summary of the Invention

[0007] The purpose of this invention is to provide a method that can accelerate the establishment of theoretical spectral libraries, thereby solving the problem of excessively long computation time in existing RCWA.

[0008] To achieve the above objectives, the present invention provides a method for constructing a theoretical spectral library in its first aspect, comprising:

[0009] A semiconductor device is geometrically modeled, and structural parameters and floating ranges of the structural parameters are set to describe the geometric model.

[0010] The geometric model is divided into multiple main modules, and a set of structural parameters for each main module is selected accordingly.

[0011] For each floating value of each structural parameter in the set of structural parameters of the main module, define the module structure set corresponding to each main module to construct the main module structure library;

[0012] Based on the conditions corresponding to OCD measurements, the scattering matrix / transmission matrix of each module structure in the main module structure library is calculated and saved one-to-one with the main module to construct the main module database.

[0013] Preferably, the semiconductor device includes all semiconductor structures of the same batch of products under different process stages and process parameters. Preferably, when a certain process stage or process parameter changes and a new main module is introduced into the original geometric model, the new main module and its corresponding set of structural parameters and scattering matrix / transmission matrix are saved to the main module matrix library.

[0014] Preferably, it further includes:

[0015] Based on the structure of the semiconductor device, arrange and combine the module structures in all the main module structure library to form the structural model of all semiconductor devices;

[0016] According to the arrangement order of all main modules corresponding to the structural model of each semiconductor device, the scattering matrix or transfer matrix is ​​iterated to obtain the scattering matrix / transfer matrix of the structural model of each semiconductor device, which is used to calculate the theoretical spectrum corresponding to the structural model of the semiconductor device.

[0017] Calculate the theoretical spectra corresponding to the structural models of all semiconductor devices and save them to the theoretical spectrum library.

[0018] Preferably, the step of calculating the theoretical spectrum corresponding to the structural model of the semiconductor device further includes:

[0019] Calculate the scattering matrix / transmission matrix of the reflecting region and the scattering matrix / transmission matrix of the transmitting region;

[0020] The scattering matrix / transmission matrix is ​​obtained by iterating through the corresponding scattering matrix / transmission matrix in the order of reflection region, semiconductor device region and transmission region. The semiconductor device region is the region corresponding to the calculated structural model of the semiconductor device.

[0021] The desired theoretical spectral values ​​are obtained based on the overall scattering / transmission matrix.

[0022] Preferably, when there are shared structural parameters between adjacent main modules, the shared structural parameters and the adjacent main modules respectively calculate the scattering matrix of each main module, and save them in a one-to-one correspondence.

[0023] Preferably, the semiconductor structure is divided into multiple main modules based on the consistency of materials and / or shape in the semiconductor device.

[0024] Preferably, the structural parameters are set according to the critical dimensions in the semiconductor device, and the fluctuation range of the structural parameters is set according to the manufacturing process of the semiconductor device.

[0025] Preferably, the scattering matrix or transmission matrix of each main module is calculated using the method of rigorous coupled-wave analysis of electromagnetic fields.

[0026] Preferably, the method for calculating the scattering matrix / transmission matrix of each main module includes:

[0027] Based on the geometric characteristics of the material distribution, the main module to be calculated is vertically layered so that the material distribution in the vertical direction of each layer can be approximated as uniform.

[0028] The scattering matrix of each layer is calculated by combining the corresponding OCD measurement conditions;

[0029] The scattering matrix or transmission matrix of the main module to be calculated is obtained by iterating through the scattering matrix of each layer of the main module in its order of arrangement.

[0030] By combining the floating range of the structural parameters corresponding to the main module, the scattering matrix or transmission matrix of the main module structure to be calculated for each set of structural parameters is obtained, so as to obtain the set of scattering matrices or transmission matrices corresponding to the main module.

[0031] Preferably, the iterative operation is obtained based on the continuous boundary conditions of the continuous electromagnetic field between the scattering matrix and the transmission matrix.

[0032] On the other hand, the present invention also provides a method for measuring a critical dimension, comprising:

[0033] The measured spectrum of the semiconductor device under test is matched with the theoretical spectral library constructed using the method described above to obtain the optimal theoretical spectrum;

[0034] The critical dimensions corresponding to the optimal theoretical spectrum are obtained, which are the critical dimension measurements of the current semiconductor device structure under test.

[0035] On the other hand, the present invention also provides an electronic device, the device including a memory storing computer-executable instructions and a processor; when the instructions are executed by the processor, the device performs according to the method described above.

[0036] On the other hand, the present invention also provides a computer-readable medium storing one or more programs that can be executed by one or more processors to implement the method described above.

[0037] On the other hand, the present invention also provides a computer program product, including a computer program that, when executed by a processor, implements the method described above.

[0038] Due to the application of the above-mentioned solution, the present invention has the following advantages and effects compared with the prior art:

[0039] In the technical solution provided by this invention, the device structure is geometrically modeled and parameterized to divide it into main modules. Based on the electromagnetic field propagation characteristics, the electromagnetic field response in each main module is calculated. Then, the main modules are modeled according to the structure of the measured semiconductor device to obtain the theoretical spectrum. This allows for the utilization of the similarity between these structures, reducing redundant calculations and significantly decreasing computation time. Attached Figure Description

[0040] Appendix Figure 1 A flowchart illustrating a method for constructing a theoretical spectral library provided by this invention;

[0041] Appendix Figure 2 This is a schematic diagram of a three-dimensional grating structure model provided in an embodiment of the present invention;

[0042] Appendix Figure 3 To be continued Figure 6 This is a schematic diagram of the main module of the semiconductor device provided in an embodiment of the present invention;

[0043] Appendix Figure 7 This is a schematic diagram of an electronic device structure for implementing a method for constructing a theoretical spectral library, as provided in an embodiment of the present invention. Detailed Implementation

[0044] Rigorous coupled-wave analysis (RCWA) and similar algorithms have been widely used in the research and design of diffraction structures. In the RCWA method, periodic boundary conditions are applied to the periodic structure along the grating direction. In the longitudinal direction perpendicular to the grating plane, sufficiently thin, flat grating slices are used to approximate a uniform distribution of the medium in the longitudinal direction. Specifically, RCWA involves three main operations: longitudinal layering of the semiconductor device; calculation of the scattering matrix / or transmission matrix of the electromagnetic field propagation in each layer and iterative calculation of the scattering matrix / transmission matrix of each layer to obtain the scattering matrix / transmission matrix of the entire semiconductor device; and coupling the scattering matrix / transmission matrix of the incident field and the transmission matrix of the emitted field according to the measured incident and emitted conditions, ultimately obtaining the reflected / emitted electromagnetic field information of the entire device under the measured incident conditions.

[0045] In the traditional process of building theoretical spectral libraries, the RCWA calculations for each device structure are independent. That is, each device is layered, and the scattering matrix of each layer is calculated. However, in actual calculations, many structures exhibit high similarity during database construction. This results in a significant amount of redundant computation during the RCWA calculation of the scattering matrix.

[0046] In the technical solution of this invention, the device structure is geometrically modeled and parameterized to divide it into main modules. Based on the electromagnetic field propagation characteristics, the electromagnetic field response in each main module is calculated. Then, the main modules are modeled according to the structure of the measured semiconductor device to obtain the theoretical spectrum. This allows for the utilization of the similarity between these structures, reducing redundant calculations and significantly decreasing computation time.

[0047] Specifically, based on the semiconductor process flow, we first modularize each device according to the process. Then, we use the RCWA algorithm to calculate and save the scattering / transfer matrix of each main module. Finally, the entire structure of the semiconductor device to be tested can be selected by combining corresponding main modules. Therefore, the scattering matrix of the entire structure of the semiconductor device under test can be obtained iteratively from the scattering matrix of the selected main module. The iterative operation is an iterative operation between scattering matrices based on electromagnetic field boundary conditions. By iterating over the scattering / transfer matrices of each main module, we obtain the scattering / transfer matrices of all structures in the structure library, and thus obtain all the spectral information of the theoretical spectral library we need.

[0048] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0049] In this invention, unless otherwise expressly specified and limited, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "a plurality of" means at least two, such as two, three, etc., unless otherwise expressly and specifically limited.

[0050] The technical solutions provided in the various embodiments of this specification are described in detail below with reference to the accompanying drawings.

[0051] Figure 1 This is a flowchart illustrating a method provided in this specification, including the following steps:

[0052] S100: Perform geometric modeling on a semiconductor device, and set structural parameters for describing the geometric model and the floating range of the structural parameters;

[0053] Specifically, methods for geometrically modeling a semiconductor device include: geometrically modeling the semiconductor device with the smallest period in a periodic grating structure. Figure 2 A model of a three-dimensional grating structure in one embodiment is shown, consisting of a series of repeating cells. Wherein, Figure 3 for Figure 2 The diagram shows a cross-sectional view of the semiconductor device with the smallest period in the grating structure, including the detailed geometry of the grating.

[0054] The semiconductor device is geometrically modeled without considering material and parameter fluctuations. The parameters describing the semiconductor device's geometric model can be structural parameters or dielectric material parameters. These parameters may include, but are not limited to, the grating period length, the groove width, the groove depth, the film thickness, and grating material parameters.

[0055] Specifically, Figure 3 The illustrated semiconductor structure A10 includes a first trapezoidal mesa formed on a semiconductor substrate 11 by a first material layer 12, and a second trapezoidal mesa formed on the first material layer 12 by a second material layer 13. In this embodiment, the structural parameters are set according to the critical dimensions in the semiconductor device. Specifically, for... Figure 3 The width BCD2 of the lower base of the first trapezoidal mesa and the length HT2 of the waist of the trapezoidal mesa, the width TCD1 of the upper base of the second trapezoidal mesa and the length HT1 of the waist of the second trapezoidal mesa, and the width BCD1 of the upper base of the overlapping first trapezoidal mesa and the width BCD1 of the lower base of the second trapezoidal mesa are set with 5 parameters P1 = P(TCD1, BCD1, HT1, BCD2, HT2).

[0056] Furthermore, in designing semiconductor devices, certain parameters have an acceptable range of variation, often referred to as the parameter float range. Setting this range requires consideration of factors such as manufacturing process tolerances, device performance requirements, and cost-effectiveness. For complex semiconductor device models, it may be necessary to float multiple parameters to explore the impact of different parameter combinations on performance. Therefore, in this embodiment, this step also includes setting the float range of the structural parameters according to the manufacturing process of the semiconductor device.

[0057] Next, step S200 is executed: the geometric model is divided into multiple main modules, and a set of structural parameters for each main module is selected accordingly.

[0058] In this step, based on the consistency of the material and / or shape in the semiconductor device, the semiconductor device with the smallest period in the periodic grating structure is divided into several main modules. Specifically, the main modules are divided according to factors such as material and shape, shape continuity, and structural similarity. Specifically, in this embodiment, based on the distribution of the material, the main modules are divided into... Figure 2 and Figure 3 The semiconductor structure A10 described above is divided into two main modules: main module a1 (Element 1 ) and main module a2 (Element 2 Among them, the structure formed by the first material layer 12 is the main module a1, and the structure formed by the second material layer 13 is the main module a2.

[0059] In this step, the structural parameters corresponding to the main module in each semiconductor structure belong to a subset of the structural parameters describing the semiconductor device. That is, each main module is only associated with a portion of the parameter set describing the entire semiconductor device. Furthermore, based on the structural parameter settings in the previous step, we can obtain the structural parameter set U1 = U(BCD1, HT2, BCD2) associated with main module a1, and the structural parameter set U2 = U(TCD1, HT1, BCD1) associated with main module a2.

[0060] Next, step S400 is executed: for each floating value of each structural parameter in the structural parameter set of the main module, a module structure set corresponding to each main module is defined to construct the main module structure library.

[0061] In this embodiment, all structural parameters set in step S100 are floating structural parameters. In other embodiments, some of the structural parameters set in step S100 may be non-floating.

[0062] Furthermore, this step also includes setting discrete values ​​for each floating variable within its set floating range. Once the discrete values ​​for each floating variable are determined, a main module structure library can be created and saved for the different structural parameters of each main module.

[0063] Specifically, Figure 3 The structural model of semiconductor device A10 has five structural parameters, P1 = P(TCD1, BCD1, HT1, BCD2, HT2). Each structural parameter has 10 discrete values ​​as a range of selectable floating values. Therefore, P1 has a total of 10 possible values. 5 Combinations of structural parameters. Each combination of structural parameters corresponds to a geometric model of a semiconductor device / structure, therefore, in the traditional approach, Figure 3 There are 10 models in the model library corresponding to semiconductor device A10. 5 A geometric model.

[0064] In this embodiment, the main module a1 of the technical solution of the present invention is associated with a set of structural parameters U1 = U(BCD1, HT2, BCD2), and the main module a2 is associated with a set of structural parameters U2 = U(TCD1, HT1, BCD1). Each structural parameter has 10 discrete values ​​as a range of selectable floating values. Therefore, U1 has a total of 10 values. 3 The group structure parameter combination, U2 has a total of 10. 3 The structural parameter combinations are grouped together. Each combination of structural parameters corresponds to a geometric model of a main module. Therefore, there are a total of 10 geometric models of the main module corresponding to main module a1. 3 There are 10 geometric models corresponding to main module a2.3 indivual.

[0065] Specifically, during the floating of structural parameters, changes in the value of each structural parameter alter the configuration of the relevant main modules in the semiconductor device, forming a new geometric model of the main module. These geometric models of main modules can be aggregated and associated with their respective main modules. Furthermore, by aggregating the geometric models corresponding to multiple main modules, a main module structure library is formed for subsequent analysis and comparison. This main module structure library can manage and access different parameter configurations. This library can be stored in a database or other storage media for quick access and use during the design process. Therefore, each parameter adjustment only requires updating the main module associated with that parameter, without needing to update the entire semiconductor device.

[0066] Furthermore, the main module structure library may include geometric models of all main modules of a semiconductor device in a series of process steps.

[0067] Specifically, the semiconductor devices include all semiconductor structures from the same batch of products under different process stages and parameters. Furthermore, when a process stage changes, a new semiconductor device / structure is generated. Information from certain main modules in the new semiconductor device / structure can be reused from the main module information of the previous stage. That is, the semiconductor device / structure has a new configuration, for example... Figures 3 to 6 The semiconductor devices / structures shown represent semiconductor structures at different process stages.

[0068] For details, please refer to Figure 4 , Figure 4 The semiconductor structure A11 shown is Figure 3 In the semiconductor device A10, a trench L1 is formed in the second material layer 13 through etching, but the trench L1 has not yet penetrated the bottom of the second material layer 13. In semiconductor manufacturing, the trench L1 can be formed by plasma etching or wet etching. The etching depth may vary under different process parameters. Figure 5 The groove L1 described herein can reach the bottom of the second material layer 13. Figure 6 The groove L1 described herein can penetrate the bottom of the second material layer 13 and reach the first material layer 12.

[0069] compared to Figure 4 In the semiconductor structure A11 shown, Figure 3 Information from the main module a1 in semiconductor device A10 can be referenced in semiconductor device A11. And... Figure 4 If the main module a3 contains the groove L1, it will be used as a new main module for calculation. Additionally, relative to... Figure 2 and Figure 3In other words, the height of main module a2 in A11 and main module a2 in A10 can be considered as the same type of main module. When calculating main module a2 in A11, only the geometric model of the parameter set not included in module a2 of A10 can be calculated.

[0070] refer to Figure 5 As shown, compared to Figure 4 Regarding the geometric model of the semiconductor structure A11 shown, Figure 5 During the calculation of the semiconductor structure, no new main module appears. The main modules a1 and a3 in A10 and A11 can be directly called to update the geometric model corresponding to the discrete values ​​of the uncalculated parameters.

[0071] refer to Figure 6 As shown, if over-etching occurs, trenches are also formed in the first material layer 12 on top of the semiconductor structure A12. Compared to Figure 5 Regarding the geometric model of the semiconductor structure A12 shown, Figure 6 A new main module a5 was introduced into the semiconductor structure A13. Figure 6 The main modules included are a1, a3, and a5. Relative Figures 2 to 5 In semiconductor structure A13, the height of the main module a1 will be reduced accordingly by the thickness of the first material layer 12 occupied by the trench L1 depth. Therefore, we only need to calculate the geometric model corresponding to the newly appearing parameter values ​​in the parameter set of the main module a1 in semiconductor structure A13.

[0072] As illustrated above, different semiconductor structures will exist at different stages of the process. In this embodiment, according to the semiconductor process flow, the geometric model of each semiconductor device is established in the form of the main modular module shown above, according to the progress of the process and the corresponding semiconductor structure at different stages. The main module sets a set of floating values ​​for structural parameters, and a main module structure library is established and saved according to different structural parameters.

[0073] Next, based on the conditions corresponding to OCD measurements, the scattering matrix / transmission matrix of all main module structures in the main module structure library is calculated for each main module, and the results are saved one-to-one with the structures in the main module structure library to construct the main module database.

[0074] In the RCWA algorithm, the scattering matrix of each main module is calculated based on the propagation characteristics of the electromagnetic field in the medium. The entire semiconductor structure is a combination of these main modules; therefore, the response of the entire semiconductor structure to the electromagnetic field can be obtained by iteratively calculating the response of each main module to the incident electromagnetic field, i.e., the scattering matrix / transmission matrix.

[0075] Specifically, methods for calculating the scattering or transmission matrix of each main module using rigorous coupled-wave electromagnetic field analysis include:

[0076] Step f31: Based on the geometric characteristics of the material distribution, the main module to be calculated is vertically layered so that the material distribution in each layer can be approximated as uniform in the longitudinal direction; the thickness of each layer is determined according to the required accuracy of the approximation. The precision of these layer divisions needs to ensure that the detailed features of the grating are captured in the longitudinal direction.

[0077] by Figure 3 Taking the semiconductor structure A10 as an example, in this embodiment, the main modules a1 and a2 are vertically layered, and the ladder structure of the main modules a1 and a2 is approximated as a multi-layered cuboid thin layer, so that the dielectric distribution in the vertical direction of each layer meets the theoretical calculation requirement of approximately uniform distribution. According to the layering accuracy, the main module a1 is divided into 5 layers in the vertical direction, and the main module a2 is divided into 10 layers in the vertical direction.

[0078] Step f32: Calculate the scattering matrix for each layer based on the corresponding OCD measurement conditions;

[0079] Specifically, based on Maxwell's equations and boundary conditions for electromagnetic field propagation, a set of equations describing the electromagnetic field distribution in each layer is constructed, and the scattering matrix / transmission matrix S for each layer is also constructed. The scattering matrix / transmission matrix S describes the relationship between the incident and emitted electromagnetic fields of the layer.

[0080] Step f33: Iterate through the scattering matrices of each layer of the main module to be calculated in their order to obtain the scattering matrix or transmission matrix of the main module to be calculated.

[0081] For multi-layered structures in the main module, the propagation of electromagnetic fields between layers needs to be considered. This typically involves iteratively calculating the scattering matrices of adjacent layers using appropriate coupling matrices to obtain the scattering / transmission matrix of the entire main module.

[0082] The first computational structure refers to the initial computation, where one structure within it is used for layered computation. A computational structure has 15 layers from top to bottom, and each layer requires the computation of a scattering matrix. Therefore, a single structure (computational structure) in the corresponding device library requires the computation of 15 scattering matrices.

[0083] Specifically, in this embodiment, Figure 3 Taking the semiconductor structure A10 in the example, for the main module a1 (Element) 1 By selecting the first computational structure, its scattering matrix can be obtained:

[0084]

[0085] A total of 5 scattering matrices / transmission matrices were calculated and their iterations were implemented.

[0086] For module a2(Element) 2 Choosing the first computational structure, its scattering matrix can be expressed as:

[0087]

[0088] A total of 10 scattering / transmission matrices were calculated and their iterations were performed.

[0089] Step f34: Calculate the scattering matrix or transmission matrix of the main module structure to be calculated for each set of parameters based on the floating range of the structural parameters corresponding to the main module, so as to obtain the set of scattering matrices or transmission matrices corresponding to the main module.

[0090] Specifically, in this embodiment, Figure 3 Taking semiconductor structure A10 as an example, the set of structural parameters U1(BCD1, HT2, BCD2) corresponding to the main module a1 to be calculated has a structural model library containing a combination of discrete values ​​of each structural parameter. For example, in one implementation, within the floating range of each parameter setting, BCD1 is set to 10 discrete values, HT2 is set to 10 discrete values, and BCD2 is set to 10 discrete values. Therefore, corresponding to the main module a1, there are a total of 10 structural models in its main module structural library based on the different combinations of discrete values ​​of the structural parameters. 3 Therefore, for the main module a1, its scattering matrix / transmission matrix can be denoted as S. Element1 i i can be iterated from 1 to 10 3 Each main module a1 requires the calculation of 5 scattering matrices. Therefore, for the structure library of main module a1, the total number of scattering matrices that need to be calculated is 5 * 10. 3 indivual.

[0091] The set of structural parameters corresponding to the main module a2 to be calculated is U2 = U(TCD1, HT1, BCD1). Within the floating range of each parameter setting, TCD1 is set with 10 discrete values, HT1 with 10 discrete values, and BCD1 with 10 discrete values. Therefore, corresponding to the main module a2, there are a total of 10 structural models in its main module structure library based on the different combinations of discrete values ​​of the structural parameters. 3 Therefore, for the main module a2, its scattering matrix / transmission matrix can be denoted as S. Element2 j j can be traversed from 1 to 10 3Each sample in main module a2 requires the calculation of 10 scattering matrices. Therefore, for the structure library in main module a1, the total number of scattering matrices to be calculated is 10 * 10. 3 indivual.

[0092] Next, step S400 is executed: for each semiconductor structure model to be calculated, the scattering matrix / transmission matrix of the semiconductor device is obtained iteratively according to the scattering matrix of its corresponding main module and its arrangement order. Combined with the measurement conditions of the OCD instrument, the calculated spectrum corresponding to the measurement conditions is obtained, and it is matched one-to-one with the variables of the structural parameters of the semiconductor device to construct a theoretical spectral database for OCD measurement of the semiconductor device.

[0093] Based on this case Figure 3 For each sample A10 of the semiconductor structure to be calculated, its overall scattering matrix can be expressed as:

[0094]

[0095] That is, iterate through all combinations of main module 1 and main module 2 to obtain the scattering matrix / transmission matrix of all semiconductor devices that need to be calculated.

[0096] After obtaining the scattering matrix of the structure, as with traditional methods, all calculated spectra under the measurement conditions corresponding to the OCD measurement spectra can be obtained and matched one-to-one with the parameters of the semiconductor device model to obtain the theoretical spectral database required for the OCD measurement of the semiconductor device.

[0097] In this invention, the total number of scattering matrices calculated is 10. 3 *5+10 3 *10 = 15,000.

[0098] In traditional methods, each computational structure is divided into 15 layers vertically, as is the case in this invention. Therefore, each structure requires the calculation of 15 scattering matrices. The calculation of the first computational structure: from top to bottom, the scattering matrix of the first layer is S1, the second layer is S2, and so on up to the last layer, S15. There are a total of 5 structural variables, and each variable has 10 discrete values, resulting in a total of 10... 5 The computational structure is complex. Therefore, the total number of scattering matrices that need to be calculated is 1,500,000, which is far greater than the computational requirements of this invention.

[0099] Furthermore, after completing the above steps, the solution provided by this invention also includes:

[0100] The arrangement and combination of the main modules corresponding to the semiconductor devices constitute a device structure library;

[0101] According to the arrangement order of all main modules corresponding to each semiconductor device in the device structure library, the scattering matrix or transfer matrix of each device is iterated to obtain the scattering matrix / transfer matrix of each device, which is used to calculate all theoretical spectra.

[0102] On the other hand, this embodiment also provides a method for measuring critical dimensions, including:

[0103] The optimal theoretical spectrum is obtained by matching the measured spectrum of the semiconductor device under test with the theoretical spectral library as described above.

[0104] The critical dimensions corresponding to the optimal theoretical spectrum are obtained, which are the critical dimension measurements of the current semiconductor device structure under test.

[0105] This specification also provides a computer-readable storage medium storing a computer program that can be used to execute the above-described... Figure 1 A method for optimizing graphics processor memory is provided.

[0106] This instruction manual also provides Figure 7 The diagram shows a schematic structural representation of the electronic device. Figure 7 As shown, at the hardware level, this electronic device includes a processor, internal bus, network interface, memory, and non-volatile memory, and may also include other hardware required for business operations. The processor reads the corresponding computer program from the non-volatile memory into memory and then runs it to achieve the above. Figure 1 The aforementioned graphics processor memory optimization method.

[0107] Of course, in addition to software implementation, this specification does not exclude other implementation methods, such as logic devices or a combination of hardware and software. In other words, the execution subject of the following processing flow is not limited to each logic unit, but can also be hardware or logic devices.

[0108] In the 1990s, improvements to a technology could be clearly distinguished as either hardware improvements (e.g., improvements to the circuit structure of diodes, transistors, switches, etc.) or software improvements (improvements to the methodology). However, with technological advancements, many methodological improvements today can be considered direct improvements to the hardware circuit structure. Designers almost always obtain the corresponding hardware circuit structure by programming the improved methodology into the hardware circuit. Therefore, it cannot be said that a methodological improvement cannot be implemented using hardware physical modules. For example, a Programmable Logic Device (PLD) (such as a Field Programmable Gate Array (FPGA)) is such an integrated circuit whose logic function is determined by the user programming the device. Designers can program and "integrate" a digital system onto a PLD themselves, without needing chip manufacturers to design and manufacture dedicated integrated circuit chips. Furthermore, nowadays, instead of manually manufacturing integrated circuit chips, this programming is mostly implemented using "logic compiler" software. Similar to the software compiler used in program development, the original code before compilation must be written in a specific programming language, called a Hardware Description Language (HDL). There are many HDLs, 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, and RHDL (Ruby Hardware Description Language). Currently, the most commonly used are VHDL (Very-High-Speed ​​Integrated Circuit Hardware Description Language) and Verilog. Those skilled in the art should understand that by simply performing some logic programming on the method flow using one of these hardware description languages ​​and programming it into an integrated circuit, the hardware circuit implementing the logical method flow can be easily obtained.

[0109] The controller can be implemented in any suitable manner. For example, it can take the form of a microprocessor or processor and a computer-readable medium storing computer-readable program code (e.g., software or firmware) executable by the (micro)processor, logic gates, switches, application-specific integrated circuits (ASICs), programmable logic controllers, and embedded microcontrollers. Examples of controllers include, but are not limited to, the following microcontrollers: ARC 625D, Atmel AT91SAM, Microchip PIC18F26K20, and Silicon Labs C8051F320. A memory controller can also be implemented as part of the control logic of the memory. Those skilled in the art will also recognize that, in addition to implementing the controller in purely computer-readable program code form, the same functionality can be achieved by logically programming the method steps to make the controller take the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers. Therefore, such a controller can be considered a hardware component, and the means included therein for implementing various functions can also be considered as structures within the hardware component. Alternatively, the means for implementing various functions can be considered as both software modules implementing the method and structures within the hardware component.

[0110] The systems, devices, modules, or units described in the above embodiments can be implemented by computer chips or entities, or by products with certain functions. A typical implementation device is a computer. Specifically, a computer can be, for example, a personal computer, laptop computer, cellular phone, camera phone, smartphone, personal digital assistant, media player, navigation device, email device, game console, tablet computer, wearable device, or any combination of these devices.

[0111] For ease of description, the above devices are described in terms of function, divided into various units. Of course, in implementing this specification, the functions of each unit can be implemented in one or more software and / or hardware components.

[0112] Those skilled in the art will understand that embodiments of this specification can be provided as methods, systems, or computer program products. Therefore, this specification may take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this specification may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0113] This specification is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this specification. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create a machine for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0114] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0115] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0116] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0117] Memory may include non-persistent storage in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0118] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, 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 technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0119] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0120] Those skilled in the art will understand that the embodiments of this specification can be provided as methods, systems, or computer program products. Therefore, this specification may take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this specification may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0121] This specification can be described in the general context of computer-executable instructions that are executed by a computer, such as program modules. Generally, program modules include routines, programs, objects, components, data structures, etc., that perform a specific task or implement a specific abstract data type. This specification can also be practiced in distributed computing environments, where tasks are performed by remote processing devices connected via a communication network. In distributed computing environments, program modules can reside in local and remote computer storage media, including storage devices.

[0122] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on describing the differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments.

[0123] The above description is merely an embodiment of this specification and is not intended to limit this specification. Various modifications and variations can be made to this specification by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this specification should be included within the scope of the claims of this specification.

Claims

1. A method for constructing a theoretical spectral library, characterized in that, include: A geometric model of the semiconductor device is performed, and structural parameters and their floating ranges are set to describe the geometric model of the semiconductor device; wherein, the semiconductor device includes all semiconductor structures of the same batch of products under different process stages and process parameters; Based on the semiconductor process flow and the consistency of materials and / or shapes in the semiconductor devices, all semiconductor structures are divided into multiple non-repeating main modules, and a set of structural parameters for each main module is selected accordingly. For each floating value of each structural parameter in the set of structural parameters of the main module, define the module structure set corresponding to each main module to construct the main module structure library; Based on the conditions corresponding to OCD measurements, the scattering matrix / transmission matrix of each module structure in the main module structure library is calculated and saved one-to-one with the main module to construct the main module database. Based on the structure of the semiconductor device, the module structures in all the main module structure library are arranged and combined, and the structural model corresponding to each semiconductor device is defined to construct the device structure library. According to the arrangement order of the main modules of the structural model corresponding to each semiconductor device in the device structure library, the scattering matrix or transfer matrix of the semiconductor device is iterated to obtain the scattering matrix / transfer matrix of the structural model corresponding to each semiconductor device, which is used to calculate all theoretical spectra and save them to the theoretical spectrum library. The theoretical spectral library is adapted to be matched with the measurement spectrum of the semiconductor device under test to obtain the optimal theoretical spectrum that is closest to the measurement spectrum.

2. The method for constructing a theoretical spectral library according to claim 1, characterized in that, When a certain process stage or process parameter changes, and a new main module is introduced into the original geometric model, the new main module and its corresponding set of structural parameters and scattering matrix / transmission matrix are saved to the main module matrix library.

3. The method for constructing a theoretical spectral library according to claim 1, characterized in that, The steps for calculating the theoretical spectrum corresponding to the structural model of the semiconductor device also include: Calculate the scattering matrix / transmission matrix of the reflecting region and the scattering matrix / transmission matrix of the transmitting region; The scattering matrix / transmission matrix is ​​obtained by iterating through the corresponding scattering matrix / transmission matrix in the order of reflection region, semiconductor device region and transmission region, where the semiconductor device region is the region corresponding to the calculated structural model of the semiconductor device; The desired theoretical spectral values ​​are obtained based on the overall scattering / transmission matrix.

4. The method for constructing a theoretical spectral library according to claim 1, characterized in that, When there are shared structural parameters between adjacent main modules, the shared structural parameters and the adjacent main modules respectively calculate the scattering matrix of each main module, and save them in a one-to-one correspondence.

5. The method for constructing a theoretical spectral library according to claim 1, characterized in that, The structural parameters are set according to the critical dimensions in the semiconductor device, and the fluctuation range of the structural parameters is set according to the manufacturing process of the semiconductor device.

6. The method for constructing a theoretical spectral library according to claim 1, characterized in that, The scattering matrix or transmission matrix of each main module is calculated using the method of rigorous coupled-wave analysis of electromagnetic fields.

7. The method for constructing a theoretical spectral library according to claim 6, characterized in that, The methods for calculating the scattering matrix / transmission matrix of each main module include: Based on the geometric characteristics of the material distribution, the main module to be calculated is vertically layered so that the material distribution in each layer is approximately uniform in the longitudinal direction. The scattering matrix of each layer is calculated by combining the corresponding OCD measurement conditions; The scattering matrix or transmission matrix of the main module to be calculated is obtained by iterating through the scattering matrix of each layer of the main module in its order of arrangement. By combining the floating range of the structural parameters corresponding to the main module, the scattering matrix or transmission matrix of the main module structure to be calculated for each set of structural parameters is obtained, so as to obtain the set of scattering matrices or transmission matrices corresponding to the main module.

8. The method for constructing a theoretical spectral library according to claim 3 or 7, characterized in that, The iterative operation is obtained based on the continuous boundary conditions of the continuous electromagnetic field between the scattering matrix and the transmission matrix.

9. A method for measuring a critical dimension, characterized in that, include: The measured spectrum of the semiconductor device under test is matched with the theoretical spectral library constructed using the method described in claim 1 to obtain the optimal theoretical spectrum; The critical dimensions corresponding to the optimal theoretical spectrum are obtained, which are the critical dimension measurements of the current semiconductor device structure under test.

10. An electronic device, characterized in that, The device includes a memory storing computer-executable instructions and a processor; when the instructions are executed by the processor, the device performs the method according to any one of claims 1 to 9.

11. A computer-readable medium, characterized in that, The computer-readable medium stores one or more programs, which can be executed by one or more processors to implement the method of any one of claims 1 to 9.

12. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by a processor, it implements the method as described in any one of claims 1 to 9.

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