Overlay error compensation method and device and photoetching machine

Abstract

The invention provides an overlay error compensation method, an overlay error compensation device and a photoetching machine, which can be applied to the field of semiconductor manufacturing. The method comprises the steps that high-order polynomial fitting is conducted on current actual overlay error data, multiple current candidate overlay parameters are obtained, the current candidate overlay parameters represent coefficients of a high-order polynomial, and the order of the high-order polynomial is larger than or equal to 4; determining a plurality of current target overlay parameters from the plurality of current candidate overlay parameters based on the significant influence values corresponding to the plurality of current candidate overlay parameters, the significant influence values representing the influence degree of the current candidate overlay parameters on overlay error compensation; and based on a preset mapping model, according to the plurality of current target overlay parameters, obtaining a plurality of current control parameters for overlay error compensation, so that an execution device of the photoetching machine executes an overlay compensation operation according to the plurality of current control parameters, and the preset mapping model represents a mapping relationship between the plurality of target overlay parameter items and the plurality of control parameter items.

Description

Technical Field

[0001] The present disclosure relates to the field of semiconductor manufacturing, and more specifically to an overlay error compensation method, device, and lithography machine. Background Art

[0002] As the number of process stacks increases in photolithography, phenomena such as local structural distortion, high-order nonlinear deformation, and non-uniform deformation caused by thermal stress differences are becoming increasingly prominent. Traditional overlay error compensation methods based on low-order linear model fitting are no longer able to meet practical needs. Summary of the Invention

[0003] In view of the above problems, the present disclosure provides an overlay error compensation method, device and lithography machine.

[0004] According to the first aspect of the present disclosure, a method for overlay error compensation is provided, comprising: performing high-order polynomial fitting on current actual overlay error data to obtain a plurality of current candidate overlay parameters, the above-mentioned current actual overlay error data representing the actual offset between the current layer lithography pattern of the wafer and the previous layer lithography pattern, the above-mentioned current candidate overlay parameters representing the coefficients of the high-order polynomial, and the order of the above-mentioned high-order polynomial being greater than or equal to 4; based on the significant influence values ​​corresponding to each of the above-mentioned multiple current candidate overlay parameters, determining a plurality of current target overlay parameters from the above-mentioned multiple current candidate overlay parameters, the above-mentioned significant influence values ​​representing the degree of influence of the above-mentioned current candidate overlay parameters on overlay error compensation; based on a preset mapping model, obtaining a plurality of current control parameters for overlay error compensation according to the above-mentioned multiple current target overlay parameters, so that the execution device of the lithography machine performs the overlay compensation operation according to the above-mentioned multiple current control parameters, the above-mentioned preset mapping model representing the mapping relationship between the multiple target overlay parameter items and the multiple control parameter items.

[0005] According to an embodiment of the present disclosure, the above method also includes: determining the standard errors corresponding to each of the above-mentioned multiple current candidate overlay parameters based on the current actual overlay error data; for any current candidate overlay parameter among the above-mentioned multiple current candidate overlay parameters, obtaining the detection statistic of the above-mentioned current candidate overlay parameter based on the above-mentioned current candidate overlay parameter and the standard error of the above-mentioned current candidate overlay parameter; and obtaining the significant influence value corresponding to the above-mentioned current candidate overlay parameter based on the detection statistic of the above-mentioned current candidate overlay parameter.

[0006] According to an embodiment of the present disclosure, based on the significant influence values ​​corresponding to the above-mentioned multiple current candidate overlay parameters, multiple current target overlay parameters are determined from the above-mentioned multiple current candidate overlay parameters, including one of the following operations: when the significant influence value corresponding to the above-mentioned current candidate overlay parameter is less than or equal to a preset threshold, the above-mentioned current candidate overlay parameter is determined as the above-mentioned current target overlay parameter; or based on the ranking of the significant influence values ​​corresponding to the above-mentioned multiple current candidate overlay parameters, the above-mentioned multiple current target overlay parameters are determined from the above-mentioned multiple current candidate overlay parameters.

[0007] According to an embodiment of the present disclosure, the current actual overlay error data is fitted with a high-order polynomial to obtain multiple current candidate overlay parameters, including: using a least squares algorithm to solve the current actual overlay error data based on a preset high-order two-dimensional polynomial to determine the multiple current candidate overlay parameters.

[0008] According to an embodiment of the present disclosure, the above-mentioned least squares algorithm is used to solve the above-mentioned current actual overlay error data based on a preset high-order two-dimensional polynomial to determine the above-mentioned multiple current candidate overlay parameters, including: based on the above-mentioned current actual overlay error data, constructing a first current actual overlay error matrix representing the offset of the above-mentioned current actual overlay error data in the x direction and a second current actual overlay error matrix representing the offset of the above-mentioned current actual overlay error data in the y direction; based on the above-mentioned preset high-order two-dimensional polynomial, constructing a first regression matrix in the x direction and a second regression matrix in the y direction; using the above-mentioned least squares method, based on the above-mentioned first current actual overlay error data, The first regression matrix is ​​used to solve the current actual overlay error matrix and the first fitting overlay error matrix, so that the square difference between the first current actual overlay error matrix in the x direction and the first fitting overlay error matrix in the x direction is minimized to obtain multiple first current candidate overlay parameters; the least squares method is used to solve the second current actual overlay error matrix and the second regression matrix, so that the square difference between the second current actual overlay error matrix in the y direction and the second fitting overlay error matrix in the y direction is minimized to obtain multiple second current candidate overlay parameters; the multiple current candidate overlay parameters are determined based on the multiple first current candidate overlay parameters and the multiple second current candidate overlay parameters.

[0009] According to an embodiment of the present disclosure, based on the preset mapping model, according to the above-mentioned multiple current target overlay parameters, multiple current control parameters for overlay error compensation are obtained, including: reversely solving the above-mentioned preset mapping model to obtain a preset reverse mapping model; inputting the above-mentioned multiple current target overlay parameters into the above-mentioned preset reverse mapping model to obtain multiple current control parameters for overlay supplement.

[0010] According to an embodiment of the present disclosure, the above-mentioned multiple current control parameters include multiple current temperature control compensation parameters corresponding to the temperature control deformation adjustment module in the above-mentioned execution device and multiple current stress compensation parameters corresponding to the mask boundary stress adjustment module in the above-mentioned execution device. The above-mentioned current temperature control compensation parameters are used to perform thermal regulation on the current mask, and the above-mentioned current stress compensation parameters are used to apply compensation stress to the current mask stage of the above-mentioned lithography machine to adjust the spatial posture of the above-mentioned current mask stage.

[0011] According to an embodiment of the present disclosure, the above-mentioned mask boundary stress adjustment module includes at least one of a piezoelectric ceramic actuator array or a micromechanical clamping structure, and the above-mentioned multiple current stress compensation parameters include a displacement stress output parameter corresponding to the piezoelectric ceramic actuator array and a clamping stress output parameter corresponding to the above-mentioned micromechanical clamping structure. The above-mentioned displacement stress output parameter is used to compensate for the mechanical deformation of the mask stage, and the above-mentioned clamping stress output parameter is used to adjust the stress distribution of the above-mentioned current mask stage.

[0012] The second aspect of the present disclosure provides an overlay error compensation device, including: a fitting module, used to perform high-order polynomial fitting on current actual overlay error data to obtain multiple current candidate overlay parameters, the above-mentioned current actual overlay error data represents the actual offset between the current layer lithography pattern of the wafer and the previous layer lithography pattern, the above-mentioned current candidate overlay parameters represent the coefficients of the high-order polynomial, and the order of the above-mentioned high-order polynomial is greater than or equal to 4; a target overlay parameter determination module, used to determine multiple current target overlay parameters from the above-mentioned multiple current candidate overlay parameters based on the significant influence values ​​corresponding to each of the above-mentioned multiple current candidate overlay parameters, the above-mentioned significant influence values ​​represent the degree of influence of the above-mentioned current candidate overlay parameters on overlay error compensation; a compensation module, used to obtain multiple current control parameters for overlay error compensation based on the above-mentioned multiple current target overlay parameters based on a preset mapping model, so that the execution device of the lithography machine performs overlay compensation operations according to the above-mentioned multiple current control parameters, and the above-mentioned preset mapping model represents the mapping relationship between multiple target overlay parameter items and multiple control parameter items.

[0013] A third aspect of the present disclosure provides a lithography machine, comprising: a controller and an execution device; the controller is electrically connected to the execution device; the controller is used to execute the steps of the method and drive the execution device.

[0014] According to an embodiment of the present disclosure, by fitting the current actual overlay error between the current layer lithography pattern of the wafer and the previous layer lithography image with a high-order polynomial of order 4 or above, the complex overlay error distributed on the wafer can be compressed into multiple current candidate overlay parameters in the high-order polynomial, while retaining the high-order distortion in the current actual overlay error data while reducing the data dimension. Furthermore, the current candidate overlay parameter with a higher degree of influence on overlay error compensation is screened from the multiple current candidate overlay parameters through the significant influence value and determined as the current target overlay parameter, thereby further compressing the data dimension and reducing the calculation of the current candidate overlay parameter with a smaller degree of influence on overlay error compensation by the hardware device. At the same time, the accuracy of overlay error compensation is also guaranteed through the screening of the significant influence value. At the same time, with the help of a preset mapping model, the multiple current target overlay parameters are parsed into multiple current control parameters of the execution device of the lithography machine, and the execution device is used to perform compensation according to the current control parameters to ensure that the current actual overlay error data is accurately compensated, thereby improving the yield rate of the chip manufactured by the wafer. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The above contents and other objects, features and advantages of the present disclosure will become more apparent through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0016] Figure 1 A diagram schematically illustrates an application scenario of the overlay error compensation method and device according to an embodiment of the present disclosure;

[0017] Figure 2 Schematically shows a flow chart of an overlay error compensation method according to an embodiment of the present disclosure;

[0018] Figure 3 Schematically shows an overlay error distribution diagram obtained by fitting current actual overlay error data using a fifth-order polynomial according to an embodiment of the present disclosure;

[0019] Figure 4 Schematically shows an overlay error distribution diagram obtained by fitting current actual overlay error data using a 4th-order polynomial according to an embodiment of the present disclosure;

[0020] Figure 5 Schematically shows an overlay error distribution diagram obtained by fitting current actual overlay error data using only a fifth-order polynomial according to an embodiment of the present disclosure;

[0021] Figure 6 Schematically shows an overlay error distribution diagram obtained by fitting current actual overlay error data using only a 4th-order polynomial according to an embodiment of the present disclosure;

[0022] Figure 7A schematic diagram of a temperature control deformation adjustment module and a mask boundary stress adjustment module of a photolithography machine is shown according to an embodiment of the present disclosure;

[0023] Figure 8 An execution device compensation schematic diagram calculated according to a target overlay parameter by using a 5th order polynomial is shown according to an embodiment of the present disclosure;

[0024] Figure 9 An execution device compensation schematic diagram calculated according to a target overlay parameter by using a 4th order polynomial is shown according to an embodiment of the present disclosure;

[0025] Figure 10 An execution device compensation schematic diagram calculated according to a target overlay parameter by using only a 5th order polynomial is shown according to an embodiment of the present disclosure;

[0026] Figure 11 An execution device compensation schematic diagram calculated according to a target overlay parameter by using only a 4th order polynomial is shown according to an embodiment of the present disclosure;

[0027] Figure 12 A residual overlay error distribution diagram after overlay compensation according to a target overlay parameter by using a 5th order polynomial is shown according to an embodiment of the present disclosure;

[0028] Figure 13 A residual overlay error distribution diagram after overlay compensation according to a target overlay parameter by using a 4th order polynomial is shown according to an embodiment of the present disclosure;

[0029] Figure 14 A residual overlay error distribution diagram after overlay compensation according to a target overlay parameter by using only a 5th order polynomial is shown according to an embodiment of the present disclosure;

[0030] Figure 15 A residual overlay error distribution diagram after overlay compensation according to a target overlay parameter by using only a 4th order polynomial is shown according to an embodiment of the present disclosure;

[0031] Figure 16 A structural block diagram of an overlay error compensation device is shown according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0032] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. It should be understood, however, that the description is merely exemplary and is not intended to limit the scope of the present disclosure. In the following detailed description of the embodiments of the present disclosure, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the present disclosure. However, it would be apparent to those skilled in the art that the embodiments of the present disclosure can be practiced without these specific details. In other instances, well-known structures and methods are not described in detail in order to avoid obscuring the concepts of the present disclosure.

[0033] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. As used herein, the term "includes" and tautological expressions thereof, such as "including," means the inclusion of but not limited to, and is not meant to be construed as a functionally limiting the scope of the embodiments.

[0034] All of the terms used herein (including technical and scientific terms) have the same meanings as those generally understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having meanings consistent with the context of the specification, and should not be interpreted in an idealized or overly formal manner.

[0035] In the case of using expressions similar to "at least one of A, B, and C, etc.", it should generally be interpreted to include any of one, or two or more of the listed items, unless otherwise specifically defined (e.g., "a system having at least one of A, B, and C" should be interpreted to include a system having A alone, a system having B alone, a system having C alone, a system having both A and B together, a system having both A and C together, a system having both B and C together, and / or a system having all of A, B, and C together, etc.).

[0036] As integrated circuit manufacturing technology continues to develop towards smaller process sizes and higher integration, the photolithography process, as the core step of pattern transfer, is facing the challenge of high precision. As a key factor restricting the precision of photolithography layering, the control ability of overlay error is directly related to the yield and performance stability of chips.

[0037] In multi-layer complex results, with the increase of process stack number, local structure distortion, high-order nonlinear deformation, and non-uniform deformation caused by thermal stress difference are increasingly significant. The traditional overlay error compensation method based on linear model or low-order polynomial fitting has been difficult to meet the actual needs.

[0038] In view of this, an embodiment of the present disclosure provides an overlay error compensation method, including: performing high-order polynomial fitting on current actual overlay error data to obtain multiple current candidate overlay parameters, the current actual overlay error data represents the actual offset between the current layer lithography pattern of the wafer and the previous layer lithography pattern, the current candidate overlay parameters represent the coefficients of the high-order polynomial, and the order of the high-order polynomial is greater than or equal to 4; based on the significant influence values ​​corresponding to each of the multiple current candidate overlay parameters, multiple current target overlay parameters are determined from the multiple current candidate overlay parameters, the significant influence values ​​represent the degree of influence of the current candidate overlay parameters on the overlay error compensation; based on a preset mapping model, according to the multiple current target overlay parameters, multiple current control parameters for overlay error compensation are obtained, so that the execution device of the lithography machine performs the overlay compensation operation according to the multiple current control parameters, and the preset mapping model represents the mapping relationship between the multiple target overlay parameter items and the multiple control parameter items.

[0039] Figure 1 The application scenario diagram of the overlay error compensation method and device according to the embodiments of the present disclosure is schematically shown.

[0040] like Figure 1 As shown, the application scenario 100 according to this embodiment may include a lithography machine 101, a network 102, and a server 103. The network 102 is used to provide a medium for a communication link between the lithography machine 101 and the server 103. The network 102 may include various connection types, such as wired or wireless communication links or fiber optic cables.

[0041] The lithography machine 101 can be a projection lithography machine, an immersion lithography machine, a proximity lithography machine, a nanoimprint lithography machine or a surface plasma lithography machine for subwavelength pattern replication, etc. The light source in the lithography machine can be a G line (435nm), an I line (365nm), a KrF (Krypton Fluoride) excimer laser (248nm), an ArF (Argon Fluoride) excimer laser (193nm) or a 13.5nm EUV (Extreme Ultraviolet) source.

[0042] The server 103 may be a server that provides various services. The backend management server may analyze and process the received request and other data, and feed back the processing results to the lithography machine 101.

[0043] It should be noted that the overlay error compensation method provided in the embodiment of the present disclosure can generally be executed by the lithography machine 101. Accordingly, the overlay error compensation device provided in the embodiment of the present disclosure can generally be provided in the lithography machine 101.

[0044] It should be understood that Figure 1The number of lithography machines, networks and servers in the system is only illustrative. Any number of lithography machines, networks and servers can be provided according to implementation needs.

[0045] The following will be based on Figure 1 The scenario described, by Figures 2 to 15 The overlay error compensation method of the disclosed embodiment is described in detail.

[0046] Figure 2 The flowchart of the overlay error compensation method according to the embodiment of the disclosure is illustratively shown.

[0047] As Figure 2 The overlay error compensation method of the embodiment includes operations S210-S230.

[0048] In operation S210, the current actual overlay error data is high-order polynomial fitted to obtain a plurality of current candidate overlay parameters.

[0049] The current actual overlay error data represents the actual offset between the current layer lithography pattern and the previous layer lithography pattern of the wafer, and the current candidate overlay parameter represents the coefficient of the high-order polynomial, and the order of the high-order polynomial is greater than or equal to 4.

[0050] According to the embodiment of the disclosure, the wafer is a semiconductor manufacturing substrate with a multi-layer structure, which is composed of monocrystalline silicon, SOI (Silicon-On-Insulator) material or III-V compound, and its surface has been coated with a photoresist suitable for the current wavelength range. The photoresist type includes positive, negative and chemically amplified photoresist, etc., which can be selected according to the subsequent process requirements. In order to ensure the fidelity of the pattern, the photoresist layer needs to be treated by soft baking to form a uniform and stable coating.

[0051] According to the embodiment of the disclosure, before obtaining the current actual overlay error, a coordinate reference system needs to be established between the wafer and the mask to realize sub-micron level position matching in combination with a laser interference system, image recognition algorithm or speckle interference technology. The exposure machine and the supporting alignment subsystem in the lithography machine can support multi-region sampling and high-order distortion modeling to improve the alignment accuracy and repeatability. Further, in the pattern exposure stage, the mask pattern can be irradiated by a light beam and projected onto the photoresist surface to form a latent image. The exposure mode can adopt step scanning, full imprint or local exposure mode according to the process path, to ensure that the pattern contour edge is sharp, the optical dose is uniform, and the mask thermal drift and workpiece micro-vibration are compensated in real time. After exposure is completed, the wafer will obtain an exposure latent image consistent with the pattern on the mask. Further, the key size of the pattern on the wafer after exposure and its overlay deviation in space can be obtained by an optical or electronic detection system, to provide a quantitative basis for subsequent error modeling and compensation.

[0052] For the convenience of understanding, the key concepts in the present disclosure are explained as follows.

[0053] Line width measurement refers to quantitative analysis of feature size of a pattern formed after exposure and development of a photoresist. CD-SEM (Critical Dimension Scanning Electron Microscope), AFM (Atomic Force Microscope), or an optical critical dimension measurement system is often used to perform line width measurement. The measurement area covers multiple points arranged to ensure coverage of line width variation under different process windows, reflecting the influence of factors such as focus of a lithography system, exposure energy, and mask transmission characteristics.

[0054] Overlay error refers to the offset of a current layer of lithography pattern relative to a previous layer of lithography pattern in a two-dimensional coordinate system, which is usually detected using double-layer marks. Detection methods include laser speckle interferometry, differential interference alignment, SEM (Scanning Electron Microscope) overlay comparison assisted by image recognition algorithms, etc. The output of overlay error is generally in the form of a vector of x-direction and y-direction offsets, and the overlay error measurement system needs to have nanometer-level measurement accuracy and error tracking capability.

[0055] According to an embodiment of the present disclosure, the measurement data can record the offset values of each sampling point in a matrix form to constitute the above-mentioned current actual overlay error data. The current actual overlay error data reflects the superimposed effects of high-order errors such as mask thermal deformation, platform displacement error, pattern offset caused by stress, and process drift. After measurement is completed, the line width data obtained through line width measurement can be used to evaluate the pattern resolution and optical stability of the previous layer of lithography pattern.

[0056] According to an embodiment of the present disclosure, when converting the measurement data into current actual overlay error data, the measurement data can be normalized according to the two-dimensional coordinates in the exposure field to convert into a set of standard coordinate points in a unit square domain.

[0057] According to an embodiment of the present disclosure, the estimated value of the candidate overlay parameter can be obtained by minimizing the sum of squares of deviations between the current actual overlay error and the current actual overlay error data obtained by high-order polynomial fitting.

[0058] In operation S220, a plurality of current target overlay parameters is determined from the plurality of current candidate overlay parameters based on the respective significant influence values of the plurality of current candidate overlay parameters.

[0059] The significant influence value represents the degree of influence of the current candidate overlay parameter on overlay error compensation.

[0060] According to the embodiment of the present disclosure, the current candidate overlay parameters can be ranked by significance to select multiple current candidate overlay parameters with greater impact on overlay error compensation as current target overlay parameters, so as to improve the efficiency and robustness of subsequent overlay error compensation.

[0061] Figure 3 The diagram schematically shows an overlay error distribution diagram obtained by fitting the current actual overlay error data using a fifth-order polynomial according to an embodiment of the present disclosure.

[0062] Figure 4 The overlay error distribution diagram obtained by fitting the current actual overlay error data using a fourth-order polynomial according to an embodiment of the present disclosure is schematically shown.

[0063] Figure 5 The overlay error distribution diagram obtained by fitting the current actual overlay error data using only a fifth-order polynomial according to an embodiment of the present disclosure is schematically shown.

[0064] Figure 6 The overlay error distribution diagram obtained by fitting the current actual overlay error data using only a 4th-order polynomial according to an embodiment of the present disclosure is schematically shown.

[0065] like Figures 3 to 6 As shown, where |M| represents the absolute value of the actual overlay error data, σ represents the standard deviation, and OVL x Indicates the overlay error in the x direction, OVL y Indicates the overlay error in the y direction, OVL x and OVL y The unit is nm. It can be seen that the overlay error data obtained by fitting the current actual overlay error data with a 5th-order polynomial is more comprehensive. Compared with the overlay error data obtained by fitting the current actual overlay error data with a 4th-order polynomial, using only the 5th-order polynomial, and using only the 4th-order polynomial, the overlay error range that can be fitted is wider.

[0066] In operation S230, based on the preset mapping model, a plurality of current control parameters for overlay error compensation are obtained according to the plurality of current target overlay parameters, so that the execution device of the lithography machine performs the overlay compensation operation according to the plurality of current control parameters.

[0067] The preset mapping model represents the mapping relationship between multiple target overlay parameter items and multiple control parameter items.

[0068] According to an embodiment of the present disclosure, the above-mentioned preset mapping model is obtained by fitting a finite element simulation model constructed through a large amount of sample data. It calculates the displacement response of the lithography pattern under different overlay compensation methods, establishes a correspondence between the complex thermomechanical coupling effect and multiple current candidate overlay parameters obtained by high-order polynomial fitting. In the process of obtaining the preset mapping model, a combination input of multiple sets of complex stresses and local thermal controls can be used, and at the same time, the deformation displacement vector of the selected measurement area on the mask pattern surface is recorded by parameter scanning as the "quasi-overlay error" obtained by simulation, so as to obtain the preset mapping model based on the combined input and the deformation displacement vector.

[0069] According to the disclosed embodiments, the finite element simulation model simulates geometric models, material properties, and load constraints. The material properties simulate parameters such as thermal conductivity, thermal expansion coefficient, elastic modulus, and Poisson's ratio. Furthermore, the temperature dependence of the material properties within the actual operating temperature range must be considered during the simulation. The load conditions are set to apply adjustable in-plane compressive stress and local thermal regulation to the surrounding boundary regions, thereby simulating the effects of actual actuators such as piezoelectric drives, thermal expansion frames, and micro-deformation platforms in photolithography machines.

[0070] According to an embodiment of the present disclosure, by fitting the current actual overlay error between the current layer lithography pattern of the wafer and the previous layer lithography image with a polynomial of order 4 or above, the complex overlay error distributed on the wafer can be compressed into multiple current candidate overlay parameters in the high-order polynomial, while retaining the high-order distortion in the current actual overlay error data while reducing the data dimension. Furthermore, the current candidate overlay parameter with a higher degree of influence on overlay error compensation is screened out from the multiple current candidate overlay parameters through the significant influence value as the current target overlay parameter, further compressing the data dimension, reducing the calculation of the current candidate overlay parameter with a smaller degree of influence on overlay error compensation by the hardware device, and also ensuring the accuracy of overlay error compensation through the screening of the significant influence value. At the same time, with the help of a preset mapping model, the multiple current target overlay parameters are parsed into multiple current control parameters of the execution device of the lithography machine, and the execution device is used to perform compensation according to the current control parameters to ensure that the current actual overlay error data is accurately compensated, thereby improving the yield rate of the chip made from the wafer.

[0071] According to an embodiment of the present disclosure, the above method also includes: determining the standard errors corresponding to multiple current candidate overlay parameters based on the current actual overlay error data; for any current candidate overlay parameter among the multiple current candidate overlay parameters, obtaining the detection statistic of the current candidate overlay parameter based on the current candidate overlay parameter and the standard error of the current candidate overlay parameter; and obtaining the significant influence value corresponding to the current candidate overlay parameter based on the detection statistic of the current candidate overlay parameter.

[0072] The detection statistic of the current candidate overlay parameter can be obtained by the following formula (1).

[0073] (1)

[0074] in, represents the detection statistic of the current candidate overlay parameter, represents the estimated value of the current candidate overlay parameter, Indicates the standard error of the current candidate overlay parameter.

[0075] The significant influence value corresponding to the current candidate overlay parameter can be calculated using the following formula (2).

[0076] (2)

[0077] Among them, P represents the significant effect value, Indicates the detection statistic of a randomly drawn value greater than the current candidate overlay parameter in the probability distribution of the t distribution probability.

[0078] According to an embodiment of the present disclosure, the detection statistic of the current candidate overlay parameter is calculated by using the standard errors corresponding to each of the multiple current candidate overlay parameters and the multiple current candidate overlay parameters, and then based on the detection statistic, the detection statistic is mapped to a significant influence value, so that when the current candidate overlay parameters are screened, the objective significant influence value after quantifying the detection statistic is used as the basis, thereby ensuring that the significant influence value has a higher confidence level.

[0079] According to an embodiment of the present disclosure, multiple current target overlay parameters can be determined from multiple current candidate overlay parameters based on the significant influence values ​​corresponding to each of the multiple current candidate overlay parameters, including one of the following operations: when the significant influence value corresponding to the current candidate overlay parameter is less than or equal to a preset threshold, the current candidate overlay parameter is determined as the current target overlay parameter; or based on the ranking of the significant influence values ​​corresponding to each of the multiple current candidate overlay parameters, multiple current target overlay parameters are determined from multiple current candidate overlay parameters.

[0080] According to an embodiment of the present disclosure, the above-mentioned preset threshold value can be 0.05, for example, that is, the current candidate overlay parameter whose corresponding significant influence value is less than or equal to 0.05 can be determined as the current target parameter, or each current candidate overlay parameter can be sorted from small to large based on the corresponding significant influence value, and a preset number of current candidate overlay parameters can be selected as the target overlay parameter.

[0081] According to an embodiment of the present disclosure, the above-mentioned high-order polynomial fitting of the current actual overlay error data to obtain multiple current candidate overlay parameters includes: using a least squares algorithm to solve the current actual overlay error data based on a preset high-order two-dimensional polynomial to determine multiple current candidate overlay parameters.

[0082] According to an embodiment of the present disclosure, the least squares algorithm is used to solve the current actual overlay error data based on a preset high-order two-dimensional polynomial to determine multiple current candidate overlay parameters, including: constructing a first current actual overlay error matrix representing the offset of the current actual overlay error data in the x direction and a second current actual overlay error matrix representing the offset of the current actual overlay error data in the y direction based on the current actual overlay error data; constructing a first regression matrix in the x direction and a second regression matrix in the y direction based on the preset high-order two-dimensional polynomial; using the least squares method, based on the first current actual overlay error data, The overlay error matrix and the first regression matrix are solved so that the square difference between the first current actual overlay error matrix in the x-direction and the first fitted overlay error matrix in the x-direction is minimized to obtain a plurality of first current candidate overlay parameters; the least squares method is used to solve based on the second current actual overlay error matrix and the second regression matrix so that the square difference between the second current actual overlay error matrix in the y-direction and the second fitted overlay error matrix in the y-direction is minimized to obtain a plurality of second current candidate overlay parameters; and a plurality of current candidate overlay parameters are determined based on the plurality of first current candidate overlay parameters and the plurality of second current candidate overlay parameters.

[0083] According to an embodiment of the present disclosure, the above-mentioned preset high-order two-dimensional polynomial can be as shown in the following formula (3) and formula (4).

[0084] (3)

[0086] (4)

[0088] in, Indicates the overlay error distribution of the current actual overlay error data in the x direction. Indicates the overlay error distribution of the current actual overlay error data in the y direction. (j=1,2,…41,42) represents the candidate overlay parameters.

[0089] According to the embodiment of the present disclosure, further, when solving the candidate overlay parameters, it is necessary to satisfy the following conditions of formula (5) and formula (6) to obtain multiple candidate overlay parameters.

[0090] (5)

[0091] (6)

[0092] wherein, is the offset in the x direction in the current actual overlay error data (i.e., the first current actual overlay error matrix), is the overlay error distribution in the x direction of the current actual overlay error data obtained by high-order polynomial fitting (i.e., the first fitted overlay error matrix), is the offset in the y direction in the current actual overlay error data (i.e., the second current actual overlay error matrix), is the overlay error distribution in the y direction of the current actual overlay error data obtained by high-order polynomial fitting (i.e., the second fitted overlay error matrix), and l represents the number of measurement points in the current actual overlay error data.

[0093] According to the embodiments of the present disclosure, by constructing the first current actual overlay error matrix and the second current actual overlay error matrix according to the division of the x direction and the y direction in the current actual overlay error data, and constructing the first regression matrix and the second regression matrix according to the preset high-order two-dimensional polynomial, the least square method is used to obtain a plurality of first current candidate overlay parameters and a plurality of second current candidate overlay parameters, which can not only completely retain the high-order distortion information of the wafer surface, but also compress the overlay error on the wafer into a plurality of analyzable current candidate overlay parameters, thereby reducing the calculation amount of subsequent calculation of the current control parameter.

[0094] According to the embodiments of the present disclosure, the above obtaining, based on the preset mapping model, a plurality of current control parameters for overlay error compensation according to a plurality of current target overlay parameters comprises: inversely solving the preset mapping model to obtain a preset inverse mapping model; and inputting the plurality of current target overlay parameters into the preset inverse mapping model to obtain the plurality of current control parameters for overlay compensation.

[0095] The plurality of current control parameters can be calculated by the following formula (7).

[0096] (7)

[0097] wherein, denotes the plurality of current control parameters, denotes the current target overlay parameter, denotes the preset inverse mapping model.

[0098] According to the embodiments of the present disclosure, by inversely solving the preset mapping model to obtain the preset inverse mapping model, the plurality of current target overlay parameters can be input into the preset inverse mapping model at one time, and the required plurality of current control parameters are inversely deduced, so as to ensure that the compensation amount accurately matches the current actual overlay error data, thereby improving the lithography precision.

[0099] According to an embodiment of the present disclosure, the above-mentioned multiple current control parameters include multiple current temperature control compensation parameters corresponding to the temperature control deformation adjustment module in the execution device and multiple current stress compensation parameters corresponding to the mask boundary stress adjustment module in the execution device. The current temperature control compensation parameters are used to perform thermal regulation on the current mask, and the current stress compensation parameters are used to apply compensation stress to the current mask stage of the lithography machine to adjust the spatial posture of the current mask stage.

[0100] Figure 7 A schematic diagram of a temperature-controlled deformation adjustment module and a mask boundary stress adjustment module of a lithography machine according to an embodiment of the present disclosure is schematically shown.

[0101] like Figure 7 As shown, the mask stage 700 is equipped with a temperature-controlled deformation adjustment module 701 and a mask boundary stress adjustment module 702. The temperature-controlled deformation adjustment module 701 is used to perform fine thermal control on the mask, and the mask boundary stress adjustment module 702 is used to apply complex piezoelectric stress control to the mask stage.

[0102] Figure 8 A schematic diagram of the compensation of the execution device calculated according to the target overlay parameters using a fifth-order polynomial according to an embodiment of the present disclosure is shown schematically.

[0103] Figure 9 A schematic diagram of the compensation of the execution device calculated according to the target overlay parameters using a 4th-order polynomial according to an embodiment of the present disclosure is shown schematically.

[0104] Figure 10 A schematic diagram of the compensation of the execution device calculated based on the target overlay parameters using only a fifth-order polynomial according to an embodiment of the present disclosure is shown schematically.

[0105] Figure 11 A schematic diagram of the compensation of the execution device calculated based on the target overlay parameters using only a 4th-order polynomial according to an embodiment of the present disclosure is shown schematically.

[0106] like Figures 8 to 11 As shown, the outer value represents the stress applied by the mask boundary stress adjustment module to the mask stage (unit is N), and the inner rectangle represents the thermal control value on the temperature control deformation adjustment block (unit is W / m 2 ).

[0107] According to an embodiment of the present disclosure, the mask boundary stress adjustment module includes at least one of a piezoelectric ceramic actuator array or a micromechanical clamping structure, and the multiple current stress compensation parameters include a displacement stress output parameter corresponding to the piezoelectric ceramic actuator array and a clamping stress output parameter corresponding to the micromechanical clamping structure. The displacement stress output parameter is used to compensate for the mechanical deformation of the mask stage, and the clamping stress output parameter is used to adjust the stress distribution of the current mask stage.

[0108] According to the embodiment of the present disclosure, the above-mentioned piezoelectric ceramic actuator array can be arranged around the mask to control the stress of the mask boundary with high precision; the above-mentioned micromechanical clamping device can mechanically control the clamping stress of the peripheral boundary of the mask to achieve translation operation in a specific direction.

[0109] According to the embodiment of the present disclosure, while the temperature-controlled deformation adjustment module in the execution device is used to perform thermal regulation on the mask, the mask boundary stress adjustment module in the execution device is used to apply compensation stress to the current mask stage according to the current stress compensation parameter, so as to adjust the spatial posture of the mask stage to further adjust the mask, that is, to actively adjust the current overlay error through physical means. Compared with the high-complexity control required for adjusting the mask with a traditional optical lens, the response speed is faster, the control accuracy is higher, and no additional optical distortion is introduced.

[0110] According to the embodiment of the present disclosure, the above-mentioned execution device will continuously perform overlay compensation operations on the current lithography according to the current control parameters during the lithography process, and iteratively update the compensation amount during each lithography process to ensure that the mask surface before each round of exposure meets the requirements of high-order overlay compensation of lithography.

[0111] Figure 12 The diagram schematically shows a distribution diagram of residual overlay errors after overlay compensation is performed according to target overlay parameters using a fifth-order polynomial according to an embodiment of the present disclosure.

[0112] Figure 13 The diagram schematically shows a distribution diagram of residual overlay errors after overlay compensation is performed according to target overlay parameters using a fourth-order polynomial according to an embodiment of the present disclosure.

[0113] Figure 14 The diagram schematically shows a distribution diagram of residual overlay errors after overlay compensation is performed based on target overlay parameters using only a fifth-order polynomial according to an embodiment of the present disclosure.

[0114] Figure 15 The diagram schematically shows a distribution diagram of residual overlay errors after overlay compensation is performed based on target overlay parameters using only a fourth-order polynomial according to an embodiment of the present disclosure.

[0115] like Figure 12-15As shown in the figure, |M| represents the absolute value of the current residual overlay error after the overlay compensation operation is performed on the current actual overlay error data, σ represents the standard deviation, OVL x Indicates the current residual overlay error in the x direction, OVL y Indicates the current residual overlay error in the y direction, OVL x and OVL y The unit is nm. It can be seen that the effect of fitting and compensating the current actual overlay error data using a fifth-order polynomial is significantly better than that of using a fourth-order polynomial, using only a fifth-order polynomial, and using only a fourth-order polynomial. That is, for a typical fifth-order overlay error field, the method provided by the embodiment of the present disclosure achieves 95.33% and 98.12% point-by-point error correction in the x-direction and y-direction, respectively, and the overall error control accuracy is improved to within 1.5 nm, which can meet the control requirements of 3 nm node logic devices; for an overlay error field with fourth-order distribution characteristics, the compensation model achieves 83.76% and 90.97% error reduction in the x-direction and y-direction, which is significantly better than traditional linear or low-order models. Further tests show that for error fields with complex fifth-order distributions, the present method still maintains a high compensation capability, with error correction rates of 63.82% and 80.92% in the x-direction and y-direction, respectively. At the same time, for overlay errors composed only of high-order terms (fourth and fifth orders), the method proposed in the embodiment of the present disclosure can still achieve effective corrections of 83.03% (x-direction) and 86.55% (y-direction). The |mean|+3σ of the residual overlay error distribution diagram calculated point by point is only about 0.5nm, verifying the wide adaptability and robustness to different types of error fields.

[0116] Based on the above-mentioned overlay error compensation method, the present disclosure also provides an overlay error compensation device. Figure 16 The device is described in detail.

[0117] Figure 16 The structural block diagram of the overlay error compensation device according to an embodiment of the present disclosure is schematically shown.

[0118] like Figure 16 As shown, the overlay error compensation device 1600 of this embodiment includes a fitting module 1610 , a target overlay parameter determination module 1620 and a compensation module 1630 .

[0119] Fitting module 1610 is configured to perform a high-order polynomial fit on the current actual overlay error data to obtain a plurality of current candidate overlay parameters. The current actual overlay error data represents the actual offset between the current lithographic pattern and the previous lithographic pattern of the wafer. The current candidate overlay parameters represent coefficients of the high-order polynomial, where the order of the high-order polynomial is greater than or equal to 4. In one embodiment, fitting module 1610 can be configured to perform operation S210 described above and will not be further described herein.

[0120] The target overlay parameter determination module 1620 is configured to determine a plurality of current target overlay parameters from the plurality of current candidate overlay parameters based on the significant influence values ​​corresponding to the plurality of current candidate overlay parameters, wherein the significant influence values ​​represent the degree of influence of the current candidate overlay parameters on overlay error compensation. In one embodiment, the target overlay parameter determination module 1620 may be configured to perform operation S220 described above, and will not be further described herein.

[0121] Compensation module 1630 is configured to obtain, based on a preset mapping model and a plurality of current target overlay parameters, a plurality of current control parameters for overlay error compensation, so that an execution device of the lithography machine performs overlay compensation according to the plurality of current control parameters. The preset mapping model represents a mapping relationship between the plurality of target overlay parameter items and the plurality of control parameter items. In one embodiment, compensation module 1630 may be configured to perform operation S230 described above, and will not be further described herein.

[0122] According to an embodiment of the present disclosure, any multiple modules among the fitting module 1610, the target overlay parameter determination module 1620, and the compensation module 1630 may be combined into a single module, or any one of these modules may be split into multiple modules. Alternatively, at least part of the functionality of one or more of these modules may be combined with at least part of the functionality of other modules and implemented in a single module. According to an embodiment of the present disclosure, at least one of the fitting module 1610, the target overlay parameter determination module 1620, and the compensation module 1630 may be at least partially implemented as a hardware circuit, such as a field programmable gate array (FPGA), a programmable logic array (PLA), a system on a chip, a system on a substrate, a system on a package, an application-specific integrated circuit (ASIC), or may be implemented in hardware or firmware by any other reasonable means of integrating or packaging circuits, or may be implemented in any one of the three implementation modes of software, hardware, and firmware, or in any appropriate combination of any of these. Alternatively, at least one of the fitting module 1610, the target overlay parameter determination module 1620, and the compensation module 1630 may be at least partially implemented as a computer program module, which may perform corresponding functions when executed.

[0123] According to an embodiment of the present disclosure, the program code for executing the computer program provided by the embodiment of the present disclosure can be written in any combination of one or more programming languages. Specifically, these computer programs can be implemented using high-level procedural and / or object-oriented programming languages, and / or assembly / machine languages. Programming languages ​​include, but are not limited to, languages ​​such as Java, C++, Python, "C" or similar programming languages. The program code can be executed entirely on the user computing device, partially on the user device, partially on a remote computing device, or entirely on a remote computing device or server. In cases involving a remote computing device, the remote computing device can be connected to the user computing device through any type of network, including a local area network (LAN) or a wide area network (WAN), or can be connected to an external computing device (for example, using an Internet service provider to connect via the Internet).

[0124] The flowcharts and block diagrams in the accompanying drawings illustrate the possible implementation architecture, functions and operations of the systems, methods and computer program products according to various embodiments of the present disclosure. In this regard, each box in the flowchart or block diagram can represent a module, program segment, or a part of code, and the above-mentioned module, program segment, or a part of code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in an order different from that marked in the accompanying drawings. For example, two boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram or flowchart, and the combination of boxes in the block diagram or flowchart, can be implemented with a dedicated hardware-based system that performs the specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions.

[0125] Those skilled in the art will appreciate that the features described in the various embodiments of the present disclosure may be combined and / or coupled in various ways, even if such combinations or couplings are not explicitly described in the present disclosure. In particular, the features described in the various embodiments of the present disclosure may be combined and / or coupled in various ways without departing from the spirit and teachings of the present disclosure. All such combinations and / or couplings fall within the scope of the present disclosure.

[0126] The above describes the embodiments of the present disclosure. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of the present disclosure. Although each embodiment has been described separately above, this does not mean that the measures in each embodiment cannot be advantageously used in combination. Without departing from the scope of the present disclosure, those skilled in the art may make various substitutions and modifications, which should all fall within the scope of the present disclosure.

Claims

1. A method for compensating overlay error, characterized in that: The method comprises: Performing high-order polynomial fitting on current actual overlay error data to obtain a plurality of current candidate overlay parameters, wherein the current actual overlay error data represents an actual offset between a current layer of lithographic patterns and a previous layer of lithographic patterns of the wafer, and the current candidate overlay parameters represent coefficients of a high-order polynomial, wherein the order of the high-order polynomial is greater than or equal to 4; determining a plurality of current target overlay parameters from the plurality of current candidate overlay parameters based on respective significant influence values ​​corresponding to the plurality of current candidate overlay parameters, wherein the significant influence values ​​represent the degree of influence of the current candidate overlay parameters on overlay error compensation; Based on a preset mapping model, multiple current control parameters for overlay error compensation are obtained according to the multiple current target overlay parameters, so that the execution device of the lithography machine performs overlay compensation operations according to the multiple current control parameters. The preset mapping model characterizes the mapping relationship between multiple target overlay parameter items and multiple control parameter items.

2. The method according to claim 1, characterized in that The method further comprises: Determining the standard errors corresponding to the plurality of current candidate overlay parameters according to the current actual overlay error data; For any current candidate overlay parameter among the multiple current candidate overlay parameters, obtaining a detection statistic of the current candidate overlay parameter based on the current candidate overlay parameter and a standard error of the current candidate overlay parameter; Based on the detection statistic of the current candidate overlay parameter, a significant influence value corresponding to the current candidate overlay parameter is obtained.

3. The method according to claim 2, characterized in that Determining a plurality of current target overlay parameters from the plurality of current candidate overlay parameters based on the respective significant influence values ​​corresponding to the plurality of current candidate overlay parameters includes one of the following operations: When the significant influence value corresponding to the current candidate overlay parameter is less than or equal to a preset threshold, determining the current candidate overlay parameter as the current target overlay parameter; or The multiple current target overlay parameters are determined from the multiple current candidate overlay parameters based on the ranking of the significant influence values ​​corresponding to the multiple current candidate overlay parameters.

4. The method according to any one of claims 1 to 3, characterized in that The current actual overlay error data is subjected to high-order polynomial fitting to obtain multiple current candidate overlay parameters, including: The current actual overlay error data is solved based on a preset high-order two-dimensional polynomial using a least squares algorithm to determine the multiple current candidate overlay parameters.

5. The method according to claim 4, characterized in that The using of the least squares algorithm to solve the current actual overlay error data based on a preset high-order two-dimensional polynomial to determine the multiple current candidate overlay parameters includes: constructing, based on the current actual overlay error data, a first current actual overlay error matrix representing an offset of the current actual overlay error data in the x-direction and a second current actual overlay error matrix representing an offset of the current actual overlay error data in the y-direction; Based on the preset high-order two-dimensional polynomial, construct a first regression matrix in the x-direction and a second regression matrix in the y-direction; Using the least squares method, based on the first current actual overlay error matrix and the first regression matrix, a solution is obtained to minimize the square difference between the first current actual overlay error matrix in the x-direction and the first fitted overlay error matrix in the x-direction, so as to obtain a plurality of first current candidate overlay parameters; Using the least squares method, based on the second current actual overlay error matrix and the second regression matrix, a solution is obtained to minimize the square difference between the second current actual overlay error matrix in the y direction and the second fitted overlay error matrix in the y direction, so as to obtain a plurality of second current candidate overlay parameters; The plurality of current candidate overlay parameters are determined based on the plurality of first current candidate overlay parameters and the plurality of second current candidate overlay parameters.

6. The method according to any one of claims 1 to 3, characterized in that The method of obtaining a plurality of current control parameters for overlay error compensation based on the plurality of current target overlay parameters based on the preset mapping model includes: Reversely solving the preset mapping model to obtain a preset reverse mapping model; The multiple current target overlay parameters are input into the preset reverse mapping model to obtain multiple current control parameters for overlay supplementation.

7. The method according to any one of claims 1 to 3, characterized in that The multiple current control parameters include multiple current temperature control compensation parameters corresponding to the temperature control deformation adjustment module in the execution device and multiple current stress compensation parameters corresponding to the mask boundary stress adjustment module in the execution device. The current temperature control compensation parameters are used to perform thermal regulation on the current mask, and the current stress compensation parameters are used to apply compensation stress to the current mask stage of the lithography machine to adjust the spatial posture of the current mask stage.

8. The method according to claim 7, characterized in that The mask boundary stress adjustment module includes at least one of a piezoelectric ceramic actuator array or a micromechanical clamping structure. The multiple current stress compensation parameters include a displacement stress output parameter corresponding to the piezoelectric ceramic actuator array and a clamping stress output parameter corresponding to the micromechanical clamping structure. The displacement stress output parameter is used to compensate for the mechanical deformation of the mask stage, and the clamping stress output parameter is used to adjust the stress distribution of the current mask stage.

9. An overlay error compensation device, characterized in that: The device comprises: a fitting module for performing a high-order polynomial fitting on current actual overlay error data to obtain a plurality of current candidate overlay parameters, wherein the current actual overlay error data represents an actual offset between a current layer of lithographic patterns and a previous layer of lithographic patterns of the wafer, and the current candidate overlay parameters represent coefficients of a high-order polynomial, wherein the order of the high-order polynomial is greater than or equal to 4; a target overlay parameter determination module, configured to determine a plurality of current target overlay parameters from the plurality of current candidate overlay parameters based on significant influence values ​​corresponding to the plurality of current candidate overlay parameters, wherein the significant influence values ​​represent the degree of influence of the current candidate overlay parameters on overlay error compensation; A compensation module is used to obtain multiple current control parameters for overlay error compensation based on a preset mapping model and the multiple current target overlay parameters, so that the execution device of the lithography machine performs overlay compensation operations according to the multiple current control parameters. The preset mapping model represents the mapping relationship between multiple target overlay parameter items and multiple control parameter items.

10. A photolithography machine, characterized in that: The lithography machine comprises: controllers and actuators; The controller is electrically connected to the execution device; The controller is used to drive the execution device according to the steps of the overlay error compensation method according to any one of claims 1 to 8.

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