A method and apparatus for determining planar position deviation

Abstract

The purpose of this invention is to provide a method and apparatus for determining planar position deviation. The method includes: selecting a measurement area for a standard thickness film; performing multiple measurements based on the selected measurement area, and analyzing the trends in film thickness values ​​and GOF (Gross-Oriented Film Function) at multiple measurement points to determine the planar position deviation of the optical system under test. The embodiments of this application have the following advantages: by calculating the planar position deviation based on the selected measurement area using film thickness analysis and goodness-of-fit calculation, the influence of minor light intensity disturbances on the film thickness measurement results is avoided, enabling rapid and accurate determination of the planar position deviation, thereby compensating for the plane center position and improving efficiency; based on the determined planar position deviation, the morphology and size of the light spot can be further analyzed, improving the accuracy of the light spot analysis.

Description

Technical Field

[0001] This invention relates to the field of semiconductor optical measurement, and more particularly to a method and apparatus for determining planar position deviation. Background Technology

[0002] In measurement equipment applications, various systems are typically included, such as image recognition optical systems, autofocus optical systems, ellipsometric measurement optical systems, and reflectance measurement optical systems. For the mechanical and optical design modules of semiconductor measurement equipment, machining and installation errors are unavoidable during the processing and assembly of mechanical parts. The planar positional relationships between the various systems of semiconductor measurement equipment are generally determined during mechanical design, and a certain degree of machining error exists during the processing of mechanical parts. On the other hand, micron-level assembly and adjustment errors are also unavoidable during the assembly and adjustment of various optical systems. As the accuracy requirements for semiconductor device measurement become increasingly stringent, accurately determining the system errors generated during machining and assembly and adjustment is crucial to the final measurement results of the measurement equipment. Generally, mechanical design accuracy can reach the millimeter to hundreds of micrometer scale, so mechanical design values ​​can generally achieve coarse adjustment, but this accuracy is far from sufficient.

[0003] The common method for determining planar position error is to gradually move the optical system under test from one type of thin film sample to another, analyzing the difference between the location of energy change on the film surface and the expected location, i.e., the magnitude of the planar position error. A motion control module moves the measurement area from one region to another. Due to differences in the thin film structure, different energy spectrum information can be obtained through a light intensity signal receiver within the movement interval. The energy information on both sides is normalized, and the deviation between the current actual position and the expected position of the optical system in the horizontal direction at the location of the energy abrupt change is calculated to obtain the current planar position error of the optical system. After completing the horizontal planar position error localization, planar position error analysis is performed in another direction to finally determine the planar position error.

[0004] However, based on the above methods using existing technologies, the light intensity stability has a significant impact on the measurement results when determining the planar position deviation. Normalization calculations lead to increased analytical errors, resulting in a large deviation between the calculated planar position error and the true value, thus causing deviations in the final measurement results. Furthermore, due to optical components and other factors, the light spot shape may not be a regular pattern, leading to a large deviation between the calculated planar position error and the true value, further deviating from the final measurement results. Moreover, for non-circular light spots, the sample scanning movement direction must be along the azimuth angle of the incident plane of the optical system and perpendicular to the azimuth angle to determine the planar position deviation. Due to hardware assembly and machining errors, the azimuth angle also has a certain degree of error, affecting the analytical results to some extent. Summary of the Invention

[0005] The purpose of this invention is to provide a method and apparatus for determining planar position deviation.

[0006] According to an embodiment of this application, a method for determining planar position deviation is provided, wherein the method includes:

[0007] Select a measurement area for a standard thickness film;

[0008] Multiple measurements were performed based on the selected measurement area, and the planar position deviation of the optical system under test was determined by analyzing the changing trends of film thickness and GOF at multiple measurement points.

[0009] According to an embodiment of this application, an apparatus for determining planar position deviation is provided, wherein the apparatus includes:

[0010] A device for selecting a measurement area for a film of a standard thickness;

[0011] An apparatus for determining the planar position deviation of an optical system under test by performing multiple measurements based on a selected measurement area and analyzing the changing trends of film thickness and GOF at multiple measurement points.

[0012] According to an embodiment of this application, a computer device is provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that the processor executes the program to implement the method of the embodiment of this application.

[0013] According to an embodiment of this application, a computer-readable storage medium is provided, on which a computer program is stored, characterized in that the program, when executed by a processor, implements the method of the embodiment of this application.

[0014] Compared with the prior art, the embodiments of this application have the following advantages: by calculating the planar position deviation based on the selected measurement area by analyzing the film thickness and calculating the goodness of fit, the influence of small disturbances in light intensity on the film thickness measurement results is avoided. The planar position deviation can be determined quickly and accurately, thereby compensating for the center position of the plane and improving efficiency. Based on the determined planar position deviation, the morphology and size of the light spot can be further analyzed, improving the accuracy of the light spot analysis. Attached Figure Description

[0015] Other features, objects, and advantages of the invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0016] Figure 1 A flowchart of a method for determining planar position deviation according to an embodiment of this application is shown;

[0017] Figure 2 A schematic diagram illustrating an exemplary optical spot center offset from the center of the measurement area according to an embodiment of this application is shown;

[0018] Figure 3 A schematic diagram illustrating the correction effect of an exemplary planar position deviation according to an embodiment of this application is shown;

[0019] Figure 4 A schematic diagram of a device for determining planar position deviation according to an embodiment of this application is shown.

[0020] The same or similar reference numerals in the accompanying drawings represent the same or similar parts. Detailed Implementation

[0021] Before discussing the exemplary embodiments in more detail, it should be noted that some exemplary embodiments are described as processes or methods depicted as flowcharts. Although the flowcharts describe the operations as sequential processes, many of these operations can be performed in parallel, concurrently, or simultaneously. Furthermore, the order of the operations can be rearranged. The process can be terminated when its operation is completed, but may also have additional steps not included in the figures. The process can correspond to a method, function, procedure, subroutine, subroutine, etc.

[0022] In this context, "computer device," also known as "PC," refers to an intelligent electronic device that can perform predetermined processing procedures such as numerical calculations and / or logical calculations by running predetermined programs or instructions. It may include a processor and memory, with the processor executing pre-stored instructions in memory to perform the predetermined processing procedures, or the predetermined processing procedures being performed by hardware such as ASICs, FPGAs, and DSPs, or a combination of both. Computer devices include, but are not limited to, servers, personal computers, laptops, tablets, and smartphones.

[0023] The computer equipment includes user equipment and network equipment. The user equipment includes, but is not limited to, computers, smartphones, and PDAs; the network equipment includes, but is not limited to, a single network server, a server group consisting of multiple network servers, or a cloud based on cloud computing, which is a type of distributed computing consisting of a super virtual computer composed of a group of loosely coupled computers. The computer equipment can operate independently to implement this application, or it can connect to a network and interact with other computer equipment within the network to implement this application. The network in which the computer equipment is located includes, but is not limited to, the Internet, wide area networks (WANs), metropolitan area networks (MANs), local area networks (LANs), and VPN networks.

[0024] It should be noted that the user equipment, network equipment, and networks mentioned are merely examples. Other existing or future computer equipment or networks that are applicable to this application should also be included within the scope of protection of this application and are incorporated herein by reference.

[0025] The methods discussed below (some of which are illustrated by flowcharts) can be implemented using hardware, software, firmware, middleware, microcode, hardware description languages, or any combination thereof. When implemented using software, firmware, middleware, or microcode, the program code or code segments used to perform the necessary tasks can be stored in a machine or computer-readable medium (such as a storage medium). One or more processors can perform the necessary tasks.

[0026] The specific structural and functional details disclosed herein are merely representative and are intended to describe exemplary embodiments of this application. However, this application may be implemented in many alternative forms and should not be construed as being limited solely to the embodiments set forth herein.

[0027] It should be understood that although the terms "first," "second," etc., may be used herein to describe various units, these units should not be limited by these terms. These terms are used merely to distinguish one unit from another. For example, without departing from the scope of the exemplary embodiments, a first unit may be referred to as a second unit, and similarly, a second unit may be referred to as a first unit. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0028] It should be understood that when a unit is referred to as "connected" or "coupled" to another unit, it may be directly connected or coupled to said other unit, or there may be intermediate units. Conversely, when a unit is referred to as "directly connected" or "directly coupled" to another unit, there are no intermediate units. Other terms used to describe the relationship between units (e.g., "between" versus "directly between," "adjacent to" versus "directly adjacent to," etc.) should be interpreted in a similar manner.

[0029] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments. Unless the context clearly indicates otherwise, the singular forms “a” and “an” as used herein are also intended to include the plural. It should also be understood that the terms “comprising” and / or “including” as used herein specify the presence of the stated features, integers, steps, operations, units, and / or components, without excluding the presence or addition of one or more other features, integers, steps, operations, units, components, and / or combinations thereof.

[0030] It should also be mentioned that in some alternative implementations, the functions / actions mentioned may occur in a different order than those shown in the figures. For example, depending on the functions / actions involved, the two figures shown successively may actually be executed substantially simultaneously or sometimes in reverse order.

[0031] The embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0032] Figure 1 A flowchart of a method for determining a planar position deviation according to an embodiment of this application is shown. The method includes steps S1 and S2.

[0033] The method is applicable to semiconductor optical measurement equipment.

[0034] Reference Figure 1 In step S1, a measurement area for a film of standard thickness is selected.

[0035] In this study, the internal and external membrane structure information of the selected measurement area is known. Furthermore, the internal and external membrane parameters within this measurement area differ, specifically in terms of different membrane information or membrane thickness. Preferably, the uniformity of the membrane structure within the measurement area meets predetermined requirements, thereby enabling the acquisition of accurate analytical results.

[0036] The size of the measurement area meets predetermined requirements. Preferably, the size of the selected measurement area is greater than 1.5 times the size of the light spot.

[0037] The selected measurement area can be of various shapes, such as circular or square.

[0038] In step S2, multiple measurements are performed based on the selected measurement area, and the planar position deviation of the optical system under test is determined by analyzing the changing trends of the film thickness and goodness of fit (GOF) at multiple measurement points.

[0039] Specifically, the scanning range, scanning step size, and scanning direction of the motion control system in the optical measurement equipment are set. Then, the motion control system is moved to each measurement point to perform measurements, so as to collect characteristic curves at multiple measurement points. By obtaining the best matching value between the characteristic curves and the theoretical values, the film thickness value and GOF at each measurement point are obtained, thereby analyzing the trend of GOF and film thickness variation.

[0040] Wherein, the planar position deviation is the distance deviation between the planar positions of different systems.

[0041] The mathematical analysis method for goodness of fit involves matching and fitting the characteristic curve information collected by the optical system of the optical measurement device with the theoretical value.

[0042] When characteristic curve information needs to be acquired, light intensity and other information can be received through a four-quadrant detector or spectrometer. The light intensity information contains sample information of the sample region to be measured, such as film structure and film thickness, and different film structures and thicknesses. Next, the light intensity spectrum information is further analyzed, such as performing Fourier expansion to obtain second-order or fourth-order Fourier coefficients; or, only analyzing the parallel and perpendicular components of polarized light to obtain the corresponding reflection coefficients, i.e., the reflection coefficients of S-ray and P-ray; or, obtaining the amplitude ratio and phase difference information of S-ray and P-ray by analyzing the ellipticity parameters related to the ellipticity system; if anisotropic materials are considered, more parameter information can be obtained by analyzing the Jones matrix or Mueller matrix, thereby obtaining more detailed information on the changes in film structure.

[0043] The collected feature curve information includes, but is not limited to, second-order Fourier coefficients, fourth-order Fourier coefficients, reflection coefficients, ellipsometry parameters, Jones matrix, Mueller matrix, etc., for different band ranges.

[0044] Specifically, when calculating GOF, it is assumed that the measured spectral information is represented as S. M ={S M1 ,...,S MN The theoretical spectral information is represented as S. i ={S1,...,S N}, then the formula for calculating GOF is expressed as follows:

[0045]

[0046] It can be seen that the higher the GOF value, the closer the fitted film thickness result is to the theoretical value.

[0047] Specifically, by analyzing the changing trends of film thickness and GOF at multiple measurement points, the measurement point with the highest film thickness that meets the predetermined conditions is found, and the planar position deviation of the optical system under test is determined based on the coordinate information of the measurement point and the coordinate information of the center of the selected measurement point.

[0048] According to one embodiment, if a measurement point with the highest GOF (Gross Array of Films) that meets the predetermined conditions for film thickness cannot be found, the currently set scanning range or scanning direction is adjusted to re-scan and measure.

[0049] For example, the scanning range can be automatically expanded when the highest GOF point is not found. If the GOF shows a continuous increasing trend, the scanning range can be automatically widened and the square movement can be continued to obtain the position of the highest GOF measurement point. If the GOF shows a continuous decreasing trend, the scanning range can be automatically widened and the scanning can be performed in the opposite direction to obtain the position of the highest GOF measurement point.

[0050] Preferably, after the motion control system moves to each measurement point, it can choose to perform automatic focusing to obtain results with higher accuracy. If the status of each system of the optical measurement equipment is good enough, the motion control system can also be stabilized at the corresponding position after the initial automatic focusing, and only move in the planar direction.

[0051] According to one embodiment, the planar position deviation is determined by scanning measurements in two directions, and step S2 includes steps S201 to S204.

[0052] In step S201, a scanning measurement is performed along a first direction of the selected measurement area to obtain the film thickness value and GOF at multiple measurement points.

[0053] Specifically, the scanning range, scanning step size, and scanning direction are set along the first direction. Then, the device moves to each measurement point to perform measurements, so as to collect characteristic curves at multiple measurement points. By obtaining the best matching value between the characteristic curve and the theoretical value, the film thickness value and GOF at each measurement point are obtained, thereby analyzing the trend of GOF and film thickness variation.

[0054] In step S202, the changing trends of the film thickness and GOF at the multiple measurement points are analyzed, and scanning measurements are continuously performed until the first measurement point with the film thickness in the first direction that meets the predetermined conditions and has the highest GOF is found.

[0055] The first direction is a direction in which the motion control system in the optical measurement device performs scanning measurements. This direction includes, but is not limited to, angles such as 0 degrees or 90 degrees. Preferably, the angle of the corresponding scanning direction is determined based on the shape of the light spot, for example, 45 degrees or 135 degrees.

[0056] Specifically, if the analysis of the film thickness and GOF trends at multiple measurement points reveals that the film thickness is approaching the target thickness while the GOF increases, then the selected scanning direction is correct; if the film thickness deviates from the target thickness while the GOF decreases, then the selected scanning direction is incorrect, and the scanning measurement should be performed in a different direction.

[0057] If a first measurement point with the highest GOF (Gross Array of Film Thickness) that meets the predetermined conditions for film thickness cannot be found in a certain direction, the scanning direction is changed and scanning continues. Preferably, a larger scanning step size and a larger scanning range can be set until a first measurement point with the highest GOF that meets the predetermined conditions for film thickness is found.

[0058] In step S203, the first measurement point is used as the starting point, and scanning measurement is performed along the second direction. The changing trends of the film thickness values ​​and GOF at multiple measurement points are analyzed, and scanning measurement is continued until a second measurement point is found that meets the predetermined conditions and has the highest GOF.

[0059] The second direction can be any direction, not limited to being perpendicular to the first direction.

[0060] In step S204, the planar position deviation is calculated based on the coordinate information of the second measurement point and the coordinate information of the center of the selected measurement area.

[0061] The method of this embodiment will be illustrated below with an example.

[0062] Assume the center coordinates of the selected measurement area (pad) are (X0, Y0), and the first direction is the horizontal X direction. In step S201, the scanning direction is set to the X direction, the scanning range is twice the size of the pad, and the scanning step size is 2 micrometers. Then, the measurement is performed at each measurement point to obtain multiple measurement points for characteristic curve acquisition. By obtaining the best matching value between the characteristic curve and the theoretical value, the film thickness value and GOF at each measurement point are obtained.

[0063] Next, in step S202, the film thickness values ​​and GOF trends at the multiple measurement points are analyzed. Specifically, the magnitude of the GOF value within the X-direction movement range is analyzed, and whether there is a certain trend in the GOF. For example, if the GOF is always decreasing or increasing, it indicates that the scanning range deviates significantly from the center position of the plane, and it is necessary to return and reset the scanning range and step size. If the GOF first increases and then decreases, there is a point with the highest GOF value. At the same time, it is compared with the expected film thickness value. If the film thickness value deviates significantly from the expected value, it indicates that the GOF point is incorrect. If the film thickness value is consistent with the expected value, then this point is taken as the first measurement point and the X-direction coordinate X1 of this point is recorded.

[0064] Next, in step S203, the first measurement point is used as the starting point, and scanning measurement is performed along the Y direction perpendicular to the X direction. The scanning direction is set to the Y direction, the scanning range is twice the size of the pad, and the scanning step size is 2 micrometers. Then, the measurement is performed at each measurement point to obtain multiple measurement points for characteristic curve acquisition. By obtaining the best matching value between the characteristic curve and the theoretical value, the film thickness value and GOF at each measurement point are obtained. Next, the magnitude of the GOF value within the Y-direction movement range is analyzed to see if there is any trend in the GOF. For example, if the GOF always shows a decreasing or increasing trend, it indicates that the deviation between the scanning range and the center position of the plane is large, and it is necessary to return and reset the scanning range and step size. If the GOF first increases and then decreases, there is a point with the highest GOF. At the same time, it is compared with the expected film thickness value. If the film thickness value deviates significantly from the expected value, it indicates that the GOF point is incorrect. If the film thickness value is consistent with the expected value, then this point is used as the second measurement point, and the Y-direction coordinate Y1 of this point is recorded.

[0065] Next, in step S204, based on the coordinates (X1, Y1) of the finally obtained GOF highest point and the coordinates (X0, Y0) of the center of the selected measurement area, the planar position deviation is calculated using the following formula:

[0066] (Δx,Δy)=(X1-X0,Y1-Y0) (2)

[0067] In this example, the direction of the two scans is not limited to X-direction first and then Y-direction; it can also be Y-direction first and then X-direction.

[0068] It should be noted that the above examples are only for better illustrating the technical solution of the present invention, and are not intended to limit the present invention. Those skilled in the art should understand that any method of determining planar position deviation by scanning measurements in two directions should be included within the scope of the present invention.

[0069] According to one embodiment, the planar position deviation is determined by performing a coarse scan followed by a fine scan, and step S2 includes steps S201' to S204'.

[0070] In step S201', the film thickness values ​​and GOF of multiple measurement points in two directions are obtained by performing a first scan measurement based on the selected measurement area.

[0071] In step S202', the changing trends of the film thickness and GOF at the multiple measurement points are analyzed, and scanning measurements are continuously performed until a candidate measurement point with a film thickness that meets the predetermined conditions and has the highest GOF is found.

[0072] In step S203', a second scan measurement is performed in two directions with the candidate measurement point as the center point. The changing trends of the film thickness values ​​and GOF of the multiple measurement points are analyzed, and the scan measurement is continued until the target measurement point with the film thickness value that meets the predetermined conditions and the highest GOF is found.

[0073] In step S204', the planar position deviation is calculated based on the coordinate information of the target measurement point and the coordinate information of the center of the pad.

[0074] The step size and range of movement in the first scan are greater than those in the second scan.

[0075] The method of this embodiment will be illustrated below with an example.

[0076] Building upon the previous example, we continue to assume that the center coordinates of the selected measurement area (pad) are (X0, Y0). In step S201', the scanning range is set to twice the size of the pad, the scanning step size is 5 micrometers, and the first scan measurement is performed to obtain the film thickness values ​​and GOF of multiple measurement points in the X and Y directions.

[0077] Next, in step S202', the changing trends of the film thickness and GOF at the multiple measurement points are analyzed, and scanning measurements are continuously performed until a candidate measurement point with a film thickness that meets the predetermined conditions and has the highest GOF is found.

[0078] Next, in step S203', with the candidate measurement point as the center point, the scanning range is set to 1.5 times the pad size and the scanning step size is 2 micrometers. A second scanning measurement is performed in the X and Y directions. The film thickness values ​​and GOF change trends of the obtained multiple measurement points are analyzed, and scanning measurements are continued until the target measurement point with the film thickness value meeting the predetermined conditions and the highest GOF is found.

[0079] In step S204', the planar position deviation is calculated based on the coordinate position (X1, Y1) of the target measurement point and the coordinates (X0, Y0) of the center of the selected measurement area.

[0080] It should be noted that the above examples are only for better illustrating the technical solution of the present invention, and are not intended to limit the present invention. Those skilled in the art should understand that any method of determining the planar position deviation by first performing a coarse scan and then a fine scan should be included within the scope of the present invention.

[0081] According to one embodiment, based on the two-scan method described in steps S201' to S204' of the above embodiments, three or more scans can be performed to determine the measurement point where the film thickness meets the predetermined conditions and has the highest GOF, and then the planar position deviation can be calculated. For example, assuming three scan measurements are performed, the first scan uses a movement step size of 10 micrometers with a pad size of 3 times, and then the second and third scans are performed sequentially with slightly smaller movement step sizes, thereby quickly obtaining the optimal planar position deviation information.

[0082] According to one embodiment, the method includes step S3.

[0083] In step S3, compensation is performed based on the planar position deviation.

[0084] Specifically, based on the determined planar position deviation, the corresponding information is compensated into the motion control system parameters of the optical measurement equipment, thereby correcting the planar position deviation.

[0085] According to one embodiment, the distance that the light spots in the two directions can move within the measurement area is obtained by scanning in two directions along the central axis of the selected measurement area.

[0086] For example, Figure 2 A schematic diagram showing the deviation of the light spot center from the center of the measurement area is shown. Figure 3 A schematic diagram illustrating the correction effect of the shown planar position deviation is presented. (Refer to...) Figure 2 , where Δx is the planar position deviation in the X direction (i.e., the horizontal direction) and Δy is the planar position deviation in the Y direction (i.e., the vertical direction).

[0087] Reference Figure 3 The sum of Lx and Rx is the distance the light spot can move in the X direction. Given that the width of the selected measurement area (pad) is D, the size of the pad that the light spot can fit on is D-(Lx+Rx).

[0088] According to one embodiment, the method includes step S4.

[0089] In step S4, the spot information is determined based on the measurement data obtained from multiple measurements of the measurement area.

[0090] The light spot information includes, but is not limited to, at least one of the following:

[0091] 1) The position of the light spot;

[0092] 2) The appearance of the light spot;

[0093] 3) Size of the light spot.

[0094] If the light spot is a regular and symmetrical spot, such as a circular spot, the size of the spot can be obtained by scanning and analyzing from any two directions; if the light spot is an irregular and symmetrical spot, such as a trailing elliptical spot, scanning and analysis from multiple directions is required.

[0095] According to one embodiment, the measurement pad capability corresponding to the light spot is determined based on the size of the selected measurement area (pad) and the analysis of the film thickness or GOF variation trend in at least two directions.

[0096] According to the method of this application embodiment, the planar position deviation is calculated by analyzing the film thickness and calculating the goodness of fit based on the selected measurement area. This avoids the influence of small perturbations in light intensity on the film thickness measurement results, and can quickly and accurately determine the planar position deviation, thereby compensating for the center position of the plane and improving efficiency. Based on the determined planar position deviation, the morphology and size of the light spot can be further analyzed, improving the accuracy of the light spot analysis.

[0097] Figure 4 A schematic diagram of a device for determining planar position deviation according to an embodiment of this application is shown.

[0098] The apparatus includes: a device for selecting a measurement area of ​​a standard thickness film (hereinafter referred to as "area selection device 1"), and a device for performing multiple measurements based on the selected measurement area and determining the planar position deviation of the optical system under test by analyzing the film thickness values ​​and GOF variation trends at multiple measurement points (hereinafter referred to as "deviation determination device 2").

[0099] Reference Figure 4The area selection device 1 selects a measurement area for a film of a standard thickness.

[0100] In this study, the internal and external membrane structure information of the selected measurement area is known. Furthermore, the internal and external membrane parameters within this measurement area differ, specifically in terms of different membrane information or membrane thickness. Preferably, the uniformity of the membrane structure within the measurement area meets predetermined requirements, thereby enabling the acquisition of accurate analytical results.

[0101] The size of the measurement area meets predetermined requirements. Preferably, the size of the selected measurement area is greater than 1.5 times the size of the light spot.

[0102] The selected measurement area can be of various shapes, such as circular or square.

[0103] The deviation determination device 2 performs multiple measurements based on the selected measurement area, and determines the planar position deviation of the optical system under test by analyzing the changing trends of the film thickness value and goodness of fit (GOF) at multiple measurement points.

[0104] Specifically, the deviation determination device 2 sets the scanning range, scanning step size and scanning direction of the motion control system in the optical measurement equipment, and then moves the motion control system to each measurement point to perform measurement, so as to collect characteristic curves at multiple measurement points, and obtain the film thickness value and GOF at each measurement point by obtaining the best matching value between the characteristic curve and the theoretical value, thereby analyzing the trend of GOF and film thickness variation.

[0105] Wherein, the planar position deviation is the distance deviation between the planar positions of different systems.

[0106] The mathematical analysis method for goodness of fit involves matching and fitting the characteristic curve information collected by the optical system of the optical measurement device with the theoretical value.

[0107] When characteristic curve information needs to be acquired, light intensity and other information can be received through a four-quadrant detector or spectrometer. The light intensity information contains sample information of the sample region to be measured, such as film structure and film thickness, and different film structures and thicknesses. Next, the light intensity spectrum information is further analyzed, such as performing Fourier expansion to obtain second-order or fourth-order Fourier coefficients; or, only analyzing the parallel and perpendicular components of polarized light to obtain the corresponding reflection coefficients, i.e., the reflection coefficients of S-ray and P-ray; or, obtaining the amplitude ratio and phase difference information of S-ray and P-ray by analyzing the ellipticity parameters related to the ellipticity system; if anisotropic materials are considered, more parameter information can be obtained by analyzing the Jones matrix or Mueller matrix, thereby obtaining more detailed information on the changes in film structure.

[0108] The collected feature curve information includes, but is not limited to, second-order Fourier coefficients, fourth-order Fourier coefficients, reflection coefficients, ellipsometry parameters, Jones matrix, Mueller matrix, etc., for different band ranges.

[0109] Specifically, when calculating GOF, it is assumed that the measured spectral information is represented as S. M ={S M1 ,...,S MN The theoretical spectral information is represented as S. i ={S1,...,S N}, then the calculation formula for GOF is expressed as formula (1).

[0110] Specifically, the deviation determination device 2 analyzes the changing trends of film thickness values ​​and GOF at multiple measurement points to find the measurement point where the film thickness value meets the predetermined conditions and the GOF is the highest. Based on the coordinate information of the measurement point and the coordinate information of the center of the selected measurement point, the planar position deviation of the optical system under test is determined.

[0111] According to one embodiment, if a measurement point with the highest GOF that meets the predetermined conditions for film thickness cannot be found, the deviation determination device 2 adjusts the currently set scanning range or scanning direction to re-scan and measure.

[0112] For example, the scanning range can be automatically expanded when the highest GOF point is not found. If the GOF shows a continuous increasing trend, the scanning range can be automatically widened and the square movement can be continued to obtain the position of the highest GOF measurement point. If the GOF shows a continuous decreasing trend, the scanning range can be automatically widened and the scanning can be performed in the opposite direction to obtain the position of the highest GOF measurement point.

[0113] Preferably, after the motion control system moves to each measurement point, it can choose to perform automatic focusing to obtain results with higher accuracy. If the status of each system of the optical measurement equipment is good enough, the motion control system can also be stabilized at the corresponding position after the initial automatic focusing, and only move in the planar direction.

[0114] According to one embodiment, the planar position deviation is determined by scanning measurements in two directions, and the deviation determination device 2 performs the following operations:

[0115] A scanning measurement is performed along a first direction within the selected measurement area to obtain film thickness values ​​and GOF at multiple measurement points. Specifically, the scanning range, scanning step size, and scanning direction are set along the first direction, and then the measurement is performed at each measurement point to acquire characteristic curves at multiple measurement points. By obtaining the best matching value between the characteristic curves and the theoretical values, the film thickness values ​​and GOF at each measurement point are obtained, thereby analyzing the variation trends of GOF and film thickness.

[0116] Next, the trends of film thickness and GOF at these multiple measurement points are analyzed, and scanning measurements are continuously performed until the first measurement point is found where the film thickness in the first direction meets the predetermined conditions and the GOF is the highest.

[0117] The first direction is a direction in which the motion control system in the optical measurement device performs scanning measurements. This direction includes, but is not limited to, angles such as 0 degrees or 90 degrees. Preferably, the angle of the corresponding scanning direction is determined based on the shape of the light spot, for example, 45 degrees or 135 degrees.

[0118] Specifically, if the analysis of the film thickness and GOF trends at multiple measurement points reveals that the film thickness is approaching the target thickness while the GOF increases, then the selected scanning direction is correct; if the film thickness deviates from the target thickness while the GOF decreases, then the selected scanning direction is incorrect, and the scanning measurement should be performed in a different direction.

[0119] If a first measurement point with the highest GOF (Gross Array of Film Thickness) that meets the predetermined conditions for film thickness cannot be found in a certain direction, the scanning direction is changed and scanning continues. Preferably, a larger scanning step size and a larger scanning range can be set until a first measurement point with the highest GOF that meets the predetermined conditions for film thickness is found.

[0120] Next, taking the first measurement point as the starting point, scanning measurements are performed along the second direction. The changing trends of the film thickness values ​​and GOF at multiple measurement points are analyzed, and scanning measurements are continued until a second measurement point is found that meets the predetermined conditions for film thickness and has the highest GOF.

[0121] The second direction can be any direction, not limited to being perpendicular to the first direction.

[0122] Based on the coordinate information of the second measurement point and the coordinate information of the center of the selected measurement area, the planar position deviation is calculated.

[0123] According to one embodiment, the planar position deviation is determined by performing a coarse scan followed by a fine scan, and the deviation determination device 2 performs the following operations:

[0124] The film thickness and GOF values ​​at multiple measurement points in two directions are obtained by performing a first scan measurement based on the selected measurement area.

[0125] Next, the trends of film thickness and GOF at these multiple measurement points were analyzed, and scanning measurements were continuously performed until a candidate measurement point was found that met the predetermined conditions and had the highest GOF.

[0126] Next, a second scan measurement is performed in two directions with the candidate measurement point as the center point. The changes in film thickness and GOF at multiple measurement points are analyzed, and the scan measurement is continued until the target measurement point with the film thickness value meeting the predetermined conditions and the highest GOF is found.

[0127] Next, based on the coordinate information of the target measurement point and the coordinate information of the center of the pad, the planar position deviation is calculated.

[0128] The step size and range of movement in the first scan are greater than those in the second scan.

[0129] According to one embodiment, based on the two-scan method described in the above embodiments, three or more scans can be performed to determine the measurement point where the film thickness meets predetermined conditions and has the highest GOF, thereby calculating the planar position deviation. For example, assuming three scan measurements are performed, the first scan uses a movement step of 10 micrometers with a pad size of 3 times, and then the second and third scans are performed sequentially with slightly smaller movement steps, thereby quickly obtaining the optimal planar position deviation information.

[0130] According to one embodiment, the device includes a compensation device.

[0131] The compensation device compensates for the planar position deviation.

[0132] Specifically, the compensation device, based on the determined planar position deviation, compensates the corresponding information into the motion control system parameters of the optical measurement equipment, thereby correcting the planar position deviation.

[0133] According to one embodiment, the device obtains the distance that the light spots in the two directions can move within the measurement area by scanning in two directions along the central axis of the selected measurement area.

[0134] According to one embodiment, the device includes a light spot analysis device.

[0135] The spot analysis device determines the spot information based on measurement data obtained from multiple measurements of the measurement area.

[0136] The light spot information includes, but is not limited to, at least one of the following:

[0137] 1) The position of the light spot;

[0138] 2) The appearance of the light spot;

[0139] 3) Size of the light spot.

[0140] If the light spot is a regular and symmetrical spot, such as a circular spot, the size of the spot can be obtained by scanning and analyzing from any two directions; if the light spot is an irregular and symmetrical spot, such as a trailing elliptical spot, scanning and analysis from multiple directions is required.

[0141] According to one embodiment, the spot analysis device determines the measurement pad capability corresponding to the spot based on the size of the selected measurement area (pad) and the analysis of the film thickness or GOF variation trend in at least two directions.

[0142] The apparatus according to the embodiments of this application calculates the planar position deviation by analyzing the film thickness and calculating the goodness of fit based on the selected measurement area. This avoids the influence of small perturbations in light intensity on the film thickness measurement results, and can quickly and accurately determine the planar position deviation, thereby compensating for the center position of the plane and improving efficiency. Based on the determined planar position deviation, the morphology and size of the light spot can be further analyzed, improving the accuracy of the light spot analysis.

[0143] The software program of this invention can be executed by a processor to implement the steps or functions described above. Similarly, the software program of this invention (including associated data structures) can be stored in a computer-readable recording medium, such as RAM memory, magnetic or optical drives, floppy disks, and similar devices. Furthermore, some steps or functions of this invention can be implemented in hardware, for example, as circuitry that works in conjunction with a processor to perform the various functions or steps.

[0144] Furthermore, a portion of this invention can be applied as a computer program product, such as computer program instructions, which, when executed by a computer, can invoke or provide the methods and / or technical solutions according to the invention through the operation of the computer. The program instructions invoking the methods of the invention may be stored in a fixed or removable recording medium, and / or transmitted via a data stream in a broadcast or other signal-carrying medium, and / or stored in the working memory of a computer device operating according to the program instructions. Here, an embodiment of the invention includes an apparatus comprising a memory for storing computer program instructions and a processor for executing the program instructions, wherein, when the computer program instructions are executed by the processor, the apparatus is triggered to operate the methods and / or technical solutions based on the foregoing embodiments of the invention.

[0145] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be embraced within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims. Furthermore, it is clear that the word "comprising" does not exclude other units or steps, and the singular does not exclude the plural. Multiple units or devices recited in the system claims may also be implemented by a single unit or device in software or hardware. The terms "first," "second," etc., are used to indicate names and do not indicate any particular order.

Claims

1. A method for determining planar position deviation, wherein, The method includes: A measurement area for a standard thickness film is selected, and the structural information of the inner and outer film layers in the selected measurement area is known and differs from each other; Based on the selected measurement area, multiple measurements are performed according to a preset scanning range, scanning step size, and scanning direction. By analyzing the changing trends of film thickness values ​​and GOF at multiple measurement points, the measurement point with the smallest deviation from the expected film thickness value and the highest GOF is identified. The theoretical center coordinates of the selected measurement area are then determined. Based on these theoretical center coordinates and the actual center coordinates of the selected measurement area, the planar position deviation of the optical system under test is determined. The preset scanning range is larger than the selected measurement area. When the film thickness values ​​of the multiple measurement points gradually deviate from the film thickness values ​​within the selected area, the scanning direction is adjusted.

2. The method according to claim 1, wherein, The step of performing multiple measurements based on a selected measurement area and analyzing the changing trends of film thickness and GOF at multiple measurement points to determine the planar position deviation of the optical system under test includes: Scanning measurements are performed along the first direction of the selected measurement area to obtain film thickness values ​​and GOF at multiple measurement points; The trends of film thickness and GOF at multiple measurement points were analyzed, and scanning measurements were continuously performed until the first measurement point with the film thickness in the first direction meeting the predetermined conditions and having the highest GOF was found. Using the first measurement point as the starting point, scanning measurements are performed along the second direction. The changing trends of the film thickness values ​​and GOF at multiple measurement points are analyzed, and scanning measurements are continued until a second measurement point is found that meets the predetermined conditions and has the highest GOF. Based on the coordinate information of the second measurement point and the coordinate information of the center of the selected measurement area, the planar position deviation is calculated.

3. The method according to claim 1, wherein, The step of performing multiple measurements based on a selected measurement area and analyzing the changing trends of film thickness and GOF at multiple measurement points to determine the planar position deviation of the optical system under test includes: The film thickness and GOF at multiple measurement points in two directions are obtained by performing a first scan measurement based on the selected measurement area. The trends of film thickness and GOF at multiple measurement points were analyzed, and scanning measurements were continuously performed until a candidate measurement point with a film thickness that met the predetermined conditions and had the highest GOF was found. Using the candidate measurement point as the center point, a second scan measurement is performed in two directions. The changes in film thickness and GOF at multiple measurement points are analyzed, and the scan measurement is continued until the target measurement point with film thickness that meets the predetermined conditions and has the highest GOF is found. Based on the coordinate information of the target measurement point and the coordinate information of the center of the pad, the planar position deviation is calculated; The step size and range of movement in the first scan are greater than those in the second scan.

4. The method according to claim 2 or 3, wherein, The method includes: If a measurement point with the highest GOF value that meets the predetermined conditions for film thickness cannot be found, adjust the currently set scanning range or scanning direction to re-scan and measure.

5. The method according to any one of claims 1 to 3, wherein, The method includes: Compensation is performed based on the aforementioned planar position deviation.

6. The method according to any one of claims 1 to 3, wherein, The method includes: Based on measurement data obtained from multiple measurements of the measurement area, spot information is determined, wherein the spot information includes at least one of the following: Location of the light spot; Size of the light spot; The appearance of the light spot.

7. An apparatus for determining planar position deviation, wherein, The device includes: A device for selecting a measurement area for a film of a standard thickness; A device for performing multiple measurements based on a selected measurement area according to a preset scanning range, scanning step size, and scanning direction, and for determining the planar position deviation of the optical system under test by analyzing the film thickness values ​​and GOF variation trends at multiple measurement points. The device analyzes the changing trends of film thickness values ​​and GOF at multiple measurement points to find the measurement point with the smallest deviation from the expected film thickness value and the highest GOF, determines the theoretical center coordinates of the selected measurement area, and determines the planar position deviation of the optical system under test based on the theoretical center coordinates and the actual center coordinates of the selected measurement area. The preset scanning range is larger than the selected measurement area, and the scanning direction is adjusted when the film thickness values ​​at the multiple measurement points gradually deviate from the film thickness values ​​within the selected area.

8. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the method as described in any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the method as described in any one of claims 1 to 6.

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