Single-wavelength light beam thickness measurement and calibration library construction method and equipment based on polishing process

Abstract

The invention provides a single-wavelength light beam thickness measurement and calibration library construction method and equipment based on a polishing process, and the method comprises the steps: carrying out the online in-situ measurement of the thickness of a wafer film through a multi-wavelength light beam in a polishing process of the wafer film, acquiring an electric signal corresponding to the light intensity of the reflected light of the wafer film to the single-wavelength light beam under a plurality of different thicknesses; and determining a calibration library for measuring the thickness of the wafer film in the polishing process based on a periodic rule presented by the electric signals along with the change of the thickness of the wafer film and the values of the electric signals corresponding to the plurality of different thicknesses.

Description

Technical Field

[0001] The present invention relates to the field of wafer feature measurement, and in particular to a single-wavelength light beam thickness measurement and calibration library construction method and equipment based on a polishing process. Background Art

[0002] In the polishing EPD (End Point Detection) project based on optical measurement methods, there are two methods for measuring the thickness of wafer films: the first method is to use a multi-wavelength light beam to irradiate the surface of the wafer film, collect the reflected light of the multi-wavelength light beam to obtain spectral data, including the reflectivity corresponding to each wavelength, and determine the thickness of the wafer film according to the characteristic information of the spectral data; the second method is to use a single laser beam (a single wavelength light beam) to irradiate the surface of the wafer film, collect the reflected light of the single wavelength light beam, and irradiate the reflected light to the photodetector. The photodetector converts the light intensity signal into an electrical signal, and determines the thickness of the wafer film by the value of the electrical signal.

[0003] Before using the single-wavelength beam measurement method for measurement in wafer polishing conditions, it is necessary to calibrate the relationship between the value of the electrical signal and the thickness, which is usually referred to as establishing a corresponding relationship library between the electrical signal and the film thickness in the art, or simply building a library. The problem with the prior art is that electrical signals are collected in an experimental environment when building a library. Since the equipment conditions during library building are different from those in polishing conditions, such as the installation positions and angles of equipment such as light sources and sensors, etc., the pre-established database will not match the actual working conditions, which will lead to inaccurate measurement results. Summary of the invention

[0004] In view of this, the present application provides a method for constructing a single-wavelength beam thickness measurement calibration library based on a polishing process, comprising: During the polishing process of the wafer film, the thickness of the wafer film is measured in situ using a multi-wavelength light beam online, and an electrical signal corresponding to the light intensity of the reflected light of the wafer film to the single-wavelength light beam is obtained at multiple different thicknesses; Based on the periodicity of the electrical signal as the wafer film thickness changes and the values ​​of the electrical signals corresponding to the multiple different thicknesses, a calibration library for measuring the wafer film thickness during the polishing process is determined.

[0005] Optionally, the relationship between the electrical signal and the thickness of the wafer film is a quasi-sinusoidal function relationship.

[0006] Optionally, determining a calibration library for measuring wafer film thickness during the polishing process comprises: Using at least two different thicknesses and corresponding electrical signal values, a corresponding relationship model between the electrical signal and the thickness is determined.

[0007] Optionally, obtaining an electrical signal corresponding to the light intensity of the reflected light of the wafer film to the single-wavelength light beam at a plurality of different thicknesses includes: Determining a sampling range according to a period of the electrical signal, wherein the sampling range is greater than or equal to half of the period; The electrical signal is collected when the thickness of the wafer film is within the sampling range.

[0008] Optionally, obtaining an electrical signal corresponding to the light intensity of the reflected light of the wafer film to the single-wavelength light beam at a plurality of different thicknesses includes: collecting the electrical signal in real time as the thickness of the wafer film changes; The collected electrical signal is monitored to determine whether at least two extreme values ​​appear in sequence, and the electrical signal between the at least two extreme values ​​is an electrical signal of at least half a cycle.

[0009] Optionally, after determining the calibration library used to measure the wafer film thickness during the polishing process, the method further includes: The calibration library is converted into a calibration library suitable for a water-deficient multilayer membrane environment using a conversion factor.

[0010] The present application also provides a method for measuring the thickness of a wafer film based on a single-wavelength light beam, comprising: During the polishing process of the wafer film, determining the starting thickness of the wafer film when the single-wavelength beam measurement is enabled, and then starting to monitor the electrical signal corresponding to the light intensity of the reflected light of the single-wavelength beam from the wafer film; The thickness of the wafer film is determined using the calibration library constructed using the above method, the value of the monitored electrical signal and the starting thickness.

[0011] Optionally, when the calibration library is a correspondence model between electrical signals and thickness, determining the thickness of the wafer film includes: Substituting the monitored electrical signal into the corresponding relationship model to calculate the corresponding periodic thickness result; The thickness of the wafer film is determined according to the initial thickness and the periodic thickness result.

[0012] Optionally, when the calibration library includes values ​​of electrical signals exceeding one cycle and corresponding thicknesses, determining the thickness of the wafer film includes: The calibration library is searched for data that matches the monitored electrical signal, and the thickness of the wafer film is inverted in combination with the initial thickness.

[0013] Optionally, when the calibration library includes values ​​of electrical signals less than one cycle and corresponding thicknesses, determining the thickness of the wafer film includes: Determining whether there is data in the calibration library that matches the monitored electrical signal; When data matching the monitored electrical signal exists in the calibration library, the corresponding thickness is acquired, and the thickness of the wafer film is inverted according to the starting thickness; When there is no data consistent with the monitored electrical signal in the calibration library, one cycle of data is obtained based on less than one cycle of data to obtain data consistent with the monitored electrical signal, and the thickness of the wafer film is inverted based on the starting thickness.

[0014] Accordingly, the present application provides a single-wavelength beam thickness measurement calibration library construction device based on a polishing process, comprising: a processor and a memory connected to the processor; wherein the memory stores instructions executable by the processor, and the instructions are executed by the processor so that the processor executes the above-mentioned single-wavelength beam thickness measurement calibration library construction method based on the polishing process.

[0015] Accordingly, the present application provides a device for measuring the thickness of a wafer thin film based on a single wavelength light beam, comprising: a processor and a memory connected to the processor; wherein the memory stores instructions that can be executed by the processor, and the instructions are executed by the processor so that the processor executes the above-mentioned method for measuring the thickness of a wafer thin film based on a single wavelength light beam.

[0016] The calibration library construction method and equipment provided in the present application use the spectral data of the wafer film's reflected light of a multi-wavelength light beam to obtain the thickness during the wafer film's polishing process. A single-wavelength light beam is used to irradiate the wafer film surface at multiple different thicknesses in this measurement environment to obtain an electrical signal corresponding to the light intensity of the reflected light. Since the thickness value and the electrical signal are obtained in an actual measurement environment, the calibration library of the thickness value and the electrical signal obtained can be accurately applied to this measurement environment.

[0017] The wafer film thickness measurement method and device provided in the present application records the current thickness when the single-wavelength beam measurement is enabled, and then starts to obtain an electrical signal based on the single-wavelength beam measurement method, and queries the calibration library established during the polishing process for data consistent with the electrical signal measured by the single-wavelength beam. The absolute thickness of the wafer film can be obtained in combination with the recorded starting thickness, and since the calibration library is established in the same environment as the thickness measurement environment, the obtained measurement result is more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1A data schematic diagram of a calibration library construction method in an embodiment of the present application; Figure 2 A data schematic diagram of another calibration library construction method in an embodiment of the present application; Figure 3 This is a data schematic diagram of the third calibration library construction method in the embodiment of the present application. DETAILED DESCRIPTION

[0020] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0022] The embodiment of the present invention provides a method for constructing a single-wavelength beam thickness measurement calibration library based on a polishing process, which can be executed by an electronic device such as a computer or a server, and includes the following operations: S1, during the polishing process of the wafer film, the thickness of the wafer film is measured in situ using a multi-wavelength light beam, and an electrical signal corresponding to the light intensity of the reflected light of the wafer film to the single-wavelength light beam is obtained at multiple different thicknesses.

[0023] The wafer film can be specifically a silicon dioxide layer on the surface of a silicon-based wafer. During the polishing process, the wafer film is polished by external force and its thickness gradually decreases. In this process, the spectral information of the multi-wavelength light beam is used to measure the thickness value in situ during the polishing process.

[0024] Multi-wavelength light beam online in-situ measurement specifically refers to the use of a multi-wavelength light source to emit a multi-wavelength light beam in a polishing process environment, collecting multi-wavelength reflected light on the surface of the wafer film, and obtaining spectral data through spectrometer analysis, which is the light intensity or reflectivity corresponding to each wavelength. This spectral data is matched with a pre-established spectral library. Each reference spectrum in the spectral library corresponds to a different thickness value, and the thickness value corresponding to the reference spectrum that matches the measured spectral data is the current thickness value of the wafer film.

[0025] In this measurement environment, a light source emitting single-wavelength light is used to emit light to the surface of the wafer film. The incident light can be perpendicular to the surface of the wafer film or obliquely incident on the surface of the wafer film at a certain angle. The reflected light from the wafer surface is received by the photoelectric sensor and converted into an analog electrical signal. After optional processing such as analog-to-digital conversion, filtering, and amplification, a digital electrical signal is obtained.

[0026] The thickness of the wafer film can affect the intensity of the reflected light, and the intensity of the light can affect the value of the digital electrical signal. According to the measurement results at different thicknesses, it can be found that the electrical signal shows a periodic change with the change of thickness.

[0027] Further, as a preferred embodiment, the same device is used to provide a single wavelength beam and a multi-wavelength beam. In this embodiment, a calibration library for the device is obtained, and when the multi-wavelength beam and the calibration library are used for subsequent measurement, the state of the device is consistent with the state during calibration, so that the measurement result is more accurate.

[0028] S2, based on the periodic law of the electrical signal as the wafer film thickness changes and the values ​​of the electrical signals corresponding to multiple different thicknesses, determine the calibration library for measuring the wafer film thickness during the polishing process.

[0029] In one embodiment, the calibration library is a mathematical model. Since the corresponding relationship between the electrical signal and the thickness is known, and the parameters involved are unknown, the complete corresponding relationship model can be obtained by solving the values ​​of the parameters in the relationship.

[0030] As an example, Figure 1 The relationship between the electrical signal and the thickness of the wafer film is a quasi-sinusoidal function relationship, where the horizontal axis is the thickness of the wafer film, and the vertical axis is the voltage (the value of the electrical signal). As the thickness of the wafer film changes (the thickness changes in the direction of the arrow in the figure), the voltage changes between the minimum value Umin and the maximum value Umax, presenting a quasi-sinusoidal curve.

[0031] The corresponding relationship between voltage signal and thickness can be expressed by mathematical model, for example ,in is the value of the electrical signal (voltage value), is the thickness, a is the amplitude of the electrical signal, is the angular frequency. It is related to the wavelength of the light source, the material of the film, and the angle of incidence, and has the following relationship: ; in is the wavelength of incident light, is the refractive index of the wafer film, is the angle of incidence. These parameters are known, so the angular frequency are known parameters.

[0032] In this embodiment, the coefficient and In this embodiment, only two different thicknesses and corresponding electrical signal values ​​are needed to find the values ​​of the two unknown quantities, that is, the corresponding relationship model between the electrical signal and the thickness is determined by using at least two different thicknesses and corresponding electrical signal values.

[0033] When there are only two unknowns in the mathematical expression model, the values ​​of the electrical signals at two thicknesses are collected in step S1, for example: Figure 1 The voltage Ua corresponding to the thickness da, and the voltage Ub corresponding to the thickness db can be used to solve all the parameters in the mathematical expression model of the corresponding relationship between the electrical signal and the wafer film. The values ​​of the electrical signal under more thicknesses can also be collected, and the values ​​of all parameters can be obtained by averaging, etc., thereby determining the corresponding relationship model between the electrical signal and the thickness. If there are more unknown quantities in the mathematical expression model, the corresponding relationship model can also be determined by sampling an appropriate number of thicknesses and electrical signals based on the principle of this embodiment and solving the unknown quantities.

[0034] In some embodiments, the periodic variation of the electrical signal may not be expressed by a mathematical model, or the calibration library calculated based on the mathematical model may not be accurate enough due to measurement environment and other reasons. In this case, two methods can be used to construct the calibration library: The first construction method is to determine the sampling range according to the period of the electrical signal in step S1 when the period of the electrical signal can be determined in advance, and the sampling range is greater than or equal to half a period; the electrical signal corresponding to the single-wavelength reflected light is collected when the thickness of the wafer film is within the sampling range. Figure 2 For example, the period is known to be T. In this embodiment, the size of the sampling range is at least T / 2, as shown in the figure dc-dd≥T / 2. As an example, assuming that the period T=220nm, the size of the sampling range is at least 110nm, and the specific sampling range can be any one or more of [700nm, 590nm], [500nm, 390nm], [450nm, 340nm], etc. When the wafer film thickness enters the sampling range (the thickness changes in the direction of the arrow in the figure), the corresponding electrical signal at each thickness is collected, that is, when the thickness reaches dc, the electrical signal is collected, and the electrical signal corresponding to dc is Uc... until the thickness reaches dd and the electrical signal corresponding to Ud is Ud, and all the data between point c and point d in the figure are obtained. After obtaining at least half a period of electrical signals, based on the periodic law, the corresponding data of any thickness range and electrical signals can be obtained as a calibration library.

[0035] The second construction method is to determine the size of the period based on continuous sampling data when the period of the electrical signal is not determined in advance, and obtain the value of the electrical signal corresponding to the thickness of at least half a period. In step S1, the electrical signal corresponding to the single-wavelength reflected light is collected in real time as the thickness of the wafer film changes; monitor whether at least two extreme values ​​appear in sequence in the collected electrical signal, and the electrical signal between at least two extreme values ​​is an electrical signal of at least half a period.

[0036] by Figure 3 For example, when the initial thickness is de, the corresponding voltage is Ue (the thickness changes according to the arrow in the figure). When the maximum value Umax and the minimum value Umin are detected successively, the difference between the thicknesses df and dg corresponding to these two extreme values ​​is half a cycle T / 2 of the electrical signal; it can also be when two maximum values ​​Umax or two minimum values ​​Umin are detected, the data of the entire cycle is obtained.

[0037] The difference between the two sampling and construction methods is that the first construction method pre-measures or calculates the period of the electrical signal based on parameters such as the wavelength of the light source and the incident angle, and determines the sampling range based on this, so as to accurately collect less data during sampling and quickly complete the establishment of the calibration library; the second construction method measures the period size of the electrical signal in real time during the wafer polishing process, and obtains a calibration library based on the measurement results with higher reliability.

[0038] According to the periodicity of the electrical signal, when at least half a period (the period is the thickness value) of the electrical signal is known, the value of the electrical signal corresponding to any thickness can be obtained. For example, assuming that the period of the electrical signal is 220nm, the electrical signal corresponding to half a period [500nm, 390nm] is currently obtained. According to this thickness range and its corresponding electrical signal value, a calibration library for any thickness range can be established. For example, if the thickness range to be measured is [0, 200nm], then 200nm corresponds to 420nm (420nm in the sampling range minus the period 220nm equals 200nm), and the value of the electrical signal at 200nm is equal to the value of the electrical signal at 420nm. According to this corresponding relationship, the value of the electrical signal corresponding to any thickness range can be obtained.

[0039] It should be noted that in the above example, the size of the thickness range to be measured exceeds half a period, while the size of the sampling range is only half a period. According to the symmetry of the periodic law, the data of the other half period can be inferred based on the sampling range of half a period, or the sampling range can be directly set to the size of one period.

[0040] In some embodiments, it is necessary to clean the surface of the wafer film after the polishing process is completed, mainly to remove the residual liquid on the surface. After cleaning, the thickness of the wafer film needs to be measured again. Specifically, during the polishing process, it is necessary to add polishing liquid to the surface of the wafer and rinse it continuously with water, and there are other transparent media such as glass and PU between the photodetector and the surface of the wafer. This complex environment is called a multilayer film environment in the art, or the wafer film is called a multilayer film state. The above-mentioned calibration library is established in this complex environment, and after cleaning, the water (polishing liquid or grinding liquid and water) on the surface of the wafer is removed, resulting in a change in the environment. The above-mentioned calibration library applicable to the multilayer film environment is no longer applicable to the environment after the water is cleaned, and errors will occur when it is used to measure the film thickness in this state. For this reason, this embodiment also includes the following operations after the above-mentioned step S2: S3, using the conversion coefficient to convert the calibration library into a calibration library suitable for a water-deficient multilayer film environment. Based on the change in the electrical signal with the thickness value to form a corresponding relationship curve, it is found that compared with the corresponding relationship curve between the electrical signal and the thickness in the environment with water on the surface, the corresponding relationship curve between the electrical signal and the thickness in the water-deficient multilayer film environment is compressed or stretched, and the curve is raised or lowered as a whole. In this embodiment, the above-mentioned corresponding relationship is determined as ; in, Represents the electrical signal in the calibration library applicable to the multilayer film environment with water (the electrical signal before conversion), and is the conversion factor, The electrical signal (converted electrical signal) in the calibration library suitable for the water-deficient multilayer membrane environment is shown in this step. and Process the electrical signals in the calibration library.

[0041] Furthermore, the conversion coefficient can be adjusted as follows: and To perform calibration: S01, obtaining the electrical signal corresponding to the light intensity of the reflected light of the single wavelength light beam of two wafer films with different known thicknesses in a water-deficient multilayer film environment and electrical signals The two wafer films having different known thicknesses refer to the fact that the thicknesses of the two wafer films are both known information and they are not equal.

[0042] S02, obtaining the electrical signal corresponding to the light intensity of the reflected light of the single wavelength light beam of the two wafer thin films in the water-deficient multilayer film environment and electrical signals The measurement object is the same as that in step S01, except for the multilayer film environment.

[0043] S03, according to the electrical signal ,electric signal ,electric signal and electrical signals Determine the conversion coefficient. According to the corresponding relationship between the signal in the multilayer film environment with water and the signal in the multilayer film environment without water, the value of the conversion coefficient can be calculated by solving the equation: ; It should be noted that the above steps S01 and S02 can be performed in an experimental environment or in the actual measurement environment of step S1. For example, in step S1, the thickness of the wafer film in the multi-layer film environment is measured using a multi-wavelength beam, step S02 is performed at any two thicknesses, and then the wafer film is placed in a multi-layer film environment lacking water (polishing liquid and water on the surface are cleaned) to perform step S01. By successively providing a multi-layer film environment with water and a multi-layer film environment lacking water at two thicknesses during the polishing process, the conversion coefficient can be calibrated.

[0044] Based on the above calibration library, an embodiment of the present application provides a method for measuring the thickness of a wafer thin film based on a single wavelength beam, which is performed by an electronic device such as a computer or a server, and includes the following operations: During the polishing process of the wafer film, determining the starting thickness of the wafer film when the single-wavelength beam measurement is enabled, and then starting to monitor the electrical signal corresponding to the light intensity of the reflected light of the wafer film to the single-wavelength beam; The thickness of the wafer film is determined by using the calibration library established during the polishing process, the value of the monitored electrical signal, and the starting thickness. Specifically, due to the periodic variation of the electrical signal, when only the value of the electrical signal is obtained, only a periodic thickness value can be obtained, and a unique result (absolute thickness) cannot be obtained. In order to obtain a unique result, the present embodiment needs to determine the absolute thickness value when the method is enabled, which can be the result of multi-wavelength beam measurement.

[0045] If the calibration library is a correspondence model, the monitored electrical signal is substituted into the correspondence model to calculate the corresponding periodic thickness result; the thickness of the wafer film is determined according to the initial thickness and the periodic thickness result.

[0046] For example, the corresponding relationship model is , assuming that the starting thickness when enabling single wavelength beam measurement is t 0 , the value of the electrical signal is U 0 , which is equivalent to determining a starting point in the curve corresponding to this model. After that, the polishing process makes the thickness change in the direction of smaller thickness. Then the electrical signal U obtained at the next moment is 1 Substituting into the model, among the corresponding periodic thicknesses, the closest to but less than t0 The thickness value is the absolute thickness value at this moment. By continuously monitoring in this way, a unique result can be obtained.

[0047] If the calibration library contains the values ​​of electrical signals exceeding one cycle and the corresponding thicknesses, the calibration library is searched for data that matches the monitored electrical signals, and the thickness of the wafer film is inverted in combination with the initial thickness.

[0048] As an example, the calibration library has the following data: Thickness dn, voltage Un; Thickness dn-1, voltage Un-1; … Thickness d0, voltage U0.

[0049] The thicknesses d0 to dn exceed the period t of the electrical signal.

[0050] For example, the period of the electrical signal is 220nm, the calibration library is [280nm, 500nm] and its corresponding electrical signal U 280 ...U 500 , the starting thickness di is 200nm. For this measurement scenario, it can be known that di plus 1 cycle falls into the thickness range of the calibration library, that is, 200nm+220nm=420nm, 420nm falls into [280nm, 500nm]; when the next detected electrical signal is U i+1 When searching for the calibration database with U i+1 The same electrical signal value corresponds to a thickness of 419.9nm, and then subtracting 1 cycle can get the value when the electrical signal is U i+1 The corresponding thickness is 199.9nm. By continuously monitoring in this way, a unique result can be obtained in real time.

[0051] For example, the calibration library is [0nm, 1000nm] and its corresponding electrical signal U 0 ...U 1000 , the initial thickness di is 200nm, when the next detected electrical signal is U i+1 When searching for the calibration database with U i+1 Equal electrical signal value, at this time, the calibration library can be queried to find the same i+1 The same multiple electrical signal values ​​correspond to different thicknesses, among which the thickness of 199.9nm, which is closest to 200nm, is the measurement result at the current moment. By continuously monitoring in this way, a unique result can be obtained in real time.

[0052] If the calibration library contains values ​​of electrical signals less than one cycle and the corresponding thicknesses, it is determined whether there is data in the calibration library that matches the monitored electrical signals.

[0053] When there is data in the calibration library that matches the monitored electrical signal, the corresponding thickness is obtained, and the thickness of the wafer film is inverted based on the starting thickness. This situation is the same as the calibration library situation that exceeds one cycle mentioned above, and the thickness value can be directly obtained.

[0054] When there is no data in the calibration library that matches the monitored electrical signal, one cycle of data is obtained based on less than one cycle of data to obtain data that matches the monitored electrical signal, and the thickness of the wafer film is inverted based on the starting thickness. In this case, the calibration library needs to be supplemented first, that is, a complete cycle of data or a specific range of data is supplemented according to the symmetry of the data, and then the thickness value is obtained in the above manner.

[0055] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0056] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0057] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0058] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0059] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A method for constructing a single-wavelength beam thickness measurement calibration library based on a polishing process, characterized in that: include: During the polishing process of the wafer film, the thickness of the wafer film is measured in situ using a multi-wavelength light beam online, and an electrical signal corresponding to the light intensity of the reflected light of the wafer film to the single-wavelength light beam is obtained at multiple different thicknesses; Based on the periodicity of the electrical signal as the wafer film thickness changes and the values ​​of the electrical signals corresponding to the multiple different thicknesses, a calibration library for measuring the wafer film thickness during the polishing process is determined.

2. The method according to claim 1, characterized in that The relationship between the electrical signal and the thickness of the wafer film is a quasi-sinusoidal function relationship.

3. The method according to claim 1 or 2, characterized in that: Determine a calibration library for measuring wafer film thickness during the polishing process, including: Using at least two different thicknesses and corresponding electrical signal values, a corresponding relationship model between the electrical signal and the thickness is determined.

4. The method according to claim 1 or 2, characterized in that: Obtaining an electrical signal corresponding to the light intensity of the reflected light of the wafer film to the single-wavelength light beam at multiple different thicknesses, including: Determining a sampling range according to a period of the electrical signal, wherein the sampling range is greater than or equal to half of the period; The electrical signal is collected when the thickness of the wafer film is within the sampling range.

5. The method according to claim 1 or 2, characterized in that: Obtaining an electrical signal corresponding to the light intensity of the reflected light of the wafer film to the single-wavelength light beam at multiple different thicknesses, including: collecting the electrical signal in real time as the thickness of the wafer film changes; The collected electrical signal is monitored to determine whether at least two extreme values ​​appear in sequence, and the electrical signal between the at least two extreme values ​​is an electrical signal of at least half a cycle.

6. The method according to claim 1 or 2, characterized in that: After determining the calibration library for measuring the wafer film thickness during the polishing process, the method further includes: The calibration library is converted into a calibration library suitable for a water-deficient multilayer membrane environment using a conversion factor.

7. A method for measuring wafer film thickness based on a single wavelength beam, characterized in that: include: During the polishing process of the wafer film, determining the starting thickness of the wafer film when the single-wavelength beam measurement is enabled, and then starting to monitor the electrical signal corresponding to the light intensity of the reflected light of the single-wavelength beam from the wafer film; The thickness of the wafer film is determined by using a calibration library constructed by the method described in any one of claims 1 to 6, the value of the monitored electrical signal and the starting thickness.

8. The method according to claim 7, characterized in that When the calibration library is a correspondence model between electrical signals and thickness, determining the thickness of the wafer film includes: Substituting the monitored electrical signal into the corresponding relationship model to calculate the corresponding periodic thickness result; The thickness of the wafer film is determined according to the initial thickness and the periodic thickness result.

9. The method according to claim 7, characterized in that: When the calibration library includes values ​​of electrical signals exceeding one cycle and corresponding thicknesses, determining the thickness of the wafer film includes: The calibration library is searched for data that matches the monitored electrical signal, and the thickness of the wafer film is inverted in combination with the initial thickness.

10. The method according to claim 7, characterized in that When the calibration library includes values ​​of electrical signals less than one cycle and corresponding thicknesses, determining the thickness of the wafer film includes: Determining whether there is data in the calibration library that matches the monitored electrical signal; When data matching the monitored electrical signal exists in the calibration library, the corresponding thickness is acquired, and the thickness of the wafer film is inverted according to the starting thickness; When there is no data consistent with the monitored electrical signal in the calibration library, one cycle of data is obtained based on less than one cycle of data to obtain data consistent with the monitored electrical signal, and the thickness of the wafer film is inverted based on the starting thickness.

11. A single wavelength beam thickness measurement calibration library construction device based on the polishing process, characterized in that: include: A processor and a memory connected to the processor; wherein the memory stores instructions executable by the processor, and the instructions are executed by the processor so that the processor executes the method for constructing a single-wavelength beam thickness measurement calibration library based on a polishing process as described in any one of claims 1 to 6.

12. A device for measuring wafer film thickness based on a single wavelength beam, characterized in that: include: A processor and a memory connected to the processor; wherein the memory stores instructions executable by the processor, and the instructions are executed by the processor so that the processor executes the method for measuring wafer thin film thickness based on a single wavelength light beam as described in any one of claims 7 to 10.

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