Wafer film thickness measurement method and equipment

Abstract

The present invention provides a wafer film thickness measurement method and device, the method comprising: obtaining a first film thickness reflectivity library and a second film thickness reflectivity library; using a calibration coefficient to convert the reflectivity value in the first film thickness reflectivity library into an electrical signal value, and using a calibration coefficient to convert the reflectivity value in the second film thickness reflectivity library into an electrical signal value; obtaining an electrical signal corresponding to the light intensity of a first single-wavelength light beam reflected by a wafer film of unknown thickness, and an electrical signal corresponding to the light intensity of a second single-wavelength light beam reflected by the wafer film; using the electrical signal to match the first film thickness electrical signal library to obtain a first thickness set, and using the electrical signal to match the second film thickness electrical signal library to obtain a second thickness set; and obtaining the thickness of the wafer film by obtaining the intersection of the first thickness set and the second thickness set.

Description

Technical Field

[0001] The present invention relates to the field of wafer feature measurement, and in particular to a wafer film thickness measurement method and device. 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] However, when performing EPD endpoint detection on a CMP (Chemical Mechanical Polishing) machine, the characteristic information of the spectral data of the multi-wavelength beam reflected light for small film thickness is not obvious, and the change of the spectrum shape with film thickness is even less obvious than that with large film thickness. Therefore, the measurement method based on multi-wavelength beam is difficult to obtain accurate film thickness information when the film thickness is small.

[0004] However, the defect of the measurement method based on a single-wavelength light beam is that the output electrical signal varies periodically with the film thickness value. Therefore, this method can only obtain the relative measurement value of the film thickness, and it is difficult to measure the absolute value of the film thickness. Summary of the invention

[0005] In view of this, the present application provides a wafer thin film thickness measurement method, comprising:

[0006] Obtain a first film thickness reflectivity library and a second film thickness reflectivity library, wherein the first film thickness reflectivity library is based on wavelength The database of different thickness values ​​and their corresponding reflectivity values ​​is established, and the second film thickness reflectivity database is based on wavelength A database of different thickness values ​​and their corresponding reflectivity values ​​is established, and the reflectivity value changes periodically with the thickness value;

[0007] Using calibration factors The reflectivity value in the first film thickness reflectivity library is converted into an electrical signal value, and the calibration coefficient is used Converting the reflectivity values ​​in the second film thickness reflectivity library into electrical signal values ​​to obtain a first film thickness electrical signal library and a second film thickness electrical signal library;

[0008] Obtaining an electrical signal corresponding to the light intensity of the first single wavelength light beam reflected by a wafer film of unknown thickness , and an electrical signal corresponding to the light intensity of the reflected light of the second single wavelength light beam , wherein the wavelengths of the first single-wavelength light beam and the second single-wavelength light beam are different, and are wavelengths and wavelength ;

[0009] Using the electrical signal The first thickness set is obtained by matching in the first film thickness electrical signal library , using the electrical signal The second thickness set is obtained by matching in the second film thickness electrical signal library ;

[0010] By finding the first thickness set With the second thickness set The intersection of .

[0011] The present application also provides another wafer film thickness measurement method, comprising:

[0012] Obtaining an electrical signal corresponding to the light intensity of the first single wavelength light beam reflected by a wafer film of unknown thickness , and an electrical signal corresponding to the light intensity of the reflected light of the second single wavelength light beam , wherein the wavelengths of the first single-wavelength light beam and the second single-wavelength light beam are different, and are wavelengths and wavelength ;

[0013] According to the electrical signal and calibration coefficient Calculate the reflectivity of the wafer film to the first single wavelength light beam According to the electrical signal and calibration coefficient Calculate the reflectivity of the wafer film to the second single wavelength light beam ;

[0014] Using the reflectivity The first thickness set is obtained by matching the first film thickness reflectivity library established in advance. , using the reflectivity The second thickness set is obtained by matching the pre-established second film thickness reflectivity library. , wherein the first film thickness reflectivity library is based on wavelength The database of different thickness values ​​and their corresponding reflectivity values ​​is established, and the second film thickness reflectivity database is based on wavelength A database of different thickness values ​​and their corresponding reflectivity values ​​is established, and the reflectivity value changes periodically with the thickness value;

[0015] By finding the first thickness set With the second thickness set The intersection of .

[0016] Optionally, the method further comprises determining the calibration coefficient by the following method: and calibration coefficient :

[0017] Calculate known thickness The reflectivity of the wafer film to the first single wavelength beam , get the known thickness The electrical signal corresponding to the light intensity of the reflected light of the first single wavelength light beam from the wafer thin film , according to the reflectivity and electrical signals Calculate the calibration coefficient , where the electrical signal is collected The position relationship between the wafer film and the acquisition device and the collected electrical signal The positional relationship between the wafer film and the collection device is consistent;

[0018] Calculate known thickness The reflectivity of the wafer film to the second single wavelength beam , get the known thickness The electrical signal corresponding to the light intensity of the reflected light of the second single wavelength light beam from the wafer thin film , according to the reflectivity and electrical signals Calculate the calibration coefficient , where the electrical signal is collected The position relationship between the wafer film and the acquisition device and the collected electrical signal At this time, the positional relationship between the wafer film and the collection device is consistent.

[0019] Optionally, the electrical signal is a voltage signal. , .

[0020] Optionally, the method further comprises determining the calibration coefficient by the following method: and calibration coefficient :

[0021] Obtain an electrical signal corresponding to the light intensity of the first single-wavelength light beam reflected by the total reflection mirror , and an electrical signal corresponding to the light intensity of the reflected light of the second single wavelength light beam ,get , , where the electrical signal is collected The position relationship between the total reflection mirror and the collection device and the collected electrical signal At this time, the positional relationship between the wafer film and the collection device is consistent.

[0022] Optionally, the corresponding relationship between the reflectivity value and the thickness value is

[0023] ;

[0024] in represents the reflectivity value, t represents the thickness value, , a and b are constants.

[0025] Optionally, the corresponding relationship between the electrical signal value and the thickness value is:

[0026] ;

[0027] in represents the electrical signal value, t represents the thickness value, represents the calibration coefficient, , a and b are constants.

[0028] Optionally, the electrical signal and electrical signals is the electrical signal collected when the wafer film of unknown thickness is in a multi-layer film environment;

[0029] The method further comprises:

[0030] Obtaining an electrical signal corresponding to the light intensity of the reflected light of the first single wavelength light beam from two wafer films of known different thicknesses and electrical signals , and an electrical signal corresponding to the light intensity of the reflected light of the second single wavelength light beam and electrical signals ;

[0031] Obtaining an electrical signal corresponding to the light intensity of the reflected light of the first single wavelength light beam by the two wafer thin films in a multilayer film environment and electrical signals , and an electrical signal corresponding to the light intensity of the reflected light of the second single-wavelength light beam and electrical signals ;

[0032] According to the electrical signal ,electric signal ,electric signal and electrical signals Determine a first conversion coefficient, and ,electric signal ,electric signal and electrical signals determining a second conversion coefficient;

[0033] The first film thickness reflectivity library is converted into a database suitable for a multi-layer film environment using the first conversion coefficient, and the second film thickness reflectivity library is converted into a database suitable for a multi-layer film environment using the second conversion coefficient.

[0034] Optionally, the first conversion coefficient is determined in the following manner:

[0035] ;

[0036] in and is the first conversion coefficient;

[0037] The second conversion coefficient is determined in the following manner:

[0038] ;

[0039] in and is the second conversion coefficient.

[0040] Optionally, the reflectivity in the first film thickness reflectivity library is converted as follows:

[0041] ;

[0042] in represents the reflectivity before conversion, It represents the converted reflectivity suitable for multilayer film environment;

[0043] The reflectivity in the second film thickness reflectivity library is converted as follows:

[0044]

[0045] in represents the reflectivity before conversion, Represents the converted reflectivity suitable for multilayer film environment.

[0046] Accordingly, the present application provides a wafer thin film thickness measurement device 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 wafer thin film thickness measurement method.

[0047] According to the wafer thin film thickness measurement method and equipment provided by the present application, two light beams with different wavelengths are used to measure the film thickness, and the electrical signals corresponding to the two light beams are matched with a pre-established film thickness electrical signal library to obtain two corresponding thickness sets. Then, a unique thickness value is obtained by finding the intersection, which overcomes the multiple solution problem caused by the periodic changes in the measurement results of the single-wavelength light beam method, so that the absolute value of the film thickness can be determined. This scheme has a small amount of calculation during measurement, a fast response speed and high accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] 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.

[0049] Figure 1 This is a flow chart of a wafer thin film thickness measurement method in an embodiment of the present application;

[0050] Figure 2 It is a schematic diagram of the double-beam voltage and thickness curve and the intersection of thickness in the embodiment of the present application;

[0051] Figure 3 This is a flow chart of another wafer film thickness measurement method in an embodiment of the present application. DETAILED DESCRIPTION

[0052] 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.

[0053] In the description of the present invention, it should be noted that the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. 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.

[0054] like Figure 1 As shown, an embodiment of the present invention provides a method for measuring wafer film thickness, which is performed by an electronic device such as a computer or a server, and includes the following operations:

[0055] S1A, obtaining a first film thickness reflectivity library and a second film thickness reflectivity library, wherein the first film thickness reflectivity library is based on wavelength The database of different thickness values ​​and their corresponding reflectivity values ​​is established. The second film thickness reflectivity database is based on wavelength A database of different thickness values ​​and their corresponding reflectivity values ​​is established, and the reflectivity value shows a periodic change with the change of the thickness value.

[0056] The film thickness reflectivity library can be generated based on a mathematical model, and the corresponding reflectivity can be calculated by giving the film thickness.

[0057] In this embodiment, the first film thickness reflectivity library and the second film thickness reflectivity library are generated using the same mathematical model, and the difference is only in the wavelength value, which are wavelength and wavelength , where the reflectivity shows a periodic change with the thickness, and the period is different due to the different wavelengths.

[0058] Furthermore, according to the principle of thin film optics, in an air environment, there is the following relationship between the film thickness and reflectivity of the wafer:

[0059] ;

[0060] Where R represents reflectivity, A, B and are coefficients related to the refractive index of the wafer surface material and can be obtained by substituting relevant parameters. . n1 represents the refractive index, h represents the thickness of the wafer film, is the wavelength of incident light, Represents the refraction angle between the incident light and the surface of the optical film.

[0061] From the above relationship, it can be seen that in a single-layer film environment, the film thickness reflectivity curve changes in a sine and cosine law, and its relationship can be simplified as follows:

[0062] ;

[0063] in represents reflectivity, t represents thickness, , a and b are constants.

[0064] S2A, using calibration coefficients to convert the film thickness reflectivity library into a film thickness electrical signal library. Specifically, the calibration coefficients are used to convert the film thickness reflectivity library into a film thickness electrical signal library. Convert the reflectivity value in the first film thickness reflectivity library into an electrical signal value and use the calibration coefficient The reflectivity values ​​in the second film thickness reflectivity library are converted into electrical signal values ​​to obtain the first film thickness electrical signal library and the second film thickness electrical signal library.

[0065] The function of the calibration coefficient is to establish the connection between the electrical signal measured by a single wavelength beam and the reflectivity of the wafer film. The calibration coefficient is at least the value determined before step S2A. Without changing the measurement environment and the wafer material, the calibration coefficient remains unchanged at different thicknesses. For example, assuming that the voltage value measured at one thickness is 1.8v, and the reflectivity can be determined to be 0.6, the calibration coefficient is the ratio of the voltage value to the reflectivity, that is, the calibration coefficient k=1.8 / 0.6=3; without changing other conditions and only changing the film thickness, for example, the voltage value measured at another thickness is 1.5v, and the reflectivity can be determined to be 0.5, the calibration coefficient k is still 3.

[0066] Furthermore, the corresponding relationship between the electrical signal value and the thickness value in the film thickness electrical signal library is:

[0067] ;

[0068] in represents the electrical signal value, t represents the thickness value, represents the calibration coefficient, , a and b are constants.

[0069] S3A, obtaining an electrical signal corresponding to the reflected light of the wafer film of unknown thickness. Specifically, it includes obtaining an electrical signal corresponding to the light intensity of the reflected light of the first single wavelength light beam by the wafer film. , and the electrical signal corresponding to the light intensity of the reflected light of the second single wavelength light beam by the wafer film , where the wavelengths of the first single-wavelength light beam and the second single-wavelength light beam are different, and are wavelengths and wavelength This step uses a single-wavelength beam measurement method to irradiate the wafer film surface with two wavelengths of light beams, and obtains a corresponding electrical signal, usually a voltage signal, through photoelectric conversion based on the intensity of the reflected light on the wafer surface.

[0070] S4A, using the electrical signals of the dual beams to match the corresponding film thickness electrical signal library to obtain two thickness sets. The first thickness set is obtained by matching in the first film thickness electrical signal library , using electrical signals The second thickness set is obtained by matching in the second film thickness electrical signal library After conversion, the electrical signals in the first film thickness electrical signal library and the second film thickness electrical signal library show periodic changes with the change of thickness. Therefore, the electrical signals in the first film thickness electrical signal library Corresponding to multiple thickness values, the same electrical signal It also corresponds to multiple thickness values, and the set of these thickness values ​​is the first thickness set and the second thickness set .

[0071] S5A, by finding the first thickness set With the second thickness set The intersection of In addition, it should be noted that in order to ensure that the intersection has only one thickness value, the wavelength used is With wavelength The ratio should be within a certain range. If the two wavelengths are too close, it is difficult to distinguish the difference in the measurement results (the same thickness set); if the two wavelengths differ too much, multiple thickness values ​​may appear in the intersection of the two thickness sets, and it is still difficult to get a unique measurement result. The wavelength of the second incident beam The ratio range is preferably 1.2~1.5, that is or .

[0072] like Figure 2 As shown, the curve corresponding to the wavelength is and wavelength is The film thickness electrical signal library, the horizontal axis d / nm is the wafer film thickness, and the vertical axis U / v is the electrical signal. For example, the electrical signal based on the first single wavelength beam measurement By matching with the first film thickness electrical signal library, a thickness set d11…d1N can be obtained; based on the electrical signal measured by the second single wavelength beam By matching with the second film thickness electrical signal library, the thickness set d21...d2N can be obtained. By finding the intersection, it can be found that the intersection of the two thickness sets has only one thickness value, such as Figure 2 The d12=d22 shown is the film thickness measurement result.

[0073] like Figure 3 As shown, an embodiment of the present invention provides a wafer film thickness measurement method, which is executed by an electronic device such as a computer or a server. Figure 1 The difference between the illustrated embodiment is that the present embodiment uses a calibration coefficient to convert the electrical signal measured by a single wavelength light beam into a reflectivity, and still uses a film thickness reflectivity library to match the thickness. The present embodiment includes the following operations:

[0074] S1B, obtaining an electrical signal corresponding to the reflected light of a wafer film of unknown thickness. Specifically, it includes obtaining an electrical signal corresponding to the light intensity of the reflected light of the first single wavelength light beam by the wafer film of unknown thickness. , and an electrical signal corresponding to the light intensity of the reflected light of the second single wavelength light beam , where the wavelengths of the first single-wavelength light beam and the second single-wavelength light beam are different, and are wavelengths and wavelength ;

[0075] S2B, calculates the reflectivity based on the electrical signal and the calibration coefficient. and calibration coefficient Calculate the reflectivity of the wafer film to the first single wavelength beam According to the electrical signal and calibration coefficient Calculate the reflectivity of the wafer film to the second single wavelength beam ;

[0076] S3B, using the reflectivity of the dual beams to match the corresponding film thickness reflectivity library to obtain two thickness sets. The first thickness set is obtained by matching the first film thickness reflectivity library established in advance. , using reflectivity The second thickness set is obtained by matching the pre-established second film thickness reflectivity library. , where the first film thickness reflectivity library is based on wavelength The database of different thickness values ​​and their corresponding reflectivity values ​​is established. The second film thickness reflectivity database is based on wavelength A database of different thickness values ​​and their corresponding reflectivity values ​​is established, and the reflectivity value changes periodically with the thickness value;

[0077] S4B, by finding the first thickness set With the second thickness set The intersection of .

[0078] Regarding the above calibration coefficients, in one embodiment, the calibration coefficients are determined based on a wafer film of known thickness. and calibration coefficient , including the following operations:

[0079] Calculate known thickness The reflectivity of the wafer film to the first single wavelength beam , get the known thickness The electrical signal corresponding to the light intensity of the reflected light of the first single wavelength light beam from the wafer thin film , according to the reflectivity and electrical signals Calculate the calibration factor ,in The measurement environment used to determine the calibration coefficient should be consistent with the actual measurement environment, especially when collecting electrical signals. The position relationship between the wafer film and the acquisition device and the collected electrical signal The positional relationship between the wafer film and the collection device is consistent;

[0080] Calculate known thickness The reflectivity of the wafer film to the second single wavelength beam , get the known thickness The electrical signal corresponding to the light intensity of the reflected light of the second single wavelength light beam from the wafer thin film , according to the reflectivity and electrical signals Calculate the calibration factor ,in . Collect electrical signals The position relationship between the wafer film and the acquisition device and the collected electrical signal At this time, the positional relationship between the wafer film and the collection device is consistent.

[0081] Regarding the above calibration coefficients, in another embodiment, the calibration coefficients are determined based on the total reflection mirror surface. and calibration coefficient , including the following operations:

[0082] Obtain an electrical signal corresponding to the light intensity of the first single-wavelength light beam reflected by the total reflection mirror , and an electrical signal corresponding to the light intensity of the reflected light of the second single wavelength light beam ,get , , where the electrical signal is collected The position relationship between the total reflection mirror and the collection device and the collected electrical signal At this time, the positional relationship between the wafer film and the collection device is consistent.

[0083] Referring to the principle of the previous embodiment ,in Indicates electrical signal, represents the reflectivity, k represents the calibration coefficient. Since the reflectivity of the total reflection mirror in this embodiment is 100%, ,Right now , .

[0084] The above measurement scheme is applicable to a single-layer film environment, and the medium between the wafer film and the collection device of the single-wavelength light beam is air. In some processing scenarios, there are liquids such as water and polishing fluid on the surface of the wafer film, or there are other media such as glass between the probe of the collection device and the surface of the wafer. This measurement environment is called a multi-layer film environment in this field. At this time, the original film thickness reflectivity curve is compressed or stretched, and the overall curve is raised or lowered. Therefore, the original film thickness reflectivity library is no longer applicable, and it is necessary to build a film thickness reflectivity library suitable for a multi-layer film environment.

[0085] Through experiments, it was found that for wafers with the same film thickness, the reflectivity under a single-layer film environment and reflectivity in multilayer environments There are the following relationships:

[0086]

[0087] Determine the coefficients and The original film thickness reflectivity library can be converted into a film thickness reflectivity library suitable for a multi-layer film environment.

[0088] In view of this, in one embodiment, the above method further includes the following operations:

[0089] S01, obtaining an electrical signal corresponding to the light intensity of the reflected light of the first single wavelength light beam from two wafer films of known different thicknesses and electrical signals , and an electrical signal corresponding to the light intensity of the reflected light of the second single wavelength light beam and electrical signals In this step It is an electrical signal collected from a wafer film in a single-layer film environment. The two wafer films with different known thicknesses refer to the fact that the thicknesses of the two wafer films are known information and they are not equal.

[0090] S02, obtaining an electrical signal corresponding to the light intensity of the reflected light of the first single wavelength light beam by the two wafer thin films in the multilayer film environment and electrical signals , and an electrical signal corresponding to the light intensity of the reflected light of the second single wavelength light beam and electrical signals The measurement object is the same as that in step S01, except that It is the electrical signal collected from the wafer film in a multi-layer film environment. The multi-layer film environment is determined according to the actual measurement environment. It can be by adding water or polishing liquid to the surface of the wafer film, or by installing glass or other transparent media between the probe of the collection device and the surface of the wafer film.

[0091] S03, according to the electrical signal ,electric signal ,electric signal and electrical signals Determine a first conversion coefficient, and according to the electrical signal ,electric signal ,electric signal and electrical signals determining a second conversion coefficient;

[0092] S04, using the first conversion coefficient to convert the first film thickness reflectivity library into a database suitable for a multilayer film environment, and using the second conversion coefficient to convert the second film thickness reflectivity library into a database suitable for a multilayer film environment.

[0093] Furthermore, in step S03, the first conversion coefficient may be determined in the following manner:

[0094] ;

[0095] in and is the first conversion coefficient. Then, in step S04, the reflectivity in the first film thickness reflectivity library is converted as follows:

[0096] ;

[0097] in represents the reflectivity before conversion, Represents the converted reflectivity suitable for multilayer film environment.

[0098] Similarly, in step S03, the second conversion coefficient may be determined in the following manner:

[0099] ;

[0100] in and is the second conversion coefficient. Then, in step S04, the reflectivity in the second film thickness reflectivity library is converted as follows:

[0101] ;

[0102] in represents the reflectivity before conversion, Represents the converted reflectivity suitable for multilayer film environment.

[0103] It should be understood by those skilled in the art that the 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. Moreover, 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, CDROM, optical storage, etc.) containing computer-usable program code.

[0104] 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.

[0105] 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.

[0106] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0107] 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 measuring wafer film thickness, characterized in that: include: Obtain a first film thickness reflectivity library and a second film thickness reflectivity library, wherein the first film thickness reflectivity library is based on wavelength The database of different thickness values ​​and their corresponding reflectivity values ​​is established, and the second film thickness reflectivity database is based on wavelength A database of different thickness values ​​and their corresponding reflectivity values ​​is established, and the reflectivity value changes periodically with the thickness value; Using calibration factors The reflectivity value in the first film thickness reflectivity library is converted into an electrical signal value, and the calibration coefficient is used Converting the reflectivity values ​​in the second film thickness reflectivity library into electrical signal values ​​to obtain a first film thickness electrical signal library and a second film thickness electrical signal library; Obtaining an electrical signal corresponding to the light intensity of the first single wavelength light beam reflected by a wafer film of unknown thickness , and an electrical signal corresponding to the light intensity of the reflected light of the second single wavelength light beam , wherein the wavelengths of the first single-wavelength light beam and the second single-wavelength light beam are different, and are wavelengths and wavelength ; Using the electrical signal The first thickness set is obtained by matching in the first film thickness electrical signal library , using the electrical signal The second thickness set is obtained by matching in the second film thickness electrical signal library ; By finding the first thickness set With the second thickness set The intersection of .

2. A wafer film thickness measurement method, characterized in that: include: Obtaining an electrical signal corresponding to the light intensity of the first single wavelength light beam reflected by a wafer film of unknown thickness , and an electrical signal corresponding to the light intensity of the reflected light of the second single wavelength light beam , wherein the wavelengths of the first single-wavelength light beam and the second single-wavelength light beam are different, and are wavelengths and wavelength ; According to the electrical signal and calibration coefficient Calculate the reflectivity of the wafer film to the first single wavelength light beam According to the electrical signal and calibration coefficient Calculate the reflectivity of the wafer film to the second single wavelength light beam ; Using the reflectivity The first thickness set is obtained by matching the first film thickness reflectivity library established in advance. , using the reflectivity The second thickness set is obtained by matching the pre-established second film thickness reflectivity library. , wherein the first film thickness reflectivity library is based on wavelength The database of different thickness values ​​and their corresponding reflectivity values ​​is established, and the second film thickness reflectivity database is based on wavelength A database of different thickness values ​​and their corresponding reflectivity values ​​is established, and the reflectivity value changes periodically with the thickness value; By finding the first thickness set With the second thickness set The intersection of .

3. The method according to claim 1 or 2, characterized in that: It also includes determining the calibration coefficient using the following method and calibration coefficient : Calculate known thickness The reflectivity of the wafer film to the first single wavelength beam , get the known thickness The electrical signal corresponding to the light intensity of the reflected light of the first single wavelength light beam from the wafer thin film , according to the reflectivity and electrical signals Calculate the calibration coefficient , where the electrical signal is collected The position relationship between the wafer film and the acquisition device and the collected electrical signal The positional relationship between the wafer film and the collection device is consistent; Calculate known thickness The reflectivity of the wafer film to the second single wavelength beam , get the known thickness The electrical signal corresponding to the light intensity of the reflected light of the second single wavelength light beam from the wafer thin film , according to the reflectivity and electrical signals Calculate the calibration coefficient , where the electrical signal is collected The position relationship between the wafer film and the acquisition device and the collected electrical signal At this time, the positional relationship between the wafer film and the collection device is consistent.

4. The method according to claim 3, characterized in that The electrical signal is a voltage signal, , .

5. The method according to claim 1 or 2, characterized in that: It also includes determining the calibration coefficient using the following method and calibration coefficient : Obtain an electrical signal corresponding to the light intensity of the first single-wavelength light beam reflected by the total reflection mirror , and an electrical signal corresponding to the light intensity of the reflected light of the second single wavelength light beam ,get , , where the electrical signal is collected The position relationship between the total reflection mirror and the collection device and the collected electrical signal At this time, the positional relationship between the wafer film and the collection device is consistent.

6. The method according to claim 1 or 2, characterized in that: The corresponding relationship between reflectivity value and thickness value is: ; in represents the reflectivity value, t represents the thickness value, , a and b are constants.

7. The method according to claim 1 or 2, characterized in that: The corresponding relationship between the electrical signal value and the thickness value is: ; in represents the electrical signal value, t represents the thickness value, represents the calibration coefficient, , a and b are constants.

8. The method according to claim 1 or 2, characterized in that: electric signal and electrical signals is the electrical signal collected when the wafer film of unknown thickness is in a multi-layer film environment; The method further comprises: Obtaining an electrical signal corresponding to the light intensity of the reflected light of the first single wavelength light beam from two wafer films of known different thicknesses and electrical signals , and an electrical signal corresponding to the light intensity of the reflected light of the second single wavelength light beam and electrical signals ; Obtaining an electrical signal corresponding to the light intensity of the reflected light of the first single wavelength light beam by the two wafer thin films in a multilayer film environment and electrical signals , and an electrical signal corresponding to the light intensity of the reflected light of the second single-wavelength light beam and electrical signals ; According to the electrical signal ,electric signal ,electric signal and electrical signals Determine a first conversion coefficient, and according to the electrical signal ,electric signal ,electric signal and electrical signals determining a second conversion coefficient; The first film thickness reflectivity library is converted into a database suitable for a multi-layer film environment using the first conversion coefficient, and the second film thickness reflectivity library is converted into a database suitable for a multi-layer film environment using the second conversion coefficient.

9. The method according to claim 8, characterized in that The first conversion coefficient is determined in the following manner: ; in and is the first conversion coefficient; The second conversion coefficient is determined in the following manner: ; in and is the second conversion coefficient.

10. The method according to claim 9, characterized in that The reflectivity in the first film thickness reflectivity library is converted as follows: ; in represents the reflectivity before conversion, It represents the converted reflectivity suitable for multilayer film environment; The reflectivity in the second film thickness reflectivity library is converted as follows: ; in represents the reflectivity before conversion, Represents the converted reflectivity suitable for multilayer film environment.

11. A wafer film thickness measurement device based on a single wavelength light 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 wafer thin film thickness measurement method as described in any one of claims 1-10.

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