Single-wavelength light beam thickness measurement reference database establishment method, measurement method and equipment

Abstract

The invention provides a single-wavelength light beam thickness measurement reference database establishment method, a measurement method and equipment, and the method comprises the steps: obtaining the reflectivity of a wafer film under different thicknesses, the thickness being a given value, the corresponding reflectivity being a value calculated through a mathematical model, and the thickness being the given value; the reflectivity is the reflectivity of the wafer film to light with a specific wavelength, and the reflectivity is periodically changed along with the change of the thickness; determining the trend information of the reflectivity changing along with the thickness; and according to the different thicknesses, the corresponding reflectivity and the trend information, establishing a reference database for measuring the thickness of the wafer film by the single-wavelength light beam.

Description

Technical Field

[0001] The present invention relates to the field of wafer feature measurement, and in particular to a single-wavelength beam thickness measurement reference database establishment method, a measurement method and a 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 thin films: the first method is to invert the film thickness through the different spectral characteristic information of multiple wavelengths in the spectrometer under different film thicknesses, which is referred to as the multi-wavelength beam measurement method; the second method is to judge the relative thickness of the wafer thin film by converting the light intensity signal of the received reflected light into an electrical signal under a single wavelength light source, which is referred to as the single-wavelength beam measurement method.

[0003] However, when performing EPD endpoint detection on a CMP (Chemical Mechanical Polishing) machine, it is difficult to obtain accurate film thickness information using the multi-wavelength beam measurement method when the film thickness is small, because there is no peak characteristic information in the wide spectrum wavelength range, and the change in the spectrum shape with film thickness is less obvious than that with large film thickness.

[0004] The defect of the single-wavelength beam method is that, since the output electrical signal varies periodically with the film thickness value, this method can only obtain the relative measurement value of the film thickness, and cannot obtain the absolute value of the film thickness. Summary of the invention

[0005] In view of this, the present application provides a method for establishing a single wavelength beam thickness measurement reference database, comprising: Obtaining the reflectivity of the wafer film at different thicknesses, wherein the thickness is a given value, and the corresponding reflectivity is a value calculated by a mathematical model, wherein the reflectivity is the reflectivity of the wafer film to light of a specific wavelength, and the reflectivity changes periodically with the change of thickness; Determining trend information of the reflectivity changing with thickness; A reference database for measuring wafer thin film thickness using a single wavelength beam is established based on the different thicknesses and corresponding reflectivities and the trend information.

[0006] Optionally, each piece of data in the reference database includes thickness, reflectivity and trend information of reflectivity, and the trend information is used to indicate a change trend of the reflectivity value in one piece of data compared with the reflectivity value in another adjacent piece of data with a larger thickness.

[0007] Optionally, there are two different thicknesses in the reference database corresponding to the same reflectivity and different trend information.

[0008] Optionally, the number of the reference databases is one or two, and the same reference database has unique trend information, which is used to indicate the change trend of the reflectivity value in each data in the reference database compared with the reflectivity in another adjacent data with a larger thickness.

[0009] Optionally, when there are two reference databases, the two reference databases have different trend information, and different thicknesses in the two reference databases correspond to the same reflectivity.

[0010] Optionally, determining the trend information of the reflectivity changing with thickness includes: Starting from the reflectivity corresponding to the maximum thickness within the specific thickness range, the reflectivity corresponding to the next smaller thickness is compared with the reflectivity corresponding to the previous larger thickness one by one; When the reflectivity corresponding to the smaller thickness is greater than the reflectivity corresponding to the larger thickness, it is determined that the trend of the reflectivity corresponding to the smaller thickness is increasing; When the reflectivity corresponding to the smaller thickness is smaller than the reflectivity corresponding to the larger thickness, it is determined that the trend of the reflectivity corresponding to the smaller thickness is decreasing.

[0011] Optionally, after obtaining the reference database, the method further includes: The reference database is converted into a reference database suitable for a multilayer film environment using a conversion factor.

[0012] The present application also provides a thickness measurement method for a wafer thin film polishing process, comprising: In the process of polishing the wafer film, an electrical signal corresponding to the light intensity of the reflected light of the wafer film to the single wavelength light beam is obtained. , while determining the electrical signal Trend information with thickness variation; According to the electrical signal and calibration coefficient Calculate the reflectivity of the wafer film to a single wavelength beam , the reflectivity shows a periodic change as the thickness changes; According to the thickness of the previous moment , the reflectivity The trend information is matched with the thickness at the current moment in the pre-established reference database. The reference database includes reflectivity corresponding to different thicknesses and trend information of reflectivity changing with thickness.

[0013] Optionally, before calculating the reflectivity, the method further includes: For known thickness The wafer film collects the electrical signal corresponding to the light intensity of the reflected light of the single wavelength beam ; According to thickness Calculate the reflectivity of the wafer film to the single wavelength reflected light ; According to the reflectivity and electrical signals Calculate the calibration coefficient .

[0014] Optionally, the electrical signal is a voltage signal, and the calibration coefficient The reflectivity .

[0015] Optionally, determining the electrical signal Trend information over thickness, including: Compare the electrical signals collected at the current moment The electrical signal collected at the previous moment , wherein the wafer film thickness at the current moment is less than the wafer film thickness at the previous moment; The trend information is obtained according to the comparison result, wherein if The trend information indicates a decrease. The trend information indicates an increase.

[0016] Optionally, get the thickness at the current moment ,include: Determining in the reference database that the thickness Data of a cycle including; According to the reflectivity Two sets of data are obtained by matching the data in the one cycle; according to The trend information of the two sets of data determines a set of data to obtain the thickness .

[0017] Accordingly, the present application provides a single-wavelength beam thickness measurement reference database establishment device, 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 single-wavelength beam thickness measurement reference database establishment method.

[0018] Accordingly, the present application provides a thickness measurement device for a wafer thin film 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 thickness measurement method for a wafer thin film polishing process.

[0019] The method and device for establishing a single-wavelength beam thickness measurement reference database provided in the present application analyze the known wafer film thickness and the corresponding reflectivity to determine the trend information of the reflectivity changing with the thickness, and establish a reference database for single-wavelength beam measurement of wafer film thickness based on different thicknesses and the corresponding reflectivity and trend information, wherein the trend information is consistent with the trend of the electrical signal measured by the single-wavelength beam. According to the reference database, during the single-wavelength beam measurement process, the two types of information, the measured electrical signal and its trend, can be used to match a unique thickness value in any thickness period in the reference database, thereby enabling the single-wavelength beam measurement method to measure the absolute thickness of the wafer film.

[0020] The thickness measurement method and device for the wafer film polishing process provided in the present application analyze the electrical signal measured by a single-wavelength light beam, determine the trend information of the electrical signal as the wafer film thickness changes during the polishing process, and calculate the reflectivity based on a predetermined calibration coefficient. In a pre-established reference database, the thickness information at the previous moment and the two types of information, namely, the reflectivity and the trend of the electrical signal, can be combined to match a unique thickness value in the reference database, thereby enabling the single-wavelength light beam measurement method to measure the absolute thickness of the wafer film during the polishing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] 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.

[0022] Figure 1 A flowchart of a method for establishing a single wavelength beam thickness measurement reference database in an embodiment of the present application; Figure 2 A schematic diagram of reflectivity and thickness data in an embodiment of the present application; Figure 3 This is a flow chart of a single wavelength light beam measurement method in an embodiment of the present application. DETAILED DESCRIPTION

[0023] 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.

[0024] 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.

[0025] The embodiment of the present invention provides a method for establishing a single wavelength beam thickness measurement reference database. Before implementing the single wavelength beam measurement, the method can obtain a database for measuring the absolute thickness of a wafer thin film using a single wavelength beam, namely, the reference database, by calculation by an electronic device such as a computer or a server. Figure 1 The method shown includes the following operations: S1A, obtain the reflectivity of the wafer film at different thicknesses. The wafer film can specifically be a silicon dioxide layer on the surface of a wafer with silicon as the substrate. The reflectivity in this scheme refers to the reflectivity of the wafer film to light of a specific wavelength, and the specific wavelength is the wavelength of light used in the single-wavelength beam measurement method. The thickness and the corresponding reflectivity can be data calculated by a theoretical spectral model. The user can give a thickness value according to the measurement requirements and use the theoretical spectral model to calculate the corresponding reflectivity.

[0026] According to theoretical calculation results, the reflectivity changes periodically with the thickness, and the relationship between the two is a periodic function relationship.

[0027] According to the principles of thin film optics, in an air environment, there is the following relationship between the film thickness and reflectivity of the wafer: ; 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.

[0028] 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: ; in represents reflectivity, d represents thickness, , A and B are constants.

[0029] like Figure 2 As shown, in one embodiment, the corresponding relationship between the reflectivity R and the thickness d is a quasi-sinusoidal function relationship. It is known that the period of the reflectivity R is T=220nm. The user pre-uses a single-wavelength light beam to measure the absolute thickness near the end point of CMP (the end point thickness of this embodiment is 0), and the thickness range is at least half a period, for example, it can be 0~200nm, 0~1000nm, etc., any range exceeding 110nm.

[0030] As an example, the corresponding reflectivities R0~R200 are calculated for all thickness values ​​in the range of 0~200nm, where the reflectivities of data point a and data point b are both Ri. Since the reflectivity varies periodically and different thicknesses within a period may correspond to the same reflectivity, it is impossible to obtain a unique thickness value when only the reflectivity can be measured or calculated.

[0031] S2A, determining the trend information of the reflectivity changing with the thickness, wherein the trend is specifically an increase or a decrease. Figure 2 For example, the thickness da of data point a is greater than the thickness db of data point b. If the thickness of the object to be measured in the application scenario changes from right to left, the reflectivity Ri of point a tends to decrease, while the reflectivity Ri of data point b tends to increase. In view of this phenomenon, the reflectivity corresponding to the current thickness can be compared with the reflectivity corresponding to the previous given larger thickness to determine the trend information of the reflectivity corresponding to the current thickness.

[0032] S3A, a reference database for measuring wafer film thickness using a single wavelength beam is established based on different thicknesses and corresponding reflectance and trend information. As a first implementation, each piece of data in the reference database includes thickness, reflectance, and reflectance trend information, and the trend information is used to indicate the change trend of the reflectance value in one piece of data compared to the reflectance value in another piece of data with a larger adjacent thickness. For example, the reference database includes the following multiple pieces of data: Thickness dn, reflectivity Rn, increases; Thickness dn-1, reflectivity Rn-1, increases; … Thickness dn-i, reflectivity Rn-i, decreases; The thickness d0, reflectivity R0, decreases.

[0033] In the reference database, there are two different thicknesses in any thickness cycle that correspond to the same reflectivity and different trend information. For example, the reflectivity Rn-1 of thickness dn-1 is equal to the reflectivity Rn-i of thickness dn-i, but the trend information of the two data is different. When this reference database is used to measure thickness with a single wavelength beam, after determining the cycle of the current thickness and measuring the reflectivity value, the only data can be matched in the database in combination with the change trend information of the reflectivity to obtain the corresponding thickness value.

[0034] As a second implementation method, reference databases can be established separately according to trend information. For example, one reference database contains all reflectivity and thickness with an increasing trend, and another reference database contains all reflectivity and thickness with a decreasing trend. The same reference database has unique trend information, and the trend information is used to indicate the changing trend of the reflectivity value in each data in the reference database compared to the reflectivity in another adjacent data with a larger thickness.

[0035] For example, the trend information of the first reference database is increasing, which includes multiple data: Thickness dn, reflectivity Rn; Thickness dn-1, reflectivity Rn-1; … The trend information of the second reference database is decreasing, which includes multiple data: Thickness dn-i, reflectivity Rn-i; … Thickness d0, reflectivity R0.

[0036] When there are two reference databases, the two reference databases have different trend information, and different thicknesses in the two reference databases correspond to the same reflectivity. For example, the reflectivity Rn-1 of thickness dn-1 is equal to the reflectivity Rn-i of thickness dn-i, but the two pieces of data belong to different reference databases. When these two reference databases are used to measure thickness with a single wavelength beam, when determining the cycle of the current thickness, first determine the corresponding reference database based on the measured reflectivity change trend information, and then match the only piece of data in the database based on the reflectivity value to obtain the corresponding thickness value.

[0037] In one embodiment, determining the trend information of reflectivity changing with thickness in the above step S2A may specifically include the following operations: Starting from the reflectivity corresponding to the maximum thickness within the specific thickness range, the reflectivity corresponding to the next smaller thickness is compared with the reflectivity corresponding to the previous larger thickness one by one; When the reflectivity corresponding to the smaller thickness is greater than the reflectivity corresponding to the larger thickness, it is determined that the trend of the reflectivity corresponding to the smaller thickness is increasing; When the reflectivity corresponding to the smaller thickness is smaller than the reflectivity corresponding to the larger thickness, it is determined that the trend of the reflectivity corresponding to the smaller thickness is decreasing.

[0038] As an example, assuming that the given thickness range is 0~200nm and the resolution is 0.1nm, for example, the reflectivity R=0.6 is calculated for 200nm and the reflectivity R=0.602 is calculated for 199.9nm, then by comparison, it can be determined that the reflectivity trend is increasing. By calculating the reflectivity to a thickness of 0 in the above manner, the trend information of each reflectivity changing with thickness can be determined.

[0039] In some embodiments, the established reference database needs to be used to measure the thickness of the wafer film during the polishing process. During the polishing process, it is necessary to add polishing liquid to the wafer surface and continuously flush it with water, and there are other transparent media such as glass and PU between the photodetector and the wafer surface. This complex environment is called a multilayer film environment in this field, or the wafer film is called a multilayer film state. If the above reference database is established without considering this complex environment, that is, the mathematical model used to calculate the reflectivity is a model suitable for a single-layer film environment, then the obtained reference database is not suitable for measuring the thickness of the wafer film in a multilayer film environment.

[0040] In order to adapt to the multi-layer film environment, this embodiment further includes the following operations after the above step S3A: S4A, using the conversion coefficient to convert the reference database into a reference database suitable for a multilayer film environment. Based on the change in reflectivity with thickness value to form a corresponding relationship curve, it is found that compared with the corresponding relationship curve of reflectivity and thickness in a single-layer film environment, the corresponding relationship curve of reflectivity and thickness in a multilayer film environment is compressed or stretched, and the curve is raised or lowered as a whole. In this embodiment, the above correspondence is determined as ; in, represents the reflectance in the reference database under the single-layer film environment (reflectance before conversion), and is the conversion factor, Represents the reflectance in the reference database applicable to the multilayer film environment (converted reflectance). This step uses the pre-calibrated conversion coefficient and Processing of reflectance in a reference database.

[0041] Furthermore, the conversion coefficient can be adjusted as follows: and To perform calibration: S01, obtain the reflectivity of two wafer films of different known thicknesses to the reflected light of a single wavelength beam in a multilayer film environment and reflectivity 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 reflectivity of the reflected light of the two wafer films to the single wavelength beam in a single-layer film environment and reflectivity The measurement object is the same as that in step S01, except that the environment is different.

[0043] S03, according to reflectivity , reflectivity , reflectivity and reflectivity Determine the conversion coefficient. According to the corresponding relationship between the reflectivity in a multilayer film environment and the reflectivity in a single-layer film environment, the value of the conversion coefficient can be calculated by solving the equation: ; The above steps S01 and S02 can be performed in an experimental environment, and the conversion coefficient can be calibrated through the actual measured reflectivity.

[0044] like Figure 3 As shown, an embodiment of the present invention provides a thickness measurement method for a wafer thin film polishing process, which can be performed by an electronic device such as a computer or a server, and includes the following operations: S1B, in the process of polishing the wafer film, obtaining the electrical signal U corresponding to the light intensity of the reflected light of the wafer film to the single wavelength light beam 1n , and determine the electrical signal U 1n Trend information with thickness changes. Specifically, 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 surface of the wafer is received by the photoelectric sensor and converted into an analog electrical signal, which is then processed by analog-to-digital conversion, filtering, amplification and other optional processing to obtain a digital electrical signal.

[0045] 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.

[0046] In this embodiment, the electrical signal The trend information with thickness change refers to the electrical signal decreasing with the thickness. During the polishing process, the wafer film is polished by external force and its thickness gradually decreases. By continuously monitoring the electrical signal, its changing trend can be determined, specifically whether it increases or decreases.

[0047] S2B, according to the electrical signal U 1n And the calibration coefficient k is used to calculate the reflectivity R of the wafer film to the single wavelength reflected light. 1n , reflectivity The reflectivity also changes periodically with the thickness. With electrical signal The relationship between is a linear correspondence, and the specific correspondence depends on the electrical signal The type of data (such as voltage or current), usually the voltage value.

[0048] The function of the calibration coefficient k is to establish the connection between the electrical signal and the reflectivity of the wafer film. The calibration coefficient k is at least the value determined before step S2B. 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, then 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, then the calibration coefficient k=1.5 / 0.5=3.

[0049] Determine the calibration factor There are many ways to calculate the calibration coefficient. According to the above examples, as long as the reflectivity can be determined, the calibration coefficient can be calculated. If the reflectivity needs to be determined, the thickness of the wafer film needs to be determined. There are many ways to measure the thickness. Specifically, for example, the thickness of the wafer film can be determined by using a contact or non-contact measurement tool before performing the wafer film polishing process; or it can be measured in situ or offline during the wafer film polishing process.

[0050] S3B, according to the thickness and reflectivity R at the previous moment 1n and trend information, and match the current thickness d in the pre-established reference database 1n The reference database includes reflectivity corresponding to different thicknesses and the trend information of reflectivity changing with thickness.

[0051] As a first implementation, each piece of data in the reference database includes thickness, reflectivity, and reflectivity trend information, and the trend information is used to indicate the change trend of the reflectivity value in one piece of data compared with the reflectivity value in another piece of data with a larger thickness. For example, the reference database includes the following multiple pieces of data: thickness , reflectivity , increase; thickness , reflectivity , increase; … thickness , reflectivity , decrease; thickness , reflectivity , decrease.

[0052] The reflectivity obtained in step S3B and electrical signals The trend information is used to match a unique piece of data in the reference database, and the thickness in the matched data is the thickness When this reference database is used to measure thickness, after the reflectivity value is measured, a unique piece of data can be matched in the database in combination with the change trend information to obtain the corresponding thickness value.

[0053] In order to match a unique thickness value in the reference database, it is first necessary to determine the thickness at the previous moment. In a certain thickness cycle in the reference database, a unique thickness value is determined in this thickness cycle as the thickness at the current moment, including: Determine including thickness in the reference database Data of a cycle including; According to the reflectivity Two sets of data are obtained by matching the data in one cycle; according to The trend information of the two sets of data is used to determine the thickness of one set of data. .

[0054] For example, from the beginning of polishing, the known initial thickness of 900nm is used as the thickness of the previous moment. The reference database contains the thickness, reflectivity, and change trend data of 0~1000nm. The thickness at the current moment can be determined by first determining the data of a thickness period of 900nm from the reference database. There are two data in the data of this thickness period that match the reflectivity at the current moment, and the trend information of these two sets of data is different. Only one set of data has the same trend information as the reflectivity at the current moment. For example, the reflectivity trend at the current moment is rising, and one of the data is (899.9nm, reflectivity R 899.9, rises), the thickness at the current moment is determined to be 899.9nm. After that, 899.9nm becomes the thickness at the previous moment. By continuously monitoring in the above manner, the absolute thickness value of the wafer film can be determined at any time during the polishing process.

[0055] As a second implementation method, reference databases can be established separately according to trend information. For example, one reference database contains all reflectivity and thickness with an increasing trend, and another reference database contains all reflectivity and thickness with a decreasing trend. The same reference database has unique trend information, and the trend information is used to indicate the changing trend of the reflectivity value in each data in the reference database compared to the reflectivity in another adjacent data with a larger thickness.

[0056] For example, the trend information of the first reference database is increasing, which includes multiple data: thickness , reflectivity ; … thickness , reflectivity ; The trend information of the second reference database is decreasing, which includes multiple data: thickness , reflectivity , decrease; … thickness , reflectivity , decrease.

[0057] When there are two reference databases, the two reference databases have different trend information, and different thicknesses exist in the two reference databases corresponding to the same reflectivity. Reflectivity Equal to thickness Reflectivity , but the two data belong to different reference databases. In step S3B, the electrical signal The trend information is used to select a reference database, the thickness of the previous moment and the reflectivity at the current moment Used to match a unique piece of data in the selected database. The thickness in the matched data is the thickness .

[0058] The calibration coefficient k can be calculated as follows before step S2B: For known thickness The wafer film collects the electrical signal corresponding to the light intensity of the reflected light of the single wavelength beam For example, before polishing begins, electrical signals can be collected for the wafer film at the initial thickness. .

[0059] According to thickness Calculate the reflectivity of wafer film for single wavelength reflected light . Calculation based on theoretical model, given thickness The unique reflectivity can be calculated .

[0060] According to the reflectivity and electrical signals Calculate the calibration factor The electrical signal is preferably a voltage signal, and the calibration coefficient , in step S2B, .

[0061] In one embodiment, the electrical signal is determined in step S1B Trend information over thickness, including: S11B, compare the electrical signal collected at the current moment The electrical signal collected at the previous moment , where the wafer film thickness at the current moment is less than the wafer film thickness at the previous moment; S12B, obtain trend information according to the comparison result, where if The trend information indicates a decrease. The trend information indicates an increase.

[0062] This solution continuously collects electrical signals during the polishing process. The electrical signals change as the thickness decreases. The electrical signals collected at the current moment The electrical signal collected at the previous moment By comparing the different thicknesses, the changing trend of the electrical signal as the thickness decreases can be determined.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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 establishing a single wavelength beam thickness measurement reference database, characterized in that: include: Obtaining the reflectivity of the wafer film at different thicknesses, wherein the thickness is a given value, and the corresponding reflectivity is a value calculated by a mathematical model, wherein the reflectivity is the reflectivity of the wafer film to light of a specific wavelength, and the reflectivity changes periodically with the change of thickness; Determining trend information of the reflectivity changing with thickness; A reference database for measuring wafer thin film thickness using a single wavelength beam is established based on the different thicknesses and corresponding reflectivities and the trend information.

2. The method according to claim 1, characterized in that Each piece of data in the reference database includes thickness, reflectivity and the trend information of reflectivity, and the trend information is used to indicate the change trend of the reflectivity value in one piece of data compared with the reflectivity in another adjacent piece of data with a larger thickness.

3. The method according to claim 2, characterized in that There are two different thicknesses in the reference database corresponding to the same reflectivity and different trend information.

4. The method according to claim 1, characterized in that: The number of the reference databases is one or two, and the same reference database has unique trend information, which is used to indicate the change trend of the reflectivity value in each data in the reference database compared with the reflectivity in another adjacent data with a larger thickness.

5. The method according to claim 4, characterized in that When there are two reference databases, the two reference databases have different trend information, and different thicknesses in the two reference databases correspond to the same reflectivity.

6. The method according to claim 1, characterized in that Determining the trend information of the reflectivity changing with thickness, including: Starting from the reflectivity corresponding to the maximum thickness within the specific thickness range, the reflectivity corresponding to the next smaller thickness is compared with the reflectivity corresponding to the previous larger thickness one by one; When the reflectivity corresponding to the smaller thickness is greater than the reflectivity corresponding to the larger thickness, it is determined that the trend of the reflectivity corresponding to the smaller thickness is increasing; When the reflectivity corresponding to the smaller thickness is smaller than the reflectivity corresponding to the larger thickness, it is determined that the trend of the reflectivity corresponding to the smaller thickness is decreasing.

7. The method according to claim 1, characterized in that After obtaining the reference database, the method further includes: The reference database is converted into a reference database suitable for a multilayer film environment using a conversion factor.

8. A method for measuring the thickness of a wafer thin film during polishing, characterized in that: include: In the process of polishing the wafer film, an electrical signal corresponding to the light intensity of the reflected light of the wafer film to the single wavelength light beam is obtained. , while determining the electrical signal Trend information with thickness variation; According to the electrical signal and calibration coefficient Calculate the reflectivity of the wafer film to a single wavelength beam , the reflectivity shows a periodic change as the thickness changes; According to the thickness of the previous moment , the reflectivity The trend information is matched with the thickness at the current moment in the pre-established reference database. The reference database includes reflectivity corresponding to different thicknesses and trend information of reflectivity changing with thickness.

9. The method according to claim 8, characterized in that Before calculating the reflectivity, it also includes: For known thickness The wafer film collects the electrical signal corresponding to the light intensity of the reflected light of the single wavelength beam ; According to thickness Calculate the reflectivity of the wafer film to the single wavelength reflected light ; According to the reflectivity and electrical signals Calculate the calibration coefficient .

10. The method according to claim 9, characterized in that The electrical signal is a voltage signal, and the calibration coefficient The reflectivity .

11. The method according to claim 8, characterized in that Determine the electrical signal Trend information over thickness, including: Compare the electrical signals collected at the current moment The electrical signal collected at the previous moment , wherein the wafer film thickness at the current moment is less than the wafer film thickness at the previous moment; The trend information is obtained according to the comparison result, wherein if The trend information indicates a decrease. The trend information indicates an increase.

12. The method according to claim 8, characterized in that Get the thickness at the current moment ,include: Determining in the reference database that the thickness Data of a cycle including; According to the reflectivity Two sets of data are obtained by matching the data in the one cycle; according to The trend information of the two sets of data determines a set of data to obtain the thickness .

13. A single wavelength beam thickness measurement reference database establishment device, 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 establishing a single-wavelength beam thickness measurement reference database as described in any one of claims 1 to 7.

14. A thickness measuring device for wafer thin film 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 thickness measurement method for wafer thin film polishing process as described in any one of claims 8-12.

Images