Online in-situ thickness measurement method and equipment for wafer thin film polishing process

Abstract

The present invention provides an online in-situ thickness measurement method and device for a wafer film polishing process. The method comprises a first measurement phase and a second measurement phase, wherein the first measurement phase comprises, during the process of polishing the wafer film, measuring the thickness of the wafer film by using a multi-wavelength light beam, and monitoring whether the thickness reaches a threshold value; the second measurement phase comprises, during the process of polishing the wafer film after the thickness reaches the threshold value, collecting an electrical signal corresponding to the light intensity of the reflected light of the wafer film to a single-wavelength light beam, and determining the thickness of the wafer film by using the electrical signal, wherein the electrical signal presents a periodic change with the change of the thickness.

Description

Technical Field

[0001] The present invention relates to the field of wafer feature measurement, and in particular to an online in-situ thickness measurement method and equipment for a wafer thin film polishing process. Background Art

[0002] The polishing EPD (End Point Detection) technology based on optical measurement methods is mainly used in chemical mechanical polishing equipment. Chemical mechanical polishing equipment usually polishes and removes 200 to 300nm of wafer film. EPD can determine the polishing endpoint, allowing the chemical mechanical polishing equipment to complete the polishing operation.

[0003] At present, there is a common range problem in the EPD mechanism of chemical mechanical polishing equipment, which means that the chemical mechanical polishing equipment can only polish wafers that meet the range of the EPD mechanism, and cannot complete the polishing of wafer films across the range. Summary of the invention

[0004] In view of this, the present application provides an online in-situ thickness measurement method for a wafer thin film polishing process, comprising a first measurement phase and a second measurement phase, wherein

[0005] The first measurement stage includes measuring the thickness of the wafer film using a multi-wavelength beam during the polishing process of the wafer film, and monitoring whether the thickness reaches a threshold value;

[0006] The second measurement stage includes collecting an electrical signal corresponding to the light intensity of the reflected light of the single-wavelength light beam from the wafer film during polishing of the wafer film after the thickness reaches a threshold, and using the electrical signal to determine the thickness of the wafer film, wherein the electrical signal shows periodic changes with changes in thickness.

[0007] Optionally, the second measurement stage uses a single wavelength beam to measure the thickness of the wafer film, including:

[0008] Collect the electrical signal corresponding to the light intensity of the reflected light of a single wavelength beam While determining the electrical signal Trend information with thickness variation;

[0009] According to the electrical signal and calibration coefficient Calculate the reflectivity of the wafer film to the single wavelength reflected light , the reflectivity shows a periodic change as the thickness changes;

[0010] Starting from the threshold, 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.

[0011] Optionally, get the thickness at the current moment ,include:

[0012] Determining in the reference database that the thickness Data of a cycle including;

[0013] According to the reflectivity Two sets of data are obtained by matching the data in the one cycle;

[0014] according to The trend information of the two sets of data determines a set of data to obtain the thickness .

[0015] Optionally, the first measurement stage further includes determining trend information of the electrical signal changing with thickness while collecting the electrical signal;

[0016] The reference database is established using the thickness measured in the first measurement phase and the electrical signal and its trend information.

[0017] Optionally, the second measurement stage uses a single wavelength beam to measure the thickness of the wafer film, including:

[0018] The electrical signal corresponding to the light intensity of the reflected light of a single wavelength beam and calibration coefficient Calculate the reflectivity of the wafer film to the single wavelength reflected light ;

[0019] Starting from the threshold, determine the thickness including the previous moment The thickness and reflectivity corresponding data of a period including , wherein the period is the period in which the reflectivity changes with the thickness;

[0020] According to the reflectivity Two sets of data are obtained by matching the data of one cycle, and the reflectivity and reflectivity in the two sets of data are Same, different values ​​of thickness;

[0021] Compare the larger thickness of the two sets of data with the thickness , when the larger thickness of the two sets of data is greater than the thickness When the thickness of the two sets of data is smaller, the thickness at the current moment is taken as ; When the larger thickness of the two sets of data is less than the thickness When the larger thickness is taken as the thickness at the current moment .

[0022] Optionally, determine the thickness including The thickness and reflectivity corresponding data of a period include:

[0023] Use thickness The thickness and reflectivity corresponding data of a period are determined with a reference database, wherein the reference database includes different thicknesses and their corresponding reflectivities.

[0024] Optionally, the first measurement phase includes collecting the electrical signal; and the reference database is established using the thickness measured in the first measurement phase and the electrical signal.

[0025] Optionally, the first measurement phase includes:

[0026] Using at least two different thicknesses and corresponding electrical signal values, a corresponding relationship model between the electrical signal and the thickness is determined.

[0027] Optionally, the first measurement phase includes:

[0028] 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;

[0029] The electrical signal is collected when the thickness of the wafer film is within the sampling range.

[0030] Optionally, the first measurement phase includes:

[0031] collecting the electrical signal in real time as the thickness of the wafer film changes;

[0032] 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.

[0033] Optionally, the second measurement stage uses at least two single-wavelength light beams with different wavelengths to measure the thickness of the wafer film, including:

[0034] For each single-wavelength light of different wavelengths, an electrical signal corresponding to the light intensity of the reflected light of the single-wavelength light beam by the wafer film is obtained;

[0035] Using the electrical signal, obtaining a thickness set of the single-wavelength light beam;

[0036] The thickness of the wafer film is obtained by taking the intersection of the thickness sets measured for the single wavelength light beams of various wavelengths.

[0037] Optionally, obtaining the thickness set of the single-wavelength light beam by using the electrical signal comprises:

[0038] The electrical signal is used to match the corresponding film thickness electrical signal library to obtain a thickness set.

[0039] Optionally, the first measurement stage includes collecting electrical signals corresponding to the at least two single-wavelength light beams of different wavelengths; the film thickness electrical signal library is established using the thickness measured in the first measurement stage and the electrical signals.

[0040] Optionally, obtaining the thickness set of the single-wavelength light beam by using the electrical signal comprises:

[0041] Calculating the reflectivity of the wafer film to the single-wavelength light beam according to the electrical signal and the corresponding calibration coefficient;

[0042] The reflectivity is used to match a thickness set in a pre-established reference database, wherein the reference database includes a library of different film thicknesses and corresponding reflectivity.

[0043] Optionally, the first measurement phase includes:

[0044] The electrical signal corresponding to the light intensity of the reflected light of the single-wavelength light beam by the wafer film at a certain moment, and the corresponding reflectivity are calculated using the currently measured thickness, and the calibration coefficient is calculated based on the reflectivity and the electrical signal.

[0045] Optionally, before calculating the reflectivity, the method further includes determining a calibration coefficient in the following manner:

[0046] The reflectivity of a wafer film of known thickness to a single-wavelength light beam is calculated, an electrical signal corresponding to the light intensity of the reflected light of the wafer film of known thickness to the single-wavelength light beam is obtained, and the calibration coefficient is calculated according to the reflectivity and the electrical signal.

[0047] Optionally, the method further comprises:

[0048] The reference database applicable to the monolayer film environment is calculated using the theoretical model of the monolayer film environment;

[0049] The conversion factor is used to convert the reference database applicable to the single-layer film environment into a reference database applicable to the multi-layer film environment.

[0050] Optionally, the period of the electrical signal varying with thickness is

[0051] ;

[0052] in, is the refraction angle of the single wavelength light beam passing through the wafer film, is the refractive index of the wafer film, is the wavelength of the single wavelength light beam, is the period; the wavelength of the single wavelength beam The value of is greater than or equal to the threshold.

[0053] Optionally, the threshold is determined according to an error of a thickness measurement result of the multi-wavelength light beam, and above the threshold, the error of the thickness measurement result of the multi-wavelength light beam is less than a set value.

[0054] Correspondingly, the present application also provides an in-situ 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 online in-situ thickness measurement method for the wafer thin film polishing process.

[0055] The present application also provides a chemical mechanical polishing device for performing chemical mechanical polishing on a wafer film and executing the above-mentioned online in-situ thickness measurement method for the wafer film polishing process during the polishing process.

[0056] The present application provides an online in-situ thickness measurement method and device for a wafer thin film polishing process, which divides the thickness measurement into two stages. In the first measurement stage when the thickness is relatively large, a multi-wavelength light beam is used to in-situ detect the wafer thin film thickness during the polishing process; in the second measurement stage when the thickness is relatively small, a single-wavelength light beam is switched to continue the in-situ measurement. By combining the two measurement methods, both larger and smaller film thicknesses can be accurately measured, thereby expanding the measurement range and being able to meet the needs of various wafer polishing operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 This is a flow chart of the online in-situ thickness measurement method in an embodiment of the present application;

[0058] Figure 2 A diagram showing the corresponding relationship between the electrical signal and the wafer film thickness in an embodiment of the present application;

[0059] Figure 3 A schematic diagram of matching wafer film thickness in an embodiment of the present application;

[0060] Figure 4 A schematic diagram of another method for matching wafer film thickness in an embodiment of the present application;

[0061] Figure 5 Schematic diagram of the dual-beam voltage and thickness curves and the intersection of thickness in an embodiment of the present application. DETAILED DESCRIPTION

[0062] 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.

[0063] 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. Embodiment 1

[0064] like Figure 1 As shown, an embodiment of the present invention provides an online in-situ thickness measurement method for a wafer thin film polishing process. The method can be performed by a general electronic device such as a computer or a server, or by a mechanical chemical polishing device. The method includes two measurement stages that are performed sequentially, specifically including the following operations:

[0065] The first measurement stage: During the polishing process of the wafer film, the thickness of the wafer film is measured using a multi-wavelength beam, and whether the thickness reaches a threshold is monitored. The wafer film can be a silicon dioxide layer on the surface of a silicon-based wafer. During the polishing process, the thickness of the wafer film is gradually reduced due to external force. In the first measurement stage, the spectral information of the multi-wavelength beam is used to measure the thickness value in situ during the polishing process.

[0066] 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.

[0067] The first measurement phase may be for a thickness value between the initial thickness and the polishing end point, for example, from 1000nm to 200nm, and then the second measurement phase is entered. The second measurement phase is for a smaller thickness, for example, from 200nm to 0.

[0068] It should be noted that the above example is only used to illustrate that the thickness of the wafer film is larger in the first measurement stage, while the thickness of the wafer film is smaller in the second measurement stage. This solution does not limit the specific thickness range.

[0069] The second measurement stage: During the polishing process after the thickness reaches the threshold, the electrical signal corresponding to the light intensity of the reflected light of the wafer film to the single-wavelength beam is collected, and the thickness of the wafer film is determined by the electrical signal, wherein the electrical signal changes periodically with the change of thickness. The measurement method based on multi-wavelength beams in the first measurement stage has a higher measurement accuracy for larger thicknesses, but as the polishing process gradually reduces the thickness to below a certain thickness, the accuracy of the multi-wavelength beam measurement results gradually decreases, so the single-wavelength beam measurement method is used to ensure accuracy.

[0070] Single-wavelength beam measurement uses a light source that emits single-wavelength light 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.

[0071] 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. Figure 2 An exemplary corresponding relationship curve between the electrical signal and the thickness is shown. In this example, 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 value (the value of the electrical signal). As the thickness of the wafer film changes, the voltage varies between the minimum value Umin and the maximum value Umax, presenting a quasi-sinusoidal curve.

[0072] Due to the periodic variation of the electrical signal, the measured electrical signal corresponds to a periodic thickness value, such as Figure 2 In the example shown, the thicknesses of points A and B are different but the voltages are the same. In order to obtain a unique measurement result, further judgment is required after the electrical signal is obtained. There are many specific judgment methods, which will be introduced in subsequent embodiments.

[0073] As a preferred embodiment, in order to improve the efficiency of the second measurement stage, the period of the electrical signal changing with the thickness in this embodiment is greater than or equal to the above threshold. As an example, assuming the threshold is 200nm, the period of this embodiment is a thickness value of 200nm and above.

[0074] The period of the electrical signal changing with thickness is related to the material of the wafer film and the parameters of the single-wavelength light beam, which can be

[0075] ;

[0076] in, is the refraction angle of a single wavelength beam passing through the wafer film, is the refractive index of the wafer film, is the wavelength of the single-wavelength beam, For cycle.

[0077] Based on the above relationship, we can first set a threshold and then determine a period greater than or equal to the threshold. , and then calculate the wavelength value according to the above relationship, and select a single wavelength beam with this wavelength to make the period For example, if the wavelength is selected so that the period is 220nm, then the thickness variation range of the wafer film in the second measurement phase does not exceed one period. Figure 2 In the example shown, the period T of the electrical signal is 220 nm, and the total range of the second measurement stage is 200 nm, which means that the electrical signal measured at any time in the second measurement stage corresponds to at most two thickness values, thereby narrowing the data range.

[0078] As a preferred embodiment, the threshold is determined based on the error of the thickness measurement result of the multi-wavelength beam. Above the threshold, the error of the thickness measurement result of the multi-wavelength beam is less than the set value. Specifically, the multi-wavelength beam measurement method is not unable to measure smaller thicknesses, but the accuracy may be reduced and cannot meet the process requirements. Therefore, in actual use, the threshold can be determined based on its measurement error, that is, to determine the thickness below which the multi-wavelength beam measurement method is no longer applicable, and above this thickness, the error of the method is acceptable for greater thicknesses.

[0079] Furthermore, for example, the error variation of the multi-wavelength measurement method can be determined by experiments before the measurement is implemented. In the experiment, the thickness of the wafer film can be measured by reliable methods including contact measurement, and then the multi-wavelength measurement method can be used to measure its thickness to determine the corresponding error at this thickness. After measuring different thicknesses, the error of the multi-wavelength measurement method at different thicknesses can be obtained. The error can be measured in percentage. Assuming that the error required by the process (set value) is 1%, it is determined above which thickness the corresponding error does not exceed 1%, and this thickness can be used as the threshold.

[0080] The online in-situ thickness measurement method and equipment for the wafer thin film polishing process provided in this embodiment divides the thickness measurement into two stages. In the first measurement stage when the thickness is relatively large, a multi-wavelength light beam is used to in-situ detect the wafer thin film thickness during the polishing process; in the second measurement stage when the thickness is relatively small, a single-wavelength light beam is switched to continue the in-situ measurement. By combining the two measurement methods, accurate measurements can be performed on both larger and smaller film thicknesses, thereby expanding the measurement range and meeting the needs of various wafer polishing operations.

[0081] Specifically, different wafer polishing operations have different wafer materials, different uses, etc., and the corresponding polishing removal amount, initial thickness, and polishing endpoint thickness are different. The processing method provided in this embodiment and the chemical mechanical polishing equipment using the method can cope with the above-mentioned various situations, and can continuously monitor thickness information and perform endpoint detection during the polishing process of various wafer types.

[0082] Embodiment 2

[0083] The second measurement stage in this embodiment uses a single wavelength beam to measure the thickness of the wafer film, including the following operations:

[0084] Collect the electrical signal corresponding to the light intensity of the reflected light of a single wavelength beam While determining the electrical signal The trend information of the change with thickness. 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.

[0085] According to the electrical signal Calculate the reflectivity of the wafer film to single wavelength reflected light using the calibration coefficient , the reflectivity 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.

[0086] The function of the calibration coefficient k in this embodiment 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 the second measurement stage. Without changing the measurement environment and the wafer material, the calibration coefficient remains unchanged at different thicknesses. As an example, assuming that the voltage value measured at a certain 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, then the calibration coefficient k=1.5 / 0.5=3.

[0087] 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. .

[0088] Then starting from the threshold, according to the thickness of the previous moment , reflectivity and trend information, and match the current thickness in the pre-established reference database The reference database includes reflectivity corresponding to different thicknesses and the trend information of reflectivity changing with thickness.

[0089] 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:

[0090] thickness , reflectivity , increase;

[0091] thickness , reflectivity , increase;

[0092] …

[0093] thickness , reflectivity , decrease;

[0094] thickness , reflectivity , decrease.

[0095] Measured reflectivity 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.

[0096] 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:

[0097] Determine including thickness in the reference database Data of a cycle including;

[0098] According to the reflectivity Two sets of data are obtained by matching the data in one cycle;

[0099] according to The trend information of the two sets of data is used to determine the thickness of one set of data. .

[0100] For example, starting from the initial threshold of 200nm, the threshold of 200nm is used as the thickness of the previous moment. The reference database contains thickness, reflectivity, and change trend data of 0~1000nm. The thickness of the current moment can be determined by first determining the data of a thickness period of 200nm from the reference database. There are two data in the data of this thickness period that match the reflectivity of 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 of the current moment. For example, the reflectivity trend at the current moment is rising, and one of the data is (199.9nm, reflectivity R 199.9 , rises), the thickness at the current moment is determined to be 199.9nm. After that, 199.9nm 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.

[0101] 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.

[0102] For example, the trend information of the first reference database is increasing, which includes multiple data:

[0103] thickness , reflectivity ;

[0104] …

[0105] thickness , reflectivity ;

[0106] The trend information of the second reference database is decreasing, which includes multiple data:

[0107] thickness , reflectivity , decrease;

[0108] …

[0109] thickness , reflectivity , decrease.

[0110] 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. The measured 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 .

[0111] Regarding the reference database, the database may be established based on a theoretical model, that is, a reference database applicable to a single-layer membrane environment is calculated using a theoretical model of a single-layer membrane environment.

[0112] Specifically, 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:

[0113] ;

[0114] Where R represents reflectivity, A, B and are all constants (related to the refractive index of the wafer surface material) and can be obtained by substituting relevant parameters. . represents the refractive index of the wafer film, h represents the thickness of the wafer film, is the wavelength of incident light, Represents the refraction angle of a single wavelength light beam passing through a wafer film.

[0115] From the above relationship, it can be seen that the film thickness reflectivity curve changes in a sine and cosine law, and the theoretical model of a single-layer film environment can be simplified as follows:

[0116] ;

[0117] in represents reflectivity, t represents thickness, , A and B are constants.

[0118] Based on this model, the corresponding reflectivity can be calculated for a given thickness value, and then the trend information of how the reflectivity changes with thickness can be determined. A reference database can be established based on different thicknesses and the corresponding reflectivity and trend information.

[0119] Furthermore, this 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 rinse it continuously with water. In addition, 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. The above-mentioned reference database is established without considering this complex environment, that is, the theoretical 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.

[0120] To this end, it is also necessary to use a conversion factor to convert the reference database applicable to a single-layer film environment into a reference database applicable to a multi-layer film environment.

[0121] Based on the corresponding relationship curve formed by the change of reflectivity with thickness value, it is found that compared with the corresponding relationship curve of reflectivity and thickness in the single-layer film environment, the corresponding relationship curve of reflectivity and thickness in the multi-layer film environment is compressed or stretched, and the curve is raised or lowered as a whole. In this embodiment, the above corresponding relationship is determined as

[0122] ;

[0123] 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.

[0124] Furthermore, the conversion coefficient can be adjusted as follows: and To perform calibration:

[0125] Obtain the reflectivity of two wafer films of known different thicknesses for a single wavelength beam in a multilayer film environment and reflectivity The two wafer films having different known thicknesses refer to that the thicknesses of the two wafer films are both known information and they are not equal.

[0126] Obtain the reflectivity of the reflected light of the two wafer films under the single-layer film environment for a single-wavelength beam and reflectivity The measurement object is the same as before, the difference is the environment.

[0127] According to the 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:

[0128] .

[0129] Embodiment 3

[0130] The second measurement stage in this embodiment uses a single wavelength beam to measure the thickness of the wafer film, including the following operations:

[0131] The electrical signal corresponding to the light intensity of the reflected light of a single wavelength beam and calibration coefficient Calculate the reflectivity of wafer film for single wavelength reflected light For details about the calibration coefficient k, please refer to the above embodiment, which will not be described in detail here.

[0132] Then starting from the threshold, determine the thickness including the previous moment The thickness and reflectivity corresponding data of a period, where the period is the period of reflectivity changing with thickness. Figure 3 and Figure 4 As shown, in this embodiment, the corresponding relationship between the reflectivity R and the thickness d is a quasi-sine function relationship. It is known that the period of the reflectivity R is T. Starting from the threshold, the threshold is used as the thickness at the previous moment. , take first There are many ways to intercept the data of a thickness period, as long as the thickness at the current moment is within this period, for example, Figure 3 The thickness of the previous moment is As the upper limit, take the data of one period T downward, that is, da~ Thickness and its corresponding reflectivity value; you can also use Figure 4 The thickness of the previous moment is As the middle value, take the data of half a period T upward and downward respectively, that is, db~dc thickness and its corresponding reflectivity value.

[0133] According to the reflectivity Two sets of data are obtained by matching the data of one cycle. The reflectivity and reflectivity in the two sets of data are The same, the thickness value is different; the reflectivity and reflectivity R in the two sets of data 1n The same, but different thickness values, the thickness of the two sets of data is one large and one small. Figure 3 or Figure 4The reflectivity R 1n Corresponding thickness and .

[0134] Compare the larger thickness and thickness in the two sets of data , when the larger thickness of the two sets of data is greater than the thickness When the thickness of the two sets of data is smaller, the thickness at the current moment is taken as Since the thickness at the current moment in the polishing process must be smaller than the thickness at the previous moment, when the larger thickness of the two sets of data exceeds the thickness at the previous moment, the smaller thickness is determined to be the thickness at the current moment. Figure 4 The relationship shown > > , then determine the thickness at the current moment is .

[0135] When the larger thickness of the two sets of data is less than the thickness When the larger thickness is taken as the thickness at the current moment When the thickness in both sets of data is smaller than the thickness at the previous moment, the larger thickness is closer to the thickness at the previous moment, so the larger thickness is the thickness at the current moment. Figure 3 The relationship shown > > , then determine the thickness at the current moment is .

[0136] Further, the thickness is determined The thickness and reflectivity corresponding data of a period include:

[0137] Use thickness The thickness and reflectivity corresponding data of a period are determined with a reference database, wherein the reference database includes different thicknesses and their corresponding reflectivities.

[0138] The reference database in this embodiment may be the thickness and its corresponding reflectivity itself, or may be a corresponding relationship model of thickness and reflectivity.

[0139] Furthermore, if the reference database is established based on the theoretical model of a single-layer film environment, a conversion coefficient is required to convert the reference database applicable to a single-layer film environment into a reference database applicable to a multi-layer film environment. The conversion coefficient can be referred to in the above embodiment and will not be described in detail here.

[0140] The difference from the second embodiment is that in this embodiment, there is no need to use the trend information of the electrical signal when constructing the database and in the second measurement phase. Instead, the absolute thickness value at the current moment is determined by intercepting the data of one cycle and then using the relationship between the two thickness matching results within the cycle and the thickness at the previous moment.

[0141] Embodiment 4

[0142] The second measurement stage in this embodiment uses at least two single-wavelength light beams with different wavelengths to measure the thickness of the wafer film, including the following operations:

[0143] For each single-wavelength light of different wavelengths, an electrical signal corresponding to the light intensity of the reflected light of the single-wavelength light beam by the wafer film is obtained. Taking two single-wavelength light beams of the same wavelength as an example, it specifically 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.

[0144] The thickness set of the single wavelength light beam is obtained by using the electrical signal. In this step, a pre-established reference database may be used, specifically a film thickness and corresponding electrical signal database or a film thickness and corresponding reflectivity database.

[0145] If the film thickness and the corresponding electrical signal library are used, the electrical signal can be used to 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 In the first film thickness electrical signal library and the second film thickness electrical signal library, the electrical signals show periodic changes with the change of thickness, so 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 .

[0146] If the film thickness and corresponding reflectivity library is used, the reflectivity of the wafer film to the corresponding single wavelength light beam is calculated based on the measured electrical signal and the corresponding 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 Regarding the calibration coefficient, please refer to the above embodiment for details. It should be noted that the present embodiment uses a plurality of single-wavelength light beams, and the calibration coefficients of the respective single-wavelength light beams are different.

[0147] Then, the reflectivity is used to match the thickness set in the pre-established reference database, which includes different film thicknesses and corresponding reflectivity libraries. 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 shows a periodic change with the change of the thickness value.

[0148] The thickness of the wafer film is obtained by taking the intersection of the thickness sets measured by the single wavelength beams of each wavelength. 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 .

[0149] like Figure 5 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 measured based on the first single wavelength beam 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 5 The d12=d22 shown is the film thickness measurement result.

[0150] In addition, a reference database, i.e., a film thickness reflectivity library or a film thickness electrical signal library, may also be required in this implementation. If the reference database is established based on a theoretical model of a single-layer film environment, a conversion coefficient is required to convert the reference database suitable for a single-layer film environment into a reference database suitable for a multi-layer film environment.

[0151] Regarding the conversion coefficient, reference may be made to the above-mentioned embodiment. It should be noted that the present embodiment uses a plurality of single-wavelength light beams, and the reference databases of the respective single-wavelength light beams are different, and the corresponding conversion coefficient values ​​are also different. Therefore, reference may be made to the above-mentioned embodiment to establish reference databases for the respective single-wavelength light beams, and determine the conversion coefficients respectively.

[0152] Embodiment 5

[0153] In the second measurement phase of some of the above embodiments, a reference database is used. According to the above embodiments, the thickness and reflectivity, or the thickness and electrical signal (the reflectivity is converted into an electrical signal using a calibration coefficient) in the reference database can be calculated using a theoretical model. However, since the actual measurement environment is different from the ideal model, the data calculated based on the theoretical model may not be accurate enough. Therefore, in order to improve the accuracy of the second phase measurement, this embodiment collects the electrical signal corresponding to the single-wavelength light beam in the first measurement phase, and combines the thickness measurement results of the multi-wavelength light beam to establish a reference database.

[0154] The first measurement phase also includes: collecting the electrical signal corresponding to the single wavelength light beam. If multiple single wavelength light beams are required in the second measurement phase, the electrical signals of each single wavelength light beam are collected respectively; if trend information is required, the trend information can be synchronously determined according to the values ​​of the electrical signals at the previous and next moments while collecting. Then, the thickness and electrical signal (trend information is optional) measured in the first measurement phase are used to establish the above-mentioned reference database.

[0155] As a preferred embodiment, the same device is used to provide a single wavelength beam and a multi-wavelength beam. In this embodiment, a library for the device is obtained. When the multi-wavelength beam and the database 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.

[0156] Furthermore, there are a variety of optional electrical signal acquisition methods and corresponding library building methods in the first measurement stage. For example, the first method is to still regard the corresponding relationship between the voltage signal and the thickness as being able to be expressed by a mathematical model, such as ,in is the value of the voltage signal, is the thickness, , A and B are constants. Indicates angular frequency, 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:

[0157] ;

[0158] 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.

[0159] In this embodiment, the coefficient and The unknown quantities are only required in this embodiment for calculating the values ​​of the two unknown quantities with two different thicknesses and the corresponding electrical signal values, that is, the corresponding relationship model between the electrical signal and the thickness is determined by using at least two different thicknesses and the corresponding electrical signal values.

[0160] When there are only two unknown quantities in the mathematical expression model, the values ​​of the electrical signals at two thicknesses are collected in the first measurement stage to solve all the parameters in the mathematical expression model of the correspondence between the electrical signals and the wafer thin film. The values ​​of the electrical signals at more thicknesses can also be collected, and the values ​​of all parameters are obtained by multiple solutions and averaging, thereby determining the correspondence model between the electrical signals and the thicknesses. If there are more unknown quantities in the mathematical expression model, the corresponding relationship model can also be determined by solving the unknown quantities based on the principle of this embodiment by sampling an appropriate number of thicknesses and electrical signals.

[0161] After obtaining the corresponding relationship model, the thickness range to be measured in the second stage can be given and the corresponding electrical signal value can be calculated to obtain a film thickness electrical signal library, which can also be converted into a film thickness reflectivity library using the above calibration coefficients.

[0162] It should be noted that the corresponding relationship model obtained by the measured data of the first stage in the above embodiment is different from the so-called theoretical model in the previous embodiment. Although they both belong to a sinusoidal function relationship in form, the values ​​of the coefficients in the relationship may be different. It can be considered that the corresponding relationship model obtained based on the measured data is more accurate or more in line with the current measurement environment than the theoretical model.

[0163] In some embodiments, the periodic variation of the electrical signal may not be expressed by a mathematical model, or considering that the database calculated based on the mathematical model may not be accurate due to measurement environment and other reasons, two methods can be used to construct a reference database for this situation:

[0164] The first construction method is to determine the sampling range according to the period of the electrical signal in the first measurement phase 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. For example, if the period T=220nm is known, 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 thickness of the wafer film enters the sampling range, the electrical signal corresponding to each thickness is collected to obtain all the data within the sampling range. 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 reference database.

[0165] 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 the first measurement stage, 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.

[0166] Starting from any moment, when the maximum value Umax and the minimum value Umin are detected successively, the difference in thickness corresponding to the two extreme values ​​is half a cycle T / 2 of the electrical signal; or when two maximum values ​​Umax or two minimum values ​​Umin are detected, the data of the entire cycle is obtained.

[0167] 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 database; the second construction method measures the period size of the electrical signal in real time during the wafer polishing process, and the database obtained based on the measurement results is more reliable.

[0168] 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 database of any thickness range can be established. For example, the thickness range of the second measurement stage is [0, 200nm], where 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 correspondence, a reference database of any thickness range can be obtained.

[0169] Embodiment 6

[0170] In some of the above embodiments, a calibration coefficient is used in the second measurement phase. The calibration coefficient may be calibrated in advance in an experimental environment, or may be calibrated before or during the first measurement phase.

[0171] Specifically, the reflectivity of a wafer film of known thickness to a single-wavelength light beam is calculated, the electrical signal corresponding to the light intensity of the reflected light of a wafer film of known thickness to a single-wavelength light beam is obtained, and the calibration coefficient is calculated based on the reflectivity and the electrical signal. The calculation is performed as follows:

[0172] According to thickness Calculate the reflectivity of wafer film for single wavelength reflected light . It can be calculated based on theoretical models, given the thickness The unique reflectivity can be calculated .

[0173] For known thickness The wafer film collects the electrical signal corresponding to the light intensity of the reflected light of the single wavelength beam This step can be performed in a laboratory environment or before the first measurement phase begins, by collecting electrical signals for the wafer film at the initial thickness. .

[0174] According to the reflectivity and electrical signals Calculate the calibration factor The electrical signal is preferably a voltage signal, and the calibration coefficient , .

[0175] Another example is that in the first measurement phase, at a certain moment, the wafer film may reflect the light intensity of the single-wavelength light beam, and the electrical signal may correspond to the light intensity. The corresponding reflectivity may be calculated using the currently measured thickness, and the calibration coefficient may be calculated based on the reflectivity and the electrical signal. The currently measured thickness refers to the thickness measured using the multi-wavelength light beam.

[0176] It should also be noted that different single-wavelength light beams have different calibration coefficients. In an embodiment using multiple single-wavelength light beams, the calibration coefficient needs to be determined for each light beam.

[0177] 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.

[0178] 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.

[0179] 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.

[0180] 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 1The steps for the functions specified in one or more boxes.

[0181] 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. An online in-situ thickness measurement method for a wafer thin film polishing process, characterized in that: It includes a first measurement phase and a second measurement phase, wherein The first measurement stage includes measuring the thickness of the wafer film using a multi-wavelength beam during the polishing process of the wafer film, and monitoring whether the thickness reaches a threshold value; The second measurement stage includes collecting an electrical signal corresponding to the light intensity of the reflected light of the wafer film to the single-wavelength light beam during the polishing of the wafer film after the thickness reaches the threshold, and determining the thickness of the wafer film using the electrical signal, wherein the electrical signal shows a periodic change with the change of the thickness, and the period of the electrical signal changing with the thickness is ; in, is the refraction angle of the single wavelength light beam passing through the wafer film, is the refractive index of the wafer film, is the wavelength of the single wavelength light beam, is the period; the wavelength of the single wavelength beam The value of is greater than or equal to the threshold, the threshold is determined according to the error of the thickness measurement result of the multi-wavelength light beam, and above the threshold, the error of the thickness measurement result of the multi-wavelength light beam is less than a set value.

2. The method according to claim 1, characterized in that The second measurement stage uses a single wavelength beam to measure the thickness of the wafer film, including: Collect the electrical signal corresponding to the light intensity of the reflected light of a single wavelength beam 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 the single wavelength reflected light , the reflectivity shows a periodic change as the thickness changes; Starting from the threshold, 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.

3. The method according to claim 2, 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 .

4. The method according to claim 2, characterized in that: The first measurement stage also includes collecting the electrical signal and determining the trend information of the electrical signal changing with the thickness; The reference database is established using the thickness measured in the first measurement phase and the electrical signal and its trend information.

5. The method according to claim 1, characterized in that The second measurement stage uses a single wavelength beam to measure the thickness of the wafer film, including: The electrical signal corresponding to the light intensity of the reflected light of a single wavelength beam and calibration coefficient Calculate the reflectivity of the wafer film to the single wavelength reflected light ; Starting from the threshold, determine the thickness including the previous moment The thickness and reflectivity corresponding data of a period including , wherein the period is the period in which the reflectivity changes with the thickness; According to the reflectivity Two sets of data are obtained by matching the data of one cycle, and the reflectivity and reflectivity in the two sets of data are Same, different values ​​of thickness; Compare the larger thickness of the two sets of data with the thickness , when the larger thickness of the two sets of data is greater than the thickness When the thickness of the two sets of data is smaller, the thickness at the current moment is taken as ; When the larger thickness of the two sets of data is less than the thickness When the larger thickness is taken as the thickness at the current moment .

6. The method according to claim 5, characterized in that Determine including thickness The thickness and reflectivity corresponding data of a period include: Use thickness The thickness and reflectivity corresponding data of a period are determined with a reference database, wherein the reference database includes different thicknesses and their corresponding reflectivities.

7. The method according to claim 6, characterized in that The first measurement phase includes collecting the electrical signal; the reference database is established using the thickness measured in the first measurement phase and the electrical signal.

8. The method according to claim 4 or 7, characterized in that: The first measurement phase includes: Using at least two different thicknesses and corresponding electrical signal values, a corresponding relationship model between the electrical signal and the thickness is determined.

9. The method according to claim 4 or 7, characterized in that: The first measurement phase 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.

10. The method according to claim 4 or 7, characterized in that: The first measurement phase 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.

11. The method according to claim 1, characterized in that The second measurement stage uses at least two single wavelength beams with different wavelengths to measure the thickness of the wafer film, including: For each single-wavelength light of different wavelengths, an electrical signal corresponding to the light intensity of the reflected light of the single-wavelength light beam by the wafer film is obtained; Using the electrical signal, obtaining a thickness set of the single-wavelength light beam; The thickness of the wafer film is obtained by taking the intersection of the thickness sets measured for the single wavelength light beams of various wavelengths.

12. The method according to claim 11, characterized in that Obtaining the thickness set of the single-wavelength light beam using the electrical signal, comprising: The electrical signal is used to match the corresponding film thickness electrical signal library to obtain a thickness set.

13. The method according to claim 12, characterized in that The first measurement stage includes collecting electrical signals corresponding to the at least two single-wavelength light beams of different wavelengths; the film thickness electrical signal library is established using the thickness measured in the first measurement stage and the electrical signals.

14. The method according to claim 11, characterized in that Obtaining the thickness set of the single-wavelength light beam using the electrical signal, comprising: Calculating the reflectivity of the wafer film to the single-wavelength light beam according to the electrical signal and the corresponding calibration coefficient; The reflectivity is used to match a thickness set in a pre-established reference database, wherein the reference database includes a library of different film thicknesses and corresponding reflectivity.

15. The method according to claim 2, 5 or 14, characterized in that: The first measurement phase includes: The electrical signal corresponding to the light intensity of the reflected light of the single-wavelength light beam by the wafer film at a certain moment, and the corresponding reflectivity are calculated using the currently measured thickness, and the calibration coefficient is calculated based on the reflectivity and the electrical signal.

16. The method according to claim 2, 5 or 14, characterized in that: Before calculating the reflectivity, the calibration coefficient is determined as follows: The reflectivity of a wafer film of known thickness to a single-wavelength light beam is calculated, an electrical signal corresponding to the light intensity of the reflected light of the wafer film of known thickness to the single-wavelength light beam is obtained, and the calibration coefficient is calculated according to the reflectivity and the electrical signal.

17. The method according to claim 2, 6 or 14, characterized in that: Also includes: The reference database applicable to the monolayer film environment is calculated using the theoretical model of the monolayer film environment; The conversion factor is used to convert the reference database applicable to the single-layer film environment into a reference database applicable to the multi-layer film environment.

18. An in-situ thickness measurement device for a 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 online in-situ thickness measurement method for the wafer thin film polishing process as described in any one of claims 1-17.

19. A chemical mechanical polishing device, characterized in that: It is used to perform chemical mechanical polishing on a wafer film, and during the polishing process, perform the online in-situ thickness measurement method for the wafer film polishing process as described in any one of claims 1 to 17.

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