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

Abstract

The present invention provides a method and equipment for single-wavelength beam thickness measurement and calibration library construction based on a polishing process. The calibration library construction method comprises: using a multi-wavelength beam to measure the thickness of a wafer film online in situ during the polishing process of the wafer film, and obtaining an electrical signal corresponding to the light intensity of the reflected light of the single-wavelength beam from the wafer film at multiple different thicknesses; and determining a calibration library for measuring the thickness of the wafer film during the polishing process based on the periodicity of the electrical signal as the thickness of the wafer film changes and the values ​​of the electrical signals corresponding to the multiple different thicknesses.

Description

Technical Field

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

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

[0003] Before applying the single-wavelength beam measurement method to wafer polishing, the relationship between the electrical signal value and the thickness needs to be calibrated. This is commonly referred to in the art as establishing a database of correspondences between the electrical signal and film thickness, or simply building a database. The problem with existing technologies is that the electrical signals are collected in an experimental environment during library building. Because the equipment conditions used during library building differ from those used in polishing operations, such as the installation position and angle of devices like light sources and sensors, the pre-established database may not match the actual working conditions, leading to inaccurate measurement results. Summary of the Invention

[0004] In view of this, the present application provides a method for constructing a single-wavelength beam thickness measurement calibration library based on a polishing process, comprising:

[0005] During the polishing process of the wafer film, the thickness of the wafer film is measured in situ using a multi-wavelength light beam, and an electrical signal corresponding to the light intensity of the reflected light of the wafer film to the single-wavelength light beam is obtained at multiple different thicknesses;

[0006] Based on the periodicity of the electrical signal as the wafer film thickness changes and the values ​​of the electrical signals corresponding to the multiple different thicknesses, a calibration library for measuring the wafer film thickness during the polishing process is determined.

[0007] Optionally, the relationship between the electrical signal and the thickness of the wafer film is a quasi-sinusoidal function relationship.

[0008] Optionally, determining a calibration library for measuring wafer film thickness during the polishing process includes:

[0009] A corresponding relationship model between the electrical signal and the thickness is determined using at least two different thicknesses and corresponding electrical signal values.

[0010] Optionally, obtaining an electrical signal corresponding to the light intensity of the reflected light of the wafer thin film to the single-wavelength light beam at multiple different thicknesses includes:

[0011] 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;

[0012] The electrical signal is collected when the thickness of the wafer film is within the sampling range.

[0013] Optionally, obtaining an electrical signal corresponding to the light intensity of the reflected light of the wafer thin film to the single-wavelength light beam at multiple different thicknesses includes:

[0014] collecting the electrical signal in real time as the thickness of the wafer film changes;

[0015] The collected electrical signal is monitored for at least two extreme values ​​appearing in sequence, and the electrical signal between the at least two extreme values ​​is an electrical signal of at least half a cycle.

[0016] Optionally, after determining the calibration library for measuring the thickness of the wafer film during the polishing process, the method further includes:

[0017] The calibration library is converted into a calibration library suitable for a water-deficient multilayer membrane environment using a conversion coefficient.

[0018] The present application also provides a method for measuring the thickness of a wafer film based on a single-wavelength light beam, comprising:

[0019] During the polishing process of the wafer film, determining the starting thickness of the wafer film when single-wavelength beam measurement is enabled, and then starting to monitor the electrical signal corresponding to the light intensity of the reflected light of the wafer film to the single-wavelength beam;

[0020] The thickness of the wafer film is determined using the calibration library constructed using the above method, the value of the monitored electrical signal, and the starting thickness.

[0021] Optionally, when the calibration library is a correspondence model between electrical signals and thicknesses, determining the thickness of the wafer film includes:

[0022] Substituting the monitored electrical signal into the corresponding relationship model to calculate the corresponding periodic thickness result;

[0023] The thickness of the wafer film is determined according to the initial thickness and the periodic thickness result.

[0024] Optionally, when the calibration library includes values ​​of electrical signals and corresponding thicknesses for more than one cycle, determining the thickness of the wafer film includes:

[0025] The calibration library is searched for data that matches the monitored electrical signal, and the thickness of the wafer film is inverted in combination with the starting thickness.

[0026] Optionally, when the calibration library includes values ​​of electrical signals and corresponding thicknesses for less than one cycle, determining the thickness of the wafer film includes:

[0027] Determining whether there is data in the calibration library that matches the monitored electrical signal;

[0028] When data matching the monitored electrical signal exists in the calibration library, the corresponding thickness is obtained, and the thickness of the wafer film is inverted based on the starting thickness;

[0029] When there is no data consistent with the monitored electrical signal in the calibration library, one cycle of data is obtained based on data less than one cycle to obtain data consistent with the monitored electrical signal, and the thickness of the wafer film is inverted based on the starting thickness.

[0030] Accordingly, the present application provides a single-wavelength beam thickness measurement calibration library construction device based on the polishing process, 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 to enable the processor to execute the above-mentioned single-wavelength beam thickness measurement calibration library construction method based on the polishing process.

[0031] Accordingly, the present application provides a device for measuring the thickness of a wafer thin film based on a single-wavelength light beam, comprising: a processor and a memory connected to the processor; wherein the memory stores instructions that can be executed by the processor, and the instructions are executed by the processor to enable the processor to execute the above-mentioned method for measuring the thickness of a wafer thin film based on a single-wavelength light beam.

[0032] The calibration library construction method and equipment provided in the present application use the spectral data of the wafer film's reflected light from a multi-wavelength light beam to obtain the thickness during the wafer film polishing process. A single-wavelength light beam is used to irradiate the wafer film surface at multiple different thicknesses in this measurement environment to obtain an electrical signal corresponding to the light intensity of the reflected light. Since the thickness value and the electrical signal are obtained in an actual measurement environment, the calibration library of the thickness value and the electrical signal obtained can be accurately applied to this measurement environment.

[0033] The wafer film thickness measurement method and equipment provided in the present application record the current thickness when single-wavelength beam measurement is enabled, and then start to obtain electrical signals based on the single-wavelength beam measurement method. The data consistent with the electrical signals measured by the single-wavelength beam is queried in the calibration library established during the polishing process. Combined with the recorded starting thickness, the absolute thickness of the wafer film can be obtained. Moreover, since the environment in which the calibration library is established is the same as that in which the thickness is measured, the measurement results obtained are more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0035] Figure 1 This is a data schematic diagram of a calibration library construction method in an embodiment of the present application;

[0036] Figure 2 This is a data schematic diagram of another calibration library construction method in an embodiment of the present application;

[0037] Figure 3 This is a data diagram of the third calibration library construction method in the embodiment of this application. DETAILED DESCRIPTION

[0038] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0039] 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.

[0040] An embodiment of the present invention provides a method for constructing a single-wavelength beam thickness measurement calibration library based on a polishing process, which can be executed by an electronic device such as a computer or a server, and includes the following operations:

[0041] S1, during the wafer film polishing process, the thickness of the wafer film is measured in situ using a multi-wavelength beam, and the electrical signal corresponding to the light intensity of the wafer film reflected by the single wavelength beam is obtained at multiple different thicknesses.

[0042] The wafer film can specifically be a silicon dioxide layer on the surface of a silicon-based wafer. During the polishing process, the wafer film is subjected to external forces, gradually reducing its thickness. During this process, the spectral information of a multi-wavelength light beam is used to measure the thickness in situ during the polishing process.

[0043] Multi-wavelength beam online in-situ measurement specifically refers to the use of a multi-wavelength light source to emit multi-wavelength beams in a polishing process environment, collect multi-wavelength reflected light from the surface of the wafer film, and obtain 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. The thickness value corresponding to the reference spectrum that matches the measured spectral data is the current thickness value of the wafer film.

[0044] In this measurement environment, a light source emitting single-wavelength light is used to emit light to the surface of the wafer film. The incident light can be perpendicular to the surface of the wafer film or obliquely incident on the surface of the wafer film at a certain angle. The photoelectric sensor receives the reflected light from the wafer surface and converts it into an analog electrical signal. After optional processing such as analog-to-digital conversion, filtering, and amplification, a digital electrical signal is obtained.

[0045] The thickness of the wafer film affects the intensity of the reflected light, which in turn affects the value of the digital electrical signal. Measurements at different thicknesses reveal that the electrical signal exhibits periodic variations as the thickness changes.

[0046] Furthermore, as a preferred embodiment, the same device is used to provide both single-wavelength and multi-wavelength beams. In this embodiment, a calibration library for the device is obtained. When subsequently measuring using a multi-wavelength beam and this calibration library, the device's state remains consistent with that during calibration, resulting in more accurate measurement results.

[0047] S2, based on the periodicity of the electrical signal as the wafer film thickness changes and the values ​​of the electrical signals corresponding to multiple different thicknesses, determine the calibration library for measuring the wafer film thickness during the polishing process.

[0048] In one embodiment, the calibration library is a mathematical model. Since the corresponding relationship between the electrical signal and the thickness is known, but the parameters involved are unknown, the complete corresponding relationship model can be obtained by solving the values ​​of the parameters in the relationship.

[0049] As an example, Figure 1The relationship between the electrical signal and the thickness of the wafer film is a quasi-sinusoidal function relationship, where the horizontal axis is the thickness of the wafer film and the vertical axis is the voltage (the value of the electrical signal). As the thickness of the wafer film changes (the thickness changes in the direction of the arrow in the figure), the voltage changes between the minimum value Umin and the maximum value Umax, presenting a quasi-sinusoidal curve.

[0050] The corresponding relationship between voltage signal and thickness can be expressed by a mathematical model, for example ,in is the value of the electrical signal (voltage value), is the thickness, a is the amplitude of the electrical signal, is the angular frequency. It is related to the wavelength of the light source, the material of the film, and the angle of incidence, and has the following relationship:

[0051] ;

[0052] in is the wavelength of incident light, is the refractive index of the wafer film, is the angle of incidence. These parameters are all known quantities, so the angular frequency are known parameters.

[0053] In this embodiment, the coefficient and The values ​​of the two unknown quantities are unknown. In this embodiment, only two different thicknesses and corresponding electrical signal values ​​are needed to calculate the values ​​of the two unknown quantities. That is, the corresponding relationship model between the electrical signal and the thickness is determined using at least two different thicknesses and corresponding electrical signal values.

[0054] When there are only two unknowns in the mathematical expression model, the values ​​of the electrical signals at two thicknesses are collected in step S1, for example Figure 1 By using the voltage Ua corresponding to thickness da and the voltage Ub corresponding to thickness db, all parameters in the mathematical expression model for the correspondence between the electrical signal and the wafer thin film can be solved. Alternatively, the electrical signal values ​​at more thicknesses can be collected, and the values ​​of all parameters can be obtained by averaging, etc., thereby determining the correspondence model between the electrical signal and thickness. If there are more unknown quantities in the mathematical expression model, the corresponding relationship model can also be determined by sampling an appropriate number of thicknesses and electrical signals and solving for the unknown quantities based on the principles of this embodiment.

[0055] In some embodiments, the periodic variation of the electrical signal may not be expressed by a mathematical model, or the calibration library calculated based on the mathematical model may not be accurate due to factors such as the measurement environment. To address this, two methods can be used to construct a calibration library:

[0056] The first construction method is to determine the period of the electrical signal in advance, and determine the sampling range in step S1 according to the period of the electrical signal, and the sampling range is greater than or equal to half a period; when the thickness of the wafer film is within the sampling range, the electrical signal corresponding to the single wavelength reflected light is collected. Figure 2 For example, given a period of T, in this embodiment, the sampling range is at least T / 2, as shown in the figure: dc-dd ≥ T / 2. For example, assuming a period of T = 220nm, the sampling range is at least 110nm. The specific sampling range can be any one or more of [700nm, 590nm], [500nm, 390nm], [450nm, 340nm], and so on. When the wafer film thickness enters the sampling range (the thickness changes according to the arrow in the figure), the electrical signal corresponding to each thickness is collected. That is, when the thickness reaches dc, electrical signal collection begins, and the electrical signal corresponding to dc is Uc... until the thickness reaches dd, and the electrical signal corresponding to Ud, obtaining all data between points c and d in the figure. After obtaining electrical signals for at least half a period, based on the periodic law, the corresponding data of any thickness range and electrical signals can be obtained as a calibration library.

[0057] The second construction method is to determine the period of the electrical signal based on continuous sampling data without predetermining the period, and simultaneously obtain the electrical signal value corresponding to the thickness of at least half a period. In step S1, the electrical signal corresponding to the single wavelength reflected light is collected in real time as the thickness of the wafer film changes. The collected electrical signal is monitored for the occurrence of at least two extreme values ​​in sequence, and the electrical signal between the at least two extreme values ​​is at least half a period of the electrical signal.

[0058] by Figure 3 For example, when the initial thickness is de, the corresponding voltage is Ue (the thickness changes according to the arrow in the figure). When the maximum value Umax and the minimum value Umin are detected successively, the difference between the thicknesses df and dg corresponding to these two extreme values ​​is half a cycle T / 2 of the electrical signal; it is also possible to obtain data for the entire cycle when two maximum values ​​Umax or two minimum values ​​Umin are detected.

[0059] 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 angle of incidence, and determines the sampling range based on this, so as to accurately collect less data during sampling and quickly complete the establishment of the calibration library; the second construction method measures the period size of the electrical signal in real time during the wafer polishing process, and the calibration library obtained based on the measurement results is more reliable.

[0060] Due to the periodicity of electrical signals, if at least half a period (the period is the thickness value) of the electrical signal is known, the corresponding electrical signal value at any thickness can be obtained. For example, assuming the electrical signal period is 220nm, and the electrical signal corresponding to half a period [500nm, 390nm] is currently obtained, a calibration library for any thickness range can be established based on this thickness range and its corresponding electrical signal value. For example, if the thickness range to be measured is [0, 200nm], then 200nm corresponds to 420nm (420nm within the sampling range minus the period of 220nm equals 200nm). The electrical signal value at 200nm is equal to the electrical signal value at 420nm. According to this correspondence, the electrical signal value corresponding to any thickness range can be obtained.

[0061] It should be noted that in the above example, the size of the thickness range to be measured exceeds half a period, while the size of the sampling range is only half a period. According to the symmetry of the periodic law, the data of the other half period can be inferred based on the sampling range of half a period, or the sampling range can be directly set to the size of one period.

[0062] In some embodiments, it is necessary to clean the surface of the wafer film after the polishing process is completed, mainly to remove the liquid remaining on the surface. After cleaning, the thickness of the wafer film needs to be measured again. Specifically, during the polishing process, it is necessary to add polishing liquid to the surface of the wafer and 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. The above-mentioned calibration library is established in this complex environment, and after cleaning, the water (polishing liquid or grinding liquid and water) on the surface of the wafer is removed, resulting in a change in the environment. The above-mentioned calibration library applicable to the multilayer film environment is no longer applicable to the environment after cleaning the water, and errors will occur when it is used to measure the film thickness in this state. For this reason, this embodiment also includes the following operations after the above-mentioned step S2:

[0063] S3, using the conversion coefficient to convert the calibration library into a calibration library suitable for a water-deficient multilayer film environment. Based on the corresponding relationship curve formed by the change of the electrical signal with the thickness value, it is found that compared with the corresponding relationship curve of the electrical signal and thickness in the environment with water on the surface, the corresponding relationship curve of the electrical signal and thickness in the water-deficient multilayer film environment is compressed or stretched, and the curve as a whole is raised or lowered. In this embodiment, the above corresponding relationship is determined to be

[0064] ;

[0065] in, Indicates the electrical signal in the calibration library applicable to a multilayer film environment with water (the electrical signal before conversion). and is the conversion factor, The electrical signal (converted electrical signal) in the calibration library for the multi-layer membrane environment with water shortage is shown in this step. and Process the electrical signals in the calibration library.

[0066] Furthermore, the conversion coefficient can be adjusted as follows: and To perform calibration:

[0067] S01, obtain the electrical signal corresponding to the light intensity of the reflected light of a single wavelength beam from two wafer films of known different thicknesses in a water-deficient multilayer film environment and electrical signals The two wafer films having different known thicknesses refer to the fact that the thicknesses of the two wafer films are both known information and are not equal.

[0068] S02, obtaining the electrical signal corresponding to the light intensity of the reflected light of the single wavelength beam from the two wafer thin films in a water-deficient multilayer film environment and electrical signals The measurement object is the same as that in step S01, except for the multilayer film environment.

[0069] S03, according to the electrical signal ,electric signal ,electric signal and electrical signals Determine the conversion coefficient. Based on the corresponding relationship between the signal in the multilayer film environment with water and the signal in the multilayer film environment without water, the value of the conversion coefficient can be calculated by solving the equation:

[0070] ;

[0071] It should be noted that the above steps S01 and S02 can be performed in an experimental environment or in the actual measurement environment of step S1. For example, in step S1, the thickness of the wafer film in a multi-layer film environment is measured using a multi-wavelength beam. Step S02 is performed at two arbitrary thicknesses. Then, the wafer film is placed in a water-deficient multi-layer film environment (to clean the polishing liquid and water on the surface) and step S01 is performed. By sequentially providing the multi-layer film environment with water and the water-deficient environment at the two thicknesses during the polishing process, the conversion coefficient can be calibrated.

[0072] Based on the above calibration library, an embodiment of the present application provides a method for measuring wafer thin film thickness based on a single-wavelength beam. The method is performed by an electronic device such as a computer or a server, and includes the following operations:

[0073] During the polishing process of the wafer film, determining the starting thickness of the wafer film when single-wavelength beam measurement is enabled, and then starting to monitor the electrical signal corresponding to the light intensity of the reflected light of the wafer film to the single-wavelength beam;

[0074] The wafer film thickness is determined using a calibration library established during the polishing process, the monitored electrical signal values, and the starting thickness. Specifically, due to the periodic nature of the electrical signal, obtaining only the electrical signal value yields only periodic thickness values, not a unique absolute thickness result. To achieve a unique result, this embodiment requires determining the absolute thickness value at the time this method is activated. This can be achieved using multi-wavelength beam measurement.

[0075] If the calibration library is a correspondence model, the monitored electrical signal is substituted into the correspondence model to calculate the corresponding periodic thickness result; the thickness of the wafer film is determined based on the starting thickness and the periodic thickness result.

[0076] For example, the corresponding relationship model is Assuming that the starting thickness when single-wavelength beam measurement is enabled is t0 and the value of the electrical signal is U0, it is equivalent to determining a starting point in the curve corresponding to this model. After that, the polishing process causes the thickness to change in a smaller direction. Then, the electrical signal U1 obtained at the next moment is substituted into the model. In the corresponding periodic thickness, the thickness value closest to but less than t0 is the absolute thickness value at this moment. Continuous monitoring in this way can obtain a unique result.

[0077] If the calibration library contains the values ​​of the electrical signal and the corresponding thickness for more than one cycle, the data that matches the monitored electrical signal is searched in the calibration library, and the thickness of the wafer film is inverted in combination with the starting thickness.

[0078] As an example, the calibration library has the following data:

[0079] Thickness dn, voltage Un;

[0080] Thickness dn-1, voltage Un-1;

[0081] …

[0082] Thickness d0, voltage U0.

[0083] The thicknesses d0 to dn exceed the period t of the electrical signal.

[0084] For example, the period of the electrical signal is 220nm, the calibration library is [280nm, 500nm] and its corresponding electrical signal U 280 ...U 500, the starting thickness di is 200nm. For this measurement scenario, it can be known that di plus 1 cycle falls into the thickness range of the calibration library, that is, 200nm+220nm=420nm, 420nm falls into [280nm, 500nm]; when the next detected electrical signal is U i+1 When querying the calibration library, i+1 The same electrical signal value corresponds to a thickness of 419.9 nm, and then subtracting 1 cycle to get the value when the electrical signal is U i+1 The corresponding thickness is 199.9 nm. By continuously monitoring in this way, a unique result can be obtained in real time.

[0085] For example, the calibration library is [0nm, 1000nm] and its corresponding electrical signals U0...U 1000 , the initial thickness di is 200nm, when the next detected electrical signal is U i+1 When querying the calibration library, i+1 Equal electrical signal value, at this time, the calibration library can be queried to find the same i+1 The same multiple electrical signal values ​​correspond to different thicknesses, and the thickness closest to 200nm, 199.9nm, is the measurement result at the current moment. By continuously monitoring in this way, a unique result can be obtained in real time.

[0086] If the calibration library contains values ​​of electrical signals less than one cycle and corresponding thicknesses, it is determined whether there is data in the calibration library that matches the monitored electrical signals.

[0087] When there is data in the calibration library that matches the monitored electrical signal, the corresponding thickness is obtained, and the thickness of the wafer film is inverted based on the starting thickness. This situation is the same as the calibration library situation with more than one cycle mentioned above, and the thickness value can be directly obtained.

[0088] If the calibration library does not contain data that matches the monitored electrical signal, the data from less than one cycle is used to obtain a cycle of data to obtain data that matches the monitored electrical signal, and the wafer film thickness is inverted based on the starting thickness. In this case, it is necessary to first complete the calibration library, that is, to add a full cycle of data or a specific range of data based on the symmetry of the data, and then obtain the thickness value using the above method.

[0089] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. 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 magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0090] 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 flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, 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 flowcharts and / or block diagrams. 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.

[0091] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work 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 The function specified in one or more boxes.

[0092] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0093] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A method for measuring wafer film thickness based on a single wavelength beam, characterized in that: include: During the polishing process of the wafer film, determining the starting thickness of the wafer film when single-wavelength beam measurement is enabled, and then starting to monitor the electrical signal corresponding to the light intensity of the reflected light of the wafer film to the single-wavelength beam; Determining the thickness of the wafer film using the constructed calibration library, the value of the monitored electrical signal, and the starting thickness, wherein constructing the calibration library specifically comprises: measuring the thickness of the wafer film in situ online using a multi-wavelength light beam during the polishing process of the wafer film, and obtaining electrical signals corresponding to the light intensity of the reflected light of the wafer film to the single-wavelength light beam at multiple different thicknesses; Determining a calibration library for measuring the thickness of a wafer film during the polishing process based on the periodicity of the electrical signal as the thickness of the wafer film changes and the values ​​of the electrical signals corresponding to the multiple different thicknesses, further comprising: using at least two different thicknesses and the corresponding electrical signal values ​​to determine a correspondence model between the electrical signal and the thickness as the calibration library; Alternatively, a sampling range is determined according to a period of the electrical signal, the sampling range being greater than or equal to half the period, and the electrical signal is collected when the thickness of the wafer film is within the sampling range, thereby obtaining corresponding data of any thickness range and the electrical signal as the calibration library; Alternatively, the electrical signal is collected in real time as the thickness of the wafer film changes, and it is monitored whether at least two extreme values ​​appear in sequence in the collected electrical signal, and the electrical signal between the at least two extreme values ​​is an electrical signal of at least half a cycle, thereby obtaining corresponding data of any thickness range and electrical signal as the calibration library.

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

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

4. The method according to claim 1, wherein When the calibration library is a correspondence model between electrical signals and thickness, determining the thickness of the wafer film includes: Substituting the monitored electrical signal into the corresponding relationship model to calculate the corresponding periodic thickness result; The thickness of the wafer film is determined according to the initial thickness and the periodic thickness result.

5. The method according to claim 1, characterized in that When the calibration library includes values ​​of electrical signals and corresponding thicknesses for more than one cycle, determining the thickness of the wafer film includes: The calibration library is searched for data that matches the monitored electrical signal, and the thickness of the wafer film is inverted in combination with the starting thickness.

6. The method according to claim 1, characterized in that When the calibration library includes values ​​of electrical signals and corresponding thicknesses for less than one cycle, determining the thickness of the wafer film includes: Determining whether there is data in the calibration library that matches the monitored electrical signal; When data matching the monitored electrical signal exists in the calibration library, the corresponding thickness is obtained, and the thickness of the wafer film is inverted based on the starting thickness; When there is no data consistent with the monitored electrical signal in the calibration library, one cycle of data is obtained based on data less than one cycle to obtain data consistent with the monitored electrical signal, and the thickness of the wafer film is inverted based on the starting thickness.

7. A device for measuring the thickness of a wafer film based on a single wavelength beam, characterized in that: include: 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 to enable the processor to perform the method for measuring the thickness of a wafer film based on a single wavelength light beam as described in any one of claims 1 to 6.

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