Calibration method and device for eddy current sensor, thickness measurement method and device and chemical mechanical polishing equipment

Abstract

The invention provides a calibration method and device for an eddy current sensor, a thickness measurement method and device and chemical mechanical polishing equipment, and the method comprises the steps: obtaining a first excitation signal generated by a signal source of the eddy current sensor before the chemical mechanical polishing of a wafer; in the chemical mechanical polishing process of the wafer, a second excitation signal generated by the signal source of the eddy current sensor is obtained, and a wafer signal collected by the eddy current sensor is obtained; correcting the wafer signal according to the first excitation signal and the second excitation signal to obtain a corrected wafer signal; and establishing a mapping relation between calibration information determined according to the corrected wafer signal and a predetermined wafer thickness so as to calibrate the eddy current sensor. According to the scheme, the accuracy of the metal film thickness measured by the eddy current sensor is improved.

Description

[0001] This application is a divisional application of the invention patent application filed on November 13, 2024 with application number 202411612206X. Technical Field

[0002] The present application relates to the technical field of wafer polishing, and in particular to a calibration method for an eddy current sensor, a thickness measurement method and device, and a chemical mechanical polishing device. Background Art

[0003] During the wafer manufacturing process, chemical mechanical polishing (CMP) is used to planarize the surface of the metal film on the wafer. The chemical mechanical polishing can be achieved by chemical mechanical polishing equipment.

[0004] During the process of CMP on the wafer by the chemical mechanical polishing equipment, the chemical mechanical polishing equipment will drive the wafer so that its metal film abuts against the polishing pad, and drive the wafer to move relative to the polishing pad with polishing liquid supplied on the surface, so as to polish the metal film of the wafer. In addition, during the process of CMP on the wafer by the chemical mechanical polishing equipment, an eddy current sensor is also provided on the side of the polishing pad away from the wafer. When the thickness of the metal film of the wafer opposite to the eddy current sensor in the direction perpendicular to the polishing pad changes, the output signal of the eddy current sensor will also change. Therefore, after obtaining the output signal of the eddy current sensor, the calibration information can be determined according to the output signal, and then the metal film thickness of the wafer currently undergoing CMP can be determined according to the correspondence between the predetermined calibration information and the metal film thickness.

[0005] However, the output signal of the eddy current sensor is generated according to the signal generated by the signal source of the eddy current sensor, that is, the signal source of the eddy current sensor causes the coil of the eddy current sensor to generate an alternating electromagnetic field, and the alternating electromagnetic field causes the eddy current sensor to generate an output signal. However, the chemical mechanical polishing environment is complex and has a great impact on the eddy current sensor. For example, after the chemical mechanical polishing equipment has been used for a period of time, the eddy current sensor itself ages, the polishing environment temperature affects the coil, and the polishing liquid affects the coil, etc., which will cause the calibration information determined according to the output signal of the eddy current sensor to change and the corresponding relationship between the metal film thickness. At this time, the actual corresponding relationship between the calibration information and the metal film thickness varies greatly relative to the predetermined corresponding relationship; in addition, the temperature of the chemical mechanical polishing process itself, the polishing liquid conditions, etc. will affect the measurement results of the eddy current sensor. Therefore, the accuracy of the metal film thickness measured by the eddy current sensor is currently poor. Summary of the invention

[0006] In view of this, the present application provides a calibration method, a thickness measurement method and device for an eddy current sensor, and a chemical mechanical polishing device to at least partially solve the above-mentioned problems.

[0007] According to a first aspect of the present application, a calibration method for an eddy current sensor is provided, comprising: before chemical mechanical polishing of a wafer, obtaining a first excitation signal generated by a signal source of the eddy current sensor; during chemical mechanical polishing of the wafer, obtaining a second excitation signal generated by the signal source of the eddy current sensor, and obtaining a wafer signal collected by the eddy current sensor; correcting the wafer signal according to the first excitation signal and the second excitation signal to obtain a corrected wafer signal; and establishing a mapping relationship between calibration information determined according to the corrected wafer signal and a predetermined wafer thickness to calibrate the eddy current sensor.

[0008] According to a second aspect of the present application, a thickness measurement method is provided, comprising: determining a mapping relationship between multiple wafer thicknesses and their respective corresponding calibration information based on the method described in the first aspect above; obtaining a first excitation signal generated by a signal source of the eddy current sensor before the chemical mechanical polishing device performs chemical mechanical polishing on the wafer; obtaining a second excitation signal generated by the signal source of the eddy current sensor during the process of the chemical mechanical polishing device performing chemical mechanical polishing on the wafer, and obtaining a wafer signal collected by the eddy current sensor; correcting the wafer signal according to the first excitation signal and the second excitation signal to obtain a corrected wafer signal; determining calibration information according to the corrected wafer signal; and determining the wafer thickness according to the calibration information and the mapping relationship.

[0009] According to a third aspect of the present application, a calibration device for an eddy current sensor is provided, comprising: a first acquisition unit, used to acquire a first excitation signal generated by a signal source of the eddy current sensor before chemical mechanical polishing of a wafer; a second acquisition unit, used to acquire a second excitation signal generated by the signal source of the eddy current sensor during chemical mechanical polishing of the wafer, and to acquire a wafer signal collected by the eddy current sensor; a first correction unit, used to correct the wafer signal according to the first excitation signal and the second excitation signal to obtain a corrected wafer signal; and a relationship determination unit, used to establish a mapping relationship between calibration information determined according to the corrected wafer signal and a predetermined wafer thickness, so as to calibrate the eddy current sensor.

[0010] According to a fourth aspect of the present application, a thickness measuring device is provided, comprising: a relationship acquisition unit, for determining a mapping relationship between a plurality of wafer thicknesses and respective corresponding calibration information based on the method described in the first aspect above; a third acquisition unit, for acquiring a first excitation signal generated by a signal source of the eddy current sensor before the chemical mechanical polishing device performs chemical mechanical polishing on the wafer; a fourth acquisition unit, for acquiring a second excitation signal generated by the signal source of the eddy current sensor during the process of the chemical mechanical polishing device performing chemical mechanical polishing on the wafer, and acquiring a wafer signal collected by the eddy current sensor; a second correction unit, for correcting the wafer signal according to the first excitation signal and the second excitation signal to obtain a corrected wafer signal; an information determination unit, for determining calibration information according to the corrected wafer signal; and a thickness determination unit, for determining the wafer thickness according to the calibration information and the mapping relationship.

[0011] According to a fifth aspect of the present application, a chemical mechanical polishing device is provided, comprising: a polishing disk, a carrier head, a liquid supply device, an eddy current sensor and a controller; a polishing pad is provided on one side of the polishing disk; the carrier head is used to limit the position of a wafer to be polished so that a metal film provided on a circular surface of the wafer abuts against the polishing pad and drives the wafer to move relative to the polishing pad to perform chemical mechanical polishing on the wafer; the liquid supply device is used to supply polishing liquid to the polishing pad during the process of chemical mechanical polishing of the wafer; the eddy current sensor is provided on the polishing disk and is used to measure the thickness of the wafer. The controller is used to perform the following processing: before chemical mechanical polishing of the wafer, obtain a first excitation signal generated by the signal source of the eddy current sensor; during the chemical mechanical polishing of the wafer, obtain a second excitation signal generated by the signal source of the eddy current sensor, and obtain a wafer signal collected by the eddy current sensor; according to the first excitation signal and the second excitation signal, correct the wafer signal to obtain a corrected wafer signal; establish a mapping relationship between the calibration information determined according to the corrected wafer signal and a predetermined wafer thickness to calibrate the eddy current sensor.

[0012] According to a sixth aspect of the present application, a chemical mechanical polishing device is provided, comprising: a polishing disc, a carrier head, a liquid supply device, an eddy current sensor and a controller; a polishing pad is provided on one side of the polishing disc; the carrier head is used to limit the position of a wafer to be polished so that a metal film provided on a circular surface of the wafer abuts against the polishing pad and drives the wafer to move relative to the polishing pad to perform chemical mechanical polishing on the wafer; the liquid supply device is used to supply polishing liquid to the polishing pad during the process of chemical mechanical polishing of the wafer; the eddy current sensor is provided on the polishing disc and is used to measure the thickness of the wafer; the controller is used to perform the following processing: based on the first aspect of the present application, The method described in the aspect determines the mapping relationship between multiple wafer thicknesses and their corresponding calibration information; before the chemical mechanical polishing equipment performs chemical mechanical polishing on the wafer, obtains a first excitation signal generated by the signal source of the eddy current sensor; during the process of the chemical mechanical polishing equipment performing chemical mechanical polishing on the wafer, obtains a second excitation signal generated by the signal source of the eddy current sensor, and obtains a wafer signal collected by the eddy current sensor; according to the first excitation signal and the second excitation signal, corrects the wafer signal to obtain a corrected wafer signal; determines the calibration information according to the corrected wafer signal; and determines the wafer thickness according to the calibration information and the mapping relationship.

[0013] According to a seventh aspect of the present application, a computer storage medium is provided, on which a computer program is stored. When the program is executed by a processor, the method described in the first aspect or the method described in the second aspect is implemented.

[0014] According to an eighth aspect of the present application, a computer program product is provided, comprising computer instructions, wherein the computer instructions instruct a computing device to execute the method described in the first aspect or the method described in the second aspect.

[0015] According to the calibration scheme for eddy current sensors provided in the present application, before chemical mechanical polishing of the wafer is performed, a first excitation signal generated by a signal source of the eddy current sensor is obtained, and during chemical mechanical polishing of the wafer, a second excitation signal generated by the signal source of the eddy current sensor is obtained, and a wafer signal collected by the eddy current sensor is obtained, and then the wafer signal is corrected according to the first excitation signal and the second excitation signal to obtain a corrected wafer signal, and then a mapping relationship between calibration information determined according to the corrected wafer signal and a predetermined wafer thickness is established to calibrate the eddy current sensor. Therefore, compared with obtaining calibration information directly based on the wafer signal, the calibration information is obtained based on the corrected wafer signal in the present application. The corrected wafer signal is corrected based on the first excitation signal and the second excitation signal. The first excitation signal and the second excitation signal are respectively signals generated by the signal source before and during chemical mechanical polishing of the wafer. The signal generated by the signal source is a signal that causes the coil of the eddy current sensor to generate an alternating electromagnetic field. Based on this, the corrected wafer signal takes into account the first excitation signal and the second excitation signal generated by the signal source that are almost unaffected by the temperature, polishing liquid, coil and aging of the eddy current sensor of chemical mechanical polishing, so that the aging of the eddy current sensor itself, the influence of the polishing environment temperature on the coil and the influence of the polishing liquid on the coil and other factors have less interference with the corrected wafer signal. Furthermore, in the actual chemical mechanical polishing process of the chemical mechanical polishing equipment, the actual mapping relationship between the calibration information obtained according to the corrected wafer signal and the thickness of the wafer is less changed than the mapping relationship in the present application. Therefore, the accuracy of the metal film thickness measured by the eddy current sensor is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the present application or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0017] Figure 1 is a schematic diagram of a chemical mechanical polishing device according to an embodiment of the present application;

[0018] Figure 2 is a flow chart of a calibration method for an eddy current sensor according to an embodiment of the present application;

[0019] Figure 3 is a flow chart of a thickness measurement method according to an embodiment of the present application;

[0020] Figure 4is a schematic diagram of a working state of a chemical mechanical polishing device according to an embodiment of the present application;

[0021] Figure 5 is a schematic diagram of trajectory information of an embodiment of the present application;

[0022] Figure 6 is a signal schematic diagram of the related technology;

[0023] Figure 7 is a signal diagram of an embodiment of the present application;

[0024] Figure 8 is a schematic diagram of a calibration device for an eddy current sensor according to an embodiment of the present application;

[0025] Fig. 9 Schematic diagram of a thickness measuring device according to an embodiment of the present application. DETAILED DESCRIPTION

[0026] The present application provides a calibration method for an eddy current sensor, which can be applied to a controller or processor in a chemical mechanical polishing device, or to a controller or processor included in a test bench. The test bench is a relatively simple test bench built according to the working principle of the chemical mechanical polishing device, and the present application does not limit this. Through this method, the eddy current sensor can be calibrated during the chemical mechanical polishing of a wafer by the chemical mechanical polishing device or the test bench.

[0027] Figure 1 Schematic diagram of a chemical mechanical polishing device according to an embodiment of the present application. Figure 1As shown, the chemical mechanical polishing equipment is used to perform chemical mechanical polishing on the wafer, specifically, to perform chemical mechanical polishing on the metal film arranged on a circular surface of the wafer, that is, the metal film is the polishing object, and the chemical mechanical polishing equipment includes: a polishing disc 1, a carrying head 2, a liquid supply device, an eddy current sensor 3 and a controller; a circular pad-shaped polishing pad 11 is arranged on one side of the polishing disc 1, and the polishing disc 1 is used to drive the polishing pad 11 to rotate around the axis of the polishing pad 11; the carrying head 2 is used to limit the wafer to be polished, so that the metal film abuts against the polishing pad 11 when the wafer is chemically mechanically polished, specifically, the metal film arranged on the wafer abuts on the side of the polishing pad 11 away from the polishing disc 1, and the carrying head 2 is also used to drive the wafer around the axis of the wafer. The polishing pad 11 is provided with a liquid supply device for supplying polishing liquid to the polishing pad 11 during chemical mechanical polishing of the wafer; the eddy current sensor 3 is arranged on the polishing disk 1 so that the eddy current sensor 3 and the wafer are respectively located on both sides of the polishing pad 11, and the eddy current sensor 3 is also driven by the polishing disk 1 to rotate around the axis of the polishing pad 11 during the process of the polishing disk 1 driving the polishing pad 11 to rotate. The eddy current sensor 3 is used to measure the thickness of the wafer, specifically to measure the thickness of the metal film arranged on the wafer; the controller is used to execute the calibration method for the eddy current sensor 3.

[0028] Optionally, whether it is a chemical mechanical polishing device or a test bench built according to the working principle of the chemical mechanical polishing device, water can be used instead of polishing liquid in the process of calibrating the eddy current sensor. That is, in the process of calibrating the eddy current sensor, chemical mechanical polishing is performed by water polishing, so that in the process of calibrating the eddy current sensor, the thickness of the wafer will not change with the polishing process, but will be consistent with the actual measured thickness, which can also save costs.

[0029] Based on the above-mentioned chemical mechanical polishing equipment and test bench (hereinafter collectively referred to as calibration equipment), the calibration method for the eddy current sensor is described in detail through multiple embodiments.

[0030] Figure 2 FIG. 1 is a flow chart of a calibration method for an eddy current sensor according to an embodiment of the present application. Figure 2 As shown, the calibration method for the eddy current sensor includes the following steps:

[0031] Step 201: Before chemical mechanical polishing of a wafer, a first excitation signal generated by a signal source of an eddy current sensor is obtained.

[0032] In a specific embodiment, after the eddy current sensor included in the calibration device is powered on and before the calibration device performs chemical mechanical polishing on the wafer, a first excitation signal generated by a signal source included in the eddy current sensor at any time is obtained.

[0033] For example, before the calibration equipment performs chemical mechanical polishing on the wafer, the eddy current sensor is powered on first. After a period of time, the signal generated by the signal source of the eddy current sensor is obtained as the first excitation signal. The signal generated by the signal source of the eddy current sensor is the source signal in the eddy current sensor that causes the coil of the eddy current sensor to generate an alternating electromagnetic field.

[0034] Step 202 : During chemical mechanical polishing of the wafer, a second excitation signal generated by a signal source of the eddy current sensor is obtained, and a wafer signal collected by the eddy current sensor is obtained.

[0035] In a specific embodiment, during the process of chemical mechanical polishing of the wafer by the calibration equipment, the second excitation signal generated by the above-mentioned signal source at any time of the eddy current sensor is obtained, and the wafer signal output at any time when the eddy current sensor is in the first state is obtained.

[0036] Among them, in order to clarify the explanation, the first state and the second state of the eddy current sensor are added to the specification of the present application, which are only used to explain the scheme and do not limit the scope of protection of the present application. The first state is a state in which the wafer and the eddy current sensor are opposite to each other in the direction perpendicular to the polishing pad, and the second state is a state in which there is no metal object opposite to the eddy current sensor in the direction perpendicular to the polishing pad.

[0037] For example, during the process of chemical mechanical polishing of the wafer by the calibration equipment, when the polishing disk drives the polishing pad to rotate around the axis of the polishing pad, not only the signal generated by the signal source of the eddy current sensor at any time can be obtained as the second excitation signal, but also the signal output at any time when the eddy current sensor is in the first state can be obtained as the wafer signal.

[0038] Therefore, the wafer signal and its corresponding second excitation signal are both obtained in the process of the polishing disk driving the polishing pad to rotate around the axis of the polishing pad. Therefore, when the second excitation signal and the wafer signal are obtained, the difference in thickness of the metal film is small, or even the thickness of the metal film is almost unchanged. Therefore, the subsequent calibration information determined based on the second excitation signal and the wafer signal will more accurately reflect the thickness of the metal film.

[0039] Step 203 : Correct the wafer signal according to the first excitation signal and the second excitation signal to obtain a corrected wafer signal.

[0040] Step 204 , establishing a mapping relationship between calibration information determined according to the corrected wafer signal and a predetermined wafer thickness, so as to calibrate the eddy current sensor.

[0041] In a specific implementation, after obtaining the corrected wafer signal, corresponding calibration information can be determined according to the corrected wafer signal, and then a mapping relationship between the calibration information and a predetermined wafer thickness can be established to complete the calibration of the eddy current sensor.

[0042] For example, a mapping relationship is established according to calibration information corresponding to the multiple target wafers and according to the thickness of the metal films set on the multiple target wafers, and the thickness of the metal films set on at least some of the multiple target wafers is different.

[0043] The multiple target wafers may include multiple wafers provided with metal films of different thicknesses, and may also include the same wafer after the chemical mechanical polishing of each stage is completed during the process of sequentially performing multiple stages of chemical mechanical polishing on the same wafer, and the present application does not limit this. Thus, the amount of data for determining the mapping relationship can be expanded.

[0044] Based on this example, the specific process of establishing the mapping relationship can be as follows:

[0045] For each target wafer, during the process of chemical mechanical polishing performed by the calibration equipment on each target wafer, the polishing disc drives the polishing pad to rotate around the axis of the polishing pad for each rotation, so that a second excitation signal, a second base value signal and multiple wafer signals can be obtained, and the thickness of the metal film before the start of the rotation or after the completion of the rotation can also be measured. Different wafer signals are generated at different times. Through the above-mentioned calibration method for eddy current sensors, for each wafer signal, a calibration information can be determined according to the second excitation signal, the second base value signal, and the first excitation signal and the first base value signal determined before chemical mechanical polishing. Furthermore, the polishing disc drives the polishing pad to rotate around the axis of the polishing pad for each rotation, so that multiple calibration information corresponding to the target wafer can be determined. The thickness of the metal film corresponding to the multiple calibration information is the thickness of the metal film obtained by the above-mentioned measurement. According to the multiple calibration information corresponding to each target wafer and the thickness of the metal film corresponding to each calibration information, a mapping relationship can be established by creating a query table, segmented fitting or linear regression fitting.

[0046] In the present application, before chemical mechanical polishing of the wafer, a first excitation signal generated by the signal source of the eddy current sensor is obtained. During the chemical mechanical polishing of the wafer, a second excitation signal generated by the signal source of the eddy current sensor is obtained, and the wafer signal collected by the eddy current sensor is obtained. Then, based on the first excitation signal and the second excitation signal, the wafer signal is corrected to obtain a corrected wafer signal, and then a mapping relationship between the calibration information determined according to the corrected wafer signal and the predetermined wafer thickness is established to calibrate the eddy current sensor. Therefore, compared with obtaining calibration information directly based on the wafer signal, the calibration information is obtained based on the corrected wafer signal in the present application. The corrected wafer signal is corrected based on the first excitation signal and the second excitation signal. The first excitation signal and the second excitation signal are respectively signals generated by the signal source before and during chemical mechanical polishing of the wafer. The signal generated by the signal source is a signal that causes the coil of the eddy current sensor to generate an alternating electromagnetic field. Based on this, the corrected wafer signal takes into account the first excitation signal and the second excitation signal generated by the signal source that are almost unaffected by the temperature, polishing liquid, coil and aging of the eddy current sensor of chemical mechanical polishing, so that the aging of the eddy current sensor itself, the influence of the polishing environment temperature on the coil and the influence of the polishing liquid on the coil and other factors have less interference with the corrected wafer signal. Furthermore, in the actual chemical mechanical polishing process of the chemical mechanical polishing equipment, the actual mapping relationship between the calibration information obtained according to the corrected wafer signal and the thickness of the wafer is less changed than the mapping relationship in the present application. Therefore, the accuracy of the metal film thickness measured by the eddy current sensor is improved.

[0047] In addition, the present application almost eliminates the influence of temperature on the coil and the influence of the medium on the coil, so that the design requirements for the coil are relatively low during the coil design stage, reducing the design difficulty of the eddy current sensor. The present application can also reduce the influence of the eddy current sensor's own flutter, its own temperature, polishing liquid conditions and other factors on the resolution of the eddy current sensor during use.

[0048] In a possible implementation, the calibration method for the eddy current sensor also includes the following specific processing: before chemical mechanical polishing of the wafer, obtaining a first base value signal collected by the eddy current sensor; during chemical mechanical polishing of the wafer, obtaining a second base value signal collected by the eddy current sensor.

[0049] In a specific embodiment, after the eddy current sensor is powered on and before the calibration equipment performs chemical mechanical polishing on the wafer, a first base value signal output at any time when the eddy current sensor is in the second state is obtained; during the process of the calibration equipment performing chemical mechanical polishing on the wafer, a second base value signal output at any time when the eddy current sensor is in the second state is obtained.

[0050] For example, before the calibration equipment performs chemical mechanical polishing on the wafer, the eddy current sensor is first powered on. After a period of time to stabilize the alternating electromagnetic field generated by the coil of the eddy current sensor, the signal output by the eddy current sensor at any time when it is in the second state is obtained as the first baseline signal; during the process of the calibration equipment performing chemical mechanical polishing on the wafer, while the polishing disk drives the polishing pad to rotate around the axis of the polishing pad one circle, the signal output by the eddy current sensor at any time when it is in the second state can also be obtained as the second baseline signal.

[0051] Therefore, the wafer signal and its corresponding second excitation signal and second base value signal are all obtained in the process of the polishing disk driving the polishing pad to rotate around the axis of the polishing pad. Therefore, when the second base value signal, the second excitation signal and the wafer signal are obtained, the thickness difference of the metal film is small, and the thickness of the metal film is even almost unchanged. Therefore, the subsequent calibration information determined according to the second base value signal, the second excitation signal and the wafer signal will more accurately reflect the thickness of the metal film.

[0052] Based on this, the above step 203 includes the following specific processing: determining the target correction amount according to the first excitation signal and the second excitation signal; correcting the first base value signal according to the target correction amount to obtain a corrected first base value signal; correcting the wafer signal according to the corrected first base value signal and the second base value signal to obtain a corrected wafer signal.

[0053] Therefore, the target correction amount is determined according to the first excitation signal and the second excitation signal, and the corrected first base value signal is obtained by correcting the first base value signal according to the target correction amount, and then the corrected first base value signal is determined by taking into account the change of the signal generated by the signal source before and after chemical mechanical polishing. Because the signal generated by the signal source is almost unaffected by the aging of the coil and the eddy current sensor, the corrected first base value signal is less affected by the aging of the coil and the eddy current sensor than the second base value signal obtained during the chemical mechanical polishing process. Based on this, according to the corrected first base value signal and the second base value signal The corrected wafer signal obtained by the signal corrects the interference of factors such as the aging of the eddy current sensor itself, the influence of the polishing environment temperature on the coil, and the influence of the polishing liquid on the coil on the wafer signal to obtain the corrected wafer signal. Therefore, compared with the wafer signal, the interference of the above factors on the corrected wafer signal is smaller, thereby realizing the correction of the wafer signal. In addition, since the wafer signal is corrected according to the corrected first base value signal and the second base value signal, the correction of the part of the wafer signal caused by the metal film can be reduced, so that the corrected wafer signal can more accurately reflect the thickness of the metal film.

[0054] In a possible implementation, the wafer signal is corrected according to the corrected first baseline signal and the second baseline signal to obtain a corrected wafer signal, including the following specific processing: determining the signal change amount of the wafer signal relative to the second baseline signal; determining the corrected wafer signal according to the corrected first baseline signal and the signal change amount.

[0055] Therefore, most of the signal change of the wafer signal relative to the second baseline signal is caused by the metal film. The corrected wafer signal determined by the corrected first baseline signal and signal change amount, which is almost unaffected by factors such as the aging of the eddy current sensor itself, the influence of the polishing environment temperature on the coil, and the influence of the polishing liquid on the coil, can not only reduce the interference of the above factors, but also make the corrected wafer signal more accurately reflect the thickness of the metal film.

[0056] In a possible implementation, the calibration method for the eddy current sensor further includes: determining calibration information according to the corrected wafer signal and the corrected first baseline signal.

[0057] Therefore, the calibration information not only takes into account the corrected wafer signal, but also takes into account the corrected first baseline signal, so that the part of the corrected wafer signal that is not caused by the metal film will have less interference with the calibration information, so that the thickness of the metal film can be determined more accurately according to the calibration information.

[0058] Optionally, the first excitation signal, the second excitation signal, the first base value signal, the second base value signal and the wafer signal are all AC signals. The phase and amplitude of the AC signal can more accurately reflect the change of the AC signal. Therefore, the above multiple processes can be determined by the following formula:

[0059] In a possible implementation, the formula for determining the target correction amount according to the first excitation signal and the second excitation signal is as follows:

[0060] drv_amp gaincofe =drv_amp t / drv_amp0, where drv_amp gaincofe is the first target correction value, drv_amp t is the amplitude of the second excitation signal, drv_amp0 is the amplitude of the first excitation signal;

[0061] drv_phi gaincofe =drv_phi t -drv_phi0, where drv_phi gaincofe is the second target correction, drv_phi t is the phase of the second excitation signal, drv_phi0 is the phase of the first excitation signal;

[0062] Based on this, the first base value signal is corrected according to the target correction amount, and the formula for obtaining the corrected first base value signal is as follows:

[0063] cali_amp t =base_amp0*drv_amp gaincofe , where cali_amp t is the amplitude of the first base value signal after correction, base_amp0 is the amplitude of the first base value signal;

[0064] cali_phi t =base_phi0+drv_phi gaincofe , where cali_phi t is the phase of the first base value signal after correction, and base_amp0 is the phase of the first base value signal.

[0065] In a possible implementation, the formula for determining the signal change amount of the wafer signal relative to the second base value signal is as follows:

[0066] EDDY intensity (X) = wafer_amp t *cos(wafer_phi t )-base_ampt *cos(base_phi t ),in,

[0067] EDDY intensity (X) is the first component of the signal change, wafer_amp t is the amplitude of the wafer signal, wafer_phi t is the phase of the wafer signal, base_amp t is the amplitude of the second base value signal, base_phi t is the phase of the second base value signal;

[0068] EDDY intensity (Y) = wafer_amp t *sin(wafer_phi t )-base_amp t *sin(base_phi t ),in,

[0069] EDDY intensity (Y) is the second component of the signal change.

[0070] In a possible implementation, the formula for determining the corrected wafer signal based on the corrected first base value signal and the signal variation is as follows:

[0071] wafer(X)=EDDY intensity (X)+cali_amp t *cos(cali_phi t ), wherein wafer(X) is the first signal component of the corrected wafer signal;

[0072] wafer(Y)=EDDY intensity (Y)+cali_amp t *sin(cali_phi t ), wherein wafer(Y) is the second signal component of the corrected wafer signal;

[0073] wafer_phi t (correct) = arctan(wafer(Y) / wafer(X)), where wafer_phi t (correct) is the phase of the wafer signal after correction;

[0074] wafer_amp t (correct)=wafer(X) / cos(wafer_phi t(correct)), where wafer_amp t (correct) is the phase of the wafer signal after correction.

[0075] In a possible implementation, the formula for determining the calibration information according to the corrected wafer signal and the corrected first base value signal is as follows:

[0076] Δ_phi t =wafer_phi t (correct)-cali_phi t , where Δ_phi t The first information included in the calibration information;

[0077] Δ_amp t =wafer_amp t (correct) / cali_amp t , where Δ_amp t The second information included in the calibration information.

[0078] Therefore, through the above formula, the wafer signal can be corrected from the two dimensions of signal amplitude and phase, so that the correction of the wafer signal is more accurate and comprehensive. Furthermore, the calibration information determined according to the corrected wafer signal can more accurately reflect the thickness of the metal film.

[0079] The present application provides a thickness measurement method. Figure 3 It is a flow chart of a thickness measurement method according to an embodiment of the present application.

[0080] like Figure 3 As shown, the thickness measurement method includes the following steps:

[0081] Step 301: Based on the calibration method for eddy current sensors, determine a mapping relationship between multiple wafer thicknesses and their corresponding calibration information.

[0082] Step 302: Before a chemical mechanical polishing device performs chemical mechanical polishing on a wafer, a first excitation signal generated by a signal source of an eddy current sensor is obtained.

[0083] Step 303 : During the process of chemical mechanical polishing of the wafer by the chemical mechanical polishing equipment, a second excitation signal generated by a signal source of the eddy current sensor is obtained, and a wafer signal collected by the eddy current sensor is obtained.

[0084] Step 304 : Correct the wafer signal according to the first excitation signal and the second excitation signal to obtain a corrected wafer signal.

[0085] Step 305: determine calibration information according to the corrected wafer signal.

[0086] Step 306: Determine the wafer thickness according to the calibration information and the mapping relationship.

[0087] The specific implementation of establishing the mapping relationship has been introduced above, and this application will not repeat the specific implementation of step 301 here.

[0088] The above steps 302 to 306 introduce the process of measuring the thickness of the wafer (specifically determining the thickness of the metal film set on the wafer) during the process of chemical mechanical polishing of the wafer by the chemical mechanical polishing equipment. The measurement process is an online measurement and is applied to the completed chemical mechanical polishing equipment; wherein, steps 302 to 305 are the same as the process of obtaining calibration information when establishing the above mapping relationship, and the present application will not repeat them here. In step 306, after obtaining the calibration information, the wafer thickness can be determined based on the mapping relationship by table lookup method or substitution method.

[0089] Based on this, after the mapping relationship is acquired, during the process of chemical mechanical polishing of the wafer to be measured by the chemical mechanical polishing equipment, the overall process of determining the thickness of the wafer to be measured based on the mapping relationship can be as follows:

[0090] First, based on the calibration method for eddy current sensors, at least one calibration information corresponding to the wafer to be measured is obtained, wherein different calibration information in the at least one calibration information corresponds to different generation times of wafer signals.

[0091] In a specific embodiment, during the process of chemical mechanical polishing of a wafer to be measured by a chemical mechanical polishing device, the polishing disk drives the polishing pad to rotate around the axis of the polishing pad once, and a second excitation signal, a second base value signal and multiple wafer signals can be obtained. Different wafer signals are generated at different times. Through the above-mentioned calibration method for eddy current sensors, for each wafer signal, a calibration information can be determined based on the second excitation signal, the second base value signal, and the first excitation signal and the first base value signal determined before chemical mechanical polishing. Furthermore, the number of calibration information is the same as the number of wafer signals.

[0092] Then, according to the mapping relationship, the thickness of the metal film at a position relative to the eddy current sensor in the wafer to be measured is determined when a wafer signal corresponding to each calibration information in the at least one calibration information is generated.

[0093] In a specific embodiment, when a wafer signal indicating the corresponding position of each of the at least one calibration information is generated, trajectory information of the relative position of the eddy current sensor in the wafer to be measured can be obtained, and the thickness of the corresponding metal film can be determined by a table lookup method or by substituting each of the at least one calibration information into a mapping relationship to determine the thickness of the metal film at each relative position in the trajectory information.

[0094] The trajectory information includes multiple trajectory data groups. When the polishing disc drives the polishing pad to rotate around the axis of the polishing pad, a corresponding trajectory data group can be obtained. For example, the rotation of the polishing disc driving the polishing pad around the axis of the polishing pad, the rotation of the wafer a to be measured driven by the carrier head around the axis of the wafer a to be measured, and the reciprocating movement of the wafer a to be measured driven by the carrier head along the radial direction of the polishing pad. Figure 4 As shown, based on this, the trajectory diagram corresponding to a trajectory data group of the wafer a to be measured can be as follows Figure 5 As shown by the dotted line in Figure 5 In the figure, the two dotted lines represent the two edges of the projection trajectory of the eddy current sensor in the direction perpendicular to the polishing pad. Each point in the dotted line on the wafer a to be measured represents the relative position of the wafer to be measured and the eddy current sensor when obtaining a corresponding wafer signal. The position data of the point is a trajectory data in the trajectory data group.

[0095] It should be noted that the thickness measurement method of this embodiment is implemented based on the aforementioned calibration method for eddy current sensors, and therefore has the corresponding beneficial effects of the calibration method embodiment for eddy current sensors, which will not be described in detail herein.

[0096] In addition, in the related art, the wafer calibration information is determined based on the uncorrected first base value signal and the uncorrected wafer signal. Based on this, a mapping relationship between the wafer calibration information and the thickness of the metal film can be established, and the thickness of the metal film set on the wafer to be measured is determined based on the mapping relationship. According to the related art and the technical solution in the present application, the following results can be obtained:

[0097] Figure 6 is a signal diagram of the related technology. Figure 6As shown, the solid line A is used to represent the first base value signal corresponding to the calibration information determined according to the mapping relationship and the target thickness in the related technology, the dotted line B is used to represent the first base value signal obtained when the thickness of the metal film is equal to the target thickness during the actual chemical mechanical polishing process in the related technology, the solid line C is used to represent the wafer signal corresponding to the calibration information determined according to the mapping relationship and the target thickness in the related technology, and the dotted line D is used to represent the wafer signal obtained when the thickness of the metal film is equal to the target thickness during the actual chemical mechanical polishing process in the related technology. For each directed line in the solid line A, the dotted line B, the solid line C and the dotted line D, the length of the directed line is the amplitude of the signal represented by it, and the angle between the directed line and the horizontal axis is the phase of the signal represented by it. Based on this, φ1 is used to represent the phase difference between the signal represented by the solid line A and the signal represented by the solid line C in the related technology, and φ2 is used to represent the phase difference between the signal represented by the dotted line B and the signal represented by the dotted line D in the related technology.

[0098] Figure 7 Schematic diagram of a signal of an embodiment of the present application. Figure 7 As shown, the solid line E is used to represent the first base value signal after correction corresponding to the calibration information determined according to the mapping relationship and the target thickness in this application, and the dotted line F (the dotted line F and the solid line E are Figure 7 The solid line G is used to represent the corrected wafer signal corresponding to the first base value signal obtained when the thickness of the metal film is equal to the target thickness during the actual chemical mechanical polishing process in this application. The dotted line H (the dotted line H and the solid line G are at Figure 7 φ3 is used to represent the phase difference between the signal represented by the solid line E and the signal represented by the solid line G in the related art, and φ4 is used to represent the phase difference between the signal represented by the dotted line F and the signal represented by the dotted line H in the related art.

[0099] Therefore, compared with the related art, the thickness measurement method implemented based on the above-mentioned calibration method for eddy current sensor in the present application, when measuring metal film of the same thickness, the difference between the corrected first base value signal obtained after correcting the acquired first base value signal and the first base value signal determined according to the mapping relationship is smaller, and the difference between the corrected wafer signal obtained after correcting the acquired wafer signal and the wafer signal determined according to the mapping relationship is smaller, thereby improving the accuracy of the metal film thickness measured by the eddy current sensor.

[0100] Corresponding to the above-mentioned calibration method embodiment for eddy current sensor, Figure 8 A schematic diagram of a calibration device for an eddy current sensor according to an embodiment of the present application is shown. Figure 8 As shown, the calibration device 800 for the eddy current sensor includes:

[0101] A first acquisition unit 801 is used to acquire a first excitation signal generated by a signal source of an eddy current sensor before chemical mechanical polishing of the wafer;

[0102] A second acquisition unit 802 is used to acquire a second excitation signal generated by a signal source of an eddy current sensor and acquire a wafer signal collected by the eddy current sensor during chemical mechanical polishing of the wafer;

[0103] A first correction unit 803 is used to correct the wafer signal according to the first excitation signal and the second excitation signal to obtain a corrected wafer signal;

[0104] The relationship determination unit 804 is used to establish a mapping relationship between the calibration information determined according to the corrected wafer signal and the predetermined wafer thickness, so as to calibrate the eddy current sensor.

[0105] It should be noted that the calibration device for eddy current sensors of this embodiment is used to implement the corresponding calibration method for eddy current sensors in the aforementioned method embodiments, and has the beneficial effects of the corresponding method embodiments, which will not be repeated here.

[0106] Corresponding to the above thickness measurement method embodiment, Fig. 9 A schematic diagram of a thickness measuring device according to an embodiment of the present application is shown. Fig. 9 As shown, the thickness measuring device 900 includes:

[0107] A relationship acquisition unit 901 is used to determine a mapping relationship between a plurality of wafer thicknesses and respective corresponding calibration information based on the calibration method for the eddy current sensor;

[0108] A third acquisition unit 902 is used to acquire a first excitation signal generated by a signal source of an eddy current sensor before the chemical mechanical polishing equipment performs chemical mechanical polishing on the wafer;

[0109] The fourth acquisition unit 903 is used to acquire the second excitation signal generated by the signal source of the eddy current sensor and acquire the wafer signal collected by the eddy current sensor during the process of the chemical mechanical polishing equipment performing chemical mechanical polishing on the wafer;

[0110] A second correction unit 904 is used to correct the wafer signal according to the first excitation signal and the second excitation signal to obtain a corrected wafer signal;

[0111] An information determination unit 905, configured to determine calibration information according to the corrected wafer signal;

[0112] The thickness determination unit 906 is used to determine the wafer thickness according to the calibration information and the mapping relationship.

[0113] It should be noted that the thickness measuring device of this embodiment is used to implement the corresponding thickness measuring method in the aforementioned method embodiment and has the beneficial effects of the corresponding method embodiment, which will not be described in detail here.

[0114] Corresponding to the above-mentioned calibration method embodiment for eddy current sensor, the present application discloses a chemical mechanical polishing device, such as Figure 1 As shown, the chemical mechanical polishing equipment includes: a polishing plate 1, a carrier head 2, a liquid supply device, an eddy current sensor 3 and a controller;

[0115] A polishing pad 11 is provided on one side of the polishing disc 1;

[0116] The carrier head 2 is used to limit the position of the wafer to be polished so that the metal film disposed on one circular surface of the wafer abuts against the polishing pad 11, and drives the wafer to move relative to the polishing pad 11, so as to perform chemical mechanical polishing on the wafer;

[0117] A liquid supply device, used to supply polishing liquid to the polishing pad 11 during chemical mechanical polishing of the wafer;

[0118] The eddy current sensor 3 is arranged on the polishing plate 1 and is used to measure the thickness of the wafer;

[0119] The controller is used to perform the following processing:

[0120] Before chemical mechanical polishing of the wafer, a first excitation signal generated by a signal source of an eddy current sensor is obtained;

[0121] During chemical mechanical polishing of the wafer, a second excitation signal generated by a signal source of the eddy current sensor is obtained, and a wafer signal collected by the eddy current sensor is obtained;

[0122] Correcting the wafer signal according to the first excitation signal and the second excitation signal to obtain a corrected wafer signal;

[0123] A mapping relationship between calibration information determined according to the corrected wafer signal and a predetermined wafer thickness is established to calibrate the eddy current sensor.

[0124] In a possible implementation, the controller is further configured to perform the following processing:

[0125] Before chemical mechanical polishing of the wafer, obtaining a first base value signal collected by an eddy current sensor;

[0126] In the process of chemical mechanical polishing the wafer, a second base value signal collected by the eddy current sensor is obtained;

[0127] The controller corrects the wafer signal according to the first excitation signal and the second excitation signal to obtain a corrected wafer signal, including:

[0128] determining a target correction amount according to the first excitation signal and the second excitation signal;

[0129] Correcting the first base value signal according to the target correction amount to obtain a corrected first base value signal;

[0130] The wafer signal is corrected according to the corrected first base value signal and the second base value signal to obtain a corrected wafer signal.

[0131] In a possible implementation, the controller corrects the wafer signal according to the corrected first base value signal and the second base value signal to obtain the corrected wafer signal, including:

[0132] Determine a signal change amount of the wafer signal relative to the second base value signal;

[0133] A corrected wafer signal is determined according to the corrected first base value signal and the signal variation.

[0134] In a possible implementation, the controller is further configured to perform the following processing:

[0135] The calibration information is determined according to the corrected wafer signal and the corrected first base value signal.

[0136] In a possible implementation, the controller determines the target correction amount according to the first excitation signal and the second excitation signal using the following formula:

[0137] drv_amp gaincofe =drv_amp t / drv_amp0, where drv_amp gaincofe is the first target correction value, drv_amp t is the amplitude of the second excitation signal, drv_amp0 is the amplitude of the first excitation signal;

[0138] drv_phi gaincofe =drv_phi t -drv_phi0, where drv_phi gaincofe is the second target correction, drv_phi t is the phase of the second excitation signal, drv_phi0 is the phase of the first excitation signal;

[0139] The first base value signal is corrected according to the target correction amount, and the formula for obtaining the corrected first base value signal is as follows:

[0140] cali_amp t =base_amp0*drv_amp gaincofe , where cali_amp t is the amplitude of the first base value signal after correction, base_amp0 is the amplitude of the first base value signal;

[0141] cali_phi t =base_phi0+drv_phi gaincofe , where cali_phi t is the phase of the first base value signal after correction, and base_amp0 is the phase of the first base value signal.

[0142] In a possible implementation, the controller executes a formula for determining a signal change amount of the wafer signal relative to the second base value signal as follows:

[0143] EDDY intensity (X) = wafer_amp t *cos(wafer_phi t )-base_amp t *cos(base_phi t ),in,

[0144] EDDY intensity (X) is the first component of the signal change, wafer_amp t is the amplitude of the wafer signal, wafer_phi t is the phase of the wafer signal, base_amp t is the amplitude of the second base value signal, base_phi t is the phase of the second base value signal;

[0145] EDDY intensity (Y) = wafer_amp t *sin(wafer_phi t )-base_amp t *sin(base_phi t ),in,

[0146] EDDY intensity (Y) is the second component of the signal change.

[0147] In a possible implementation, the controller executes the following formula to determine the corrected wafer signal based on the corrected first base value signal and the signal variation:

[0148] wafer(X)=EDDY intensity (X)+cali_amp t *cos(cali_phi t ), wherein wafer(X) is the first signal component of the corrected wafer signal;

[0149] wafer(Y)=EDDY intensity (Y)+cali_amp t *sin(cali_phi t ), wherein wafer(Y) is the second signal component of the corrected wafer signal;

[0150] wafer_phi t (correct) = arctan(wafer(Y) / wafer(X)), where wafer_phi t (correct) is the phase of the wafer signal after correction;

[0151] wafer_amp t (correct)=wafer(X) / cos(wafer_phi t (correct)), where wafer_amp t (correct) is the phase of the wafer signal after correction.

[0152] In a possible implementation, the controller executes the following formula to determine the calibration information based on the corrected wafer signal and the corrected first base value signal:

[0153] Δ_phi t =wafer_phi t (correct)-cali_phi t, where Δ_phi t The first information included in the calibration information;

[0154] Δ_amp t =wafer_amp t (correct) / cali_amp t , where Δ_amp t The second information included in the calibration information.

[0155] In a specific embodiment, the chemical mechanical polishing device may be the chemical mechanical polishing device described in the above-mentioned embodiment of the calibration method for the eddy current sensor 3 , and the controller is used to execute the above-mentioned calibration method for the eddy current sensor.

[0156] It should be noted that the controller included in the chemical mechanical polishing equipment of this embodiment is used to implement the calibration method for the eddy current sensor in the aforementioned method embodiment, and has the beneficial effects of the corresponding method embodiment, which will not be repeated here.

[0157] Corresponding to the above-mentioned thickness measurement method embodiment, the present application discloses a chemical mechanical polishing device, such as Figure 1 As shown, the chemical mechanical polishing equipment includes: a polishing plate 1, a carrier head 2, a liquid supply device, an eddy current sensor 3 and a controller;

[0158] A polishing pad 11 is provided on one side of the polishing disc 1;

[0159] The carrier head 2 is used to limit the position of the wafer to be polished so that the metal film disposed on one circular surface of the wafer abuts against the polishing pad 11, and drives the wafer to move relative to the polishing pad 11, so as to perform chemical mechanical polishing on the wafer;

[0160] A liquid supply device, used to supply polishing liquid to the polishing pad 11 during chemical mechanical polishing of the wafer;

[0161] The eddy current sensor 3 is arranged on the polishing plate 1 and is used to measure the thickness of the wafer;

[0162] The controller is used to perform the following processing:

[0163] Based on a calibration method for an eddy current sensor, a mapping relationship between a plurality of wafer thicknesses and respective corresponding calibration information is determined;

[0164] Before the chemical mechanical polishing device performs chemical mechanical polishing on the wafer, obtaining a first excitation signal generated by a signal source of the eddy current sensor;

[0165] During the process of the chemical mechanical polishing device performing chemical mechanical polishing on the wafer, obtaining a second excitation signal generated by the signal source of the eddy current sensor, and obtaining a wafer signal collected by the eddy current sensor;

[0166] Correcting the wafer signal according to the first excitation signal and the second excitation signal to obtain a corrected wafer signal;

[0167] Determining calibration information according to the corrected wafer signal;

[0168] The wafer thickness is determined according to the calibration information and the mapping relationship.

[0169] In a specific implementation, the chemical mechanical polishing equipment may be the chemical mechanical polishing equipment introduced in the above thickness measurement method embodiment, and the controller is used to execute the above thickness measurement method.

[0170] It should be noted that the controller included in the chemical mechanical polishing equipment of this embodiment is used to implement the thickness measurement method in the aforementioned method embodiment and has the beneficial effects of the corresponding method embodiment, which will not be described in detail here.

[0171] In this embodiment, a computer-readable storage medium is provided, storing instructions for causing a machine to execute the calibration method or thickness measurement method for an eddy current sensor as described herein. Specifically, a system or device equipped with a storage medium can be provided, on which a software program code for implementing the functions of any of the above embodiments is stored, and a computer (or CPU or MPU) of the system or device is enabled to read and execute the program code stored in the storage medium.

[0172] In this case, the program code read from the storage medium itself can implement the functions in the above method embodiments, so the program code and the storage medium storing the program code constitute part of the present application.

[0173] The storage medium embodiments for providing the program code include a floppy disk, a hard disk, a magneto-optical disk, an optical disk (such as CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-RAM, DVD-RW, DVD+RW), a magnetic tape, a non-volatile memory card, and a ROM. Alternatively, the program code can be downloaded from a server computer by a communication network.

[0174] In this embodiment, a computer program product is provided, including computer instructions, which instruct a computing device to perform operations corresponding to the above method embodiments.

[0175] It should be pointed out that, according to the needs of implementation, the various components / steps described in this application can be split into more components / steps, or two or more components / steps or partial operations of components / steps can be combined into new components / steps to achieve the purpose of this application.

[0176] The above-mentioned method according to the present application can be implemented in hardware, firmware, or implemented as software or computer code that can be stored in a recording medium (such as CD ROM, RAM, floppy disk, hard disk or magneto-optical disk), or implemented as a computer code originally stored in a remote recording medium or a non-temporary machine-readable medium downloaded through a network and stored in a local recording medium, so that the method described herein can be stored in such software processing on a recording medium using a general-purpose computer, a special-purpose processor or programmable or special-purpose hardware (such as ASIC or FPGA). It can be understood that a computer, a processor, a microprocessor controller or programmable hardware includes a storage component (e.g., RAM, ROM, flash memory, etc.) that can store or receive software or computer code, and when the software or computer code is accessed and executed by a computer, a processor or hardware, the method described herein is implemented. In addition, when a general-purpose computer accesses the code for implementing the method shown here, the execution of the code converts the general-purpose computer into a special-purpose computer for executing the method shown here. Although the present application has been shown and described with respect to one or more implementations, those skilled in the art will think of equivalent deformations and modifications based on the reading and understanding of this specification and the accompanying drawings. The present application includes all such modifications and changes, and is limited only by the scope of the appended claims. In particular, with respect to the various functions performed by the above-described components, the terms used to describe such components are intended to correspond to any component that performs the specified function of the component (e.g., which is functionally equivalent) (unless otherwise indicated), even if not structurally equivalent to the disclosed structure that performs the function in the exemplary implementation of the present specification shown herein.

[0177] That is, the above description is only an embodiment of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the specification and drawings of the present application, such as the mutual combination of technical features between the embodiments, or direct or indirect application in other related technical fields, are also included in the patent protection scope of the present application.

[0178] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0179] In order to enable any technician in the field to implement and use the application, the application provides the above description. In the above description, various details are listed for the purpose of explanation. It should be understood that those of ordinary skill in the art can recognize that the application can also be implemented without using these specific details. In other embodiments, the well-known process will not be elaborated in detail to avoid unnecessary details that make the description of the application obscure. Therefore, the application is not intended to be limited to the embodiments shown, but is consistent with the widest range of principles and features disclosed in the application.

[0180] It should be noted that, under the premise of no conflict, the various embodiments and / or the technical features in the various embodiments described in this application can be arbitrarily combined with each other, and the technical solution obtained after the combination should also fall within the protection scope of this application.

[0181] It should be understood that the specific examples in this application are only to help those skilled in the art to better understand this application, rather than to limit the scope of this application. Those skilled in the art can make various improvements and modifications based on the above embodiments, and these improvements or modifications are all within the scope of protection of this application.

[0182] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A calibration method for an eddy current sensor, characterized in that: include: Before chemical mechanical polishing of the wafer, a first excitation signal generated by a signal source of the eddy current sensor and a first base value signal collected are obtained; In the process of chemical mechanical polishing of the wafer, a second excitation signal generated by the signal source of the eddy current sensor and a collected second base value signal are obtained, and a wafer signal collected by the eddy current sensor is obtained; determining a target correction amount according to the first excitation signal and the second excitation signal; Correcting the first base value signal according to the target correction amount to obtain a corrected first base value signal; Determining a signal change amount of the wafer signal relative to the second base value signal; Determine a corrected wafer signal according to the corrected first base value signal and the signal variation; Establishing a mapping relationship between calibration information determined according to the corrected wafer signal and a predetermined wafer thickness to calibrate the eddy current sensor; Repeat the above steps to establish a mapping relationship according to the calibration information corresponding to the multiple target wafers and according to the wafer thicknesses of the multiple target wafers, wherein at least some of the multiple target wafers have different wafer thicknesses.

2. The method according to claim 1, characterized in that The method further comprises: The calibration information is determined according to the corrected wafer signal and the corrected first baseline signal.

3. The method according to claim 1, characterized in that The method further comprises: For each target wafer, during the process of chemical mechanical polishing performed by the calibration device on each target wafer, the polishing disc drives the polishing pad to rotate around the axis of the polishing pad once, and obtains a second excitation signal, a second base value signal and a plurality of wafer signals corresponding to the target wafer; Measuring the thickness of the metal film before the start of one rotation or after the completion of one rotation as the wafer thickness; The calibration information corresponding to the target wafer is determined according to the second excitation signal, the second base value signal, and the first excitation signal and the first base value signal determined before chemical mechanical polishing.

4. The method according to claim 1, characterized in that: The mapping relationship is established by creating a query table, piecewise fitting or linear regression fitting.

5. The method according to claim 1, characterized in that Acquiring the collected first base value signal includes: After the eddy current sensor is powered on and before the calibration equipment performs chemical mechanical polishing on the wafer, a first base value signal output by the eddy current sensor at any time when the eddy current sensor is in a second state is obtained, and the second state is a state in which there is no metal object opposite to the eddy current sensor in a direction perpendicular to the polishing pad.

6. The method according to claim 5, characterized in that Acquiring the collected second base value signal includes: acquiring the second base value signal output at any time when the eddy current sensor is in the second state during the process of chemical mechanical polishing of the wafer by the calibration equipment.

7. A thickness measurement method, characterized in that: include: Based on the method according to any one of claims 1 to 6, determining a mapping relationship between a plurality of wafer thicknesses and respective corresponding calibration information; Before the chemical mechanical polishing equipment performs chemical mechanical polishing on the wafer, a first excitation signal generated by a signal source of the eddy current sensor is obtained; During the process of the chemical mechanical polishing device performing chemical mechanical polishing on the wafer, obtaining a second excitation signal generated by the signal source of the eddy current sensor, and obtaining a wafer signal collected by the eddy current sensor; Correcting the wafer signal according to the first excitation signal and the second excitation signal to obtain a corrected wafer signal; Determining calibration information according to the corrected wafer signal; The wafer thickness is determined according to the calibration information and the mapping relationship.

8. A calibration device for an eddy current sensor, characterized in that: include: A first acquisition unit is used to acquire a first excitation signal generated by a signal source of the eddy current sensor and a collected first base value signal before chemical mechanical polishing of the wafer; A second acquisition unit is used to acquire the second excitation signal generated by the signal source of the eddy current sensor and the collected second base value signal during the process of chemical mechanical polishing of the wafer, and to acquire the wafer signal collected by the eddy current sensor; A first correction unit is used to determine a target correction amount according to the first excitation signal and the second excitation signal; and to correct the first base value signal according to the target correction amount to obtain a corrected first base value signal; Determining a signal change amount of the wafer signal relative to the second base value signal; Determine a corrected wafer signal according to the corrected first base value signal and the signal variation; a relationship determination unit, configured to establish a mapping relationship between calibration information determined according to the corrected wafer signal and a predetermined wafer thickness, so as to calibrate the eddy current sensor; By repeatedly executing the above-mentioned units, a mapping relationship is established according to the calibration information corresponding to the multiple target wafers and according to the wafer thicknesses of the multiple target wafers, and at least some of the multiple target wafers have different wafer thicknesses.

9. A thickness measuring device, characterized in that: include: A relationship acquisition unit, configured to determine a mapping relationship between a plurality of wafer thicknesses and respective corresponding calibration information based on the method according to any one of claims 1 to 6; A third acquisition unit is used to acquire a first excitation signal generated by a signal source of the eddy current sensor before the chemical mechanical polishing equipment performs chemical mechanical polishing on the wafer; a fourth acquisition unit, configured to acquire, during the process of the chemical mechanical polishing device performing chemical mechanical polishing on the wafer, a second excitation signal generated by the signal source of the eddy current sensor, and acquire a wafer signal collected by the eddy current sensor; A second correction unit, used for correcting the wafer signal according to the first excitation signal and the second excitation signal to obtain a corrected wafer signal; an information determining unit, configured to determine calibration information according to the corrected wafer signal; The thickness determination unit is used to determine the wafer thickness according to the calibration information and the mapping relationship.

10. A chemical mechanical polishing device, characterized in that: include: Polishing disc, carrier head, fluid supply device, eddy current sensor and controller; A polishing pad is provided on one side of the polishing disc; The carrier head is used to limit the position of the wafer to be polished so that the metal film disposed on one circular surface of the wafer abuts against the polishing pad and drives the wafer to move relative to the polishing pad to perform chemical mechanical polishing on the wafer; The liquid supply device is used to supply polishing liquid to the polishing pad during chemical mechanical polishing of the wafer; The eddy current sensor is arranged on the polishing plate and is used to measure the thickness of the wafer; The controller is used to perform the following processing: Before chemical mechanical polishing of the wafer, obtaining a first excitation signal generated by a signal source of the eddy current sensor and a collected first base value signal; In the process of chemical mechanical polishing of the wafer, a second excitation signal generated by the signal source of the eddy current sensor and a collected second base value signal are obtained, and a wafer signal collected by the eddy current sensor is obtained; determining a target correction amount according to the first excitation signal and the second excitation signal; Correcting the first base value signal according to the target correction amount to obtain a corrected first base value signal; Determining a signal change amount of the wafer signal relative to the second base value signal; Determine a corrected wafer signal according to the corrected first base value signal and the signal variation; Establishing a mapping relationship between calibration information determined according to the corrected wafer signal and a predetermined wafer thickness to calibrate the eddy current sensor; Repeat the above steps to establish a mapping relationship according to the calibration information corresponding to the multiple target wafers and according to the wafer thicknesses of the multiple target wafers, wherein at least some of the multiple target wafers have different wafer thicknesses.

11. The device according to claim 10, characterized in that The controller is also used to perform the following processing: The calibration information is determined according to the corrected wafer signal and the corrected first baseline signal.

12. The device according to claim 11, characterized in that The controller is also used to perform the following processing: for each target wafer, during the process of chemical mechanical polishing of each target wafer by the calibration device, the polishing plate drives the polishing pad to rotate around the axis of the polishing pad once, and obtains a second excitation signal, a second base value signal and multiple wafer signals corresponding to the target wafer; Measuring the thickness of the metal film before the start of one rotation or after the completion of one rotation as the wafer thickness; The calibration information corresponding to the target wafer is determined according to the second excitation signal, the second base value signal, and the first excitation signal and the first base value signal determined before chemical mechanical polishing.

13. The device according to claim 12, characterized in that The mapping relationship is established by creating a query table, piecewise fitting or linear regression fitting.

14. The device according to claim 13, characterized in that Acquiring the collected first baseline signal includes: after the eddy current sensor is powered on and before the calibration equipment performs chemical mechanical polishing on the wafer, acquiring the first baseline signal outputted by the eddy current sensor at any time when the eddy current sensor is in a second state, the second state being a state in which there is no metal object opposite to the eddy current sensor in a direction perpendicular to the polishing pad.

15. The device according to claim 14, characterized in that Acquiring the collected second base value signal includes: acquiring the second base value signal output at any time when the eddy current sensor is in the second state during the process of chemical mechanical polishing of the wafer by the calibration equipment.

16. A chemical mechanical polishing device, characterized in that: include: Polishing disc, carrier head, fluid supply device, eddy current sensor and controller; A polishing pad is provided on one side of the polishing disc; The carrier head is used to limit the position of the wafer to be polished so that the metal film disposed on one circular surface of the wafer abuts against the polishing pad and drives the wafer to move relative to the polishing pad to perform chemical mechanical polishing on the wafer; The liquid supply device is used to supply polishing liquid to the polishing pad during chemical mechanical polishing of the wafer; The eddy current sensor is arranged on the polishing plate and is used to measure the thickness of the wafer; The controller is used to perform the following processing: Based on the method according to any one of claims 1 to 6, determining a mapping relationship between a plurality of wafer thicknesses and respective corresponding calibration information; Before the chemical mechanical polishing device performs chemical mechanical polishing on the wafer, obtaining a first excitation signal generated by a signal source of the eddy current sensor; During the process of the chemical mechanical polishing device performing chemical mechanical polishing on the wafer, obtaining a second excitation signal generated by the signal source of the eddy current sensor, and obtaining a wafer signal collected by the eddy current sensor; Correcting the wafer signal according to the first excitation signal and the second excitation signal to obtain a corrected wafer signal; Determining calibration information according to the corrected wafer signal; The wafer thickness is determined according to the calibration information and the mapping relationship.

17. A computer storage medium, characterized in that: A computer program is stored thereon, and when the program is executed by a processor, the method according to any one of claims 1 to 6 or the method according to claim 7 is implemented.

18. A computer program product, characterized in that The method comprises computer instructions, wherein the computer instructions instruct a computing device to execute the method according to any one of claims 1 to 6 or the method according to claim 7.

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