Metal film thickness measurement method, device and chemical mechanical polishing equipment based on eddy current

Abstract

The present application provides a method, device and chemical mechanical polishing equipment for measuring the thickness of a metal film based on eddy current, the method comprising: in the process of polishing a metal layer on a wafer, collecting an original signal through an eddy current sensor, the original signal is used to indicate the thickness of the metal layer on the wafer or the thickness of the metal layer on the retaining ring outside the wafer; separating an amplitude signal and a phase signal from the original signal, and determining a target feature point located in the area where the retaining ring is located according to the amplitude signal, and obtaining the thickness information of the target feature point; determining the position information corresponding to the target feature point in the original signal according to the thickness information of the target feature point; determining an offset according to the position information; calibrating at least the phase signal according to the offset, and determining the thickness of the metal film according to at least the calibrated phase signal. This solution improves the measurement accuracy of the metal film thickness of the wafer during the polishing process.

Description

Technical Field

[0001] The present application relates to the field of integrated circuit technology, and in particular to a metal film thickness measurement method and device based on eddy current and chemical mechanical polishing equipment. Background Art

[0002] In the chemical mechanical polishing process in the field of integrated circuit manufacturing, due to communication delays and the influence of the machine polishing head, the signal data collected during the polishing process will be affected by jitter. This jitter will interfere with the accuracy of the metal film thickness measurement, thereby affecting the accuracy of the entire polishing process and the uniformity of the surface treatment. Therefore, how to accurately measure the metal film thickness based on the received eddy current signal data, thereby improving the accuracy of wafer polishing, is an urgent problem to be solved in this application. Summary of the invention

[0003] In view of this, the present application provides a metal film thickness measurement method, device and chemical mechanical polishing equipment solution based on eddy current to at least partially solve the above problems.

[0004] According to the first aspect of the present application, a method for measuring the thickness of a metal film based on eddy current is provided, the method comprising: in the process of polishing a metal layer on a wafer, collecting an original signal through an eddy current sensor, the original signal being used to indicate the thickness of the metal layer on the wafer or the thickness of the metal layer on a retaining ring outside the wafer; separating an amplitude signal and a phase signal from the original signal, and determining a target feature point located in the area where the retaining ring is located according to the amplitude signal, and obtaining thickness information of the target feature point; determining position information corresponding to the target feature point in the original signal according to the thickness information of the target feature point; determining an offset according to the position information; calibrating at least the phase signal according to the offset, and determining the thickness of the metal film according to at least the calibrated phase signal.

[0005] According to a second aspect of the present application, a metal film thickness measurement device based on eddy current is provided, and the device includes: an acquisition module, which is used to collect original signals through eddy current sensors during a polishing process of a metal layer on a wafer, and the original signals are used to indicate thickness information corresponding to the wafer, and the thickness information is used to indicate the thickness of the metal layer on the wafer or the thickness of the metal layer on a retaining ring around the wafer; an acquisition module, which is used to separate an amplitude signal and a phase signal from the original signal, and determine a target feature point located in the area where the retaining ring is located according to the amplitude signal, and obtain the thickness information of the target feature point; a determination module, which is used to determine the position information corresponding to the target feature point in the original signal according to the thickness information of the target feature point; and determine an offset according to the position information; a measurement module, which is used to calibrate at least the phase signal according to the offset, and determine the metal film thickness at least according to the calibrated phase signal.

[0006] According to a third 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 arranged on the polishing disk; the carrier head is used to limit the wafer to be polished so that a metal film arranged on a circular surface of the wafer abuts against the polishing pad, driving the wafer to move relative to the polishing pad, so as 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 used to collect original signals, and the original signals are used to indicate the thickness of the metal layer on the wafer or the thickness of the metal layer on the retaining ring around the wafer; the controller is used to perform operations corresponding to the following method: measuring the thickness of the metal layer on the wafer by eddy current The sensor collects an original signal, wherein the original signal is used to indicate the thickness of the metal layer on the wafer or the thickness of the metal layer on the retaining ring around the wafer; separates an amplitude signal and a phase signal from the original signal, and determines a target feature point located in the area where the retaining ring is located according to the amplitude signal, and obtains thickness information of the target feature point; determines position information corresponding to the target feature point in the original signal according to the thickness information of the target feature point; determines an offset according to the position information; calibrates at least the phase signal according to the offset, and determines the thickness of the metal film according to at least the calibrated phase signal.

[0007] According to a fourth aspect of the present application, a computer storage medium is provided, on which a computer program is stored, and when the program is executed by a processor, the method described in the first aspect is implemented.

[0008] According to the eddy current-based metal film thickness measurement scheme provided by the present application, the amplitude signal and the phase signal are separated from the original signal collected by the eddy current sensor, and the target feature point located in the area where the retaining ring is located and the thickness information of the feature point are determined according to the amplitude signal. Compared with the original signal, the amplitude signal can more accurately reflect the thickness information and position information of the feature point in the retaining ring area, so that according to the thickness information and position information of the feature point in the retaining ring area, the position information of the feature point is more accurately determined based on the thickness value of the feature point in the original signal; thus, according to the position information of the feature point in the original signal, the offset of the feature point in the original signal is more accurately determined, and the phase signal is at least calibrated based on the offset, and then the metal film thickness is determined according to the calibrated phase signal, which can effectively avoid the deviation caused by the data jitter phenomenon in the signal transmission process, resulting in inaccurate metal film thickness measurement, thereby reducing the polishing accuracy. At the same time, the method proposed in the present application can be applied to the metal film thickness measurement of wafers of different types and sizes during the polishing process, and has good versatility and applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] 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.

[0010] Figure 1 A schematic diagram of an exemplary system for applying the eddy current based metal film thickness measurement method of the present application;

[0011] Figure 2 A schematic diagram of an amplitude signal of the present application;

[0012] Figure 3 This is a schematic diagram of linear fitting of characteristic points on the retaining ring area in this application;

[0013] Figure 4 A schematic diagram of calibrating a phase signal for this application;

[0014] Figure 5 A schematic diagram of a chemical mechanical polishing apparatus in the illustrated embodiment;

[0015] Figure 6 is a structural block diagram of a metal film thickness measurement device based on eddy current according to the present application;

[0016] Description of reference numerals:

[0017] 1. Polishing disc; 11. Polishing pad; 2. Carrying head; 3. Eddy current sensor; 500. Metal film thickness measuring device; 501. Acquisition module; 502. Acquisition module; 503. Determination module; 504. Measurement module. DETAILED DESCRIPTION

[0018] In order to enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in this application will be clearly and completely described below in conjunction with the drawings in this application. Obviously, the described embodiments are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field should fall within the scope of protection of this application.

[0019] The specific implementation of this application is further explained below in conjunction with the drawings of this application.

[0020] Figure 1 A schematic diagram of an optional processing flow of the correction method provided by the present application is shown below. Figure 1 Steps S101-S105 are shown for explanation.

[0021] Step 101 : In the process of polishing the conductive layer on the wafer, an original signal is collected by an eddy current sensor.

[0022] In some embodiments, during a chemical mechanical polishing (CMP) process, an eddy current sensor can be used to monitor and acquire the original signal of the wafer during the polishing process in real time. The original signal can be used to indicate the thickness of the metal layer in different areas on the wafer or the thickness of the metal layer on a retaining ring around the wafer.

[0023] In the present application, the polishing process of the conductive layer on the wafer can be a testing process or a processing process, both of which are within the protection scope of the present application.

[0024] Step 102: Separate the amplitude signal and the phase signal from the original signal, determine the target feature point located in the area where the retaining ring is located according to the amplitude signal, and obtain the thickness information of the target feature point.

[0025] In some embodiments, the original signal collected in real time using the eddy current sensor contains information about the thickness change of the metal layer on the wafer, and the amplitude signal and the phase signal can be separated from the original signal.

[0026] The target feature point in the area where the retaining ring is located can be determined based on the preset position range in the amplitude signal. Figure 2 As shown, Figure 2The figure shows a schematic diagram of the amplitude signal. The target feature point corresponding to the position range of 160 mm-190 mm from the center of the circle in the amplitude signal can be determined as the target feature point of the area where the retaining ring is located. Figure 2 In the figure, the target feature point corresponding to the AC curve can be determined as the target feature point of the area where the retaining ring is located, and the target feature point corresponding to the curve DE symmetrical to AC on the right side of the coordinate axis is also the target feature point of the area where the retaining ring is located.

[0027] The first area and the second area where the retaining ring is located can be determined based on the amplitude value and position information corresponding to the target feature point in the area where the retaining ring is located. Figure 2 As shown in the curve corresponding to the amplitude signal, the target feature point corresponding to the peak value of point B is located at the center of the retaining ring; the target feature point corresponding to the AB curve is located outside the retaining ring; and the target feature point corresponding to the BC curve is located inside the retaining ring. The position corresponding to point O is the center point of the retaining ring. The retaining ring is symmetrical around the center point of the circle. Therefore Figure 2 The curves corresponding to the target feature points on both sides of point O should also be symmetrical around point O.

[0028] After determining the retaining ring area, the first area and the second area in the area where the retaining ring is located can be determined based on the position information corresponding to each feature point in the amplitude signal. The target feature point in the first area can be determined as the first feature point, and the target feature point in the second area can be determined as the second feature point. The thickness information corresponding to the first feature point on the first area can be further determined, and the thickness information corresponding to the second feature point on the second area can be determined. The positions of the first area and the second area on the retaining ring are in a left-right symmetrical relationship based on point O. The first area and the second area can both be the outer area of ​​the retaining ring, or both can be the inner area of ​​the retaining ring. As an example, Figure 2 As shown, the area corresponding to the AB curve or the BC curve on the retaining ring can be determined as the first area; correspondingly, the area in the DE curve that is symmetrical to the first area (AB curve or BC curve) is determined as the second area; the target feature point in the first area is determined as the first feature point, and the target feature point in the second area is determined as the second feature point.

[0029] Step 103: Determine the position information corresponding to the target feature point in the original signal according to the thickness information of the target feature point.

[0030] In some embodiments, the average value of the thickness information corresponding to the first feature point can be determined as the first thickness average value; the average value of the thickness information corresponding to the second feature point can be determined as the second thickness average value; based on the first thickness average value and the second thickness average value, the position information corresponding to the feature point in the original signal is determined.

[0031] The specific method for determining the position information corresponding to the feature point in the original signal according to the first thickness average value and the second thickness average value can be: determining the first candidate feature point and the second candidate feature point in the first area on the retaining ring according to the first thickness average value, the thickness information corresponding to the first candidate feature point is less than the first thickness average value, and the thickness information corresponding to the second candidate feature point is greater than the first thickness average value; determining a first linear fitting line according to the thickness information and position information corresponding to the first candidate feature point, and the thickness information and position information corresponding to the second candidate feature point, and the first linear fitting line can be used to indicate the relationship between the thickness value and position information corresponding to a point on the wafer.

[0032] like Figure 3 As shown, Figure 3 Figure 2 shows a schematic diagram of linear fitting of characteristic points on the retaining ring area. Figure 3 In , the horizontal axis represents the position information corresponding to the feature point, and the vertical axis represents the thickness information corresponding to the feature point. Taking the feature points including data point 1, data point 2 and data point 3 as an example, the horizontal axis represents the position information corresponding to the feature point; the vertical axis represents the thickness information corresponding to the feature point, and the thickness of the target feature point corresponding to the intersection F of the dotted line represents the average thickness corresponding to these feature points. The coordinates of the target feature point corresponding to the intersection represent the position information corresponding to the thickness average when the thickness of the feature point is the thickness average. Two adjacent data points can be determined from adjacent data point 1 and data point 2, and adjacent data point 2 and data point 3, where the thickness information corresponding to one data point is less than the thickness information corresponding to point F, and the thickness information corresponding to the other data point is greater than the thickness information corresponding to point F. Therefore, data point 1 can be determined as the first candidate feature point, and data point 2 can be determined as the second candidate feature point; the corresponding linear fitting line is determined according to the thickness information and position information corresponding to the first candidate feature point, and the thickness information and position information corresponding to the second candidate feature point.

[0033] Similarly, the third candidate feature point and the fourth candidate feature point of the second area on the retaining ring can be determined based on the second thickness average value, the thickness information of the third candidate feature point is less than the second thickness average value, and the thickness information of the fourth candidate feature point is greater than the second thickness average value; the second linear fitting line can be determined based on the thickness information and position information corresponding to the third candidate feature point, and based on the thickness information and position information corresponding to the fourth candidate feature point.

[0034] After obtaining the thickness information of the feature point on the area where the retaining ring is located through the amplitude signal, the first target position corresponding to the thickness information of the feature point in the first linear fitting line can be determined based on the first target position corresponding to the feature point in the second linear fitting line, and the second target position corresponding to the feature point in the second linear fitting line can be determined. The first target position and the second target position are determined as the position information corresponding to the feature point.

[0035] Step 104: Determine an offset according to the position information.

[0036] In some embodiments, after obtaining the position information corresponding to the feature point, the difference between the first target position and the second target position can be determined as an offset, which is used to indicate the deviation between the actual position and the theoretical position of the target feature point being polished during the polishing process of the wafer.

[0037] Since the retaining ring and the wafer are theoretically symmetrical based on the center of the circle, and the collected signal may have deviations that lead to asymmetry, the collected signal can be calibrated according to the symmetry of the retaining ring to correct the signal deviation. By dividing the area where the retaining ring is located into a first area and a second area, determining the first target position according to the first linear fitting line and determining the second target position according to the second linear fitting line, a more accurate position offset of the target feature point can be obtained, thereby achieving a more accurate calibration of the deviation later.

[0038] Step 105: calibrate at least the phase signal according to the offset, and determine the metal film thickness at least according to the calibrated phase signal.

[0039] In some embodiments, after obtaining the offset, the correction direction of the phase signal can be determined based on the value of the offset, the phase signal can be offset-calibrated based on the correction direction and the offset, and the thickness of the metal film can be determined based on the calibrated phase signal; the amplitude signal can also be calibrated in the same way; or the phase signal can be calibrated based on the offset, and then the original signal can be updated based on the calibrated phase signal and amplitude signal, and the thickness of the metal film can be determined based on the updated original signal; or the thickness of the metal film can be determined based on the calibrated phase signal and the updated original signal. As an example, Figure 4 This is a schematic diagram for calibrating the phase signal. Figure 4 In the example, if the magnitude of the offset is the distance between HI, the phase signal is moved to the right along the horizontal axis by the distance corresponding to the offset HI.

[0040] For the above-mentioned embodiment of the metal film thickness measurement method based on eddy current, Figure 5 FIG. 1 is a schematic diagram of a metal film thickness measuring device for eddy current in one embodiment of the present application. Figure 5 As shown, the metal film thickness measuring device 500 comprises:

[0041] The acquisition module 501 is used to acquire the original signal through the eddy current sensor during the process of polishing the metal layer on the wafer, wherein the original signal is used to indicate the thickness of the metal layer on the wafer or the thickness of the metal layer on the retaining ring outside the wafer;

[0042] An acquisition module 502 is used to separate an amplitude signal and a phase signal from the original signal, and determine a target feature point located in the area where the retaining ring is located according to the amplitude signal, and obtain thickness information of the target feature point;

[0043] A determination module 503 is used to determine the position information corresponding to the target feature point in the original signal according to the thickness information of the target feature point; and determine the offset according to the position information;

[0044] The measuring module 504 is configured to calibrate at least the phase signal according to the offset, and determine the metal film thickness at least according to the calibrated phase signal.

[0045] It should be noted that the eddy current-based metal film thickness measurement device 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.

[0046] Corresponding to the above-mentioned embodiment of the metal film thickness measurement method based on eddy current, the present application discloses a chemical mechanical polishing device, such as Figure 6 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;

[0047] A polishing pad 11 is provided on the polishing disc 1;

[0048] 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;

[0049] A liquid supply device, used to supply polishing liquid to the polishing pad 11 during chemical mechanical polishing of the wafer;

[0050] An eddy current sensor 3, arranged on the polishing plate 1, for collecting an original signal, wherein the original signal is used to indicate the thickness of the metal layer on the wafer or the thickness of the metal layer on the retaining ring around the wafer;

[0051] A controller is used to execute the above-mentioned metal film thickness measurement method based on eddy current.

[0052] 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.

[0053] The above-mentioned method according to the present application can be implemented in hardware, firmware, or as software or computer code that can be stored in a recording medium (such as a CD ROM, RAM, floppy disk, hard disk or magneto-optical disk), or as a computer code originally stored in a remote recording medium or a non-temporary machine-readable medium downloaded through a network and to be 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 dedicated processor or programmable or dedicated hardware (such as an ASIC or FPGA). It can be understood that a computer, a processor, a microprocessor controller or programmable hardware includes a storage component (for example, 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 eddy current-based metal film thickness measurement method described herein is implemented. In addition, when a general-purpose computer accesses the code for implementing the eddy current-based metal film thickness measurement method shown herein, the execution of the code converts the general-purpose computer into a dedicated computer for executing the eddy current-based metal film thickness measurement method shown herein.

[0054] Those of ordinary skill in the art will appreciate that the units and method steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0055] The above implementation modes are only used to illustrate the present application, and are not intended to limit the present application. Ordinary technicians in the relevant technical field may make various changes and modifications without departing from the spirit and scope of the present application. Therefore, all equivalent technical solutions also belong to the scope of the present application, and the scope of patent protection of the present application shall be limited by the claims.

Claims

1. A method for measuring metal film thickness based on eddy current, characterized in that: The method comprises: In the process of polishing the metal layer on the wafer, an original signal is collected by an eddy current sensor, wherein the original signal is used to indicate the thickness of the metal layer on the wafer or the thickness of the metal layer on the retaining ring around the wafer; Separating an amplitude signal and a phase signal from the original signal, and determining a target feature point in the area where the retaining ring is located according to a preset position range in the amplitude signal; Determine, according to the amplitude value and position information corresponding to the target feature point, a first area and a second area of ​​the area where the retaining ring is located, wherein the positions of the first area and the second area on the retaining ring are symmetrical; Determine a first feature point on the first area and thickness information corresponding to the first feature point, determine a second feature point on the second area and thickness information corresponding to the second feature point, as the thickness information of the target feature point; Determining, according to the thickness information of the target feature point, the position information corresponding to the target feature point in the original signal; Determine an offset according to the position information; At least the phase signal is calibrated according to the offset, and the metal film thickness is determined at least according to the calibrated phase signal.

2. The method according to claim 1, characterized in that The step of determining, according to the thickness information of the target feature point, the position information corresponding to the target feature point in the original signal includes: Determine an average value of thickness information corresponding to a first feature point among the target feature points as a first thickness average value; Determine the average value of the thickness information corresponding to the second feature point in the target feature points as the second thickness average value; According to the first average thickness value and the second average thickness value, position information corresponding to the target feature point in the original signal is determined.

3. The method according to claim 2, characterized in that The determining, according to the first average thickness value and the second average thickness value, the position information corresponding to the target feature point in the original signal includes: Determine a first candidate feature point and a second candidate feature point in the first area of ​​the retaining ring according to the first thickness average value; the thickness information of the first candidate feature point is less than the first thickness average value, and the thickness information of the second candidate feature point is greater than the first thickness average value; Determine a third candidate feature point and a fourth candidate feature point of the second region on the retaining ring according to the second thickness average value; the thickness information of the third candidate feature point is less than the second thickness average value, and the thickness information of the fourth candidate feature point is greater than the second thickness average value; According to the first candidate feature point, the second candidate feature point, the third candidate feature point and the fourth candidate feature point, position information corresponding to the target feature point in the original signal is determined.

4. The method according to claim 3, characterized in that The determining, according to the first candidate feature point, the second candidate feature point, the third candidate feature point and the fourth candidate feature point, the position information corresponding to the target feature point in the original signal includes: Determine a first linear fitting line according to the thickness information and position information corresponding to the first candidate feature point, and the thickness information and position information corresponding to the second candidate feature point; Determine a second linear fitting line according to the thickness information and position information corresponding to the third candidate feature point, and the thickness information and position information corresponding to the fourth candidate feature point; Determine a first target position corresponding to the thickness information corresponding to the target feature point in the original signal in the first linear fitting line, and determine a second target position corresponding to the thickness information corresponding to the target feature point in the original signal in the second linear fitting line.

5. The method according to claim 1, characterized in that The step of determining the offset according to the position information includes: A difference between the first target position in the position information and the second target position in the position information is determined as the offset.

6. A chemical mechanical polishing device, characterized in that: The device comprises: a polishing disc, a carrier head, a liquid supply device, an eddy current sensor and a controller; The polishing disc is provided with a polishing pad; 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, driving the wafer to move relative to the polishing pad, so as 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 collect original signals, wherein the original signals are used to indicate the thickness of the metal layer on the wafer or the thickness of the metal layer on the retaining ring around the wafer; The controller is used to perform operations corresponding to the following methods: Collecting original signals by means of eddy current sensors, wherein the original signals are used to indicate the thickness of the metal layer on the wafer or the thickness of the metal layer on the retaining ring around the wafer; Separating the amplitude signal and the phase signal from the original signal, Determine a target feature point in the area where the retaining ring of the wafer periphery is located according to a preset position range in the amplitude signal; Determine, according to the amplitude value and position information corresponding to the target feature point, a first area and a second area of ​​the area where the retaining ring is located, wherein the positions of the first area and the second area on the retaining ring are symmetrical; Determine a first feature point on the first area and thickness information corresponding to the first feature point, determine a second feature point on the second area and thickness information corresponding to the second feature point, as the thickness information of the target feature point; Determining, according to the thickness information of the target feature point, the position information corresponding to the target feature point in the original signal; Determine an offset according to the position information; At least the phase signal is calibrated according to the offset, and the metal film thickness is determined at least according to the calibrated phase signal.

7. The chemical mechanical polishing equipment according to claim 6, characterized in that: The controller is used to: Determine an average value of thickness information corresponding to a first feature point among the target feature points as a first thickness average value; Determine the average value of the thickness information corresponding to the second feature point in the target feature points as the second thickness average value; According to the first average thickness value and the second average thickness value, position information corresponding to the target feature point in the original signal is determined.

8. The chemical mechanical polishing equipment according to claim 7, characterized in that: The determining, according to the first average thickness value and the second average thickness value, the position information corresponding to the target feature point in the original signal includes: Determine a first candidate feature point and a second candidate feature point in the first area of ​​the retaining ring according to the first thickness average value; the thickness information of the first candidate feature point is less than the first thickness average value, and the thickness information of the second candidate feature point is greater than the first thickness average value; Determine a third candidate feature point and a fourth candidate feature point of the second region on the retaining ring according to the second thickness average value; the thickness information of the third candidate feature point is less than the second thickness average value, and the thickness information of the fourth candidate feature point is greater than the second thickness average value; According to the first candidate feature point, the second candidate feature point, the third candidate feature point and the fourth candidate feature point, position information corresponding to the target feature point in the original signal is determined.

9. The chemical mechanical polishing equipment according to claim 8, characterized in that: The determining, according to the first candidate feature point, the second candidate feature point, the third candidate feature point and the fourth candidate feature point, the position information corresponding to the target feature point in the original signal includes: Determine a first linear fitting line according to the thickness information and position information corresponding to the first candidate feature point, and the thickness information and position information corresponding to the second candidate feature point; Determine a second linear fitting line according to the thickness information and position information corresponding to the third candidate feature point, and the thickness information and position information corresponding to the fourth candidate feature point; Determine a first target position corresponding to the thickness information corresponding to the target feature point in the original signal in the first linear fitting line, and determine a second target position corresponding to the thickness information corresponding to the target feature point in the original signal in the second linear fitting line.

10. The chemical mechanical polishing equipment according to claim 6, characterized in that: The controller is used to: A difference between the first target position in the position information and the second target position in the position information is determined as the offset.

11. A computer storage medium having a computer program stored thereon, wherein when the program is executed by a processor, the method for measuring metal film thickness based on eddy current as claimed in any one of claims 1 to 5 is implemented.

12. A computer program product, comprising computer instructions, wherein the computer instructions instruct a computing device to execute operations corresponding to the metal film thickness measurement method based on eddy current according to any one of claims 1 to 5.

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