Wafer metal film thickness measurement method, device, polishing equipment and medium

Abstract

Embodiments of the present application provide a wafer metal film thickness measurement method and device, polishing equipment and medium, wherein the method comprises: obtaining a first wear parameter and a first measurement signal, wherein the first wear parameter is used to indicate a current thickness of a polishing pad, and the first measurement signal is collected by an eddy current sensor, and the first measurement signal is related to the thickness of a metal film on the wafer and the thickness of the polishing pad; determining target mapping information according to the first wear parameter, wherein the target mapping information is used to indicate a corresponding relationship between the measurement signal collected by the eddy current sensor and the thickness of the metal film under the current thickness of the polishing pad; and determining the thickness of the metal film according to the first measurement signal and the target mapping information.

Description

TECHNICAL FIELD

[0001] Embodiments of the present application relate to the technical field of semiconductor manufacturing, and in particular, to a wafer metal film thickness measurement method and device, a polishing apparatus, and a medium. BACKGROUND

[0002] In a chemical mechanical polishing process, the thickness of a metal film on a wafer surface is measured by an eddy current sensor, and when the thickness of the metal film reaches a preset value, a correct signal is given to terminate the chemical mechanical polishing process. The eddy current sensor needs to maintain a fixed distance from the measured object to accurately measure the thickness of the metal film on the wafer surface.

[0003] However, as the polishing pad used for polishing the metal film wears, the thickness of the polishing pad changes. The change in the thickness of the polishing pad changes the distance between the eddy current sensor and the metal film on the wafer, causing the correspondence between the measurement signal of the eddy current sensor and the thickness of the metal film to change. At this time, the thickness of the metal film measured by the existing technology according to the measurement signal will no longer be accurate. Therefore, there is an urgent need for a new wafer metal film thickness measurement method that can accurately measure the thickness of the metal film on the wafer. SUMMARY

[0004] In view of the above, embodiments of the present application provide a wafer metal film thickness measurement method, device, polishing apparatus, and medium to at least partially solve the above problems.

[0005] According to a first aspect of embodiments of the present application, a wafer metal film thickness measurement method is provided, comprising: obtaining a first wear parameter and a first measurement signal, wherein the first wear parameter is used to indicate the current thickness of a polishing pad, and the first measurement signal is collected by an eddy current sensor, and the first measurement signal is related to the thickness of a metal film on the wafer and the thickness of the polishing pad; determining target mapping information according to the first wear parameter, wherein the target mapping information is used to indicate the correspondence between the measurement signal collected by the eddy current sensor and the thickness of the metal film at the current thickness of the polishing pad; and determining the thickness of the metal film according to the first measurement signal and the target mapping information.

[0006] According to a second aspect of the embodiments of the present application, a chemical mechanical polishing device is provided, comprising: an acquisition unit configured to acquire a first wear parameter and a first measurement signal, wherein the first wear parameter is used to indicate a current thickness of a polishing pad, and the first measurement signal is collected by an eddy current sensor, and the first measurement signal is related to a thickness of a metal film on the wafer and the thickness of the polishing pad; a mapping information determination unit configured to determine target mapping information according to the first wear parameter, wherein the target mapping information is used to indicate a corresponding relationship between the measurement signal collected by the eddy current sensor and the thickness of the metal film under the current thickness of the polishing pad; and a thickness determination unit configured to determine the thickness of the metal film according to the first measurement signal and the target mapping information.

[0007] According to a third aspect of the embodiments 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; the carrier head is configured to load a wafer to be polished and abut the wafer against a polishing pad above the polishing disc, and the liquid supply device is configured to supply a polishing liquid towards the polishing pad and the wafer; the eddy current sensor is configured to collect a measurement signal corresponding to a metal film of the wafer; and the controller is configured to execute the method according to any one of the preceding embodiments.

[0008] According to a fourth aspect of the embodiments of the present application, a computer storage medium is provided, and the computer storage medium stores a computer program, and the computer program is executed by a processor to implement the method according to any one of the preceding embodiments.

[0009] In the embodiments of the present application, the first wear parameter is used to indicate the current thickness of the polishing pad, and the first measurement signal is a measurement signal collected by the eddy current sensor during current thickness measurement. After the first wear parameter and the first measurement signal are acquired, the target mapping information is determined according to the first wear parameter, and an accurate corresponding relationship between the measurement signal collected by the eddy current sensor and the thickness of the metal film under the current thickness of the polishing pad can be obtained, that is, an accurate corresponding relationship between the measurement signal and the thickness of the metal film on the wafer under the distance between the current eddy current sensor and the metal film can be obtained. Therefore, according to the target mapping information, the first measurement signal can be mapped to the current thickness of the metal film on the wafer, and an accurate measurement value of the thickness of the metal film can be obtained. BRIEF DESCRIPTION OF DRAWINGS

[0010] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the drawings needed in the embodiments or the prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments described in the embodiments of the present application, and other drawings can also be obtained by those skilled in the art according to these drawings.

[0011] Figure 1This is a schematic diagram of the structure of a chemical mechanical polishing device provided in an optional embodiment of this application;

[0012] Figure 2 This is a schematic diagram of the motion trajectory between a wafer and an eddy current sensor provided in an optional embodiment of this application;

[0013] Figure 3 This is a flowchart of a method for measuring the thickness of a wafer metal thin film provided in an optional embodiment of this application;

[0014] Figure 4 This is a flowchart of another method for measuring the thickness of a wafer metal thin film provided in an optional embodiment of this application;

[0015] Figure 5 This is a schematic diagram illustrating the correlation between wear parameters of a polishing pad and a measurement signal, provided in an optional embodiment of this application.

[0016] Figure 6 This is a schematic diagram of mapping information provided in an optional embodiment of this application;

[0017] Figure 7 This is a structural block diagram of a wafer metal thin film thickness measuring device provided in an optional embodiment of this application. Detailed Implementation

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

[0019] According to a first aspect of the embodiments of this application, a method for measuring the thickness of a wafer metal thin film is provided to solve the above-mentioned problems.

[0020] The method provided in this application embodiment can be used to measure the thickness of a metal film on a wafer when polishing it using a chemical mechanical polishing (CMP) device. It should be understood that chemical mechanical polishing (CMP) is an ultra-precision surface processing technology that achieves global planarization, enabling the wafer to undergo chemical mechanical polishing through the combined action of chemicals and machinery.

[0021] like Figure 1As shown, the chemical mechanical polishing apparatus 10 can include a polishing disc 11, a carrier head 12, an eddy current sensor 13, a polishing pad 14, a controller 15 and a liquid supply device. The carrier head 12 loads a wafer to be polished and abuts a metal film on the wafer against the polishing pad 14 above the polishing disc 11. The liquid supply device supplies a polishing liquid toward the polishing pad 14 and the wafer. The eddy current sensor 13 is used to collect a corresponding measurement signal when measuring the thickness of the metal film on the wafer. The controller 15 is used to control the process of measuring the thickness of the metal film on the wafer. The wafer metal film thickness measurement method provided by the embodiments of the present application can be used to control the controller 15 to perform the process of measuring the thickness of the metal film on the wafer loaded by the carrier head 12.

[0022] During the polishing operation, due to the rotational movement of the polishing disc 11 and the rotational and translational movement of the carrier head 12, the eddy current sensor can pass under the wafer along a trajectory as shown in Figure 2 The trajectory can be divided into three parts: a wafer inner part 206, a wafer outer part 207 and a wafer boundary part 208. At the same time, a recording module in the controller 15 of the chemical mechanical polishing apparatus will record the measurement signal collected by the eddy current sensor on the trajectory.

[0023] It should be understood that, due to the basic measurement principle of the eddy current sensor, when the eddy current sensor measures the thickness at the wafer boundary part 208, it will inevitably be affected by the loss of the magnetic field, so that the measurement signal collected by the eddy current sensor will be attenuated. In this regard, the measurement signal collected by the eddy current sensor at the wafer boundary part 208 can be compensated, and the thickness of the metal film on the wafer is determined based on the compensated measurement signal. The specific process of compensation can refer to related technologies, which will not be described here. The measurement signal collected by the eddy current sensor recorded in the embodiments of the present application can be the measurement signal collected at the wafer inner part 206 or the measurement signal collected at the wafer boundary part 208 after compensation.

[0024] As shown in Figure 3 The wafer metal film thickness measurement method provided by the embodiments of the present application comprises:

[0025] S310: obtaining a first wear parameter and a first measurement signal, wherein the first wear parameter is used to indicate the current thickness of the polishing pad, and the first measurement signal is collected by the eddy current sensor, and the first measurement signal is related to the thickness of the metal film on the wafer and the thickness of the polishing pad.

[0026] The wear parameter of the polishing pad is a parameter used to indicate the thickness of the polishing pad. The first wear parameter is one of the wear parameters of the polishing pad, which is used to indicate the current thickness or real-time thickness of the polishing pad.

[0027] The chemical mechanical polishing apparatus can include a parameter recording unit configured to record a change in a wear parameter of the polishing pad during a polishing process of a wafer. The method provided by the embodiments of the present application can directly obtain the current wear parameter from the parameter recording unit, i.e., obtain the first wear parameter.

[0028] In some optional embodiments, the wear parameter of the polishing pad includes at least one of the following: a thickness of the polishing pad, a service time of the polishing pad, and a service number of the polishing pad. When the thickness of the polishing pad cannot be measured, the service time and / or the service number of the polishing pad can be used as the wear parameter of the polishing pad, thereby indirectly indicating the thickness of the polishing pad. The service number of the polishing pad can be the number of times of polishing wafers completed by the polishing pad. The service time of the polishing pad can include a time of polishing wafers by the polishing pad and a time of trimming the polishing pad by a trimmer, and the sum of the two times can be the service time of the polishing pad. The service time and the service number of the polishing pad can be recorded by a recording program, and the specific implementation of the recording program can refer to related technologies, which will not be described here.

[0029] It should be noted that by constructing the mapping relationship between the service time of the polishing pad and the thickness of the polishing pad and the mapping relationship between the service number of the polishing pad and the thickness of the polishing pad, the service time and the service number of the polishing pad can be mapped to the thickness of the polishing pad. When the service time and the service number of the polishing pad are used as the wear parameter of the polishing pad at the same time, the average value of the thickness of the polishing pad mapped by the service time and the service number respectively can be calculated, and the average value can be used to indicate the thickness of the polishing pad. The specific process of constructing the mapping relationship between the service time and the service number of the polishing pad and the thickness of the polishing pad can refer to related technologies, which will not be described here.

[0030] The wear parameter of the polishing pad provided by the embodiments of the present application can not only use the thickness of the polishing pad as the wear parameter to directly indicate the thickness of the polishing pad, but also use the service time or the service number of the polishing pad as the wear parameter to indirectly indicate the thickness of the polishing pad, thereby effectively improving the application range of the method provided by the embodiments of the present application.

[0031] In some optional embodiments, as shown in FIG. 1, Figure 1 The chemical mechanical polishing apparatus 10 can further include a trimmer 16 configured to trim the polishing pad 14. When the wear parameter of the polishing pad 14 includes the thickness of the polishing pad 14, obtaining the first wear parameter can include:

[0032] The polishing pad 14 is trimmed by a trimming disc 161 of the trimmer 16, and a displacement of the trimming disc 161 along the thickness direction of the polishing pad 14 during the trimming process of the polishing pad 14 is detected; and the thickness of the polishing pad 14 is determined according to the displacement and the original thickness of the polishing pad 14.

[0033] It should be noted that, in the process of modifying the polishing pad 14 by the modifying disc 161, the displacement of the modifying disc 161 along the thickness direction of the polishing pad 14 can indicate the thickness variation of the polishing pad 14.

[0034] The original thickness of the polishing pad 14 is the thickness of the polishing pad 14 when the modification of the polishing pad 14 is started by the modifying disc 161. The remaining thickness of the polishing pad 14 can be obtained by subtracting the displacement of the modifying disc 161 along the thickness direction of the polishing pad 14 from the original thickness of the polishing pad 14.

[0035] Exemplarily, as shown in Figure 1 In addition to the modifying disc 161, the modifier 16 can further include a cantilever 162, the modifying disc 161 can be fixed below the cantilever 162, and the cantilever 162 below the modifying disc 161 can be used to modify the polishing pad 14, and the cantilever 162 of the modifier 16 can be synchronously moved with the modifying head in the thickness direction of the polishing pad 14. In a feasible implementation, as shown in Figure 1 The modifier 16 can include a displacement sensor 17 arranged below the cantilever 162, and the displacement sensor 17 can be used to detect the displacement of the cantilever 162 along the thickness direction of the polishing pad 14, so that the displacement of the modifying disc 161 along the thickness direction of the polishing pad 14 can be indirectly detected by detecting the displacement of the cantilever 162 along the thickness direction of the polishing pad 14.

[0036] In the embodiment of the application, the polishing pad 14 can be modified by the modifying disc 161 of the modifier 16, and the displacement of the modifying disc 161 along the thickness direction of the polishing pad 14 in the process of modifying the polishing pad 14 can be detected. The thickness of the polishing pad 14 can be determined according to the displacement and the original thickness of the polishing pad 14, the thickness detection of the polishing pad 14 can be realized, and the wear parameter of the polishing pad 14 can be obtained.

[0037] When the eddy current sensor measures the thickness of the metal film, an alternating electromagnetic field can be excited in the metal film, and the change of the induced electromotive force generated by the mutual inductance effect caused by the metal film with different thicknesses can be measured. Since the induced electromotive force and the thickness of the metal film have a one-to-one correspondence under other conditions, that is, the measurement signal collected by the eddy current sensor is related to the thickness of the metal film, and the measurement signal can be used to indicate the measurement thickness of different positions on the metal film. In the embodiment of the application, the first measurement signal is the measurement signal currently collected by the eddy current sensor.

[0038] S320: determining target mapping information according to the first wear parameter, wherein the target mapping information is used to indicate the correspondence between the measurement signal collected by the eddy current sensor and the thickness of the metal film under the current thickness of the polishing pad.

[0039] The target mapping information can be pre-stored mapping information or live determined mapping information, both of which are within the protection scope of the embodiments of the present application. Moreover, the content of the mapping information can be a relational expression, a data table or a mapping curve corresponding to the thickness of the metal film, etc., as long as it can represent the corresponding relationship between the measurement signal collected by the eddy current sensor and the thickness of the metal film.

[0040] S330: determining the thickness of the metal film according to the first measurement signal and the target mapping information.

[0041] After the target mapping information is determined, the first measurement signal can be substituted into the target mapping information to determine the thickness value mapped by the first measurement signal, and the thickness value is taken as the thickness of the metal film on the wafer.

[0042] In the embodiments of the present application, the first wear parameter is used to indicate the current thickness of the polishing pad, and the first measurement signal is the measurement signal collected by the eddy current sensor during the current thickness measurement. After the first wear parameter and the first measurement signal are obtained, the target mapping information is determined according to the first wear parameter, and the accurate corresponding relationship between the measurement signal collected by the eddy current sensor and the thickness of the metal film under the current thickness of the polishing pad can be obtained, that is, the accurate corresponding relationship between the measurement signal and the thickness of the metal film on the wafer under the distance between the current eddy current sensor and the metal film can be obtained. Thus, according to the target mapping information, the first measurement signal can be mapped to the current thickness of the metal film on the wafer to obtain the accurate measurement value of the thickness of the metal film.

[0043] As shown in Figure 4 Optionally, the method for measuring the thickness of the metal film on the wafer in the embodiments of the present application comprises:

[0044] S310: obtaining the first wear parameter and the first measurement signal.

[0045] S321: determining at least one relevant mapping information from a plurality of mapping information according to the first wear parameter, wherein the plurality of mapping information is used to indicate the corresponding relationship between the measurement signal collected by the eddy current sensor and the thickness of the metal film under different wear parameters, and different mapping information corresponds to different wear parameters.

[0046] In the embodiments of the present application, a plurality of mapping information can be pre-stored, wherein different mapping information corresponds to different wear parameters. It should be understood that the relevant mapping information can be the target mapping information itself or the mapping information associated with the target mapping information.

[0047] S322: determining the target mapping information according to the at least one relevant mapping information.

[0048] As shown in Figure 5As shown in the figure, the abscissa is the wear parameter of the polishing pad, the ordinate is the value of the measurement signal collected by the eddy current sensor, and each point in the figure represents the measurement signal value corresponding to different polishing pad wear parameters when the thickness of the metal film of the wafer is constant. It can be seen from the line segment fitted by the points in the figure that there is a correlation between the wear parameter of the polishing pad and the measurement signal collected by the eddy current sensor when the thickness of the metal film of the wafer is constant. Since the difference between the mapping information can be manifested as that the mapping information in each mapping information is different when the thickness of the metal film of the wafer is constant. Therefore, according to the correlation between the wear parameter of the polishing pad and the measurement signal, the target mapping information corresponding to the first wear parameter can be determined from the mapping information corresponding to a wear parameter. Figure 5 As shown in the figure, the abscissa is the wear parameter of the polishing pad, the ordinate is the value of the measurement signal collected by the eddy current sensor, and each point in the figure represents the measurement signal value corresponding to different polishing pad wear parameters when the thickness of the metal film of the wafer is constant. It can be seen from the line segment fitted by the points in the figure that there is a correlation between the wear parameter of the polishing pad and the measurement signal collected by the eddy current sensor when the thickness of the metal film of the wafer is constant. Since the difference between the mapping information can be manifested as that the mapping information in each mapping information is different when the thickness of the metal film of the wafer is constant. Therefore, according to the correlation between the wear parameter of the polishing pad and the measurement signal, the target mapping information corresponding to the first wear parameter can be determined from the mapping information corresponding to a wear parameter.

[0049] S330: Determine the thickness of the metal film according to the first measurement signal and the target mapping information.

[0050] The specific implementation of S310 and S330 can refer to the above embodiments, which will not be described here.

[0051] In the embodiments of the present application, the pre-stored mapping information from the plurality of mapping information can be obtained. According to the first wear parameter, at least one related mapping information is determined from the plurality of mapping information, and the target mapping information is determined according to the related mapping information. Thus, when facing any first wear parameter, the corresponding target mapping information can be indirectly determined by determining the related mapping information, which can significantly improve the practicability of the method provided by the embodiments of the present application.

[0052] In some optional embodiments, according to the first wear parameter, at least one related mapping information is determined from the plurality of mapping information, including: if the plurality of mapping information includes mapping information corresponding to the first wear parameter, the mapping information corresponding to the first wear parameter is determined as the related mapping information.

[0053] According to at least one related mapping information, the target mapping information is determined, including: the related mapping information is determined as the target mapping information.

[0054] In the embodiments of the present application, when the above plurality of mapping information includes the mapping information corresponding to the first wear parameter, the mapping information can be used as the related mapping information, and the related mapping information at this time can be directly determined as the target mapping information, which does not have to go through complex operation, and the target mapping information can be quickly and efficiently determined, thereby improving the efficiency of measuring the thickness of the metal film of the wafer.

[0055] In some optional embodiments, determining at least one relevant mapping information from multiple mapping information according to a first wear parameter includes: if the mapping information corresponding to the wear parameter of the first wear parameter is not included in the multiple mapping information, determining the two mapping information with the wear parameter closest to the first wear parameter in the multiple mapping information as the first mapping information and the second mapping information respectively, and determining the first mapping information and the second mapping information as the relevant mapping information respectively.

[0056] The multiple mapping information can be multiple mapping curves. Exemplarily, as Figure 6 shown, each mapping information can be a mapping curve mapping between the measurement signal collected by an eddy current sensor and the thickness of the wafer metal thin film. Among them, the wear parameters corresponding to the mapping curves L1, L2, and L3 are a, b, and c respectively, where a > b > c (or a < b < c). Let the first wear parameter be t. If t is not equal to a, b, and c, then determine the two wear parameters closest to t from a, b, and c, and determine the mapping information corresponding to these two wear parameters as the first mapping information and the second mapping information. For example, if t > a > b > c, the two wear parameters closest to t are a and b. At this time, L1 and L2 can be determined as the first mapping information and the second mapping information respectively, and the first mapping information and the second mapping information are determined as the relevant mapping information. If a > b > t > c, the two wear parameters closest to t are b and c. At this time, L2 and L3 can be determined as the first mapping information and the second mapping information respectively, and the first mapping information and the second mapping information are determined as the relevant mapping information.

[0057] Determining target mapping information according to at least one relevant mapping information includes: determining target mapping information according to the first mapping information and the second mapping information.

[0058] In some optional embodiments, after obtaining the first mapping information and the second mapping information as the relevant mapping information, the target mapping information can be determined by using the "interpolation method" according to the first mapping information, the second mapping information, the wear parameter corresponding to the first mapping information, and the wear parameter corresponding to the second mapping information.

[0059] From Figure 5 the line segments fitted by the points in, it can be seen that when the thickness of the metal thin film of the wafer is constant, there is approximately a linear relationship between the polishing pad wear parameter and the measurement signal collected by the eddy current sensor. Therefore, through the "interpolation method", according to the coordinates of the points on the curves of the first mapping information and the second mapping information, the coordinates of the points on the target mapping curve corresponding to the target mapping information can be determined. After determining the coordinates of the points on the target mapping curve, the target mapping curve can be obtained by means of machine learning or curve fitting, etc., that is, the target mapping information is obtained.

[0060] It should be noted that the "interpolation method" adopted in the embodiments of the present application includes "interpolation" and "extrapolation" (also known as extrapolation). The specific process of determining the target mapping information according to the first mapping information and the second mapping information by using the interpolation method will be described below.

[0061] As shown in Figure 6 some embodiments, when the ordinate is Y1, the points on L1, L2 and L3 are N1, N2 and N3 respectively. The coordinates of N1, N2 and N3 are (X1, Y1), (X2, Y1) and (X3, Y1) respectively. The target mapping curve corresponding to the target mapping information is Lt, and the point on Lt with the ordinate Y1 is Nt(Xt, Y1).

[0062] If a > b > c > t, that is, the first mapping information and the second mapping information are L2 and L3, then the abscissa Xt of Nt can be calculated according to the coordinates (X2, Y1) and (X3, Y1) of the points N2 and N3 on L2 and L3, and the proportional relationship between the wear parameters b and c corresponding to L2 and L3 and the wear parameter t corresponding to Lt by using "extrapolation". Exemplarily, the abscissa Xt of Nt can be calculated by (b-c) / (c-t) = (X2-X3) / (X3-Xt).

[0063] If a > t > b > c, that is, the first mapping information and the second mapping information are L1 and L2, then the abscissa Xt of Nt can be calculated according to the coordinates (X1, Y1) and (X2, Y1) of the points N1 and N2 on L1 and L2, and the proportional relationship between the wear parameters a and b corresponding to L1 and L2 and the wear parameter t corresponding to Lt by using "interpolation". Exemplarily, the abscissa Xt of Nt can be calculated by (t-b) / (a-b) = (Xt-X2) / (X1-X2). Similarly, the coordinates of the points on Lt corresponding to the target mapping information when the ordinates are Y2, Y3, Y4,... can be obtained in a similar manner, so that the target mapping curve Lt, that is, the target mapping information, can be obtained according to the coordinates of the points on Lt when the ordinates are Y1, Y2, Y3, Y4,..., and then by using machine learning or curve fitting.

[0064] The method provided in the embodiments of the present application can determine the target mapping information by simple interpolation operation, the operation process is simple and convenient, the computer computing power can be saved, and the efficiency of measuring the thickness of the metal film on the wafer surface can be effectively improved.

[0065] In the embodiments of the present application, when the mapping information corresponding to the first wear parameter is not included in the plurality of mapping information, the two mapping information corresponding to the wear parameters closest to the first wear parameter in the plurality of mapping information are determined as the first mapping information and the second mapping information respectively, and the first mapping information and the second mapping information are determined as the related mapping information respectively, and then the target mapping information is determined according to the first mapping information and the second mapping information. It can be seen that the method provided in the embodiments of the present application can determine the corresponding target mapping information when the first wear parameter is any value, that is, the target mapping information corresponding to any wear condition of the polishing pad can be determined, so that the thickness of the metal film on the wafer can be accurately measured in any condition.

[0066] In some optional embodiments, the determining at least one related mapping information from the plurality of mapping information according to the first wear parameter comprises: if the mapping information corresponding to the first wear parameter is not included in the plurality of mapping information, the mapping information corresponding to the wear parameter closest to the first wear parameter in the plurality of mapping information is determined as the related mapping information.

[0067] For example, if the wear parameter closest to the first wear parameter t is a, the mapping information (mapping curve L1) corresponding to the wear parameter a can be determined as the target mapping information.

[0068] The determining the target mapping information according to the at least one related mapping information comprises: determining the target mapping information according to the related mapping information and the linear relationship between the wear parameter and the measurement signal.

[0069] With reference to Figure 5 , the slope of the linear relationship between the wear parameter and the measurement signal can be determined according to the straight line fitted according to each point in Figure 5 For example, if the related mapping information is the mapping curve corresponding to L1 in Figure 6 , the horizontal coordinate of the vertical coordinate Y1 point on the mapping curve corresponding to the target mapping information can be calculated according to the coordinates (X1, Y1) of the point N1 on L1 and the slope of the linear relationship between the wear parameter and the measurement signal. In this way, the coordinates of multiple points on the mapping curve corresponding to the target mapping information can be obtained. According to the coordinates of the multiple points on the mapping curve corresponding to the target mapping information, the target mapping information can be determined.

[0070] In the embodiments of the present application, the target mapping information is determined according to the related mapping information and the linear relationship between the wear parameter and the measurement signal, that is, the unknown target mapping information is determined according to the linear relationship between the wear parameter and the measurement signal based on the known related mapping information, which can effectively improve the accuracy of the determined target mapping information, so that the thickness of the metal film on the wafer can be accurately measured.

[0071] In some optional embodiments, the first wear parameter and the first measurement signal are acquired by: acquiring the first wear parameter according to a polishing instruction, and polishing the metal film; wherein the polishing instruction is used to instruct to polish the metal film on the wafer; and the first measurement signal is acquired during the polishing of the metal film.

[0072] In the embodiments of the present application, when the polishing instruction is received, the first wear parameter is acquired, and the metal film on the wafer is polished after the first wear parameter is acquired, and the first measurement signal is acquired during the polishing of the metal film, so that the first wear parameter is obtained before the thickness of the metal film corresponding to the first measurement signal is determined, so as to determine the thickness of the metal film corresponding to the first measurement signal according to the target mapping information corresponding to the first wear parameter, which can provide accurate target mapping information for determining the thickness of the metal film, thereby improving the accuracy of determining the thickness of the metal film.

[0073] As a feasible implementation manner, the first wear parameter can be acquired once before each acquisition of the first measurement signal, and the corresponding target mapping information is determined according to the acquired first wear parameter, so as to update the target mapping information, thereby ensuring the timeliness of the target mapping information and improving the accuracy of determining the thickness of the metal film according to the target mapping information. Alternatively, the first wear parameter can also be acquired according to other time sequences to update the target mapping information, which are all within the protection scope of the embodiments of the present application.

[0074] In some optional embodiments, after the thickness of the metal film is determined according to the first measurement signal and the target mapping information, the method further comprises: stopping polishing the metal film when the thickness of the metal film reaches a target thickness.

[0075] The target thickness can be preset according to the user's requirement for the thickness of the metal film on the wafer, for example, the target thickness can be equal to the thickness of the metal film required by the user, or slightly less than / greater than the thickness of the metal film required by the user, which are all within the protection scope of the embodiments of the present application.

[0076] The embodiments of the present application can sequentially acquire the first measurement signal during the polishing of the metal film on the wafer, and the thickness of the corresponding metal film can be determined after each acquisition of the first measurement signal in combination with the target mapping information, so as to determine the polishing progress of the metal film on the wafer, and the polishing of the metal film is stopped when the obtained thickness of the metal film reaches the target thickness, which can accurately control the progress of polishing the metal film on the wafer, thereby accurately completing the polishing of the metal film on the wafer.

[0077] In some optional embodiments, the method provided by the present application further comprises the step of determining the above plurality of mapping information, comprising:

[0078] A plurality of polishing pad samples with different polishing pad wear parameters and wafer samples with different thicknesses of metal films are set.

[0079] For each polishing pad sample, measurement signals collected by the eddy current sensor for different wafer samples when using the polishing pad sample are measured.

[0080] According to the measurement signals collected by the eddy current sensor and the corresponding wafer samples, a corresponding relationship between the measurement signals collected by the eddy current sensor and the thicknesses of the metal films of the wafer samples when using each polishing pad sample is determined, that is, mapping information corresponding to the polishing pad wear parameters of each polishing pad sample is obtained.

[0081] In addition, after the mapping information corresponding to the plurality of polishing pad wear parameters is determined, the mapping information corresponding to more polishing pad wear parameters can also be determined according to the determined mapping information by using the interpolation method described above. The specific implementation of the interpolation method can refer to the above embodiment, and will not be described here.

[0082] In the embodiments of the present application, a plurality of polishing pad samples with different polishing pad wear parameters and wafer samples with different thicknesses of metal films can be set, and a plurality of mapping information is determined for wafer metal film thickness measurement, so that the time for determining the target mapping information can be reduced, and the efficiency of the metal film thickness measurement can be improved.

[0083] According to a second aspect of the embodiments of the present application, a wafer metal film thickness measurement device is provided.

[0084] As shown in Figure 7 The wafer metal film thickness measurement device includes:

[0085] The acquisition unit 710 is configured to acquire a first wear parameter and a first measurement signal, wherein the first wear parameter is used to indicate the current thickness of the polishing pad, and the first measurement signal is collected by the eddy current sensor, and the first measurement signal is related to the thickness of the metal film on the wafer and the thickness of the polishing pad.

[0086] The mapping information determination unit 720 is configured to determine target mapping information according to the first wear parameter, wherein the target mapping information is used to indicate the corresponding relationship between the measurement signal collected by the eddy current sensor and the thickness of the metal film at the current thickness of the polishing pad.

[0087] The thickness determination unit 730 is configured to determine the thickness of the metal film according to the first measurement signal and the target mapping information.

[0088] The wafer metal thin film thickness measuring device of the embodiment and the wafer metal thin film thickness measuring method of the embodiment are based on the same inventive concept, and are used to implement the wafer metal thin film thickness measuring method of the corresponding method embodiment, and have the beneficial effects of the corresponding method embodiment, which will not be described herein again. In addition, the functions of each unit in the wafer metal thin film thickness measuring device of the embodiment can be implemented by referring to the description of the corresponding part in the method embodiment, which will not be described herein again.

[0089] As shown in Figure 1 According to a third aspect of the embodiments of the present application, a chemical mechanical polishing device 10 is provided, which comprises a polishing disc 11, a carrier head 12, an eddy current sensor 13, a polishing pad 14, a controller 15 and a liquid supply device. The carrier head 12 loads a wafer to be polished and abuts the polishing pad 14 above the polishing disc 11, and the liquid supply device supplies polishing liquid towards the polishing pad and the wafer. The eddy current sensor 13 is used to collect a measurement signal corresponding to the metal thin film of the wafer. The controller 15 is used to implement the method of any of the method embodiments. As a feasible implementation manner, the controller 15 can comprise a processor and a computer program, and the processor can implement the method of any of the method embodiments when running the computer program.

[0090] According to a fourth aspect of the embodiments of the present application, a computer storage medium is provided, which stores a computer program. The program is executed by a processor to implement the method described in any of the method embodiments. The computer storage medium includes but is not limited to a compact disc read-only memory (CD-ROM), a random access memory (RAM), a floppy disk, a hard disk or a magneto-optical disk.

[0091] It should be noted that, according to the needs of implementation, each component / step described in the embodiments of the present application can be split into more components / steps, or two or more components / steps or part of the operations of the components / steps can be combined into a new component / step, to achieve the purpose of the embodiments of the present application.

[0092] The method according to the embodiments of the present application can be implemented in hardware, firmware, or software, or be implemented as software or computer code that can be stored in a recording medium such as a CD-ROM, a RAM, a floppy disk, a hard disk, or a magneto-optical disk, or be implemented by computer code originally stored in a remote recording medium or a non-transitory machine readable medium and downloaded into a local recording medium, so that the method described herein can be stored on a recording medium in the form of such software processing using a general purpose computer, a special purpose processor, or programmable or special hardware such as an Application Specific Integrated Circuit (ASIC) or a Field Programmable Gate Array (FPGA).

[0093] Those skilled in the art can realize that the units and method steps of each example described in combination with the embodiments disclosed herein can be realized in electronic hardware or in a combination of computer software and electronic hardware. Whether the functions are realized in hardware or software depends on the specific application and design constraints of the technical solution. A person skilled in the art can use different methods to realize the described functions for each specific application, but such implementation should not be considered beyond the scope of the embodiments of the present application.

[0094] The above embodiments are only used to illustrate the present application, and not to limit the present application, and those skilled in the art can 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, the patent protection scope of the present application should be defined by the claims.

Claims

1. A method of measuring the thickness of a metal thin film of a wafer, characterized by, The method comprises: obtaining a first wear parameter and a first measurement signal, wherein the first wear parameter is used to indicate a current thickness of the polishing pad, the first measurement signal is collected by the eddy current sensor, and the first measurement signal is related to the thickness of the metal film on the wafer and the thickness of the polishing pad; determining target mapping information according to the first wear parameter, wherein the target mapping information is used to indicate a corresponding relationship between the measurement signal collected by the eddy current sensor and the thickness of the metal film under the current thickness of the polishing pad; determining the thickness of the metal film according to the first measurement signal and the target mapping information; The method comprises: determining at least one related mapping information from a plurality of mapping information according to the first wear parameter, wherein the plurality of mapping information is used to indicate a corresponding relationship between the measurement signal collected by the eddy current sensor and the thickness of the metal film under different wear parameters, and different mapping information corresponds to different wear parameters; determining the target mapping information according to the at least one related mapping information; The method comprises: if the plurality of mapping information does not include mapping information corresponding to the first wear parameter, determining two mapping information corresponding to the wear parameters closest to the first wear parameter in the plurality of mapping information as first mapping information and second mapping information respectively, and determining the first mapping information and the second mapping information as related mapping information respectively.

2. The method of claim 1, wherein, The method comprises: determining the target mapping information according to the first mapping information and the second mapping information.

3. The method of claim 1, wherein, The method comprises: determining the target mapping information according to the first mapping information, the second mapping information, the wear parameter corresponding to the first mapping information, and the wear parameter corresponding to the second mapping information. The method comprises:

4. The method of claim 3, wherein, obtaining the first wear parameter according to a polishing instruction, and polishing the metal film, wherein the polishing instruction is used to indicate polishing the metal film on the wafer; 5. The method according to any one of claims 1-4, characterized in that, obtaining the first measurement signal in the process of polishing the metal film.

6. The method of claim 5, wherein, After determining the thickness of the metal film according to the first measurement signal and the target mapping information, the method further comprises: stopping polishing the metal film when the thickness of the metal film reaches a target thickness. The wear parameter of the polishing pad at least includes one of the following: the thickness of the polishing pad, the use time length of the polishing pad, and the use frequency of the polishing pad. The method further comprises:

7. A device for measuring the thickness of a wafer metal thin film, characterized in that, when the wear parameter of the polishing pad includes the thickness of the polishing pad, the method comprises: trimming the polishing pad by a trimming disc of a trimmer, and detecting displacement of the trimming disc in the thickness direction of the polishing pad in the process of trimming the polishing pad; and determining the thickness of the polishing pad according to the displacement and the original thickness of the polishing pad. The method comprises: An acquisition unit is configured to acquire a first wear parameter and a first measurement signal, wherein the first wear parameter is used to indicate a current thickness of a polishing pad, and the first measurement signal is collected by an eddy current sensor and is related to a thickness of a metal film on a wafer and a thickness of the polishing pad; A mapping information determination unit is configured to determine target mapping information according to the first wear parameter, wherein the target mapping information is used to indicate a corresponding relationship between a measurement signal collected by the eddy current sensor and the thickness of the metal film under the current thickness of the polishing pad; A thickness determination unit is configured to determine the thickness of the metal film according to the first measurement signal and the target mapping information. The determination of the target mapping information according to the first wear parameter comprises: According to the first wear parameter, at least one related mapping information is determined from a plurality of mapping information, wherein the plurality of mapping information is used to indicate a corresponding relationship between a measurement signal collected by the eddy current sensor and the thickness of the metal film under different wear parameters, and different mapping information corresponds to different wear parameters; The target mapping information is determined according to the at least one related mapping information. The determination of the at least one related mapping information from the plurality of mapping information according to the first wear parameter comprises: if the plurality of mapping information does not include mapping information corresponding to the first wear parameter, then two mapping information corresponding to wear parameters closest to the first wear parameter in the plurality of mapping information are determined as first mapping information and second mapping information respectively, and the first mapping information and the second mapping information are determined as related mapping information respectively. The determination of the target mapping information according to the at least one related mapping information comprises: the target mapping information is determined according to the first mapping information and the second mapping information.

8. A chemical mechanical polishing apparatus characterized by comprising: Comprise: Comprise a polishing disc, a carrier head, a liquid supply device, an eddy current sensor and a controller; The carrier head loads a wafer to be polished and abuts the wafer to a polishing pad above the polishing disc, the liquid supply device supplies a polishing liquid towards the polishing pad and the wafer, the eddy current sensor is configured to collect a measurement signal corresponding to a metal film of the wafer, and the controller is configured to perform the method of any one of claims 1-6.

9. A computer storage medium, characterized in that A computer program is stored thereon, which is executed by a processor to implement the method of any one of claims 1-6.

Images