Metal film thickness measuring method, device and equipment, polishing method and storage medium

Abstract

The invention discloses a metal film thickness measuring method, device and equipment, a polishing method and a storage medium, and the method comprises the steps: detecting the thickness of a metal film on a wafer through an eddy current sensor, and obtaining a measurement signal outputted by the eddy current sensor; obtaining a measurement temperature; obtaining a measurement thickness value according to the measurement signal and the base value signal; obtaining a thickness compensation value according to the measured temperature and the base value temperature; and determining the thickness of the metal film according to the measured thickness value and the thickness compensation value. According to the method and the device, the thickness compensation value for compensating the measurement signal obtained by detection of the eddy current sensor is determined through the measurement temperature and the base value temperature when the thickness of the metal film on the wafer is detected, the influence of the working environment temperature on the eddy current sensor can be eliminated to a great extent, and the precision of metal film thickness detection is further improved.

Description

Technical Field

[0001] The present application relates to the technical field of chemical mechanical polishing, and in particular to a metal film thickness measurement method, device, wafer polishing method, chemical mechanical polishing equipment and computer storage medium. Background Art

[0002] Chemical mechanical polishing (CMP) is one of the most important process steps in the semiconductor integrated circuit manufacturing industry. During the entire CMP process, temperature is one of the main factors affecting the final polishing effect of the wafer. Using a film thickness sensor in an environment with large temperature changes will produce large errors. For the manufacturing process of semiconductor devices, too much or too little material removal will cause the electrical properties of the device to deteriorate or even fail. In order to minimize the measurement error, the film thickness sensor must be effectively temperature compensated in some special environments.

[0003] At present, the heating condition of the resistor in the film thickness sensor is mainly referred to. According to the influence of the resistivity of the resistor on the working temperature of the film thickness sensor, a corresponding compensation model is constructed, and compensation is performed according to the output results of the model.

[0004] However, during the polishing process, as the polishing time increases, the working environment temperature of the film thickness sensor will increase due to heat generated by friction or chemical reaction. As a result, the working temperature of the film thickness sensor is not only affected by the resistivity of the resistor in the film thickness sensor, but also by the working environment temperature, resulting in a large change in the base value signal. The difference between the metal film thickness signal and the base value signal changes accordingly, resulting in abnormal display of the metal film thickness during the polishing process. Summary of the invention

[0005] In view of this, the present application provides a metal film thickness measurement method, device, wafer polishing method, chemical mechanical polishing equipment and computer storage medium to solve the technical problem of inaccurate metal film thickness measurement in traditional solutions.

[0006] In a first aspect, the present application provides a method for measuring the thickness of a metal film, the method comprising: detecting the thickness of a metal film on a wafer by means of an eddy current sensor to obtain a measurement signal output by the eddy current sensor; obtaining a measurement temperature, wherein the measurement temperature is the temperature of the eddy current sensor when the eddy current sensor outputs the measurement signal; obtaining a measurement thickness value according to the measurement signal and a base signal, wherein the base signal is a signal output by the eddy current sensor when it is unloaded at the base temperature; obtaining a thickness compensation value according to the measurement temperature and the base temperature, wherein the thickness compensation value is used to indicate a deviation of the measurement temperature from the base temperature, resulting in a deviation of the measurement thickness value from a true thickness value of the metal film; determining the thickness of the metal film according to the measurement thickness value and the thickness compensation value.

[0007] Optionally, the process of obtaining the thickness compensation value according to the measured temperature and the base temperature may further include: inputting the measured temperature and the base temperature into a temperature compensation model to obtain the thickness compensation value output by the temperature compensation model.

[0008] Optionally, the temperature compensation model is trained in the following manner: obtaining a first mapping relationship, wherein the first mapping relationship is used to indicate the mapping relationship between a no-load signal output by the eddy current sensor when it is no-load and the temperature of the eddy current sensor; obtaining multiple second mapping relationships, wherein different second mapping relationships correspond to different metal film thicknesses, and the second mapping relationship is used to indicate the mapping relationship between a loaded signal output by the eddy current sensor when detecting a wafer with a corresponding metal film thickness and the temperature of the eddy current sensor; constructing the temperature compensation model based on the first mapping relationship and the multiple second mapping relationships.

[0009] Optionally, the process of obtaining the first mapping relationship may also include: placing the eddy current sensor without a wafer in a preset test environment, and collecting the no-load signal output by the eddy current sensor when it is no-load; changing the temperature of the test environment, and determining a first change in the no-load signal as the temperature of the test environment changes; obtaining the first mapping relationship based on the first change and a standard no-load signal output by the eddy current sensor, wherein the standard no-load signal is a signal output when the eddy current sensor is no-load and at normal operating temperature.

[0010] Optionally, the process of changing the temperature of the test environment and determining a first change of the no-load signal as the temperature of the test environment changes may also include: increasing the temperature of the test environment at a fixed rate, and collecting a plurality of no-load signals output by the eddy current sensor during the temperature increase of the test environment; determining a first change of the no-load signal as the temperature of the test environment changes based on the collected plurality of no-load signals and the temperature of the test environment when the no-load signals are collected.

[0011] Optionally, the process of collecting a plurality of no-load signals output by the eddy current sensor during the temperature rise of the test environment may further include: when the eddy current sensor is in a stable working state in the test environment, collecting the no-load signals output by the eddy current sensor.

[0012] Optionally, the process of obtaining multiple second mapping relationships may also include: placing the eddy current sensor loaded with wafers with metal films of different thicknesses in a preset test environment, and collecting the carried signal output by the eddy current sensor; changing the temperature of the test environment, and determining a second change in the carried signal as the temperature of the test environment changes; obtaining the second mapping relationship based on the second change and a standard carried signal output by the eddy current sensor, wherein the standard carried signal is a signal output by the eddy current sensor when the wafer is loaded and is at normal operating temperature.

[0013] Optionally, the process of constructing the temperature compensation model according to the first mapping relationship and the multiple second mapping relationships may also include: obtaining a third mapping relationship corresponding to the metal film thickness corresponding to the second mapping relationship according to the first mapping relationship and the second mapping relationship, wherein the third mapping relationship is used to indicate the mapping relationship between the thickness signal and the temperature of the eddy current sensor under the corresponding metal film thickness, and the thickness signal is the deviation between the loaded signal and the no-load signal of the eddy current sensor at the same temperature; determining a fourth mapping relationship corresponding to the metal film thickness corresponding to the third mapping relationship according to the third mapping relationship and the metal film thickness corresponding to the third mapping relationship, wherein the fourth mapping relationship is used to indicate the deviation between the metal film thickness indicated by the corresponding thickness signal and the true value of the metal film thickness; determining the temperature compensation model according to the fourth mapping relationship corresponding to different metal film thicknesses.

[0014] Optionally, the process of obtaining a third mapping relationship corresponding to the metal film thickness corresponding to the second mapping relationship based on the first mapping relationship and the second mapping relationship may also include: for the second mapping relationships corresponding to different metal film thicknesses, executing: obtaining the no-load signal corresponding to the first mapping relationship and the loaded signal corresponding to the second mapping relationship at the same temperature; determining the difference between the no-load signal and the loaded signal at the same temperature as the thickness signal at the temperature; and determining the third mapping relationship corresponding to the metal film thickness corresponding to the second mapping relationship based on the thickness signals at multiple temperatures.

[0015] Optionally, the process of determining the temperature compensation model according to the fourth mapping relationship corresponding to different metal film thicknesses may also include: constructing a pre-trained model according to multiple fourth mapping relationships corresponding to different metal film thicknesses; compensating the pre-trained model according to temperature compensation parameters to obtain the temperature compensation model, wherein the temperature compensation parameters are determined according to at least one of the temperature of the working environment of the eddy current sensor, the temperature of the wafer loaded by the eddy current sensor, and the temperature of the polishing equipment connected to the eddy current sensor.

[0016] A second aspect of the present application provides a metal film thickness measuring device, comprising: a controller and an eddy current sensor; the controller is used to detect the thickness of the metal film on a wafer through the eddy current sensor, obtain a measurement signal output by the eddy current sensor, and obtain a measurement temperature, obtain a measurement thickness value according to the measurement signal and a base value signal, obtain a thickness compensation value according to the measurement temperature and the base value temperature, and determine the thickness of the metal film according to the measurement thickness value and the thickness compensation value, wherein the measurement temperature is the temperature of the eddy current sensor when the eddy current sensor collects the measurement signal, the base value signal is a signal output by the eddy current sensor when it is unloaded at the base value temperature, and the thickness compensation value is used to indicate the deviation of the measurement temperature relative to the base value temperature causing the deviation of the measurement thickness value.

[0017] Optionally, the metal film thickness measuring device further includes: a temperature sensor; the temperature sensor is used to obtain the measured temperature.

[0018] Optionally, the controller is used to input the measured temperature and the base temperature into a temperature compensation model to obtain a thickness compensation value output by the temperature compensation model.

[0019] The third aspect of the present application provides a chemical mechanical polishing equipment, comprising: a polishing disk, a carrier head, a liquid supply device, a trimmer and a metal film thickness measuring device as provided in the second aspect of the present application; the carrier head is used to load the wafer to be polished and abut it against the polishing pad above the polishing disk; the liquid supply device is used to supply polishing liquid between the polishing pad and the wafer during the polishing process; the trimmer is used to trim the surface of the polishing pad; the metal film thickness measuring device is used to detect the thickness of the metal film on the wafer during the polishing process.

[0020] Optionally, the metal film thickness measuring device is used to collect the temperature of the working environment, the temperature of the polished wafer and the temperature of the liquid supply device during the polishing process, and compensate the measured thickness of the metal film based on at least one of the temperature of the working environment, the temperature of the polished wafer and the temperature of the liquid supply device.

[0021] Optionally, the metal film thickness measuring device is used to compensate the temperature compensation model according to the temperature of the working environment, the temperature of the polished wafer and at least one of the temperatures of the liquid supply device, and to compensate the measured thickness of the metal film according to the thickness compensation value output by the compensated temperature compensation model.

[0022] The fourth aspect of the present application provides a wafer polishing method, the method comprising: in the process of polishing the wafer, executing the metal film thickness measurement method of the first aspect of the present application to obtain the thickness of the metal film on the wafer; when the thickness of the metal film meets the preset thickness value, determining that the polishing process is over, and controlling the polishing equipment to stop polishing the wafer.

[0023] Optionally, after it is determined that the polishing process is finished, the carrier head is controlled to grab the polished wafer.

[0024] A fifth aspect of the present application provides a computer storage medium having a computer program stored thereon, which, when executed by a processor, implements the method described in the first aspect or the fourth aspect of the embodiment.

[0025] In a sixth aspect, the present application provides a computer program product, including computer instructions, which instruct a computing device to perform operations corresponding to the method described in the first aspect or the fourth aspect of the embodiment.

[0026] The present application determines the thickness compensation value for compensating the measurement signal obtained by the eddy current sensor by detecting the measurement temperature and base temperature when the thickness of the metal film on the wafer is detected. This can largely eliminate the influence of the working environment temperature on the eddy current sensor, thereby improving the accuracy of metal film thickness detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present application or the technical solutions in 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 embodiments of the present application. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0028] Figure 1 is a flowchart of a method for measuring the thickness of a metal film according to an embodiment of the present application; Figure 2 is a flowchart of the steps of a temperature compensation model training method according to an embodiment of the present application; Figure 3 Schematic diagram of a first variation and a second variation of an embodiment of the present application Figure 4 is a schematic diagram of a metal film thickness measuring device according to an embodiment of the present application; Figure 5 is a schematic diagram of a chemical mechanical polishing device according to an embodiment of the present application; Figure 6 is a flow chart of the steps of a wafer polishing method according to an embodiment of the present application; Figure 7 It is a schematic diagram of the change of metal film thickness detected by eddy current sensor with polishing time; Figure 8 This is a schematic diagram of the change in metal film thickness detected by the compensated eddy current sensor with polishing time. DETAILED DESCRIPTION

[0029] In order to enable those skilled in the art to better understand the technical solutions in the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments in the embodiments of the present application should fall within the scope of protection of the embodiments of the present application.

[0030] The terms used in this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The singular forms of "a", "said" and "the" used in this application and the appended claims are also intended to include plural forms unless the context clearly indicates other meanings. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0031] It should be understood that although the terms first, second, third, etc. may be used in the present application to describe various information, these information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining".

[0032] The technical solutions in the embodiments of the present application are clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application. In the absence of conflict, the following embodiments and their technical features can be combined with each other.

[0033] Figure 1 FIG. 1 is a flowchart showing a method for measuring the thickness of a metal film according to an embodiment of the present invention. Figure 1 As shown, the metal film thickness measurement method includes the following steps: Step 101: Detect the thickness of the metal film on the wafer by using an eddy current sensor to obtain a measurement signal output by the eddy current sensor.

[0034] Step 102: Obtain the measured temperature.

[0035] Step 103: Obtain a measured thickness value according to the measurement signal and the base value signal.

[0036] Step 104: Obtain a thickness compensation value according to the measured temperature and the base temperature.

[0037] Step 105: Determine the thickness of the metal film according to the measured thickness value and the thickness compensation value.

[0038] In the process of detecting the thickness of the metal film on the wafer, the thickness of the metal film on the wafer is first detected by an eddy current sensor to obtain a measurement signal output by the eddy current sensor. At this time, the measurement signal can characterize the thickness of the metal film on the wafer, but its accuracy is low. The eddy current sensor measures the thickness of the metal film on the wafer by applying an AC voltage of a certain frequency to generate an alternating magnetic field, and then forms an eddy current effect on the surface of the metal film on the wafer through the alternating magnetic field, forming a magnetic field opposite to the eddy current sensor coil, thereby changing the impedance of the eddy current sensor coil, and correlating the metal film thickness with related electrical parameters to achieve metal film thickness measurement. The impedance of the eddy current sensor coil will change due to temperature influences such as ambient temperature. Therefore, it is necessary to compensate for the measurement signal obtained by the preliminary detection of the eddy current sensor.

[0039] Specifically, it is necessary to obtain the measurement temperature, which is the temperature of the eddy current sensor when the eddy current sensor outputs the measurement signal. In addition, since the measurement signal detected by the eddy current sensor does not directly correspond to the thickness of the metal film on the wafer, but is the sum of the signal corresponding to the thickness of the metal film on the wafer and the base value signal, it is necessary to obtain the measurement thickness value according to the measurement signal and the base value signal, that is, to determine the measurement thickness value according to the difference between the measurement signal and the base value signal. The base value signal is the signal output by the eddy current sensor when it is unloaded at the base value temperature. According to the measurement temperature and the base value temperature, the thickness compensation value used to compensate the measurement signal obtained by the preliminary detection is determined. The method of obtaining the thickness compensation value can be to input the measurement temperature and the base value temperature as input values ​​into the temperature compensation model to obtain the thickness compensation value output by the temperature compensation model. The thickness compensation value is used to indicate the deviation of the measurement temperature relative to the base value temperature, resulting in the deviation of the measurement thickness value relative to the true thickness value of the metal film. Finally, the thickness of the metal film is determined according to the measurement thickness value and the thickness compensation value.

[0040] In an embodiment of the present application, by detecting the measurement temperature and the base temperature when the thickness of the metal film on the wafer is measured, a thickness compensation value for compensating the measurement signal obtained by the eddy current sensor is determined. This can eliminate the influence of the working environment temperature on the eddy current sensor to a large extent, thereby improving the accuracy of metal film thickness detection.

[0041] Figure 2 is a flow chart of the steps of the temperature compensation model training method according to an embodiment of the present application. Figure 2 The temperature compensation model training method includes the following steps: Step 201: Obtain a first mapping relationship.

[0042] The first mapping relationship is used to indicate a mapping relationship between a no-load signal output by the eddy current sensor when the eddy current sensor is no-load and the temperature of the eddy current sensor.

[0043] Specifically, the process of obtaining the first mapping relationship may further include: An eddy current sensor without a wafer is placed in a preset test environment, and a no-load signal output by the eddy current sensor when it is no-load is collected. Then, the temperature of the test environment is changed, and a first change of the no-load signal with the change of the temperature of the test environment is determined. Finally, a first mapping relationship is obtained based on the first change and the standard no-load signal output by the eddy current sensor.

[0044] In order to obtain the first mapping relationship, the eddy current sensor without wafer loading can be placed in a preset test environment. For example, the preset test environment can be an incubator with adjustable temperature. The eddy current sensor without wafer loading is placed in an incubator with adjustable temperature. The temperature in the incubator is gradually changed, and the no-load signal output by the eddy current sensor is continuously collected during the process. According to the change of the temperature in the incubator during the process of the no-load signal, the first change situation can be determined. Further combined with the standard no-load signal output by the eddy current sensor, the first mapping relationship can be obtained. The standard no-load signal is a signal output when the eddy current sensor is no-load and at normal operating temperature.

[0045] Specifically, the process of collecting multiple no-load signals output by the eddy current sensor during the temperature increase of the test environment may also include: when the eddy current sensor is in a stable working state in the test environment, collecting the no-load signals output by the eddy current sensor.

[0046] When the eddy current sensor is just placed in the test environment, it needs to be started first. The signal stability generated during the startup process is poor. Therefore, the no-load signal output by the eddy current sensor can be collected after the eddy current sensor is in a stable working state in the test environment. This can ensure the stability of the collected no-load signal, thereby improving the accuracy of the first mapping relationship.

[0047] Specifically, the process of changing the temperature of the test environment and determining a first change of the no-load signal as the temperature of the test environment changes may also include: The temperature of the test environment is increased at a fixed rate, and a plurality of no-load signals output by the eddy current sensor are collected during the temperature increase of the test environment. Then, based on the collected plurality of no-load signals and the temperature of the test environment when the no-load signals are collected, a first change of the no-load signal as the temperature of the test environment changes is determined.

[0048] In order to further stabilize the acquisition of no-load signals, the temperature of the test environment can be increased at a fixed rate, for example, by 1°C every 10 seconds. During the temperature increase of the test environment, multiple no-load signals output by the eddy current sensor are continuously collected. Then, based on the multiple no-load signals collected and the temperature of the test environment when the no-load signals are collected, the first change of the no-load signal with the change of the temperature of the test environment is determined.

[0049] The first mapping relationship obtained can be expressed by the following formula: S_air=S_airbase+F_1 (T-T_base) Among them, S_air is used to characterize the no-load signal, S_airbase is used to characterize the standard no-load signal, F_1 ​​is used to characterize the first change situation, T is used to characterize the temperature of the test environment, and T_base is used to characterize the normal working temperature of the eddy current sensor.

[0050] Step 202: Acquire multiple second mapping relationships.

[0051] Different second mapping relationships correspond to different metal film thicknesses, and the second mapping relationship is used to indicate the mapping relationship between the carried signal output by the eddy current sensor when detecting a wafer with a corresponding metal film thickness and the temperature of the eddy current sensor.

[0052] Specifically, the process of acquiring multiple second mapping relationships may also include: An eddy current sensor loaded with a wafer having metal films of different thicknesses is placed in a preset test environment, and a loaded signal output by the eddy current sensor is collected. The temperature of the test environment is then changed to determine a second change in the loaded signal as the temperature of the test environment changes. Finally, a second mapping relationship is obtained based on the second change and the standard loaded signal output by the eddy current sensor.

[0053] In order to obtain the first mapping relationship, the eddy current sensor loaded with the wafer can be placed in a preset test environment. For example, the preset test environment can be an incubator with adjustable temperature. First, the eddy current sensor loaded with the wafer with a metal film thickness of 100 is placed in an incubator with adjustable temperature, and the temperature in the incubator is gradually changed. During the process, the loaded signal output by the eddy current sensor is continuously collected. According to the change of the temperature in the incubator during the process of the loaded signal, the second change can be determined. Further combined with the standard loaded signal output by the eddy current sensor, a second mapping relationship can be obtained. The standard loaded signal is the signal output by the eddy current sensor when the wafer is loaded and at normal operating temperature. After that, the eddy current sensor loaded with the wafer with a metal film thickness of 200 is placed in an incubator with adjustable temperature, and the above operation is repeated until multiple second mapping relationships are obtained.

[0054] The obtained second mapping relationship can be expressed by the following formula: S_metal=S_metalbase+F_2 (T-T_base) Among them, S_metal is used to characterize the loaded signal, S_metalbase is used to characterize the standard loaded signal, F_2 is used to characterize the second change situation, T is used to characterize the temperature of the test environment, and T_base is used to characterize the normal working temperature of the eddy current sensor.

[0055] The first variation and the second variation can be Figure 3As shown, the first change is as follows Figure 3 The change relationship corresponding to the air base value in the upper left corner is specifically the relationship between the difference between the no-load signal and the standard no-load signal in the first mapping relationship and the temperature difference. The temperature difference is the difference between the temperature of the test environment and the normal working temperature of the eddy current sensor. The second change relationship is the relationship between the difference between the loaded signal and the standard loaded signal in the second mapping relationship and the temperature difference. Since there are multiple second mapping relationships, there are also multiple second change relationships. Figure 3 , respectively, show the second variation relationship under the conditions of metal film thickness of 0 (Si), metal film thickness of 1000, and metal film thickness of 8000.

[0056] Step 203: construct a temperature compensation model according to the first mapping relationship and the plurality of second mapping relationships.

[0057] In order to train the temperature compensation model, it is necessary to first obtain a first mapping relationship indicating the mapping relationship between the no-load signal output by the eddy current sensor when it is unloaded and the temperature of the eddy current sensor, and a second mapping relationship indicating the mapping relationship between the loaded signal output by the eddy current sensor when it detects a wafer of corresponding metal film thickness and the temperature of the eddy current sensor. Since one second mapping relationship can only correspond to one metal film thickness, it is necessary to obtain multiple second mapping relationships, and different second mapping relationships correspond to different metal film thicknesses. A temperature compensation model is constructed based on the obtained first mapping relationship and multiple second mapping relationships.

[0058] Specifically, according to the first mapping relationship and the plurality of second mapping relationships, the process of constructing the temperature compensation model may further include: According to the first mapping relationship and the second mapping relationship, a third mapping relationship corresponding to the metal film thickness corresponding to the second mapping relationship is obtained, and then according to the third mapping relationship and the metal film thickness corresponding to the third mapping relationship, a fourth mapping relationship corresponding to the metal film thickness corresponding to the third mapping relationship is determined, and finally, according to the fourth mapping relationship corresponding to different metal film thicknesses, a temperature compensation model is determined.

[0059] In the process of constructing the temperature compensation model, a second mapping relationship can be selected from a plurality of second mapping relationships, and then the first mapping relationship is subtracted from the second mapping relationship according to the difference method to obtain a third mapping relationship corresponding to the metal film thickness corresponding to the second mapping relationship. Repeat the above operation until a third mapping relationship corresponding to the metal film thickness corresponding to each second mapping relationship is obtained. The third mapping relationship is used to indicate the mapping relationship between the thickness signal and the temperature of the eddy current sensor under the corresponding metal film thickness, and the thickness signal is the deviation between the loaded signal and the unloaded signal of the eddy current sensor at the same temperature. After obtaining the third mapping relationship, the fourth mapping relationship corresponding to the metal film thickness corresponding to the third mapping relationship is determined according to the deviation between the third mapping relationship and the standard loaded signal, and the fourth mapping relationship is used to indicate the deviation between the metal film thickness indicated by the corresponding thickness signal and the true value of the metal film thickness.

[0060] Specifically, according to the first mapping relationship and the second mapping relationship, the process of obtaining a third mapping relationship corresponding to the metal film thickness corresponding to the second mapping relationship may further include: For the second mapping relationship corresponding to different metal film thicknesses, the following is performed: Obtain an unloaded signal corresponding to the first mapping relationship and a loaded signal corresponding to the second mapping relationship at the same temperature, and determine the difference between the unloaded signal and the loaded signal at the same temperature as the thickness signal at the temperature, and then determine a third mapping relationship corresponding to the metal film thickness corresponding to the second mapping relationship based on the thickness signals at multiple temperatures.

[0061] In order to obtain the third mapping relationship, the no-load signal corresponding to the first mapping relationship and the loaded signal corresponding to the second mapping relationship at the same temperature can be obtained, and the difference between the no-load signal and the loaded signal at the same temperature is determined as the thickness signal at the temperature, and the thickness signals at multiple temperatures are further obtained. That is, the third mapping relationship corresponding to the metal film thickness corresponding to the second mapping relationship can be determined based on the thickness signals at multiple temperatures.

[0062] Specifically, according to the fourth mapping relationship corresponding to different metal film thicknesses, the process of determining the temperature compensation model may also include: A pre-trained model is constructed according to a plurality of fourth mapping relationships corresponding to different metal film thicknesses, and then the pre-trained model is compensated according to a temperature compensation parameter to obtain a temperature compensation model.

[0063] The temperature compensation parameter can be determined according to at least one of the temperature of the working environment of the eddy current sensor, the temperature of the wafer loaded by the eddy current sensor, and the temperature of the polishing device connected to the eddy current sensor. By adding the temperature compensation parameter during the training of the temperature compensation model, the accuracy of the temperature compensation model can be further improved.

[0064] In the embodiment of the present application, a temperature compensation model is constructed by using a first mapping relationship and multiple second mapping relationships, which can eliminate some of the effects caused by temperature, and then the compensation value output by the temperature compensation model can further improve the measurement accuracy of the metal film thickness.

[0065] Figure 4 Schematic diagram of a metal film thickness measuring device according to an embodiment of the present application. Figure 4 The metal film thickness measuring device 300 comprises: a controller 301 and an eddy current sensor 302 .

[0066] The controller 301 is used to detect the thickness of the metal film on the wafer 10 through the eddy current sensor 302, obtain the measurement signal output by the eddy current sensor 302, and obtain the measurement temperature, obtain the measurement thickness value according to the measurement signal and the base value signal, obtain the thickness compensation value according to the measurement temperature and the base value temperature, and determine the thickness of the metal film according to the measurement thickness value and the thickness compensation value, wherein the measurement temperature is the temperature of the eddy current sensor 302 when the eddy current sensor 302 collects the measurement signal, the base value signal is the signal output by the eddy current sensor 302 when it is idling at the base value temperature, and the thickness compensation value is used to indicate the deviation of the measurement temperature relative to the base value temperature, resulting in the deviation of the measurement thickness value relative to the true thickness value of the metal film.

[0067] In the process of detecting the thickness of the metal film on the wafer 10, the controller 301 first detects the thickness of the metal film on the wafer 10 through the eddy current sensor 302, and obtains the measurement signal output by the eddy current sensor 302. At this time, the measurement signal can characterize the thickness of the metal film on the wafer 10, but its accuracy is low. Therefore, the controller 301 further obtains the measurement temperature, which is the temperature of the eddy current sensor when the eddy current sensor 302 outputs the measurement signal. In addition, since the measurement signal detected by the eddy current sensor 302 does not directly correspond to the thickness of the metal film on the wafer 10, but is the sum of the signal corresponding to the thickness of the metal film on the wafer 10 and the base value signal, the controller 301 needs to obtain the measurement thickness value based on the measurement signal and the base value signal, that is, determine the measurement thickness value based on the difference between the measurement signal and the base value signal, and the base value signal is the signal output by the eddy current sensor 302 when it is unloaded at the base value temperature. According to the measured temperature and the base temperature, a thickness compensation value is determined for compensating the measurement signal obtained by the preliminary detection. The thickness compensation value is used to indicate the deviation of the measured temperature relative to the base temperature, resulting in the deviation of the measured thickness value relative to the true thickness value of the metal film. Finally, the thickness of the metal film on the wafer 10 is determined according to the measured thickness value and the thickness compensation value.

[0068] Specifically, the measured temperature may be obtained by using the temperature sensor 303 included in the metal film thickness measuring device 300 .

[0069] In the embodiment of the present application, the controller 301 detects the measurement temperature and the base temperature of the thickness of the metal film on the wafer 10 through the eddy current sensor 302, and determines the thickness compensation value for compensating the measurement signal obtained by the eddy current sensor 302. This can eliminate the influence of the working environment temperature on the eddy current sensor 302 to a large extent, thereby improving the accuracy of metal film thickness detection.

[0070] Figure 5 Schematic diagram of a chemical mechanical polishing device according to an embodiment of the present application. Figure 5 As shown, the chemical mechanical polishing equipment 400 includes: a polishing plate 401 , a carrier head 402 , a liquid supply device 403 , a dresser 404 and a metal film thickness measuring device 300 .

[0071] The carrier head 402 is used to load the wafer to be polished and abut it against the polishing pad 405 above the polishing plate 401. The liquid supply device 403 is used to supply polishing liquid between the polishing pad 405 and the wafer during the polishing process. The trimmer 404 is used to trim the surface of the polishing pad 405. The metal film thickness measuring device 300 is used to detect the thickness of the metal film on the wafer loaded by the carrier head 402 during the polishing process.

[0072] The carrier head 402 loads the wafer to be polished, and places the metal film on the wafer against the polishing pad 405 above the polishing plate 401. The liquid supply device 403 supplies polishing liquid between the polishing pad 405 and the wafer, and the trimmer 404 is used to trim the surface of the polishing pad 405. The metal film thickness measuring device 300 detects the thickness of the metal film on the wafer loaded by the carrier head 402 during the polishing process through the metal film thickness measuring method provided in the embodiment of the present application.

[0073] The specific implementation of the metal film thickness measuring device 300 detecting the thickness of the metal film on the wafer during the polishing process can refer to the corresponding descriptions in the corresponding steps and units in the aforementioned metal film thickness measuring method embodiment or the metal film thickness measuring device embodiment, which will not be repeated here. Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working process of the above-described equipment and modules can refer to the corresponding process description in the aforementioned method embodiment, which will not be repeated here.

[0074] In one possible implementation, the metal film thickness measuring device 300 is used to collect the temperature of the working environment, the temperature of the polished wafer, and the temperature of the liquid supply device 403 during the polishing process, and compensate the measured thickness of the metal film based on at least one of the temperature of the working environment, the temperature of the polished wafer, and the temperature of the liquid supply device.

[0075] The metal film thickness measuring device 300 will compensate the measured thickness value according to the thickness compensation value to measure the thickness of the metal film. However, during the polishing process, the polished wafer will generate heat due to friction and transmit it to the metal film thickness measuring device 300. The liquid supply device 403 will also generate heat during operation, and the temperature of the working environment will further change. Therefore, the measured thickness of the metal film can be further compensated based on at least one of the temperature of the working environment, the temperature of the polished wafer and the temperature of the liquid supply device.

[0076] Specifically, the metal film thickness measuring device compensates the temperature compensation model according to at least one of the temperature of the working environment, the temperature of the polished wafer and the temperature of the liquid supply device, and compensates the measured thickness of the metal film according to the thickness compensation value output by the compensated temperature compensation model.

[0077] In an embodiment of the present application, the measured thickness of the metal film is compensated by at least one of the temperature of the working environment, the temperature of the polished wafer and the temperature of the liquid supply device, which can further improve the detection accuracy of the thickness of the metal film.

[0078] Figure 6 : is a flow chart of the steps of a wafer polishing method according to an embodiment of the present application. Figure 6 As shown, the wafer polishing method comprises the following steps: Step 501 : During the process of polishing a wafer, the metal film thickness measurement method in the above-mentioned embodiment is executed to obtain the thickness of the metal film on the wafer.

[0079] Step 502: When the thickness of the metal film meets a preset thickness value, it is determined that the polishing process is finished, and the polishing equipment is controlled to stop polishing the wafer.

[0080] Step 503: After determining that the polishing process is completed, control the carrier head to grab the polished wafer.

[0081] During the wafer polishing process, the wafer and the polishing equipment will generate corresponding heat during the friction of the wafer, and the temperature of the entire working environment will also be affected and changed. For the eddy current sensor used to detect the thickness of the metal film on the wafer, its impedance will change due to the influence of ambient temperature and other temperatures, which will affect the measurement accuracy. Generally speaking, during the wafer polishing process, the thickness of the metal film on the wafer detected by the eddy current sensor will gradually decrease, but under the influence of temperature changes, the change of the metal film thickness detected by the eddy current sensor with polishing time can be shown as follows: Figure 7 As shown, it can be seen that the thickness of the metal film detected by the eddy current sensor during the polishing process has increased abnormally. The main reason is that the temperature change causes the measured film thickness to be much smaller than the actual film thickness. The basis for judging the end point of the polishing process using eddy current detection is the film thickness threshold. If the measured film thickness is much smaller than the actual film thickness, it will lead to an incorrect judgment of the end point of the polishing process, making the stability of the end point detection poor.

[0082] Therefore, in order to solve the problem of the influence of temperature on the thickness of the metal film on the wafer detected by the eddy current sensor, the metal film thickness measurement method in the above embodiment can be executed during the process of polishing the wafer to obtain the thickness of the metal film on the wafer, and the influence of temperature on the measured film thickness can be avoided as much as possible. The thickness of the metal film measured by the compensated eddy current sensor during the polishing process can be as follows: Figure 8 As shown, when the thickness of the metal film meets the preset thickness value, it is determined that the polishing process is finished, and the polishing device is controlled to stop polishing the wafer, and then the carrier head is controlled to grab the polished wafer.

[0083] In the embodiment of the present application, by accurately measuring the thickness of the metal film on the wafer, the polishing process can be terminated in time, thereby improving the production quality of the polished wafer.

[0084] The specific implementation of obtaining the thickness of the metal film on the wafer in step 501 can refer to the corresponding descriptions in the corresponding steps in the above-mentioned embodiment of the metal film thickness measurement method, which will not be repeated here.

[0085] In this embodiment, a computer-readable storage medium is provided, which stores instructions for causing a machine to execute the metal film thickness measurement method or wafer polishing method as described herein. Specifically, a system or device equipped with a storage medium can be provided, on which a software program code for implementing the functions of any of the above embodiments is stored, and a computer (or CPU or MPU) of the system or device reads and executes the program code stored in the storage medium.

[0086] In this case, the program code read from the storage medium itself can implement the functions in the above method embodiments, so the program code and the storage medium storing the program code constitute part of the present application.

[0087] The storage medium embodiments for providing the program code include a floppy disk, a hard disk, a magneto-optical disk, an optical disk (such as CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-RAM, DVD-RW, DVD+RW), a magnetic tape, a non-volatile memory card, and a ROM. Alternatively, the program code can be downloaded from a server computer via a communication network.

[0088] In this embodiment, a computer program product is provided, including computer instructions, which instruct a computing device to perform operations corresponding to the above method embodiments.

[0089] It should be pointed out that, according to the needs of implementation, the various components / steps described in the embodiments of the present 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 the embodiments of the present application.

[0090] The above-mentioned method according to the embodiment of the present application can be implemented in hardware, firmware, or implemented as software or computer code that can be stored in a recording medium (such as a CD ROM, RAM, floppy disk, hard disk or magneto-optical disk), or implemented as a computer code originally stored in a remote recording medium or a non-temporary machine-readable medium downloaded through a network and 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 (e.g., RAM, ROM, flash memory, etc.) that can store or receive software or computer code, and when the software or computer code is accessed and executed by a computer, a processor or hardware, the method described herein is implemented. In addition, when a general-purpose computer accesses the code for implementing the method shown herein, the execution of the code converts the general-purpose computer into a dedicated computer for executing the method shown herein. Although the present application has been shown and described with respect to one or more implementations, those skilled in the art will think of equivalent deformations and modifications based on the reading and understanding of this specification and the accompanying drawings. The present application includes all such modifications and changes and is limited only by the scope of the appended claims. In particular, with respect to the various functions performed by the above-described components, the terms used to describe such components are intended to correspond to any component that performs the specified function of the component (e.g., which is functionally equivalent) (unless otherwise indicated), even if not structurally equivalent to the disclosed structure that performs the function in the exemplary implementation of the present specification shown herein.

[0091] That is, the above description is only an embodiment of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the specification and drawings of the present application, such as the mutual combination of technical features between the embodiments, or direct or indirect application in other related technical fields, are also included in the patent protection scope of the present application.

[0092] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0093] In order to enable any technician in the field to implement and use the application, the application provides the above description. In the above description, various details are listed for the purpose of explanation. It should be understood that those of ordinary skill in the art can recognize that the application can also be implemented without using these specific details. In other embodiments, the well-known process will not be elaborated in detail to avoid unnecessary details that make the description of the application obscure. Therefore, the application is not intended to be limited to the embodiments shown, but is consistent with the widest range of principles and features disclosed in the application.

[0094] It should be noted that, under the premise of no conflict, the various embodiments and / or the technical features in the various embodiments described in this application can be arbitrarily combined with each other, and the technical solution obtained after the combination should also fall within the protection scope of this application.

[0095] It should be understood that the specific examples in the embodiments of the present application are only to help those skilled in the art to better understand the embodiments of the present application, rather than to limit the scope of the embodiments of the present application. Those skilled in the art can make various improvements and modifications based on the above embodiments, and these improvements or modifications all fall within the scope of protection of the present application.

[0096] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for measuring the thickness of a metal film, It is characterized in that include: Detecting the thickness of the metal film on the wafer by using an eddy current sensor to obtain a measurement signal output by the eddy current sensor; Acquiring a measured temperature, wherein the measured temperature is the temperature of the eddy current sensor when the eddy current sensor outputs the measurement signal; Obtaining a measured thickness value according to the measurement signal and the base value signal, wherein the base value signal is a signal output by the eddy current sensor when it is unloaded at the base value temperature; Obtaining a thickness compensation value according to the measured temperature and the base temperature, wherein the thickness compensation value is used to indicate a deviation of the measured temperature relative to the base temperature, resulting in a deviation of the measured thickness value relative to a true thickness value of the metal film; The thickness of the metal film is determined according to the measured thickness value and the thickness compensation value.

2. The method according to claim 1, It is characterized in that The step of obtaining a thickness compensation value according to the measured temperature and the base temperature includes: The measured temperature and the base temperature are input into a temperature compensation model to obtain a thickness compensation value output by the temperature compensation model.

3. The method according to claim 2, It is characterized in that The temperature compensation model is obtained by training in the following way: Acquire a first mapping relationship, wherein the first mapping relationship is used to indicate a mapping relationship between a no-load signal output by the eddy current sensor when the eddy current sensor is no-load and a temperature of the eddy current sensor; Acquire a plurality of second mapping relationships, wherein different second mapping relationships correspond to different metal film thicknesses, and the second mapping relationships are used to indicate a mapping relationship between a loaded signal output by the eddy current sensor when detecting a wafer having a corresponding metal film thickness and a temperature of the eddy current sensor; The temperature compensation model is constructed according to the first mapping relationship and the plurality of second mapping relationships.

4. The method according to claim 3, It is characterized in that The obtaining of the first mapping relationship includes: Placing the eddy current sensor without a wafer in a preset test environment, and collecting the no-load signal output by the eddy current sensor when the sensor is no-load; Changing the temperature of the test environment to determine a first change of the no-load signal as the temperature of the test environment changes; The first mapping relationship is obtained according to the first change condition and a standard no-load signal output by the eddy current sensor, wherein the standard no-load signal is a signal output when the eddy current sensor is no-load and at a normal operating temperature.

5. The method according to claim 4, It is characterized in that The step of changing the temperature of the test environment and determining a first change of the no-load signal as the temperature of the test environment changes includes: Raising the temperature of the test environment at a fixed rate, and collecting a plurality of no-load signals output by the eddy current sensor during the temperature increase of the test environment; According to the received multiple no-load signals and the temperature of the test environment when the no-load signals are received, a first change of the no-load signal caused by a change in the temperature of the test environment is determined.

6. The method according to claim 5, It is characterized in that The collecting of a plurality of no-load signals output by the eddy current sensor during the temperature rise of the test environment comprises: When the eddy current sensor is in a stable working state in the test environment, a no-load signal output by the eddy current sensor is collected.

7. The method according to claim 3, It is characterized in that The obtaining of multiple second mapping relationships includes: Placing the eddy current sensor loaded with wafers having metal films of different thicknesses in a preset test environment, and collecting a loaded signal output by the eddy current sensor; Changing the temperature of the test environment to determine a second change of the carried signal caused by the change in the temperature of the test environment; The second mapping relationship is obtained according to the second change condition and the standard loaded signal output by the eddy current sensor, wherein the standard loaded signal is a signal output by the eddy current sensor when a wafer is loaded and the eddy current sensor is at a normal operating temperature.

8. The method according to claim 3, It is characterized in that The step of constructing the temperature compensation model according to the first mapping relationship and the plurality of second mapping relationships includes: According to the first mapping relationship and the second mapping relationship, a third mapping relationship corresponding to the metal film thickness corresponding to the second mapping relationship is obtained, wherein the third mapping relationship is used to indicate a mapping relationship between a thickness signal and a temperature of the eddy current sensor at a corresponding metal film thickness, and the thickness signal is a deviation between the loaded signal and the unloaded signal of the eddy current sensor at the same temperature; Determine, according to the third mapping relationship and the metal film thickness corresponding to the third mapping relationship, a fourth mapping relationship corresponding to the metal film thickness corresponding to the third mapping relationship, wherein the fourth mapping relationship is used to indicate a deviation between the metal film thickness indicated by the corresponding thickness signal and a true value of the metal film thickness; The temperature compensation model is determined according to the fourth mapping relationship corresponding to different metal film thicknesses.

9. The method according to claim 8, It is characterized in that The step of obtaining, according to the first mapping relationship and the second mapping relationship, a third mapping relationship corresponding to the metal film thickness corresponding to the second mapping relationship comprises: For the second mapping relationship corresponding to different metal film thicknesses, the following is performed: Acquire a no-load signal corresponding to the first mapping relationship and a loaded signal corresponding to the second mapping relationship at the same temperature; Determine the difference between the no-load signal and the loaded signal at the same temperature as the thickness signal at the temperature; A third mapping relationship corresponding to the metal film thickness corresponding to the second mapping relationship is determined according to the thickness signals at multiple temperatures.

10. The method according to claim 8, It is characterized in that Determining the temperature compensation model according to the fourth mapping relationship corresponding to different metal film thicknesses includes: Constructing a pre-training model according to the fourth mapping relationships corresponding to the different metal film thicknesses; The pre-trained model is compensated according to the temperature compensation parameters to obtain the temperature compensation model, wherein the temperature compensation parameters are determined according to at least one of the temperature of the working environment of the eddy current sensor, the temperature of the wafer loaded with the eddy current sensor, and the temperature of the polishing equipment connected to the eddy current sensor.

11. A metal film thickness measuring device, It is characterized in that include: Controller and eddy current sensor; The controller is used to detect the thickness of the metal film on the wafer through the eddy current sensor, obtain the measurement signal output by the eddy current sensor, and obtain the measurement temperature, obtain the measurement thickness value according to the measurement signal and the base value signal, obtain the thickness compensation value according to the measurement temperature and the base value temperature, and determine the thickness of the metal film according to the measurement thickness value and the thickness compensation value, wherein the measurement temperature is the temperature of the eddy current sensor when the eddy current sensor collects the measurement signal, the base value signal is the signal output by the eddy current sensor when it is unloaded at the base value temperature, and the thickness compensation value is used to indicate the deviation of the measurement thickness value caused by the deviation of the measurement temperature relative to the base value temperature.

12. The metal film thickness measuring device according to claim 11, It is characterized in that Also includes: Temperature sensor; The temperature sensor is used to obtain the measured temperature.

13. The metal film thickness measuring device according to claim 11, It is characterized in that The controller is used to input the measured temperature and the base temperature into a temperature compensation model to obtain a thickness compensation value output by the temperature compensation model.

14. A chemical mechanical polishing device, It is characterized in that include: A polishing disc, a carrier head, a liquid supply device, a dresser, and a metal film thickness measuring device as described in any one of claims 11 to 13; The carrier head is used to load the wafer to be polished and abut it against the polishing pad above the polishing plate; The liquid supply device is used to supply polishing liquid between the polishing pad and the wafer during the polishing process; The dresser is used to dress the surface of the polishing pad; The metal film thickness measuring device is used to detect the thickness of the metal film on the wafer loaded by the carrier head during the polishing process.

15. The chemical mechanical polishing apparatus according to claim 14, It is characterized in that The metal film thickness measuring device is used to collect the temperature of the working environment, the temperature of the polished wafer and the temperature of the liquid supply device during the polishing process, and compensate the measured thickness of the metal film according to at least one of the temperature of the working environment, the temperature of the polished wafer and the temperature of the liquid supply device.

16. The chemical mechanical polishing apparatus according to claim 15, It is characterized in that The metal film thickness measuring device is used to compensate the temperature compensation model according to the temperature of the working environment, the temperature of the polished wafer and at least one of the temperatures of the liquid supply device, and to compensate the measured thickness of the metal film according to the thickness compensation value output by the compensated temperature compensation model.

17. A wafer polishing method, It is characterized in that include: In a process of polishing a wafer, performing the metal film thickness measurement method as described in any one of claims 1 to 10 to obtain the thickness of the metal film on the wafer; When the thickness of the metal film meets a preset thickness value, it is determined that the polishing process is finished, and the polishing device is controlled to stop polishing the wafer.

18. The method according to claim 17, It is characterized in that The method further comprises: After it is determined that the polishing process is completed, the carrier head is controlled to grab the polished wafer.

19. A computer storage medium having a computer program stored thereon, wherein when the program is executed by a processor, the method according to any one of claims 1 to 10 or 17 to 18 is implemented.

20. A computer program product, It is characterized in that The method comprises computer instructions, wherein the computer instructions instruct a computing device to execute operations corresponding to the method according to any one of claims 1-10 or 17-18.

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