Thickness-compensated eddy current detection method and device, equipment and storage medium

Abstract

The invention provides a thickness compensation eddy current detection method and device, equipment and a storage medium, the thickness compensation eddy current detection method and device are applied to chemical mechanical polishing equipment, and the method comprises the steps that when a wafer runs to a detection area of an eddy current sensor, a first induction signal of the eddy current sensor is acquired, the eddy current sensor is arranged in a polishing disc of the chemical mechanical polishing equipment, and a polishing pad used for polishing a metal layer on a wafer is arranged on the top face of the polishing disc. When a finishing head included in the chemical mechanical polishing equipment sweeps over the detection area, a second induction signal of the eddy current sensor is obtained; determining a first thickness value of an area, opposite to the eddy current sensor, on the polishing pad according to the second induction signal; and determining the thickness of the metal layer on the wafer according to the first induction signal and the first thickness value. According to the thickness compensation eddy current detection method provided by the invention, the detection precision of the thickness of the metal layer on the wafer can be improved.

Description

[0001] This application is a divisional application of the invention patent application with the application number 202411628959X and filed on November 15, 2024. Technical Field

[0002] This application relates to the field of semiconductor manufacturing technology, and in particular, to an eddy current detection method with thickness compensation, a device, equipment, and a storage medium. Background Art

[0003] Integrated circuits (ICs) are the core and lifeline of the development of the information technology industry. Integrated circuits are generally formed by successively depositing conductive layers, semiconductor layers, or insulating layers on a silicon wafer. As a result, a thin film formed by a filler layer is deposited on the wafer surface. In the manufacturing process, it is necessary to continuously planarize the filler layer until the patterned top surface is exposed to form a conductive path between the raised patterns.

[0004] Chemical Mechanical Polishing (CMP) technology is the preferred planarization process in the IC manufacturing process. In chemical mechanical polishing, for the manufacturing process of semiconductor devices, too much or too little material removal will lead to a decline or even failure of the device's electrical properties. In order to improve the controllability of the chemical mechanical polishing process, enhance the stability of products, reduce the defect rate of products, and achieve uniform production for each wafer, the endpoint detection technology (Endpoint Detection, EPD) of chemical mechanical polishing came into being.

[0005] In the endpoint detection of metal CMP, eddy current detection is the most commonly used method, and the output induction signal is a voltage signal. Through experimental verification, the magnitude of this voltage signal is related to the thickness of the metal layer of the measured wafer and also related to the distance between the eddy current sensor and the measured metal layer. Among them, this distance is called the lift-off distance of the sensor, which is related to the thickness of the polishing pad in the chemical mechanical polishing equipment. Under different lift-off heights, the corresponding relationship between the thickness of the metal layer and the voltage value is different. In actual processing, the polishing pad is between the sensor and the wafer to be polished. Therefore, the thickness of the polishing pad is the lift-off height. The thickness of the polishing pad will become thinner as the processing progresses, that is, the lift-off height becomes smaller. At this time, the corresponding relationship between the voltage value and the thickness of the metal layer changes, resulting in a larger measurement error and affecting the polishing effect. Summary of the Invention

[0006] In view of this, this application provides an eddy current detection method with thickness compensation, a device, equipment, and a storage medium to at least partially solve the above problems.

[0007] According to a first aspect of the present application, a thickness compensation eddy current detection method is provided, which is applied to a chemical mechanical polishing apparatus. The method includes: when a wafer runs to a detection area of an eddy current sensor, acquiring a first induction signal of the eddy current sensor, wherein the eddy current sensor is disposed in a polishing platen included in the chemical mechanical polishing apparatus, and a polishing pad for polishing a metal layer on the wafer is disposed on a top surface of the polishing platen; when a dressing head included in the chemical mechanical polishing apparatus sweeps across the detection area, acquiring a second induction signal of the eddy current sensor; determining a first thickness value of a region on the polishing pad opposite to the eddy current sensor according to the second induction signal; and determining a thickness of the metal layer on the wafer according to the first induction signal and the first thickness value.

[0008] According to a second aspect of the present application, a chemical mechanical polishing apparatus is provided, including: a polishing platen, a polishing pad, a dressing head, a carrier head, a liquid supply module, and a control module. The carrier head is configured to carry a wafer so that the wafer abuts against the polishing pad. The polishing platen includes an eddy current sensor disposed in the polishing platen. A polishing pad for polishing a metal layer on the wafer is disposed on a top surface of the polishing platen. The liquid supply module is configured to supply a polishing liquid between the wafer and the polishing pad. The dressing head is configured to dress the polishing pad. The control module is configured to, when the wafer runs to a detection area of the eddy current sensor, acquire a first induction signal of the eddy current sensor, and when the dressing head sweeps across the detection area, acquire a second induction signal of the eddy current sensor, and determine a first thickness value of a region on the polishing pad opposite to the eddy current sensor according to the second induction signal.

[0009] According to a third aspect of the present application, an eddy current detection device based on polishing pad thickness compensation is provided, including: an induction signal acquisition module configured to, when a wafer runs to a detection area of an eddy current sensor, acquire a first induction signal of the eddy current sensor, wherein the eddy current sensor is disposed in a polishing platen included in the chemical mechanical polishing apparatus, and a polishing pad for polishing a metal layer on the wafer is disposed on a top surface of the polishing platen; and when a dressing head included in the chemical mechanical polishing apparatus sweeps across the detection area, acquire a second induction signal of the eddy current sensor; a first thickness value determination module configured to determine a first thickness value of a region on the polishing pad opposite to the eddy current sensor according to the second induction signal; and a metal layer thickness determination module configured to determine a thickness of the metal layer on the wafer according to the first induction signal and the first thickness value.

[0010] According to a fourth aspect of the present application, there is provided an electronic device, including: a processor, a memory, a communication interface, and a communication bus. The processor, the memory, and the communication interface complete communication with each other through the communication bus; the memory is used for storing at least one executable instruction, and the executable instruction causes the processor to perform operations corresponding to the method described in the first aspect.

[0011] According to a fifth aspect of the present application, there is provided a computer storage medium, on which a computer program is stored, and when the program is executed by a processor, it implements the method described in the first aspect.

[0012] According to a sixth aspect of the present application, there is provided a computer program product, including computer instructions, and the computer instructions direct a computing device to execute the method described in the first aspect.

[0013] According to the thickness compensation eddy current detection method provided by the present application, when the wafer runs to the detection area of the eddy current sensor, a first induction signal of the eddy current sensor is obtained, and when the dressing head sweeps across the detection area, a second induction signal of the eddy current sensor is obtained. The first thickness of the area on the polishing pad opposite to the eddy current sensor is determined according to the second induction signal. Thus, the thickness of the metal layer on the wafer can be determined according to the first thickness and the first induction signal. Since when determining the thickness of the metal layer, the thickness of the polishing pad is considered, that is, the lift-off height of the wafer is considered. Therefore, compared with the prior art where the lift-off height is not considered, since the influence of the lift-off height on the induction signal generated by the eddy current sensor is considered, the thickness of the metal layer on the detected wafer is more accurate. And since the thickness of the polishing pad is detected by the eddy current sensor arranged on the polishing disk, there is no need to set an additional eddy current sensor on the dressing head, which can prevent the polishing liquid from damaging the eddy current sensor. And since the detected area is the thickness of the area opposite to the eddy current sensor, compared with detecting the average thickness of the polishing pad, the lift-off height of the detected wafer is more accurate, and thus the thickness of the metal layer on the wafer determined thereby is more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments recorded in the present application. For those of ordinary skill in the art, other drawings can also be obtained according to these drawings.

[0015] Figure 1 is a flowchart of a thickness compensation eddy current detection method provided by the present application;

[0016] Figure 2 is a schematic diagram of a chemical mechanical polishing process for a wafer;

[0017] Figure 3 is a schematic diagram of a dressing head for dressing a polishing pad provided by the present application;

[0018] Figure 4 is a schematic diagram of a mapping relationship provided by the present application;

[0019] Figure 5 is a schematic diagram of a detection area provided by the present application;

[0020] Figure 6 is a schematic diagram of a chemical mechanical polishing equipment provided by the present application;

[0021] Figure 7 is a schematic structural diagram of an electronic device provided by the present application.

[0022] 200, chemical mechanical polishing equipment; 201, polishing pad; 202, dressing head; 203, polishing disc; 2031, eddy current sensor; 204, carrier head; 205, liquid supply module; 206, control module; 300, wafer; 400, annular area; 702, processor; 704, communication interface; 706, memory; 708, communication bus; 710, program. Detailed implementation manners

[0023] In order to enable those skilled in the art to better understand the technical solutions in the present application, the technical solutions in the present application will be clearly and completely described below in conjunction with the accompanying drawings in the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art shall fall within the protection scope of the present application.

[0024] The terms used in the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms of "a", "the" and "said" used in the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the term "and / or" as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0025] It should be understood that although the terms first, second, third, etc. may be used in the present application to describe various information, such 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 "when" or "while" or "in response to a determination".

[0026] The following describes the eddy current detection method with thickness compensation provided by the present application through specific embodiments:

[0027] Figure 1 is a flowchart of an eddy current detection method with thickness compensation provided by the present application. This method is applied to a chemical mechanical polishing equipment, such as Figure 1 shown. The eddy current detection method for polishing pad thickness compensation includes the following steps 101 to 104:

[0028] Step 101: When the wafer moves to the detection area of the eddy current sensor, obtain the first induction signal of the eddy current sensor.

[0029] The eddy current sensor is arranged in the polishing disc included in the chemical mechanical polishing equipment. The top surface of the polishing disc is provided with a polishing pad for polishing the metal layer on the wafer. Figure 2 is a schematic diagram of a chemical mechanical polishing process for the wafer 300 provided by the present application. As Figure 2 shown, when the chemical mechanical polishing equipment polishes the wafer 300, the chemical mechanical polishing equipment body rotates, the wafer 300 rotates under the action of the carrier head and moves radially along the polishing disc of the chemical mechanical polishing equipment. Thus, the wafer 300 can be chemically mechanically polished through the polishing pad 201. Since the eddy current sensor is arranged in the polishing disc included in the chemical mechanical polishing equipment, the polishing pad 201 is arranged on the top surface of the polishing disc, and the wafer 300 moves radially along the polishing pad 201 of the chemical mechanical polishing equipment. Therefore, when the wafer 300 moves to the detection area of the eddy current sensor, the first induction signal of the eddy current sensor is collected. It should be noted that there is a layer of metal material on the surface of the wafer 300, such as copper, tungsten, aluminum, tantalum, titanium, etc. The thickness of the metal layer of the wafer 300 can be from 0.01 μm to 50 μm.

[0030] It should also be noted that the detection principle of the eddy current sensor is that when the wafer moves to the detection area of the eddy current sensor, the metal layer on the wafer surface will generate an eddy current effect, which causes the magnetic field generated by the eddy current sensor to change. Thus, the thickness of the metal layer can be measured according to the change of the magnetic field.

[0031] Step 102: When the dressing head included in the chemical mechanical polishing equipment sweeps across the detection area, obtain the second induction signal of the eddy current sensor.

[0032] When chemically mechanical polishing a wafer, since the polishing pad will wear, it is necessary to trim the polishing pad in real time through a trimming head. In one example, the wafer is polished on the left half of the polishing pad, and the trimming head trims the polishing pad on the right half of the polishing pad. When the trimming head sweeps across the detection area, the second induction signal of the eddy current sensor is obtained. Since there is metal inside the trimming head, the eddy current sensor can detect the metal inside the trimming head and generate a second induction signal.

[0033] Step 103: Determine the first thickness value of the area on the polishing pad opposite to the eddy current sensor according to the second induction signal.

[0034] According to the second induction signal generated by the eddy current sensor, determine the distance between the eddy current sensor and the trimming head. It should be understood that since the trimming head trims the polishing pad and the polishing pad is arranged on the polishing disc, and the eddy current sensor is arranged inside the polishing disc, the distance between the eddy current sensor and the trimming head is the first thickness value of the area on the polishing pad opposite to the eddy current sensor.

[0035] It should be understood that since when the trimming head included in the chemical mechanical polishing equipment sweeps across the detection area, the eddy current sensor obtains the second induction signal and determines the first thickness value of the area opposite to the eddy current sensor according to the second induction signal, at least part of the area on the polishing pad opposite to the eddy current sensor is located within the detection area. The radius and angle of the detection area located on the polishing pad can be determined in advance.

[0036] Step 104: Determine the thickness of the metal layer on the wafer according to the first induction signal and the first thickness value.

[0037] Determine the thickness of the metal layer on the wafer according to the first induction signal and the first thickness value. In one example, the mapping relationship between the induction signal and the thickness of the metal layer can be determined according to the first thickness value, and the thickness of the metal layer on the wafer can be determined according to the mapping relationship and the first induction signal.

[0038] In this application, when the wafer runs to the detection area of the eddy current sensor, the first induction signal of the eddy current sensor is obtained. When the dressing head sweeps across the detection area, the second induction signal of the eddy current sensor is obtained. The first thickness of the area on the polishing pad opposite to the eddy current sensor is determined according to the second induction signal. Thus, the thickness of the metal layer on the wafer can be determined based on the first thickness and the first induction signal. Since the thickness of the polishing pad, that is, the lift-off height of the wafer, is considered when determining the thickness of the metal layer, compared with the prior art where the lift-off height is not considered, because the influence of the lift-off height on the induction signal generated by the eddy current sensor is considered, the thickness of the metal layer detected on the wafer is more accurate. And since the thickness of the polishing pad is detected by the eddy current sensor arranged on the polishing disk, there is no need to set an additional eddy current sensor on the dressing head, which saves costs, can prevent the polishing liquid from damaging the eddy current sensor. And since the area for detecting the thickness is the thickness of the area on the polishing pad opposite to the eddy current sensor, compared with detecting the average thickness of the polishing pad, the lift-off height of the wafer detected is more accurate, and thus the thickness of the metal layer determined on the wafer is more accurate.

[0039] In a possible implementation manner, when determining the first thickness value of the area on the polishing pad opposite to the eddy current sensor according to the second induction signal, the positional relationship between the dressing surface of the dressing head and the metal flange in the dressing head can be obtained. Wherein, the dressing surface contacts the polishing pad and is used for dressing the polishing pad. According to the second induction signal, the distance between the eddy current sensor and the metal flange is determined. Based on the distance between the eddy current sensor and the metal flange and the positional relationship, the first thickness value is determined.

[0040] In an example, Figure 3 is a schematic diagram of a dressing head for dressing a polishing pad provided by this application. As Figure 3 shown, the dressing head 202 dresses the polishing pad 201 through the dressing surface that contacts the polishing pad 201.

[0041] The positional relationship between the dressing surface and the metal flange on the dressing head is obtained. This positional relationship is a fixed relationship and will not change with the rotation of the polishing pad and the movement of the dressing head. The positional relationship between the dressing surface and the metal flange on the dressing head is a fixed attribute during the manufacturing of the dressing head.

[0042] The distance between the eddy current sensor and the metal flange of the dressing head is determined according to the signal intensity of the second induction signal. It should be understood that the eddy current effect between the eddy current sensor and the metal flange in the dressing head causes a change in the magnetic field generated by the eddy current sensor. According to the change in the magnetic field, that is, the second induction signal, the distance between the eddy current sensor and the metal flange can be determined.

[0043] According to the distance between the eddy current sensor and the metal flange and the positional relationship between the dressing surface and the metal flange in the dressing head, the first thickness of the area on the dressing pad opposite to the eddy current sensor is determined. Specifically, in the order from the eddy current sensor on the dressing disc to the metal flange, there are the eddy current sensor, the dressing pad, the dressing surface in contact with the dressing pad, and the metal flange. Therefore, after knowing the positional relationship between the dressing surface and the metal flange and the relationship between the eddy current sensor and the metal flange, the first thickness of the area on the dressing pad opposite to the eddy current sensor can be known.

[0044] It should be noted that there is no order of priority between the two steps of determining the distance between the eddy current sensor and the metal flange according to the second induction signal and obtaining the positional relationship between the dressing surface of the dressing head and the metal flange in the dressing head. Any one of the steps can be executed first, or the two steps can be executed simultaneously, which is not limited here.

[0045] Optionally, the positional relationship between the eddy current sensor and the surface of the dressing disc can also be obtained, and then the first thickness is determined according to the positional relationship between the eddy current sensor and the surface of the dressing disc, the distance between the eddy current sensor and the metal flange, and the positional relationship between the dressing surface and the metal flange in the dressing head, which will not be elaborated here.

[0046] In this application, by obtaining the positional relationship between the dressing surface of the dressing head and the metal flange in the dressing head and determining the distance between the eddy current sensor and the metal flange according to the second induction signal, the first thickness of the area on the dressing pad opposite to the eddy current sensor can be determined based on the distance between the eddy current sensor and the metal flange and the positional relationship between the dressing surface and the metal flange, realizing the detection of the thickness of the polishing pad by the eddy current sensor. Since the thickness of the polishing pad is detected by the eddy current sensor arranged on the polishing disc, there is no need to set an additional eddy current sensor on the dressing head, which can prevent the polishing liquid from damaging the eddy current sensor. Moreover, since the detected area is the thickness of the area opposite to the eddy current sensor, compared with detecting the average thickness of the polishing pad, the lift-off height of the wafer detected is more accurate, and the thickness of the metal layer on the wafer determined thereby is more accurate.

[0047] In a possible implementation, the relative area between the polishing pad and the eddy current sensor is the second thickness. Determine the first mapping relationship between the thickness of the metal layer and the third induction signal output by the eddy current sensor according to multiple thicknesses of the metal layer. Change the thickness of the polishing pad, and respectively determine multiple second mapping relationships between the thickness of the metal layer and the fourth induction signal output by the eddy current sensor when the polishing pad is at different thicknesses. Based on the first mapping relationship and the multiple second mapping relationships, determine the signal conversion formula. Based on this, when determining the thickness of the metal layer on the wafer according to the first induction signal and the first thickness value, the thickness of the metal layer can be determined according to the first induction signal, the first thickness value, and the signal conversion formula.

[0048] Let the relative area between the polishing pad and the eddy current sensor be the second thickness. Place wafers with multiple different metal layer thicknesses in the detection area respectively, and obtain different third induction signals output by the eddy current sensor for wafers with different metal layer thicknesses. For example: when the thickness of the relative area between the polishing pad and the eddy current sensor is, place n wafers with metal layer thicknesses of m1 to mn in the detection area respectively, and respectively determine the n third induction signals output by the eddy current sensor corresponding to the n wafers with metal layer thicknesses of m1 to mn. Thus, determine the first mapping relationship between the metal layer thickness and the third induction signal.

[0049] After determining the first mapping relationship, change the size of the second thickness, and determine multiple second mapping relationships between the thickness of the metal layer and the fourth induction signal output by the eddy current sensor when the polishing pad is at different thicknesses. For example: when the thickness of the relative area between the polishing pad and the eddy current sensor is h2 to h(t + 1) respectively, determine the n fourth induction signals output by the eddy current sensor corresponding to the n wafers with metal layer thicknesses of m1 to mn. Thus, t second mapping relationships can be determined, and different second mapping relationships correspond to different thicknesses of the relative area between the polishing pad and the eddy current sensor.

[0050] In one example, Figure 4 is a schematic diagram of a mapping relationship provided by this application. The first mapping relationship or the second mapping relationship, that is, the mapping relationship between the thickness of the metal layer on the wafer and the value of the induction signal output by the eddy current sensor (for example: the intensity of the induction signal) can be as Figure 4 shown.

[0051] Determine the signal conversion formula according to the first mapping relationship and the multiple second mapping relationships. The signal conversion formula can indicate the relationship between the polishing pad thickness, the eddy current sensor signal, and the thickness of the metal layer on the wafer. Thus, when determining the thickness of the metal layer on the wafer, the thickness of the metal layer on the wafer can be determined according to the first induction signal, the thickness of the relative area between the polishing pad and the eddy current sensor, and the signal conversion formula.

[0052] In this application, let the thickness of the polishing pad be the second thickness, determine the first mapping relationship between the thickness of the metal layer and the third induction signal output by the eddy current sensor, and then change the thickness of the polishing pad multiple times. Respectively determine multiple second mapping relationships between the thickness of the metal layer and the fourth induction signal output by the eddy current sensor under different thicknesses of the polishing pad. Thus, the signal conversion formula can be determined according to the first mapping relationship and the multiple second mapping relationships. Thus, the thickness of the metal layer on the wafer can be determined according to the signal conversion formula, the first induction signal, and the first thickness, realizing the detection of the thickness of the metal layer. Since the signal conversion is performed according to the determined signal conversion formula, there is no need to determine the signal conversion formula in real time during each detection, which can improve the efficiency of detecting the thickness of the metal layer.

[0053] In a possible implementation manner, when determining the signal conversion formula according to the first mapping relationship and the multiple second mapping relationships, numerical fitting can be performed on the first mapping relationship and the multiple second mapping relationships to determine the third mapping relationship between the mapping coefficient in the first mapping relationship and the thickness of the polishing pad, and the mapping coefficient in the first mapping relationship can be corrected according to the third mapping relationship to obtain the signal conversion formula.

[0054] Perform numerical fitting on the first mapping relationship and the multiple second mapping relationships to determine the third mapping relationship between the mapping coefficient in the first mapping relationship and the thickness of the polishing pad. The first mapping relationship and the second mapping relationship can be linear, quadratic, or cubic functions. The following will take the quadratic function as an example for illustration.

[0055] In one example, the first mapping relationship and the second mapping relationship can be expressed as: T(x) = Ax^2 + Bx + C, where T(x) represents the induced signal output by the eddy current sensor, x represents the thickness of the metal layer on the wafer, and A, B, and C represent the mapping coefficients. The first mapping relationship is the mapping relationship between the induced signal generated by the eddy current sensor when the second thickness is h1 and the thickness of the metal layer on the wafer, that is, when the second thickness is h1, T1(x) = A1x^2 + B1x + C1. The multiple second mapping relationships are respectively for the induced signals generated by the eddy current sensor when the second thicknesses are h2 to h(t + 1) and the thickness of the metal layer on the wafer, that is, when the second thickness is h2, T2(x) = A2x^2 + B2x + C2, when the second thickness is h3, T3(x) = A3x^2 + B3x + C3,..., when the second thickness is h(t + 1), T(t + 1)(x) = A(t + 1)x^2 + B(t + 1)x + C(t + 1). By numerically fitting the first mapping relationship and the multiple second mapping relationships, the third mapping relationship between the mapping coefficients and the thickness h of the polishing pad can be determined. For example: A = g1(h), B = g2(h), C = g3(h), where g(h) represents a function with the unknown h. By correcting the mapping coefficients in the first mapping relationship through the third mapping relationship, a signal conversion formula is obtained. The signal conversion formula is: T(x) = g1(h)x^2 + g2(h)x + g3(h). Thus, substituting the first thickness h and the first induced signal T into the signal conversion formula, x in the formula can be obtained, that is, the thickness of the metal layer on the wafer is determined.

[0056] In the present application, the first mapping relationship and the multiple second mapping relationships are numerically fitted to determine the third mapping relationship between the mapping coefficients in the first mapping relationship and the thickness of the polishing pad. According to the third mapping relationship, the mapping coefficients are corrected. Thus, a signal conversion formula can be obtained. Since the multiple mapping relationships are numerically fitted, the third mapping relationship between the mapping coefficients and the thickness of the polishing pad is relatively accurate. Therefore, in use, different mapping coefficients can be determined according to the thickness of the polishing pad, realizing the consideration of the thickness of the polishing pad when detecting the thickness of the metal layer on the wafer. Since the influence of the thickness of the polishing pad on the induced signal of the eddy current sensor is considered, the thickness of the metal layer on the wafer detected is more accurate.

[0057] In a possible implementation manner, the eddy current sensor includes a first induction coil and a second induction coil. When the eddy current sensor rotates with the polishing disc to be below the moving wafer, a first induced signal is obtained through the first induction coil. And when the eddy current sensor rotates with the polishing disc to sweep under the dressing head in the detection area, a second induced signal is obtained through the second induction coil.

[0058] The eddy current sensor may include a first induction coil and a second induction coil. The induction range of the first induction coil and the second induction coil may be different. It should be understood that the eddy current sensor rotates together with the polishing pad. Since the distance between the metal layer on the wafer and the eddy current sensor is less than the distance between the eddy current sensor and the metal flange on the dressing head, when the eddy current sensor rotates below the wafer, a first induction signal is obtained through the first induction coil with a smaller range. When it rotates below the dressing surface of the dressing head, a second induction signal is obtained through the second induction coil with a larger range.

[0059] In the present application, the eddy current sensing includes a first induction coil and a second induction coil. Thus, a first induction signal can be obtained through the first induction coil, and a second induction signal can be obtained through the second induction coil. Thus, the first induction signal and the second induction signal can be obtained simultaneously through different induction coils. And since the first induction coil and the second induction coil can be set with different ranges, it can be applicable to signal induction at different distances.

[0060] In a possible implementation manner, the eddy current sensor includes a third induction coil. The method further includes: collecting the first induction signal or the second induction signal generated by the third induction coil according to a preset measurement timing, where the measurement timing is set at least according to the rotation speed of the polishing pad.

[0061] The eddy current sensor may also include only one third induction coil. The induction signal generated by the third induction coil can be collected according to a preset measurement timing. For example: when the eddy current sensor rotates to below the moving wafer rotating with the polishing pad, the first induction signal generated by the third induction coil is collected. When the eddy current sensor rotates with the polishing pad to below the dressing head sweeping through the detection area, the second induction signal generated by the third induction coil is collected.

[0062] It should be noted that the rotation speed can determine the time for the eddy current sensor to rotate to the corresponding position each time (for example: rotating below the moving wafer, rotating below the dressing head sweeping through the detection area). That is, the faster the rotation speed, the shorter the time required to rotate to the corresponding position. Therefore, the measurement timing can be set at least according to the rotation speed of the polishing pad.

[0063] In one example, it is also possible to determine whether the currently acquired induction signal is the first induction signal or the second induction signal according to the signal strength of the induction signal generated by the third induction coil. It should be understood that since the distance between the metal layer on the wafer and the eddy current sensor is less than the distance between the eddy current sensor and the metal flange on the dressing head, for the third induction coil, the signal strength of the second induction signal is less than that of the first induction signal. Therefore, the induction signal generated by the eddy current sensor can be continuously acquired, the induction signal with a higher signal strength is determined as the first induction signal, and the induction signal with a lower signal strength is determined as the second induction signal.

[0064] In the present application, the eddy current sensor includes a third induction coil, and the first induction signal or the second induction signal generated by the third induction coil is acquired through a preset measurement timing. Since only one induction coil is included, the cost is lower compared with the solution of setting two induction coils in the above embodiment.

[0065] In a possible implementation manner, the dressing head is controlled to sweep across the detection area according to the movement track of the wafer on the polishing pad, so that when the wafer is located in the detection area, the dressing head is also located in the detection area. Herein, the detection area is an annular area, and the wafer and the dressing head are located in different areas of the annular area.

[0066] Since the eddy current sensor is disposed on the polishing platen and rotates together with the polishing platen during operation, an annular detection area will be formed on the polishing pad. Figure 5 FIG. is a schematic diagram of a detection area provided by the present application. As Figure 5 shown, the detection area is an annular area 400. When the wafer 300 moves to the annular area 400, the dressing head 202 is controlled to sweep across the annular area 400. The control logic is to control the dressing head 202 to sweep across the annular area according to the movement track of the wafer 300 on the polishing pad 201. In this way, each time the wafer 300 moves to the annular area 400, the dressing head 202 is also located in the annular area 400 at the same time. Thus, the second induction signal can be acquired after the first induction signal is acquired, and the acquisition times of the first induction signal and the second induction signal are relatively short.

[0067] It should be noted that, as Figure 2 shown, the wafer 300 moves along the radial direction of the polishing pad 201. Therefore, the time when the wafer passes through the detection area (annular area) can be determined according to the movement track of the wafer, and thus the dressing head can be controlled to sweep across the detection area so that when the wafer is located in the detection area, the dressing head is also located in the detection area at the same time.

[0068] In the present application, the dressing head is controlled to sweep across the detection area according to the movement track of the wafer on the polishing pad, so that when the wafer is located in the detection area, the dressing head is also located in the detection area. Thus, the second induction signal can be collected after the first induction signal is collected, and the collection times of the first induction signal and the second induction signal are relatively close. Therefore, after determining the first thickness according to the second induction signal, it is more accurate to determine the thickness of the metal layer on the wafer according to the first thickness and the first induction signal.

[0069] Figure 6 FIG. 4 is a schematic diagram of a chemical mechanical polishing apparatus 200 provided in the present application. As Figure 6 shown, the chemical mechanical polishing apparatus 200 may include: a polishing platen 203, a polishing pad 201, a dressing head 202, a carrier head 204, a liquid supply module 205, and a control module 206. The carrier head 204 is used to carry the wafer 300 so that the wafer 300 abuts against the polishing pad 201. The polishing platen 203 includes an eddy current sensor 2031. The eddy current sensor 2031 is disposed within the polishing platen 203. A polishing pad 201 for polishing the metal layer on the wafer 300 is disposed on the top surface of the polishing platen 203. The liquid supply module 205 is used to supply polishing liquid between the wafer 300 and the polishing pad 201. The dressing head 202 is used to dress the polishing pad 201. The control module 206 is configured to obtain a first induction signal of the eddy current sensor 2031 when the wafer 300 runs to the detection area of the eddy current sensor 2031, and obtain a second induction signal of the eddy current sensor 2031 when the dressing head 202 sweeps across the detection area, and determine a first thickness value of the area on the polishing pad 201 opposite to the eddy current sensor 2031 according to the second induction signal.

[0070] The control module 206 is configured to obtain the positional relationship between the dressing surface of the dressing head 202 and the metal flange in the dressing head 202, wherein the dressing surface contacts the polishing pad 201 and is used to dress the polishing pad 201, determine the distance between the eddy current sensor 2031 and the metal flange according to the second induction signal, and determine the first thickness according to the distance between the eddy current sensor 2031 and the metal flange and the positional relationship.

[0071] In a possible implementation, the control module 206 is configured to, when the relative area between the polishing pad 201 and the eddy current sensor 2031 is the second thickness, determine a first mapping relationship between the thickness of the metal layer and the third induction signal output by the eddy current sensor 2031 according to metal layers of multiple thicknesses, change the thickness of the polishing pad 201, respectively determine multiple second mapping relationships between the thickness of the metal layer and the fourth induction signal output by the eddy current sensor 2031 when the polishing pad 201 is at different thicknesses, determine a signal conversion formula according to the first mapping relationship and the multiple second mapping relationships, and determine the thickness of the metal layer according to the first induction signal, the first thickness value, and the signal conversion formula.

[0072] In a possible implementation, the control module 206 is configured to perform numerical fitting on the first mapping relationship and a plurality of second mapping relationships, determine a third mapping relationship between the mapping coefficient in the first mapping relationship and the thickness of the polishing pad 201, and correct the mapping coefficient in the first mapping relationship according to the third mapping relationship to obtain a signal conversion formula.

[0073] In a possible implementation, the eddy current sensor includes a first induction coil and a second induction coil. The control module 206 is configured to obtain a first induction signal through the first induction coil when the eddy current sensor 2031 rotates with the polishing disc 203 to be below the moving wafer 300, and obtain a second induction signal through the second induction coil when the eddy current sensor 2031 rotates with the polishing disc 203 to sweep below the dressing head 202 in the detection area.

[0074] In a possible implementation, the eddy current sensor 2031 includes a third induction coil. The control module 206 is configured to collect a first induction signal or a second induction signal generated by the third induction coil according to a preset measurement timing, where the measurement timing is set at least according to the rotation speed of the polishing disc 203.

[0075] In a possible implementation, the control module 206 is configured to control the dressing head 202 to sweep through the detection area according to the movement trajectory of the wafer 300 on the polishing pad 201, so that when the wafer 300 is located in the detection area, the dressing head 202 is located in the detection area, where the detection area is an annular area, and the wafer 300 and the dressing head 202 are located in different areas of the annular area.

[0076] Another embodiment of the present application further provides an eddy current detection device based on polishing pad thickness compensation, including: an induction signal acquisition module, configured to acquire a first induction signal of the eddy current sensor when the wafer runs to the detection area of the eddy current sensor, where the eddy current sensor is disposed in a polishing disc included in a chemical mechanical polishing device, and a polishing pad for polishing a metal layer on the wafer is disposed on the top surface of the polishing disc; and, when a dressing head included in the chemical mechanical polishing device sweeps through the detection area, acquire a second induction signal of the eddy current sensor; a first thickness value determination module, configured to determine a first thickness value of a region on the polishing pad opposite to the eddy current sensor according to the second induction signal; a metal layer thickness determination module, configured to determine the thickness of the metal layer on the wafer according to the first induction signal and the first thickness value.

[0077] Referring to Figure 7 , a schematic structural diagram of an electronic device according to the present application is shown. The specific implementation of the electronic device in the specific embodiments of the present application is not limited.

[0078] As Figure 7 shown, the electronic device may include: a processor 702, a communications interface 704, a memory 706, and a communication bus 708.

[0079] Among them:

[0080] The processor 702, the communications interface 704, and the memory 706 communicate with each other through the communication bus 708.

[0081] The communications interface 704 is used to communicate with other electronic devices or servers.

[0082] The processor 702 is used to execute the program 710, and specifically may execute the relevant steps in the above-mentioned embodiments of the eddy current detection method for thickness compensation.

[0083] Specifically, the program 710 may include program code, and the program code includes computer operation instructions.

[0084] The processor 702 may be a central processing unit CPU, or a graphics processing unit GPU (Graphics Processing Unit), or an application specific integrated circuit ASIC (Application Specific Integrated Circuit), or one or more integrated circuits configured to implement the present application. One or more processors included in the intelligent device may be of the same type of processor, such as one or more CPUs; one or more GPUs; or may be of different types of processors, such as one or more CPUs and one or more GPUs and one or more ASICs.

[0085] The memory 706 is used to store the program 710. The memory 706 may include high-speed RAM memory, and may also include non-volatile memory, such as at least one disk memory.

[0086] The program 710 is specifically used to cause the processor 702 to execute the eddy current detection method for thickness compensation in any of the foregoing embodiments.

[0087] For the specific implementation of each step in the program 710, reference may be made to the corresponding steps and descriptions in the corresponding units in any of the foregoing embodiments of the eddy current detection method for thickness compensation, which will not be elaborated here. Those skilled in the art can clearly understand that for the convenience and conciseness of description, the specific working processes of the above-described devices and modules may refer to the corresponding process descriptions in the foregoing method embodiments, which will not be elaborated here.

[0088] In the present application, when the wafer runs to the detection area of the eddy current sensor, the first induction signal of the eddy current sensor is obtained. When the dressing head sweeps across the detection area, the second induction signal of the eddy current sensor is obtained. The first thickness of the area on the polishing pad opposite to the eddy current sensor is determined according to the second induction signal. Thus, the thickness of the metal layer on the wafer can be determined based on the first thickness and the first induction signal. Since the thickness of the polishing pad, that is, the lift-off height of the wafer, is taken into account when determining the thickness of the metal layer, compared with the prior art where the lift-off height is not considered, because the influence of the lift-off height on the induction signal generated by the eddy current sensor is considered, the thickness of the metal layer on the wafer detected is more accurate. And since the thickness of the polishing pad is detected by the eddy current sensor arranged on the polishing disk, there is no need to set an additional eddy current sensor on the dressing head, which can prevent the polishing liquid from damaging the eddy current sensor. Also, since the detected area is the thickness of the area opposite to the eddy current sensor, compared with detecting the average thickness of the polishing pad, the lift-off height of the wafer detected is more precise, and thus the thickness of the metal layer on the wafer determined is more accurate.

[0089] The present application also provides a computer program product, including computer instructions, which direct a computing device to perform the operations corresponding to any one of the above-mentioned multiple method embodiments.

[0090] It should be noted that, according to the needs of implementation, each component / step described in 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 present application.

[0091] The method according to the present application described above can be implemented in hardware, firmware, or be 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 be implemented as computer code originally stored in a remote recording medium or a non-transitory machine-readable medium and downloaded through a network and will be stored in a local recording medium, so that the method described herein can be processed by such software stored on a recording medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware (such as an ASIC or an FPGA). It can be understood that a computer, a processor, a microprocessor controller, or programmable hardware includes a storage component (such as a RAM, a ROM, a flash memory, etc.) that can store or receive software or computer code. When the software or computer code is accessed and executed by the computer, the processor, or the hardware, the eddy current detection method for thickness compensation described herein is implemented. In addition, when a general-purpose computer accesses the code for implementing the eddy current detection method for thickness compensation shown herein, the execution of the code converts the general-purpose computer into a dedicated computer for executing the eddy current detection method for thickness compensation shown herein.

[0092] Those of ordinary skill in the art can realize that the units and method steps of each example described in combination with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. Professional technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of this application.

[0093] The above embodiments are only used to illustrate this application, rather than limiting this application. Those of ordinary skill in the relevant technical field can also make various changes and modifications without departing from the spirit and scope of this application. Therefore, all equivalent technical solutions also belong to the scope of this application. The patent protection scope of this application shall be defined by the claims.

Claims

1. A thickness compensation eddy current detection method, applied to a chemical mechanical polishing equipment, characterized in that The method includes: When the wafer runs to the detection area of the eddy current sensor, acquiring a first induction signal of the eddy current sensor, where the eddy current sensor is disposed in a polishing platen included in a chemical mechanical polishing device, and a polishing pad for polishing a metal layer on the wafer is disposed on the top surface of the polishing platen; When a dressing head included in the chemical mechanical polishing device sweeps across the detection area, acquiring a second induction signal of the eddy current sensor; Determining a first thickness value of a region on the polishing pad opposite to the eddy current sensor according to the second induction signal; Making the region on the polishing pad opposite to the eddy current sensor a second thickness, and determining a first mapping relationship between the thickness of the metal layer and a third induction signal output by the eddy current sensor according to metal layers of multiple thicknesses; Changing the thickness of the polishing pad, and respectively determining multiple second mapping relationships between the thickness of the metal layer and a fourth induction signal output by the eddy current sensor when the polishing pad is at different thicknesses; Performing numerical fitting on the first mapping relationship and the multiple second mapping relationships to determine a third mapping relationship between a mapping coefficient in the first mapping relationship and the thickness of the polishing pad; Performing coefficient correction on the mapping coefficient in the first mapping relationship according to the third mapping relationship to obtain a signal conversion formula; Determining the thickness of the metal layer according to the first induction signal, the first thickness value, and the signal conversion formula, where the signal conversion formula is: T(x) = g1(h)x^2 + g2(h)x + g3(h), where h is the first thickness, T is the first induction signal, g1(h), g2(h), and g3(h) are corrected mapping coefficients, and x is the thickness of the metal layer on the wafer.

2. The method according to claim 1, characterized in that The determining the first thickness value of the region on the polishing pad opposite to the eddy current sensor according to the second induction signal includes: Acquiring a positional relationship between a dressing surface of the dressing head and a metal flange in the dressing head, where the dressing surface contacts the polishing pad and is used for dressing the polishing pad; Determining a distance between the eddy current sensor and the metal flange according to the second induction signal; Determining the first thickness value according to the distance between the eddy current sensor and the metal flange and the positional relationship.

3. The method according to claim 1, wherein The eddy current sensor includes a first induction coil and a second induction coil, and the method further includes: When the eddy current sensor rotates with the polishing platen to be below the moving wafer, acquiring the first induction signal through the first induction coil, and when the eddy current sensor rotates with the polishing platen to be below the dressing head sweeping across the detection area, acquiring the second induction signal through the second induction coil.

4. The method according to claim 1, characterized in that The eddy current sensor includes a third induction coil, and the method further includes: Collecting the first induction signal or the second induction signal generated by the third induction coil according to a preset measurement timing, where the measurement timing is set at least according to the rotation speed of the polishing platen.

5. The method according to claim 1, characterized in that The method further includes: Controlling the dressing head to sweep across the detection area according to the movement track of the wafer on the polishing pad, so that when the wafer is located in the detection area, the dressing head is also located in the detection area, wherein the detection area is an annular area, and the wafer and the dressing head are located in different areas of the annular area.

6. A chemical mechanical polishing apparatus, characterized in that, Comprising: A polishing disc, a polishing pad, a dressing head, a carrier head, a liquid supply module and a control module. The carrier head is used to carry the wafer so that the wafer abuts against the polishing pad. The polishing disc includes an eddy current sensor disposed inside the polishing disc. The top surface of the polishing disc is provided with a polishing pad for polishing the metal layer on the wafer. The liquid supply module is used to supply polishing liquid between the wafer and the polishing pad. The dressing head is used to dress the polishing pad; The control module is configured to obtain a first induction signal of the eddy current sensor when the wafer runs to the detection area of the eddy current sensor, and obtain a second induction signal of the eddy current sensor when the dressing head sweeps across the detection area, and determine a first thickness value of the area on the polishing pad opposite to the eddy current sensor according to the second induction signal; Let the area of the polishing pad opposite to the eddy current sensor be the second thickness, determine a first mapping relationship between the thickness of the metal layer and a third induction signal output by the eddy current sensor according to metal layers of multiple thicknesses, change the thickness of the polishing pad, and respectively determine multiple second mapping relationships between the thickness of the metal layer and a fourth induction signal output by the eddy current sensor when the polishing pad is at different thicknesses, perform numerical fitting on the first mapping relationship and the multiple second mapping relationships, and determine a third mapping relationship between the mapping coefficient in the first mapping relationship and the thickness of the polishing pad; correct the mapping coefficient in the first mapping relationship according to the third mapping relationship to obtain a signal conversion formula; determine the thickness of the metal layer according to the first induction signal, the first thickness value and the signal conversion formula. The signal conversion formula is: T(x) = g1(h)x^2 + g2(h)x + g3(h), where h is the first thickness, T is the first induction signal, g1(h), g2(h), g3(h) are the corrected mapping coefficients, and x is the thickness of the metal layer on the wafer.

7. The device according to claim 6, wherein The control module is configured to obtain the positional relationship between the dressing surface of the dressing head and the metal flange in the dressing head, wherein the dressing surface contacts the polishing pad and is used to dress the polishing pad, determine the distance between the eddy current sensor and the metal flange according to the second induction signal, and determine the first thickness according to the distance between the eddy current sensor and the metal flange and the positional relationship.

8. The device according to claim 6, characterized in that, The eddy current sensor includes a first induction coil and a second induction coil; The control module is configured to obtain the first induction signal through the first induction coil when the eddy current sensor rotates with the polishing disc to be below the moving wafer, and obtain the second induction signal through the second induction coil when the eddy current sensor rotates with the polishing disc to sweep below the dressing head in the detection area.

9. The device according to claim 6, characterized in that, The eddy current sensor includes a third induction coil; The control module is configured to collect the first induction signal or the second induction signal generated by the third induction coil according to a preset measurement timing, wherein the measurement timing is set at least according to the rotation speed of the polishing disc.

10. The device according to claim 6, wherein The control module is configured to control the dressing head to sweep through the detection area according to the movement trajectory of the wafer on the polishing pad, so that when the wafer is in the detection area, the dressing head is in the detection area, wherein the detection area is an annular area, and the wafer and the dressing head are in different areas of the annular area.

11. An electronic device, characterized in that, Comprising: A processor, a memory, a communication interface and a communication bus, and the processor, the memory and the communication interface complete communication with each other through the communication bus; The memory is configured to store at least one executable instruction, and the executable instruction causes the processor to execute the eddy current detection method for thickness compensation according to any one of claims 1-5.

12. A computer storage medium, characterized in that, A computer program is stored thereon, and when the program is executed by the processor, the eddy current detection method for thickness compensation according to any one of claims 1-5 is implemented.

13. A computer program product, characterized in that, Comprising computer instructions, and the computer instructions instruct a computing device to execute the eddy current detection method for thickness compensation according to any one of claims 1-5.

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