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

Abstract

The present application provides a thickness-compensated eddy current detection method, device, and storage medium, which are applied to chemical mechanical polishing equipment. The method includes: when a wafer runs to the detection area of ​​the eddy current sensor, a first induction signal of the eddy current sensor is obtained, wherein the eddy current sensor is arranged in a polishing disk included in the chemical mechanical polishing equipment, and a polishing pad for polishing the metal layer on the wafer is arranged on the top surface of the polishing disk; when a trimming head included in the chemical mechanical polishing equipment sweeps over the detection area, a second induction signal of the eddy current sensor is obtained; according to the second induction signal, a first thickness value of the area on the polishing pad opposite to the eddy current sensor is determined; according to the first induction signal and the first thickness value, the thickness of the metal layer on the wafer is determined. The thickness-compensated eddy current detection method provided by the present application can improve the detection accuracy of the thickness of the metal layer on the wafer.

Description

Technical Field

[0001] The present application relates to the field of semiconductor manufacturing technology, and in particular to a thickness-compensated eddy current detection method, device, and storage medium. Background Art

[0002] Integrated Circuit (IC) is the core and lifeblood of the development of the information technology industry. Integrated circuits are generally formed by depositing a conductive layer, a semiconductor layer or an insulating layer on a silicon wafer. As a result, a thin film formed by a filler layer is deposited on the surface of the wafer. In the manufacturing process, it is necessary to continuously flatten the filler layer until the patterned top surface is exposed to form a conductive path between the raised patterns.

[0003] 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 the degradation of device electrical properties or even failure. In order to improve the controllability of the chemical mechanical polishing process, enhance the stability of the product, reduce the defect rate of the product, and achieve uniform production for each wafer, the endpoint detection technology (EPD) of chemical mechanical polishing came into being.

[0004] In metal CMP endpoint detection, eddy current detection is the most commonly used method. The induction signal it outputs is a voltage signal. Experimental verification shows that the size of the voltage signal is related to the thickness of the metal layer of the measured wafer, and is also related to the distance between the eddy current sensor and the measured metal layer. 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. The corresponding relationship between the thickness of the metal layer and the voltage value is different at different lift-off heights. In actual processing, there is a polishing pad between the sensor and the polished wafer, so 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

[0005] In view of this, the present application provides a thickness-compensated eddy current detection method, device, and storage medium to at least partially solve the above-mentioned problems.

[0006] According to a first aspect of the present application, a thickness-compensated eddy current detection method is provided, which is applied to chemical mechanical polishing equipment, and the method comprises: when a wafer runs to a detection area of ​​the eddy current sensor, obtaining a first induction signal of the eddy current sensor, wherein the eddy current sensor is arranged in a polishing disk included in the chemical mechanical polishing equipment, and a polishing pad for polishing a metal layer on the wafer is arranged on the top surface of the polishing disk; when a trimming head included in the chemical mechanical polishing equipment sweeps over the detection area, obtaining a second induction signal of the eddy current sensor; determining a first thickness value of an area on the polishing pad opposite to the eddy current sensor 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.

[0007] According to a second aspect of the present application, a chemical mechanical polishing device is provided, comprising: a polishing disk, a polishing pad, a dressing head, a carrying head, a liquid supply module and a control module, wherein the carrying head is used to carry a wafer so that the wafer abuts against the polishing pad, the polishing disk comprises an eddy current sensor, the eddy current sensor is arranged in the polishing disk, a polishing pad for polishing a metal layer on the wafer is arranged on the top surface of the polishing disk, the liquid supply module is used to supply polishing liquid between the wafer and the polishing pad, and the dressing head is used to dress the polishing pad; the control module is used to obtain a first induction signal of the eddy current sensor when the wafer runs to a detection area of ​​the eddy current sensor, obtain a second induction signal of the eddy current sensor when the dressing head scans the detection area, and determine a first thickness value of an area on the polishing pad opposite to the eddy current sensor according to the second induction signal.

[0008] According to a third aspect of the present application, an eddy current detection device based on polishing pad thickness compensation is provided, comprising: an induction signal acquisition module, used to acquire a first induction signal of the eddy current sensor when the wafer runs to the detection area of ​​the eddy current sensor, wherein the eddy current sensor is arranged in a polishing disk included in a chemical mechanical polishing device, and a polishing pad for polishing a metal layer on the wafer is arranged on the top surface of the polishing disk; and, when a trimming head included in the chemical mechanical polishing device sweeps over the detection area, a second induction signal of the eddy current sensor is acquired; a first thickness value determination module, used to determine a first thickness value of an area on the polishing pad opposite to the eddy current sensor according to the second induction signal; and a metal layer thickness determination module, used to determine the thickness of the metal layer on the wafer according to the first induction signal and the first thickness value.

[0009] According to the fourth aspect of the present application, an electronic device is provided, comprising: a processor, a memory, a communication interface and a communication bus, wherein the processor, the memory and the communication interface communicate with each other through the communication bus; the memory is used to store at least one executable instruction, and the executable instruction enables the processor to perform an operation corresponding to the method described in the first aspect.

[0010] According to a fifth aspect of the present application, a computer storage medium is provided, on which a computer program is stored, and when the program is executed by a processor, the method described in the first aspect is implemented.

[0011] According to a sixth aspect of the present application, a computer program product is provided, comprising computer instructions, wherein the computer instructions instruct a computing device to execute the method as described in the first aspect.

[0012] According to the thickness-compensated eddy current detection method provided by the present application, when the wafer moves 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 over the detection area, a second induction signal of the eddy current sensor is obtained, and a first thickness of an area on the polishing pad opposite to the eddy current sensor is determined according to the second induction signal, thereby determining the thickness of the metal layer on the wafer according to the first thickness and the first induction signal. Since the thickness of the polishing pad is taken into account when determining the thickness of the metal layer, that is, the lift-off height of the wafer is taken into account, compared with the prior art in which the lift-off height is not considered, the thickness of the metal layer on the wafer detected is more accurate because the influence of the lift-off height on the induction signal generated by the eddy current sensor is taken into account. Moreover, since the thickness of the polishing pad is detected according to the eddy current sensor arranged on the polishing disk, there is no need to arrange 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, the lift-off height of the wafer detected is more accurate compared with the average thickness of the polishing pad, thereby determining the thickness of the metal layer on the wafer more accurately. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solutions in the present application or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0014] Figure 1 It is a flow chart of a thickness-compensated eddy current testing method provided by the present application;

[0015] Figure 2 It is a schematic diagram of a chemical mechanical polishing process for a wafer provided by the present application;

[0016] Figure 3 is a schematic diagram of a dressing head dressing a polishing pad provided by the present application;

[0017] Figure 4 It is a schematic diagram of a mapping relationship provided by this application;

[0018] Figure 5 is a schematic diagram of a detection area provided by the present application;

[0019] Figure 6 is a schematic diagram of a chemical mechanical polishing device provided by the present application;

[0020] Figure 7 A schematic diagram of the structure of an electronic device provided in this application.

[0021] 200, chemical mechanical polishing equipment; 201, polishing pad; 202, dressing head; 203, polishing disk; 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 DESCRIPTION

[0022] In order to enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in this application will be clearly and completely described below in conjunction with the drawings in this application. Obviously, the described embodiments are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field should fall within the scope of protection of this application.

[0023] 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.

[0024] 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".

[0025] The thickness compensation eddy current detection method provided by the present application is described below by means of specific embodiments:

[0026] Figure 1 is a flow chart of a thickness compensation eddy current detection method provided by the present application, which is applied to chemical mechanical polishing equipment, such as Figure 1 As shown, the eddy current detection method for polishing pad thickness compensation includes the following steps 101 to 104:

[0027] Step 101: When the wafer moves to the detection area of ​​the eddy current sensor, a first sensing signal of the eddy current sensor is obtained.

[0028] The eddy current sensor is arranged in a polishing plate included in the chemical mechanical polishing equipment. The top surface of the polishing plate 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 a wafer 300 provided in the present application, such as Figure 2 As shown, when the chemical mechanical polishing device polishes the wafer 300, the chemical mechanical polishing device body rotates, and the wafer 300 rotates under the action of the carrier head and moves radially along the polishing disk of the chemical mechanical polishing device, so that the wafer 300 can be chemically mechanically polished by the polishing pad 201. Since the eddy current sensor is arranged in the polishing disk included in the chemical mechanical polishing device, the polishing pad 201 is arranged on the top surface of the polishing disk, and the wafer 300 moves radially along the polishing pad 201 of the chemical mechanical polishing device, when the wafer 300 runs to the detection area of ​​the eddy current sensor, the first sensing 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 0.01μm to 50μm.

[0029] 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 surface of the wafer will produce an eddy current effect, causing the magnetic field generated by the eddy current sensor to change, thereby measuring the thickness of the metal layer based on the change in the magnetic field.

[0030] Step 102: When a dressing head included in the chemical mechanical polishing equipment scans the detection area, a second sensing signal of the eddy current sensor is obtained.

[0031] When performing chemical mechanical polishing on the wafer, the polishing pad will wear out, so it is necessary to use a dressing head to dress the polishing pad in real time. In one example, the wafer is polished on the left half of the polishing pad, and the dressing head dresses the polishing pad on the right half of the polishing pad. When the dressing head sweeps across the detection area, the second induction signal of the eddy current sensor is obtained. Since there is metal inside the dressing head, the eddy current sensor can detect the metal inside the dressing head and generate a second induction signal.

[0032] Step 103: Determine a first thickness value of an area on the polishing pad opposite to the eddy current sensor according to the second sensing signal.

[0033] According to the second induction signal generated by the eddy current sensor, the distance between the eddy current sensor and the dressing head is determined. It should be understood that since the dressing head dresses the polishing pad, the polishing pad is set on the polishing disk, and the eddy current sensor is set in the polishing disk, the distance between the eddy current sensor and the dressing head is the first thickness value of the area on the polishing pad opposite to the eddy current sensor.

[0034] It should be understood that, when the dressing head included in the chemical mechanical polishing device sweeps over the detection area, the eddy current sensor acquires the second sensing signal, and determines the first thickness value of the area opposite to the eddy current sensor according to the second sensing signal, the area opposite to the polishing pad and the eddy current sensor is at least partially located within the detection area. The radius and angle of the detection area on the polishing pad can be predetermined.

[0035] Step 104: Determine the thickness of the metal layer on the wafer according to the first sensing signal and the first thickness value.

[0036] According to the first sensing signal, the first thickness value determines the thickness of the metal layer on the wafer. In one example, the mapping relationship between the sensing 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 sensing signal.

[0037] 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, and when the dressing head sweeps over the detection area, the second induction signal of the eddy current sensor is obtained, and the first thickness of the area on the polishing pad opposite to the eddy current sensor is determined according to the second induction signal, thereby the thickness of the metal layer on the wafer can be determined according to the first thickness and the first induction signal. Since the thickness of the polishing pad is taken into account when determining the thickness of the metal layer, that is, the lift-off height of the wafer is taken into account, compared with the prior art that does not consider the lift-off height, the detected thickness of the metal layer on the wafer is more accurate because the influence of the lift-off height on the induction signal generated by the eddy current sensor is taken into account, and since the thickness of the polishing pad is detected according to the eddy current sensor arranged on the polishing disk, there is no need to arrange an additional eddy current sensor on the dressing head, which saves costs and can prevent the polishing liquid from damaging the eddy current sensor. Moreover, since the area for detecting the thickness is the thickness of the area on the polishing pad opposite to the eddy current sensor, the lift-off height of the wafer detected is more accurate compared with detecting the average thickness of the polishing pad, and the thickness of the metal layer on the wafer determined thereby is more accurate.

[0038] In one possible implementation, when determining a first thickness value of an area on the polishing pad opposite to the eddy current sensor based on a second induction signal, the positional relationship between a dressing surface of the dressing head and a metal flange in the dressing head can be obtained, wherein the dressing surface contacts the polishing pad, and the dressing surface is used to dress the polishing pad. According to the second induction signal, the distance between the eddy current sensor and the metal flange is determined, and according to the distance and positional relationship between the eddy current sensor and the metal flange, the first thickness value is determined.

[0039] In one example, Figure 3 Schematic diagram of a dressing head dressing polishing pad provided in the present application, such as Figure 3 As shown, the conditioning head 202 conditions the polishing pad 201 via a conditioning surface in contact with the polishing pad 201 .

[0040] 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 property when the dressing head is manufactured.

[0041] The distance between the eddy current sensor and the metal flange of the dressing head is determined according to the signal strength of the second induction signal. It should be understood that the eddy current effect generated by the eddy current sensor and the metal flange in the dressing head causes the magnetic field generated by the eddy current sensor to change. Based on 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.

[0042] According to the distance between the eddy current sensor and the metal flange and the positional relationship between the trimming surface and the metal flange on the trimming head, the first thickness of the area on the trimming pad opposite to the eddy current sensor is determined. Specifically, the order from the eddy current sensor on the trimming disk to the metal flange is the eddy current sensor, the trimming pad, the trimming surface in contact with the trimming pad, and the metal flange. Therefore, after knowing the positional relationship between the trimming 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 trimming pad opposite to the eddy current sensor can be known.

[0043] It should be noted that there is no particular order between the steps of determining the distance between the eddy current sensor and the metal flange based on the second induction signal and obtaining the positional relationship between the trimming surface of the trimming head and the metal flange in the trimming head. Any one of the two steps can be executed first, or the two steps can be executed simultaneously, which is not limited here.

[0044] Optionally, the positional relationship between the eddy current sensor and the surface of the dressing disk can also be obtained, and then the first thickness can be determined based on the positional relationship between the eddy current sensor and the surface of the dressing disk, 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 repeated here.

[0045] In the present application, the positional relationship between the trimming surface of the trimming head and the metal flange in the trimming head is obtained, and the distance between the eddy current sensor and the metal flange is determined according to the second induction signal. Therefore, the first thickness of the area on the trimming pad opposite to the eddy current sensor can be determined according to the distance between the eddy current sensor and the metal flange and the positional relationship between the trimming surface and the metal flange, thereby realizing the detection of the thickness of the polishing pad by the eddy current sensor. Since the thickness of the polishing pad is detected according to the eddy current sensor arranged on the polishing disk, there is no need to set an additional eddy current sensor on the trimming 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 detected lift-off height of the wafer is more precise, and the thickness of the metal layer on the wafer determined thereby is more accurate.

[0046] In one possible implementation, the relative area between the polishing pad and the eddy current sensor is set to a second thickness, and a first mapping relationship between the thickness of the metal layer and the third induction signal output by the eddy current sensor is determined based on metal layers of multiple thicknesses. The thickness of the polishing pad is changed, and multiple second mapping relationships between the thickness of the metal layer and the fourth induction signal output by the eddy current sensor are determined when the polishing pad has different thicknesses. A signal conversion formula is determined based on the first mapping relationship and the multiple second mapping relationships. Based on this, when determining the thickness of the metal layer on the wafer based on the first induction signal and the first thickness value, the thickness of the metal layer can be determined based on the first induction signal, the first thickness value and the signal conversion formula.

[0047] The relative area between the polishing pad and the eddy current sensor is set to the second thickness, and a plurality of wafers with different metal layer thicknesses are placed in the detection area respectively, and different third sensing signals output by the eddy current sensor for wafers with different metal layer thicknesses are obtained. For example, when the relative area between the polishing pad and the eddy current sensor has a thickness of m1 to mn, n wafers with metal layer thicknesses of m1 to mn are placed in the detection area respectively, and n third sensing signals output by the eddy current sensor corresponding to the n wafers with metal layer thicknesses of m1 to mn are determined respectively. Thus, the first mapping relationship between the metal layer thickness and the third sensing signal is determined.

[0048] After determining the first mapping relationship, the size of the second thickness is changed to 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 has different thicknesses. For example: when the thickness of the relative area between the polishing pad and the eddy current sensor is h2~h(t+1), the n fourth induction signals output by the eddy current sensor corresponding to n wafers with metal layer thicknesses of m1~mn are determined, thereby 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.

[0049] In one example, Figure 4 is a schematic diagram of a mapping relationship provided by the present 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 sensing signal value (for example, the strength of the sensing signal) output by the eddy current sensor can be as follows: Figure 4 shown.

[0050] A signal conversion formula is determined based on the first mapping relationship and 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. Therefore, when determining the thickness of the metal layer on the wafer, the thickness of the metal layer on the wafer can be determined based on the first sensing signal, the thickness of the area on the polishing pad opposite to the eddy current sensor and the signal conversion formula.

[0051] In the present application, the thickness of the polishing pad is set to the second thickness, and the first mapping relationship between the thickness of the metal layer and the third induction signal output by the eddy current sensor is determined. Then, the thickness of the polishing pad is changed multiple times, and multiple second mapping relationships between the thickness of the metal layer and the fourth induction signal output by the eddy current sensor are determined under different polishing pad thicknesses. Thus, a signal conversion formula can be determined based on the first mapping relationship and the multiple second mapping relationships. Thus, the thickness of the metal layer on the wafer can be determined based on the signal conversion formula, the first induction signal and the first thickness, thereby 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, and the efficiency of the metal layer thickness detection can be improved.

[0052] In one possible implementation, when determining a signal conversion formula based on a first mapping relationship and multiple second mapping relationships, the first mapping relationship and the multiple second mapping relationships can be numerically fitted to determine a 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 is corrected based on the third mapping relationship to obtain the signal conversion formula.

[0053] The first mapping relationship and multiple second mapping relationships are numerically fitted to determine a 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 a linear, quadratic or cubic function, and the quadratic function is used as an example for explanation below.

[0054] 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 sensing signal output by the eddy current sensor, x represents the thickness of the metal layer on the wafer, and ABC represents the mapping coefficient. The first mapping relationship is the mapping relationship between the sensing 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)=A1 x^2+B1 x+C1. The multiple second mapping relationships are respectively for the sensing signal generated by the eddy current sensor when the second thickness is h2~h(t+1) and the thickness of the metal layer on the wafer, that is, when the second thickness is h2, T2 (x)=A2 x^2+B2 x+C2, when the second thickness is h3, T3 (x)=A3 x^2+B3 x+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 with the multiple second mapping relationships, the third mapping relationship between the mapping coefficient and the polishing pad thickness h can be determined, for example: A=g1 (h), B=g2 (h), C=g3 (h), wherein g(h) represents a function with unknown number h. The mapping coefficients in the first mapping relationship are corrected through the third mapping relationship to obtain a signal conversion formula, which is: T(x)=g1(h) x^2+g2 (h)x+g3 (h). Therefore, the first thickness h and the first sensing signal T are substituted into the signal conversion formula to obtain x in the formula, that is, to determine the thickness of the metal layer on the wafer.

[0055] In the present application, the first mapping relationship and multiple second mapping relationships are numerically fitted to determine the third mapping relationship between the mapping coefficient in the first mapping relationship and the thickness of the polishing pad. The mapping coefficient is corrected according to the third mapping relationship, thereby obtaining a signal conversion formula. Since the multiple mapping relationships are numerically fitted, the third mapping relationship between the mapping coefficient and the thickness of the polishing pad is more accurate. Therefore, when used, different mapping coefficients can be determined according to the thickness of the polishing pad, so that the thickness of the polishing pad is taken into consideration when detecting the thickness of the metal layer of the wafer. Since the influence of the thickness of the polishing pad on the induction signal of the eddy current sensor is taken into account, the detected thickness of the metal layer on the wafer is more accurate.

[0056] In one possible implementation, the eddy current sensor includes a first induction coil and a second induction coil. When the eddy current sensor rotates with the polishing plate to under the moving wafer, a first induction signal is obtained through the first induction coil, and when the eddy current sensor rotates with the polishing plate to under the dressing head that sweeps across the detection area, a second induction signal is obtained through the second induction coil.

[0057] The eddy current sensor may include a first induction coil and a second induction coil. The induction ranges of the first induction coil and the second induction coil may be different. It should be understood that the eddy current sensor rotates with the polishing disk, and since the distance between the metal layer on the wafer and the eddy current sensor is smaller than the distance between the eddy current sensor and the metal flange on the dressing head, when the eddy current sensor rotates to below the wafer, a first induction signal is obtained through the first induction coil with a smaller range, and when it rotates to below the dressing surface of the dressing head, a second induction signal is obtained through the second induction coil with a larger range.

[0058] In the present application, the eddy current induction includes a first induction coil and a second induction coil, thereby obtaining a first induction signal through the first induction coil and obtaining a second induction signal through the second induction coil, thereby obtaining the first induction signal and the second induction signal at the same time through different induction coils, and since the first induction coil and the second induction coil can be set with different ranges, they can be suitable for signal sensing at different distances.

[0059] In a possible implementation, 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 sequence, wherein the measurement sequence is set at least according to the rotation speed of the polishing disk.

[0060] The eddy current sensor may also include only one third induction coil, and may collect the induction signal generated by the third induction coil according to a preset measurement sequence. For example, when the eddy current sensor rotates to under the moving wafer along with the polishing disk, the first induction signal generated by the third induction coil is collected; when the eddy current sensor rotates to under the dressing head that sweeps across the detection area along with the polishing disk, the second induction signal generated by the third induction coil is collected.

[0061] It should be noted that the rotational speed can determine the time it takes for the eddy current sensor to rotate to the corresponding position each time (for example, rotating to under the moving wafer, rotating to under the dressing head that scans the detection area), that is, the faster the rotational speed, the shorter the time required to rotate to the corresponding position. Therefore, the measurement timing can at least be set according to the rotational speed of the polishing disk.

[0062] In one example, it is also possible to determine whether the currently collected induction signal is the first induction signal or the second induction signal based on 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 smaller than the distance between the eddy current sensor and the metal flange on the trimming head, the signal strength of the second induction signal is smaller than the signal strength of the first induction signal for the third induction coil. Therefore, the induction signal generated by the eddy current sensor can be continuously collected, and the induction signal with higher induction signal strength can be determined as the first induction signal, and the induction signal with lower induction signal strength can be determined as the second induction signal.

[0063] 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 collected through a preset measurement sequence. Since only one induction coil is included, the cost is lower than the solution of setting two induction coils in the above embodiment.

[0064] In one possible implementation, the trimming head is controlled to scan the detection area according to the movement trajectory of the wafer on the polishing pad, so that the trimming head is located in the detection area when the wafer is located in the detection area, wherein the detection area is an annular area, and the wafer and the trimming head are located in different areas of the annular area.

[0065] Since the eddy current sensor is set on the polishing plate, and during operation, the eddy current sensor rotates with the polishing plate, an annular detection area is formed on the polishing pad. Figure 5 is a schematic diagram of a detection area provided in this application, such as Figure 5 As shown, the detection area is the annular area 400. When the wafer 300 moves to the annular area 400, the dressing head 202 is controlled to scan the annular area 400. The control logic is to control the dressing head 202 to scan the annular area according to the moving trajectory 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. Therefore, the second sensing signal can be collected after the first sensing signal is collected, so that the difference in collection time between the first sensing signal and the second sensing signal is short.

[0066] It should be noted that if Figure 2 As shown, the wafer 300 moves radially along the polishing pad 201, so the time when the wafer passes through the detection area (annular area) can be determined according to the movement trajectory of the wafer, thereby controlling the trimming head to scan the detection area so that the trimming head is also located in the detection area when the wafer is located in the detection area.

[0067] In the present application, the dressing head is controlled to scan the detection area according to the movement trajectory of the wafer on the polishing pad, so that the dressing head is located in the detection area when the wafer is located in the detection area, thereby the second sensing signal can be collected after the first sensing signal is collected, so that the difference in collection time between the first sensing signal and the second sensing signal is short, thereby after determining the first thickness according to the second sensing signal, the thickness of the metal layer on the wafer can be determined more accurately according to the first thickness and the first sensing signal.

[0068] Figure 6 is a schematic diagram of a chemical mechanical polishing device 200 provided in the present application, such as Figure 6 As shown, the chemical mechanical polishing device 200 may include: a polishing disc 203, a polishing pad 201, a trimming head 202, a carrier head 204, a liquid supply module 205 and a control module 206. The carrier head 204 is used to carry a wafer 300 so that the wafer 300 abuts against the polishing pad 201. The polishing disc 203 includes an eddy current sensor 2031, which is arranged in the polishing disc 203. The top surface of the polishing disc 203 is provided with a polishing pad 201 for polishing the metal layer on the wafer 300. The liquid supply module 205 is used to carry the wafer 300 so that the wafer 300 abuts against the polishing pad 201. 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, and the control module 206 is used to obtain a first sensing 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 sensing signal of the eddy current sensor 2031 when the dressing head 202 scans 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 sensing signal.

[0069] The control module 206 is used to obtain the positional relationship between the trimming surface of the trimming head 202 and the metal flange in the trimming head 202, wherein the trimming surface is in contact with the polishing pad 201, and the trimming surface is used to trim the polishing pad 201; based on the second sensing signal, the distance between the eddy current sensor 2031 and the metal flange is determined; based on the distance and positional relationship between the eddy current sensor 2031 and the metal flange, the first thickness is determined.

[0070] In one possible implementation, the control module 206 is used to 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 when the relative area between the polishing pad 201 and the eddy current sensor 2031 is of the second thickness, change the thickness of the polishing pad 201, 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 2031 when the polishing pad 201 has 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.

[0071] In one possible implementation, the control module 206 is used to perform numerical fitting on the first mapping relationship and multiple 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, perform coefficient correction on the mapping coefficient in the first mapping relationship according to the third mapping relationship, and obtain a signal conversion formula.

[0072] In one possible implementation, the eddy current sensor includes a first induction coil and a second induction coil, and the control module 206 is used to obtain a first induction signal through the first induction coil when the eddy current sensor 2031 rotates with the polishing plate 203 to under the moving wafer 300, and to obtain a second induction signal through the second induction coil when the eddy current sensor 2031 rotates with the polishing plate 203 to under the dressing head 202 that scans the detection area.

[0073] In one possible implementation, the eddy current sensor 2031 includes a third induction coil, and the control module 206 is used to collect the first induction signal or the second induction signal generated by the third induction coil according to a preset measurement sequence, wherein the measurement sequence is set at least according to the rotation speed of the polishing disk 203.

[0074] In one possible implementation, the control module 206 is used to control the dressing head 202 to scan the detection area according to the movement trajectory of the wafer 300 on the polishing pad 201, so that the dressing head 202 is located in the detection area when the wafer 300 is located in the detection area, wherein 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.

[0075] Another embodiment of the present application also provides an eddy current detection device based on polishing pad thickness compensation, including: an induction signal acquisition module, used to acquire a first induction signal of the eddy current sensor when the wafer runs to the detection area of ​​the eddy current sensor, wherein the eddy current sensor is arranged in a polishing disk included in a chemical mechanical polishing device, and the top surface of the polishing disk is provided with a polishing pad for polishing the metal layer on the wafer; and, when a trimming head included in the chemical mechanical polishing device sweeps over the detection area, a second induction signal of the eddy current sensor is acquired; a first thickness value determination module, used to determine a first thickness value of an area on the polishing pad opposite to the eddy current sensor according to the second induction signal; a metal layer thickness determination module, used to determine the thickness of the metal layer on the wafer according to the first induction signal and the first thickness value.

[0076] Reference Figure 7 , shows a schematic diagram of the structure of an electronic device according to the present application. The specific embodiments of the present application do not limit the specific implementation of the electronic device.

[0077] like Figure 7 As shown, the electronic device may include: a processor (processor) 702 , a communication interface (Communications Interface) 704 , a memory (memory) 706 , and a communication bus 708 .

[0078] in:

[0079] The processor 702 , the communication interface 704 , and the memory 706 communicate with each other via a communication bus 708 .

[0080] The communication interface 704 is used to communicate with other electronic devices or servers.

[0081] The processor 702 is used to execute the program 710, and specifically can execute the relevant steps in the above-mentioned embodiment of the thickness compensated eddy current testing method.

[0082] Specifically, the program 710 may include program codes, which include computer operation instructions.

[0083] The processor 702 may be a central processing unit (CPU), a graphics processing unit (GPU), an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the present application. The one or more processors included in the smart device may be processors of the same type, such as one or more CPUs; one or more GPUs; or processors of different types, such as one or more CPUs, one or more GPUs, and one or more ASICs.

[0084] The memory 706 is used to store the program 710. The memory 706 may include a high-speed RAM memory, and may also include a non-volatile memory (non-volatile memory), such as at least one disk memory.

[0085] The program 710 may be specifically used to enable the processor 702 to execute the thickness-compensated eddy current detection method in any of the aforementioned embodiments.

[0086] The specific implementation of each step in program 710 can refer to the corresponding description of the corresponding steps and units in any of the aforementioned thickness compensation eddy current detection method embodiments, 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.

[0087] 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, and when the dressing head scans the detection area, the second induction signal of the eddy current sensor is obtained, and the first thickness of the area on the polishing pad opposite to the eddy current sensor is determined according to the second induction signal, thereby the thickness of the metal layer on the wafer can be determined according to the first thickness and the first induction signal. Since the thickness of the polishing pad is taken into account when determining the thickness of the metal layer, that is, the lift-off height of the wafer is taken into account, compared with the prior art that does not consider the lift-off height, the detected thickness of the metal layer on the wafer is more accurate because the influence of the lift-off height on the induction signal generated by the eddy current sensor is taken into account, and since the thickness of the polishing pad is detected according to the eddy current sensor arranged on the polishing disk, there is no need to arrange 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, the detected lift-off height of the wafer is more accurate compared with detecting the average thickness of the polishing pad, and the thickness of the metal layer on the wafer determined thereby is more accurate.

[0088] The present application also provides a computer program product, including computer instructions, which instruct a computing device to execute operations corresponding to any one of the above-mentioned multiple method embodiments.

[0089] It should be pointed out that, according to the needs of implementation, the various components / steps described in this application can be split into more components / steps, or two or more components / steps or partial operations of components / steps can be combined into new components / steps to achieve the purpose of this application.

[0090] The above-mentioned method according to the present application can be implemented in hardware, firmware, or as software or computer code that can be stored in a recording medium (such as a CD ROM, RAM, floppy disk, hard disk or magneto-optical disk), or as a computer code originally stored in a remote recording medium or a non-temporary machine-readable medium downloaded through a network and to be stored in a local recording medium, so that the method described herein can be stored in such software processing on a recording medium using a general-purpose computer, a dedicated processor or programmable or dedicated hardware (such as an ASIC or FPGA). It can be understood that a computer, a processor, a microprocessor controller or programmable hardware includes a storage component (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 thickness-compensated eddy current detection method described herein is implemented. In addition, when a general-purpose computer accesses the code for implementing the thickness-compensated eddy current detection method shown herein, the execution of the code converts the general-purpose computer into a dedicated computer for executing the thickness-compensated eddy current detection method shown herein.

[0091] Those of ordinary skill in the art will appreciate that the units and method steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0092] The above implementation modes are only used to illustrate the present application, and are not intended to limit the present application. Ordinary technicians in the relevant technical field may make various changes and modifications without departing from the spirit and scope of the present application. Therefore, all equivalent technical solutions also belong to the scope of the present application, and the scope of patent protection of the present application shall be limited by the claims.

Claims

1. A thickness-compensated eddy current detection method, applied to chemical mechanical polishing equipment, characterized in that: The method comprises: When the wafer moves to the detection area of ​​the eddy current sensor, a first sensing signal of the eddy current sensor is obtained, wherein the eddy current sensor is arranged in a polishing plate included in the chemical mechanical polishing equipment, and a polishing pad for polishing the metal layer on the wafer is arranged on the top surface of the polishing plate; When a dressing head included in the chemical mechanical polishing device sweeps across the detection area, acquiring a second sensing 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 sensing signal; The relative area between the polishing pad and the eddy current sensor is set to a second thickness, and a first mapping relationship between the thickness of the metal layer and a third sensing signal output by the eddy current sensor is determined according to metal layers of multiple thicknesses; Changing the thickness of the polishing pad to respectively determine a plurality of second mapping relationships between the thickness of the metal layer and the fourth sensing signal output by the eddy current sensor when the polishing pad has different thicknesses; Performing numerical fitting on the first mapping relationship and a plurality of the second mapping relationships to determine a third mapping relationship between a mapping coefficient in the first mapping relationship and a thickness of the polishing pad; Perform coefficient correction on the mapping coefficients in the first mapping relationship according to the third mapping relationship to obtain a signal conversion formula; The thickness of the metal layer is determined according to the first sensing signal, the first thickness value and the signal conversion formula.

2. The method according to claim 1, characterized in that The step of determining a first thickness value of an area on the polishing pad opposite to the eddy current sensor according to the second sensing signal comprises: Acquiring a positional relationship between a dressing surface of the dressing head and a metal flange in the dressing head, wherein the dressing surface contacts the polishing pad and is used to dress the polishing pad; determining a distance between the eddy current sensor and the metal flange according to the second sensing signal; The first thickness value is determined according to the distance and the positional relationship between the eddy current sensor and the metal flange.

3. The method according to claim 1, characterized in that The eddy current sensor comprises a first induction coil and a second induction coil, and the method further comprises: When the eddy current sensor rotates with the polishing plate to under the moving wafer, the first induction signal is acquired through the first induction coil, and when the eddy current sensor rotates with the polishing plate to under the dressing head that sweeps the detection area, the second induction signal is acquired 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: The first induction signal or the second induction signal generated by the third induction coil is collected according to a preset measurement sequence, wherein the measurement sequence is set at least according to the rotation speed of the polishing disk.

5. The method according to claim 1, characterized in that The method further comprises: The trimming head is controlled to scan the detection area according to the movement trajectory of the wafer on the polishing pad, so that the trimming head is located in the detection area when the wafer is located in the detection area, wherein the detection area is an annular area, and the wafer and the trimming head are located in different areas of the annular area.

6. A chemical mechanical polishing device, characterized in that: include: A polishing disc, a polishing pad, a trimming head, a carrying head, a liquid supply module and a control module, wherein the carrying head is used to carry a wafer so that the wafer abuts against the polishing pad, the polishing disc comprises an eddy current sensor, the eddy current sensor is arranged in the polishing disc, a polishing pad for polishing a metal layer on the wafer is arranged on the top surface of the polishing disc, the liquid supply module is used to supply polishing liquid between the wafer and the polishing pad, and the trimming head is used to trim the polishing pad; The control module is used to obtain a first sensing signal of the eddy current sensor when the wafer moves to a detection area of ​​the eddy current sensor, obtain a second sensing signal of the eddy current sensor when the trimming head sweeps over the detection area, and determine a first thickness value of an area on the polishing pad opposite to the eddy current sensor according to the second sensing signal; The relative area between the polishing pad and the eddy current sensor is set to a second thickness, and a first mapping relationship between the thickness of the metal layer and a third induction signal output by the eddy current sensor is determined according to metal layers of multiple thicknesses. The thickness of the polishing pad is changed to 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 has different thicknesses. The first mapping relationship and multiple second mapping relationships are numerically fitted to determine a third mapping relationship between a mapping coefficient in the first mapping relationship and the thickness of the polishing pad. The mapping coefficient in the first mapping relationship is coefficient-corrected according to the third mapping relationship to obtain a signal conversion formula. The thickness of the metal layer is determined according to the first induction signal, the first thickness value and the signal conversion formula.

7. The device according to claim 6, characterized in that The control module is used to obtain the positional relationship between the trimming surface of the trimming head and the metal flange in the trimming head, wherein the trimming surface is in contact with the polishing pad, and the trimming surface is used to trim the polishing pad; determine the distance between the eddy current sensor and the metal flange according to the second sensing 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 comprises a first induction coil and a second induction coil; The control module is used to obtain the first induction signal through the first induction coil when the eddy current sensor rotates with the polishing plate to under the moving wafer, and to obtain the second induction signal through the second induction coil when the eddy current sensor rotates with the polishing plate to under the dressing head that sweeps across the detection area.

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

10. The device according to claim 6, characterized in that The control module is used to control the trimming head to scan the detection area according to the movement trajectory of the wafer on the polishing pad, so that the trimming head is located in the detection area when the wafer is located in the detection area, wherein the detection area is an annular area, and the wafer and the trimming head are located in different areas of the annular area.

11. An electronic device, characterized in that: include: A processor, a memory, a communication interface and a communication bus, wherein the processor, the memory and the communication interface communicate with each other via the communication bus; The memory is used to store at least one executable instruction, and the executable instruction enables the processor to execute the thickness compensated eddy current detection method as described in 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 a processor, the thickness-compensated eddy current detection method as claimed in any one of claims 1 to 5 is implemented.

13. A computer program product, characterized in that The method comprises computer instructions, wherein the computer instructions instruct a computing device to execute the thickness compensated eddy current detection method as claimed in any one of claims 1 to 5.

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