Metal film thickness measurement method, device, electronic device and storage medium using multi-modal signal compensation

Abstract

The present application provides a metal film thickness measurement method, device, electronic device and storage medium using multi-modal signal compensation, the method comprising: detecting the thickness of the polishing pad, and determining the lift-off height corresponding to the eddy current sensor according to the thickness; detecting the conductivity of the polishing liquid on the polishing pad of the chemical mechanical polishing device; correcting the lift-off height according to the conductivity; obtaining the measurement signal output by the eddy current sensor for non-contact measurement of the metal layer of the wafer; obtaining the metal film thickness of the wafer according to the corrected lift-off height and the measurement signal output by the eddy current sensor. The solution provided by the present application not only takes into account the thickness of the polishing pad, but also the conductivity of the polishing liquid during the correction process, corrects the lift-off height based on multi-modal data, improves the accuracy of the lift-off height, and makes the metal film thickness on the wafer obtained according to the lift-off height more accurate.

Description

Technical Field

[0001] The present application relates to the field of semiconductor manufacturing technology, and in particular to a metal film thickness measurement method, device, electronic device and storage medium using multi-modal signal compensation. 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. In metal CMP endpoint detection, eddy current detection is the most commonly used method. Summary of the invention

[0004] In view of this, the present application provides a metal film thickness measurement method, device, electronic device and storage medium using multi-modal signal compensation to at least partially solve the above-mentioned problems.

[0005] According to the first aspect of the present application, a method for measuring the thickness of a metal film using multimodal signal compensation is provided, which is applied to a chemical mechanical polishing device, and the method includes: detecting the thickness of the polishing pad, and determining a lift-off height corresponding to an eddy current sensor based on the thickness; detecting the conductivity of the polishing liquid on the polishing pad of the chemical mechanical polishing device; correcting the lift-off height based on the conductivity; obtaining a measurement signal output by the eddy current sensor for non-contact measurement of the metal layer of the wafer; and obtaining the metal film thickness of the wafer based on the corrected lift-off height and the measurement signal output by the eddy current sensor.

[0006] Optionally, in any embodiment of the present application, the chemical mechanical polishing device includes a polishing head, and a conductivity sensor is provided on the outer wall of the polishing head body. The detection of the conductivity of the polishing liquid on the polishing pad of the chemical mechanical polishing device includes: measuring the polishing liquid flowing out from under the polishing head through the conductivity sensor to obtain the conductivity.

[0007] Optionally, in any embodiment of the present application, the conductivity is measured by a conductivity sensor on the polishing liquid flowing out from under the polishing head to obtain the conductivity, including: respectively detecting the conductivity corresponding to the polishing liquid flowing into under the polishing head and the polishing liquid flowing out from under the polishing head; substituting the two detected conductivity values ​​into a predetermined conductivity curve to obtain the conductivity of the polishing liquid under the polishing head.

[0008] Optionally, in any embodiment of the present application, the lift-off height is corrected according to the conductivity, including: determining the groove depth on the polishing pad according to the thickness of the polishing pad, and determining the degree of glazing of the polishing pad; determining the liquid film thickness parameters of the polishing liquid according to the groove depth and the degree of glazing; and correcting the lift-off height according to the liquid film thickness parameters and the conductivity.

[0009] Optionally, in any embodiment of the present application, determining the liquid film thickness parameter of the polishing liquid according to the groove depth and the glazing degree includes: determining the liquid film thickness parameter according to the following formula: hw=am+bn+c, wherein m is the groove depth, n is the glazing degree, abc is a constant, m=hp-d, hp is the thickness of the polishing pad, d is the thickness of the base layer of the polishing pad, and hw is the liquid film thickness parameter corresponding to the polishing liquid.

[0010] Optionally, in any embodiment of the present application, the lift-off height is corrected according to the liquid film thickness parameter and the conductivity, including: correcting the lift-off height according to the following formula: ht=(hp+e)*hw*σ, wherein hp is the thickness of the polishing pad, hw is the liquid film thickness parameter corresponding to the polishing liquid, σ is the conductivity, and e is a constant.

[0011] Optionally, in any embodiment of the present application, the chemical mechanical polishing device includes a dresser, and a morphology measurement sensor is provided on the dressing head of the dresser. The thickness or degree of glazing of the polishing pad is determined by the following method: when the dressing head sweeps over the detection area of ​​the eddy current sensor, the polishing pad is measured by the morphology measurement sensor to obtain the thickness and / or degree of glazing corresponding to the detection area on the polishing pad.

[0012] 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 polishing head, a liquid supply module and a control module, wherein the polishing 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 detect the thickness of the polishing pad and determine the lift-off height corresponding to the eddy current sensor according to the thickness; detect the conductivity of the polishing liquid on the polishing pad of the chemical mechanical polishing device; correct the lift-off height according to the conductivity; obtain a measurement signal output by the eddy current sensor for non-contact measurement of the metal layer of the wafer; obtain the metal film thickness of the wafer according to the corrected lift-off height and the measurement signal output by the eddy current sensor.

[0013] Optionally, in any embodiment of the present application, the chemical mechanical polishing device includes a polishing head, and a conductivity sensor is provided on the outer wall of the polishing head body, which detects the conductivity of the polishing liquid on the polishing pad of the chemical mechanical polishing device, and the control module is used to measure the polishing liquid flowing out from under the polishing head through the conductivity sensor to obtain the conductivity.

[0014] Optionally, in any embodiment of the present application, the control module is used to respectively detect the conductivity corresponding to the polishing liquid flowing into the bottom of the polishing head and the polishing liquid flowing out of the bottom of the polishing head; and substitute the two detected conductivity values ​​into a predetermined conductivity curve to obtain the conductivity of the polishing liquid under the polishing head.

[0015] Optionally, in any embodiment of the present application, the control module is used to determine the depth of the groove on the polishing pad according to the thickness of the polishing pad, and determine the degree of glazing of the polishing pad; determine the liquid film thickness parameters of the polishing liquid according to the groove depth and the degree of glazing; and correct the lift-off height according to the liquid film thickness parameters and the conductivity.

[0016] Optionally, in any embodiment of the present application, the liquid film thickness parameter is determined according to the following formula: hw=am+bn+c, wherein m is the groove depth, n is the degree of glazing, abc is a constant, m=hp-d, hp is the thickness of the polishing pad, d is the thickness of the base layer of the polishing pad, and hw is the liquid film thickness parameter corresponding to the polishing liquid.

[0017] Optionally, in any embodiment of the present application, the lift-off height is corrected according to the following formula: ht=(hp+e)*hw*σ, wherein hp is the thickness of the polishing pad, hw is the liquid film thickness parameter corresponding to the polishing liquid, σ is the conductivity, and e is a constant.

[0018] Optionally, in any embodiment of the present application, the control module is used to measure the polishing pad through a morphology measurement sensor when the dressing head sweeps over the detection area of ​​the eddy current sensor, so as to obtain the thickness and / or degree of glazing corresponding to the detection area on the polishing pad.

[0019] According to the third 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.

[0020] According to a fourth aspect of the present application, a computer storage medium is provided, on which a computer program is stored, and when the program is executed by a processor, the method described in the first aspect is implemented.

[0021] According to a fifth 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.

[0022] According to the metal film thickness measurement method using multi-modal signal compensation provided by the present application, the conductivity of the polishing liquid on the polishing pad of the chemical mechanical polishing device is detected; the thickness of the polishing pad is detected, and the lift-off height corresponding to the eddy current sensor is determined according to the thickness; the lift-off height is corrected according to the conductivity; the lift-off height of the eddy current can be corrected by taking into account both the thickness of the polishing pad and the conductivity of the polishing liquid, so that the corrected lift-off height is more accurate, and then the measurement signal output by the eddy current sensor for non-contact measurement of the metal layer of the wafer is obtained; and the metal film thickness of the wafer is obtained according to the corrected lift-off height and the measurement signal output by the eddy current sensor. Since not only the thickness of the polishing pad but also the conductivity of the polishing liquid are taken into account in the correction process, the lift-off height is corrected based on the multi-modal data, which improves the accuracy of the lift-off height, and makes the metal film thickness obtained according to the lift-off height more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] 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.

[0024] Figure 1 It is a flow chart of a metal film thickness measurement method using multi-modal signal compensation provided by the present application;

[0025] Figure 2 It is a schematic diagram of each layer in a chemical mechanical polishing process provided by the present application;

[0026] Figure 3 is a schematic diagram of a chemical mechanical polishing device provided by the present application;

[0027] Figure 4 It is a curve diagram of conductivity provided by the present application;

[0028] Figure 5 It is a schematic diagram of the effect of the grooves of a polishing pad provided by the present application on the thickness of a liquid film;

[0029] Figure 6 is a schematic diagram of a chemical mechanical polishing device provided by the present application;

[0030] Figure 7 A schematic diagram of the structure of an electronic device provided in this application. DETAILED DESCRIPTION

[0031] 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.

[0032] The terms used in this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The singular forms of "a", "a", "an" 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 in this article refers to and includes any or all possible combinations of one or more associated listed items.

[0033] 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".

[0034] The following is a specific example of a method for measuring the thickness of a metal film using multi-modal signal compensation provided by the present application:

[0035] Figure 1 The present application provides a flow chart of a metal film thickness measurement method using multi-modal signal compensation, which is applied to a chemical mechanical polishing device, such as Figure 1 As shown, the eddy current detection method for polishing pad thickness compensation includes the following steps 101 to 105:

[0036] Step 101 : Detect the thickness of the polishing pad and determine the corresponding lift-off height of the eddy current sensor according to the thickness.

[0037] In the application of eddy current sensors, lift-off refers to the distance between the sensor and the surface of the object being measured. This distance is critical to the measurement accuracy and stability of the sensor. Changes in lift-off height affect the strength of the eddy current and thus the output signal of the sensor. If the lift-off height changes too much, it may lead to inaccurate measurement results. Within a certain range of lift-off heights, eddy current sensors can provide stable measurement signals. Beyond this range, the signal may become unstable. Temperature, humidity, and other environmental factors may affect the propagation of eddy currents, thereby affecting the optimal value of lift-off height.

[0038] In chemical mechanical polishing equipment, eddy current sensors are usually installed on the polishing plate, see Figure 2 , shows a schematic diagram, which includes an eddy current sensor, a polishing pad, a polishing liquid, and a wafer from bottom to top. The eddy current sensor is installed in the polishing plate.

[0039] In the process of chemical mechanical polishing, there are two main factors that affect the lift-off height, namely the thickness of the polishing pad and the metal ions in the polishing liquid. The thickness of the polishing pad directly determines the lift-off height, and the metal ions in the polishing liquid affect the optimal value of the lift-off height.

[0040] Step 102: Detect the conductivity of the polishing liquid on the polishing pad of the chemical mechanical polishing device.

[0041] Electrical conductivity is a physical quantity that measures the electrical conductivity of a material. It describes the amount of current that flows through a conductor per unit length and per unit cross-sectional area under the action of an electric field. The unit of conductivity is Siemens per meter (S / m). In the International System of Units (SI), 1 S / m is equal to 1 A / (V·m).

[0042] Different metals result in different metal ions in the polishing solution, thereby making the polishing solution have different electrical conductivities.

[0043] The metals involved in the chemical mechanical polishing (CMP) process mainly include copper (Cu), tungsten (W), aluminum (Al), tantalum (Ta), titanium (Ti), titanium nitride (TiN), cobalt (Co), etc.

[0044] Copper (Cu): Copper is a widely used interconnect metal in modern integrated circuits.

[0045] Tungsten (W): Tungsten is commonly used as a filling material in vias and high-density interconnect structures.

[0046] Aluminum (Al): Aluminum was an early interconnect metal and is still used in some older or low-power chip designs.

[0047] Tantalum (Ta): Tantalum is often used as a diffusion barrier and adhesion layer material.

[0048] Titanium (Ti) and its compounds (such as TiN, TiNxCy): Titanium and its compounds are often used in diffusion barrier layers and adhesion layers.

[0049] Cobalt (Co): Currently mainly used in advanced interconnect technology at sub-7nm nodes.

[0050] In addition, the polishing liquid includes abrasives for physically removing materials. The abrasives can be hard oxides, metals or carbide particles. Different metals use different abrasives, so that the polishing liquid has different conductivity. The abrasives can be, for example, silicon dioxide (SiO2), aluminum oxide (Al2O3), cerium oxide (CeO2), etc.

[0051] Step 103: Correct the lift-off height according to the conductivity.

[0052] After measuring the conductivity, the lift-off height can be corrected according to the conductivity to obtain the lift-off height coupled with the metal particles in the polishing liquid, so that the lift-off height is closer to the actual chemical mechanical polishing environment.

[0053] Step 104 : obtaining a measurement signal output by the eddy current sensor for non-contact measurement of the metal layer of the wafer.

[0054] The eddy current sensor is arranged in the polishing disk included in the 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. When the chemical mechanical polishing device polishes the wafer, the chemical mechanical polishing device body rotates, and the wafer rotates under the action of the polishing head and moves radially along the polishing disk of the chemical mechanical polishing device, thereby chemical mechanical polishing can be performed on the wafer through the polishing pad. Since the eddy current sensor is arranged in the polishing disk included in the chemical mechanical polishing device, the polishing pad is arranged on the top surface of the polishing disk, and the wafer moves radially along the polishing pad of the chemical mechanical polishing device, the first induction signal of the eddy current sensor is collected when the wafer runs to the detection area of ​​the eddy current sensor.

[0055] 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 performing non-contact measurement of the thickness of the metal layer based on the change in the magnetic field, and outputting a measurement signal.

[0056] Step 105 : Obtain the metal film thickness of the wafer according to the corrected lift-off height and the measurement signal output by the eddy current sensor.

[0057] The corresponding relationship between the measurement signal and the metal film thickness can be calibrated according to the lift-off height, and then the metal film thickness corresponding to the measurement signal can be determined according to the calibrated corresponding relationship.

[0058] The solution provided by the present application obtains the measurement signal output by the eddy current sensor for non-contact measurement of the metal layer of the wafer; detects the conductivity of the polishing liquid on the polishing pad of the chemical mechanical polishing device; detects the thickness of the polishing pad, and determines the lift-off height corresponding to the eddy current sensor according to the thickness; corrects the lift-off height according to the conductivity; and can simultaneously consider the thickness of the polishing pad and the conductivity of the polishing liquid to correct the lift-off height of the eddy current, so that the corrected lift-off height is more accurate, and then obtains the metal film thickness of the wafer according to the corrected lift-off height and the measurement signal output by the eddy current sensor. Since not only the thickness of the polishing pad but also the conductivity of the polishing liquid are taken into account during the correction process, the lift-off height is corrected based on multimodal data, which improves the accuracy of the lift-off height, so that the metal film thickness on the wafer obtained according to the lift-off height is also more accurate.

[0059] In one example, see Figure 3The chemical mechanical polishing device includes a polishing head 204. The outer wall of the main body of the polishing head 204 (the outer wall is not shown) is provided with a conductivity sensor 2041. The outer wall does not rotate with the polishing head, so that the conductivity sensor also does not rotate with the polishing head. The conductivity of the polishing liquid on the polishing pad of the chemical mechanical polishing device is detected, including: measuring the polishing liquid flowing out from the bottom of the polishing head through the conductivity sensor 2041 to obtain the conductivity.

[0060] See also Figure 3 The polishing liquid flows from one side of the liquid supply module 205 to the bottom of the polishing head 204, and flows out of the bottom of the polishing head 204 from the side away from the liquid supply module 205, and can be recovered after flowing out of the polishing disk area. In order to make the components in the measured polishing liquid closer to the polishing liquid under the polishing head, a conductivity sensor 2041 can be set on the outer wall of the polishing head to detect the conductivity of the polishing liquid flowing out from the bottom of the polishing head.

[0061] Furthermore, conductivity sensors can be arranged on both sides of the outer wall of the polishing head to detect the conductivity of the polishing liquid flowing into the bottom of the polishing head and the polishing liquid flowing out of the bottom of the polishing head respectively, and then the two detected conductivity values ​​are brought into a predetermined conductivity curve to obtain the conductivity of the polishing liquid under the polishing head. The conductivity curve corresponds to the type of metal layer and is used to characterize the relationship between the conductivity of a point on the polishing pad and the distance between the point and the center of the polishing head.

[0062] See also Figure 3 The path of the polishing liquid on the polishing pad may include: from the liquid supply module to the polishing head, flowing under the polishing head, flowing out from under the polishing head and being recovered. Figure 4 , shows a conductivity curve. In the part from the liquid supply module to the polishing head, the metal ions in the polishing liquid are mainly abrasives. When flowing under the polishing head, the metal ions corresponding to the metal layer are added to the polishing liquid. At this time, the amount of metal ions reaches the maximum. In the process of flowing out of the polishing head and being recovered, the metal ions are continuously diluted, that is, the conductivity of the polishing liquid decreases. Figure 4 The two measurement positions of the two conductivity values ​​measured are located at the two ends of the part of the curve corresponding to the polishing head.

[0063] Of course, the conductivity curves corresponding to different metal layers have similar trends but different specific slopes, thresholds, etc. The conductivity curve corresponding to each type of metal layer can be obtained through the simulation model. The corresponding conductivity curve can be determined according to the type of metal layer, and then the two conductivity values ​​can be substituted into the determined conductivity curve to obtain the conductivity of the polishing liquid under the polishing head.

[0064] After obtaining the conductivity of the polishing liquid, the lift-off height can be corrected according to the conductivity.

[0065] In one implementation, the liquid film thickness of the polishing liquid can be assumed to be fixed, and the lift-off height can be corrected based on the conductivity combined with the fixed liquid film thickness. For example, a conductivity adjustment item is added to the lift-off height determined according to the thickness of the polishing pad. The adjustment item is the conductivity multiplied by a fixed parameter. The fixed parameter is used to characterize the liquid film thickness, and the value obtained after the addition is determined as the corrected lift-off height.

[0066] In another implementation, the lift-off height is corrected, including: determining the groove depth on the polishing pad according to the thickness of the polishing pad; determining the liquid film thickness parameter of the polishing liquid according to the groove depth and the degree of glazing; and correcting the lift-off height according to the liquid film thickness parameter and conductivity.

[0067] The polishing liquid is located on the polishing pad, see Figure 5 The groove depth of the polishing pad will change after being used for a period of time. The groove depth and glazing degree of the polishing pad directly affect the liquid film thickness hw of the polishing liquid. Therefore, the liquid film thickness parameters can be determined according to the groove depth and the glazing degree, and then the lift-off height can be corrected according to the liquid film thickness parameters and the conductivity of the liquid film reflected by the conductivity.

[0068] Specifically, according to the groove depth and the degree of glazing, the liquid film thickness parameters of the polishing liquid are determined, including: determining the liquid film thickness parameters according to the following formula: hw=am+bn+c, wherein m is the groove depth, n is the degree of glazing, a, b, c are constants, m=hp-d, hp is the thickness of the polishing pad, d is the thickness of the base layer of the polishing pad, and hw is the liquid film thickness parameter corresponding to the polishing liquid.

[0069] The lift-off height is corrected according to the liquid film thickness parameter and the conductivity, including: correcting the lift-off height according to the following formula: ht=(hp+e)*hw*σ, wherein hp is the thickness of the polishing pad, hw is the liquid film thickness parameter corresponding to the polishing liquid, σ is the conductivity, and e is a constant.

[0070] Similarly, the above formula can be transformed into: ht=a*σ*hp^2+f(n) *σ*hp+g(n) *σ, where hp^2 is the square of hp, σ is the conductivity, hp is the thickness of the polishing pad, n is the degree of glazing, f(n) and g(n) are parameter formulas obtained by the degree of glazing, f(n)=bn-ad+c+ae, which can be simplified to bn+i; g(n)=ben-ade+ec, which can be simplified to kn+j.

[0071] The solution of correcting the lift-off height by the above adjusted formula is also within the protection scope of this application. Alternatively, some correction terms can be simplified, for example, the terms where f(n) or g(n) are simplified, and the lift-off height is corrected only according to a*σ*hp^2, which is also within the protection scope of this application.

[0072] In addition, the thickness and degree of glazing of the polishing pad involved in the above formula can be measured by the following method: the chemical mechanical polishing device includes a dresser, and a morphology measurement sensor is provided on the dressing head of the dresser. The thickness or degree of glazing of the polishing pad is determined by the following method: when the dressing head sweeps over the detection area of ​​the eddy current sensor, the polishing pad is measured by the morphology measurement sensor to obtain the thickness and / or degree of glazing of the corresponding detection area on the polishing pad.

[0073] Of course, the thickness or glazing degree of the polishing pad may also be measured by other methods, all of which are within the protection scope of this application.

[0074] 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 polishing head 204, a liquid supply module 205 and a control module 206. The polishing 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 Polishing liquid is supplied 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 detect the thickness of the polishing pad and determine the corresponding lift-off height of the eddy current sensor according to the thickness; obtain the measurement signal output by the eddy current sensor for non-contact measurement of the metal layer of the wafer; detect the conductivity of the polishing liquid on the polishing pad of the chemical mechanical polishing device; correct the lift-off height according to the conductivity; and obtain the metal film thickness of the wafer according to the corrected lift-off height and the measurement signal output by the eddy current sensor.

[0075] In one possible implementation, the chemical mechanical polishing device includes a polishing head, and a conductivity sensor is provided on the outer wall of the polishing head body to detect the conductivity of the polishing liquid on the polishing pad of the chemical mechanical polishing device. The control module is used to measure the polishing liquid flowing out from under the polishing head through the conductivity sensor to obtain the conductivity.

[0076] In one possible implementation, the control module is used to respectively detect the conductivity of the polishing liquid flowing into the bottom of the polishing head and the polishing liquid flowing out of the bottom of the polishing head; the two detected conductivity values ​​are substituted into a predetermined conductivity curve to obtain the conductivity of the polishing liquid under the polishing head.

[0077] In one possible implementation, the control module is used to determine the groove depth on the polishing pad and the degree of glazing of the polishing pad according to the thickness of the polishing pad; determine the liquid film thickness parameters of the polishing liquid according to the groove depth and the degree of glazing; and correct the lift-off height according to the liquid film thickness parameters and conductivity.

[0078] In one possible implementation, the liquid film thickness parameter is determined according to the following formula: hw=am+bn+c, where m is the groove depth, n is the degree of glazing, abc is a constant, m=hp-d, hp is the thickness of the polishing pad, d is the thickness of the polishing pad base layer, and hw is the liquid film thickness parameter corresponding to the polishing liquid.

[0079] In one possible implementation, the lift-off height is corrected according to the following formula: ht=(hp+e)*hw*σ, where hp is the thickness of the polishing pad, hw is the liquid film thickness parameter corresponding to the polishing liquid, σ is the conductivity, and e is a constant.

[0080] In a possible implementation, the control module is used to measure the polishing pad by using a topography measurement sensor when the trimming head sweeps over the detection area of ​​the eddy current sensor to obtain the thickness and / or glazing degree of the corresponding detection area on the polishing pad.

[0081] 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.

[0082] 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 .

[0083] in:

[0084] The processor 702 , the communication interface 704 , and the memory 706 communicate with each other via a communication bus 708 .

[0085] The communication interface 704 is used to communicate with other electronic devices or servers.

[0086] The processor 702 is used to execute the program 710, and specifically can execute the relevant steps in the above-mentioned embodiment of the metal film thickness measurement method using multi-modal signal compensation.

[0087] Specifically, the program 710 may include program codes, which include computer operation instructions.

[0088] 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.

[0089] 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.

[0090] The program 710 may be specifically used to enable the processor 702 to execute the metal film thickness measurement method using multi-modal signal compensation in any of the aforementioned embodiments.

[0091] 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 above-mentioned embodiments of the metal film thickness measurement method using multimodal signal compensation, 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 devices and modules can refer to the corresponding process description in the above-mentioned method embodiment, which will not be repeated here.

[0092] 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.

[0093] 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.

[0094] 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.

[0095] The above-mentioned method according to the present application can be implemented in hardware, firmware, or implemented as software or computer code that can be stored in a recording medium (such as a CD ROM, RAM, floppy disk, hard disk or magneto-optical disk), or implemented as a computer code originally stored in a remote recording medium or a non-temporary machine-readable medium downloaded through a network and to be stored in a local recording medium, so that the method described herein can be stored in such software processing on a recording medium using a general-purpose computer, a dedicated processor or programmable or dedicated hardware (such as an ASIC or FPGA). It can be understood that a computer, a processor, a microprocessor controller or programmable hardware includes a storage component (for example, RAM, ROM, flash memory, etc.) that can store or receive software or computer code, and when the software or computer code is accessed and executed by a computer, a processor or hardware, the metal film thickness measurement method using multimodal signal compensation described herein is implemented. In addition, when a general-purpose computer accesses the code for implementing the metal film thickness measurement method using multimodal signal compensation shown herein, the execution of the code converts the general-purpose computer into a dedicated computer for executing the metal film thickness measurement method using multimodal signal compensation shown herein.

[0096] 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.

[0097] 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 metal film thickness measurement method using multi-modal signal compensation, applied to a chemical mechanical polishing device, characterized in that: The method comprises: Detect the thickness of the polishing pad and determine the corresponding lift-off height of the eddy current sensor according to the thickness; detecting the conductivity of the polishing liquid on the polishing pad of the chemical mechanical polishing device; According to the conductivity, the lift-off height is corrected; Obtaining a measurement signal output by an eddy current sensor for non-contact measurement of a metal layer of a wafer; The metal film thickness of the wafer is obtained according to the corrected lift-off height and the measurement signal output by the eddy current sensor.

2. The method according to claim 1, characterized in that The chemical mechanical polishing device comprises a polishing head, and an outer wall of the polishing head body is provided with a conductivity sensor. The method for detecting the conductivity of the polishing liquid on the polishing pad of the chemical mechanical polishing device comprises: The conductivity of the polishing liquid flowing out from below the polishing head is measured by a conductivity sensor to obtain the conductivity.

3. The method according to claim 2, characterized in that The step of measuring the polishing liquid flowing out from below the polishing head by a conductivity sensor to obtain the conductivity comprises: Respectively detecting the conductivity of the polishing liquid flowing into the bottom of the polishing head and the conductivity of the polishing liquid flowing out of the bottom of the polishing head; The two detected conductivity values ​​are brought into a predetermined conductivity curve to obtain the conductivity of the polishing liquid below the polishing head.

4. The method according to claim 1, characterized in that The step of correcting the lift-off height according to the conductivity comprises: determining the depth of the grooves on the polishing pad according to the thickness of the polishing pad, and determining the degree of glazing of the polishing pad; Determining a film thickness parameter of the polishing liquid according to the groove depth and the glazing degree; The lift-off height is corrected according to the liquid film thickness parameter and the conductivity.

5. The method according to claim 4, characterized in that Determining the film thickness parameter of the polishing liquid according to the groove depth and the glazing degree includes: The liquid film thickness parameter is determined according to the following formula: hw=am+bn+c, wherein m is the groove depth, n is the degree of glazing, abc is a constant, m=hp-d, hp is the thickness of the polishing pad, d is the thickness of the polishing pad base layer, and hw is the liquid film thickness parameter corresponding to the polishing liquid.

6. The method according to claim 5, characterized in that The step of correcting the lift-off height according to the liquid film thickness parameter and the conductivity includes: The lift-off height is corrected according to the following formula: ht=(hp+e)*hw*σ, wherein hp is the thickness of the polishing pad, hw is the liquid film thickness parameter corresponding to the polishing liquid, σ is the conductivity, e is a constant, and ht is the corrected lift-off height.

7. The method according to claim 4, characterized in that The chemical mechanical polishing device comprises a dresser, a dresser head of which is provided with a topography measurement sensor, and the thickness or glazing degree of the polishing pad is determined by the following method: When the trimming head sweeps over the detection area of ​​the eddy current sensor, the polishing pad is measured by the topography measurement sensor to obtain the thickness and / or glazing degree of the polishing pad corresponding to the detection area.

8. A chemical mechanical polishing device, characterized in that: include: A polishing disc, a polishing pad, a trimming head, a polishing head, a liquid supply module and a control module, wherein the polishing 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 detect the thickness of the polishing pad and determine the lift-off height corresponding to the eddy current sensor according to the thickness; Detect the conductivity of the polishing liquid on the polishing pad of the chemical mechanical polishing device; correct the lift-off height according to the conductivity; obtain a measurement signal output by an eddy current sensor for non-contact measurement of the metal layer of the wafer; and obtain the metal film thickness of the wafer according to the corrected lift-off height and the measurement signal output by the eddy current sensor.

9. The device according to claim 8, characterized in that The chemical mechanical polishing device includes a polishing head, and a conductivity sensor is arranged on the outer wall of the polishing head body to detect the conductivity of the polishing liquid on the polishing pad of the chemical mechanical polishing device. The control module is used to measure the polishing liquid flowing out from under the polishing head through the conductivity sensor to obtain the conductivity.

10. The device according to claim 9, characterized in that The control module is used to detect the conductivity of the polishing liquid flowing into the bottom of the polishing head and the polishing liquid flowing out of the bottom of the polishing head respectively; the two detected conductivity values ​​are put into a predetermined conductivity curve to obtain the conductivity of the polishing liquid under the polishing head.

11. The device according to claim 8, characterized in that The control module is used to determine the groove depth on the polishing pad and the glazing degree of the polishing pad according to the thickness of the polishing pad; and determine the liquid film thickness parameter of the polishing liquid according to the groove depth and the glazing degree; The lift-off height is corrected according to the liquid film thickness parameter and the conductivity.

12. The device according to claim 11, characterized in that The liquid film thickness parameter is determined according to the following formula: hw=am+bn+c, wherein m is the groove depth, n is the degree of glazing, abc is a constant, m=hp-d, hp is the thickness of the polishing pad, d is the thickness of the polishing pad base layer, and hw is the liquid film thickness parameter corresponding to the polishing liquid.

13. The device according to claim 12, characterized in that The lift-off height is corrected according to the following formula: ht=(hp+e)*hw*σ, wherein hp is the thickness of the polishing pad, hw is the liquid film thickness parameter corresponding to the polishing liquid, σ is the conductivity, e is a constant, and ht is the corrected lift-off height.

14. The device according to claim 11, characterized in that The control module is used to measure the polishing pad by using a topography measurement sensor when the trimming head sweeps over the detection area of ​​the eddy current sensor, so as to obtain the thickness and / or glazing degree of the polishing pad corresponding to the detection area.

15. 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 metal film thickness measurement method using multi-modal signal compensation as described in any one of claims 1-7.

16. A computer storage medium, characterized in that: A computer program is stored thereon, and when the program is executed by a processor, the method for measuring the thickness of a metal film using multi-modal signal compensation as claimed in any one of claims 1 to 7 is implemented.

17. A computer program product, characterized in that The method comprises computer instructions, wherein the computer instructions instruct a computing device to execute the metal film thickness measurement method using multi-modal signal compensation as claimed in any one of claims 1 to 7.

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