Metal film thickness calibration method and device, computer equipment, medium and product

Abstract

The invention relates to the technical field of semiconductor manufacturing, and discloses a metal film thickness calibration method and device, computer equipment, a medium and a product, and the method comprises the steps: obtaining a reference piecewise function which represents the corresponding relation between the metal film thickness and a measurement signal in different metal film thickness intervals, the measurement signal is a signal value output by the eddy current sensor; determining a corresponding first measurement signal when the thickness of the metal film of the calibration wafer is a first thickness, and determining a corresponding second measurement signal when the thickness of the metal film of the calibration wafer is a second thickness, the value range of the first thickness and the second thickness being 0 to the maximum value of the thickness of the metal film of the calibration wafer; a reference piecewise function is calibrated according to a first signal offset value between the first measurement signal and the third measurement signal and a second signal offset value between the second measurement signal and the fourth measurement signal. According to the invention, the thickness change condition of the metal film in the manufacturing process can be monitored more accurately.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing technology, and specifically to a method, apparatus, computer equipment, medium, and product for calibrating the thickness of a metal film. Background Technology

[0002] With the development of integrated circuit manufacturing technology, different processes have a strong demand for real-time feedback on the thickness of metal films on the wafer surface. The online measurement process of metal film thickness usually uses a non-contact eddy current sensor integrated into the process equipment. For example, by calibrating the metal film thickness corresponding to different signal values ​​output by the eddy current sensor, the linear relationship between the signal value and the metal film thickness is obtained, and then the metal film thickness is measured based on the linear relationship.

[0003] In actual measurements, various factors can affect the correlation between the signal value output by the eddy current sensor and the metal film thickness, leading to inaccurate measurements. Therefore, it is necessary to calibrate the aforementioned linear relationship during actual measurements. Generally, the linear relationship between the metal film thickness and the signal value is first calibrated using the signal values ​​corresponding to the maximum and minimum metal film thicknesses. However, the metal film thickness and the signal value are not necessarily linearly related, causing errors between the calculated theoretical film thickness and the actual film thickness, which may result in inaccurate real-time detection of the metal film thickness during the polishing process. Summary of the Invention

[0004] In view of this, the present invention provides a method, apparatus, computer equipment, medium and product for calibrating the thickness of a metal film, so as to improve the problem of large error between the calculated theoretical film thickness and the actual film thickness.

[0005] In a first aspect, the present invention provides a method for calibrating the thickness of a metal film, the method comprising: obtaining a reference piecewise function, wherein the reference piecewise function is used to characterize the correspondence between the metal film thickness and the measurement signal in various different metal film thickness ranges, and the measurement signal is the signal value output by an eddy current sensor; determining a first measurement signal corresponding to a first thickness when the metal film thickness of the calibration wafer is a first thickness, and determining a second measurement signal corresponding to a second thickness when the metal film thickness of the calibration wafer is a second thickness, wherein the first thickness is greater than the second thickness, and the values ​​of the first thickness and the second thickness range from 0 to the maximum value of the metal film thickness of the calibration wafer; calibrating the reference piecewise function according to a first signal offset value between the first measurement signal and a third measurement signal and a second signal offset value between the second measurement signal and a fourth measurement signal, wherein the third measurement signal is the measurement signal corresponding to the first thickness in the reference piecewise function, and the fourth measurement signal is the measurement signal corresponding to the second thickness in the reference piecewise function.

[0006] This embodiment uses a piecewise function to characterize the correspondence between the metal film thickness and the measurement signal, which can more accurately determine the metal film thickness corresponding to the measurement signal obtained during the processing. This allows for more accurate monitoring of the metal film thickness change during the process, effectively improving the accuracy of wafer surface metal film thickness monitoring in related integrated circuit manufacturing technologies.

[0007] In one optional implementation, calibrating the reference piecewise function based on a first signal offset value between the first and third measurement signals and a second signal offset value between the second and fourth measurement signals includes: determining a signal offset function based on the first and second signal offset values; and calibrating the reference piecewise function based on the signal offset function.

[0008] This embodiment improves calibration accuracy by calibrating the reference piecewise function using a signal offset function.

[0009] In one optional implementation, before determining the first measurement signal corresponding to the metal film thickness of the calibration wafer being a first thickness, the method further includes: determining a detection interval, wherein the detection interval is the interval of the acquisition position of the eddy current sensor on the calibration wafer; determining the first measurement signal corresponding to the metal film thickness of the calibration wafer being a first thickness, and determining the second measurement signal corresponding to the metal film thickness of the calibration wafer being a second thickness, including: when the metal film thickness of the calibration wafer is a first thickness, determining the average of multiple measurement signals obtained by the eddy current sensor in the detection interval as the first measurement signal; when the metal film thickness of the calibration wafer is a second thickness, determining the average of multiple measurement signals obtained by the eddy current sensor in the detection interval as the second measurement signal.

[0010] In this embodiment, the detection range is first determined. Then, when the metal film thickness of the calibrated wafer is a first thickness, the average of multiple measurement signals obtained by the eddy current sensor in the detection range is determined as the first measurement signal. When the metal film thickness of the calibrated wafer is a second thickness, the average of multiple measurement signals obtained by the eddy current sensor in the detection range is determined as the second measurement signal. The detection range eliminates interference signals and reduces attenuation, which can ensure the accuracy of the determined first and second measurement signals, thereby improving the accuracy of the subsequently determined signal offset function.

[0011] In one alternative implementation, the diameter of the calibration wafer is 300 mm, and the detection range is 60 mm to 110 mm with the center of the calibration wafer as the origin.

[0012] In one alternative implementation, the first thickness is the maximum value of the metal film thickness of the calibration wafer, and the second thickness is...

[0013] In an optional implementation, before obtaining the reference piecewise function, the method further includes: obtaining the metal film thicknesses of multiple different calibration wafers; determining measurement signals corresponding one-to-one with the multiple metal film thicknesses using an eddy current sensor; and generating a reference piecewise function based on the multiple metal film thicknesses and the multiple measurement signals.

[0014] Secondly, the present invention provides a calibration device for metal film thickness, the device comprising: an acquisition module for acquiring a reference piecewise function, wherein the reference piecewise function characterizes the correspondence between metal film thickness and measurement signal in various metal film thickness ranges, and the measurement signal is the signal value output by an eddy current sensor; a signal determination module for determining a first measurement signal corresponding to a first thickness of the metal film on the calibration wafer, and determining a second measurement signal corresponding to a second thickness of the metal film on the calibration wafer, wherein the first thickness is greater than the second thickness, and the values ​​of the first thickness and the second thickness range from 0 to the maximum value of the metal film thickness on the calibration wafer; and a calibration module for calibrating the reference piecewise function according to a first signal offset value between the first measurement signal and a third measurement signal, and a second signal offset value between the second measurement signal and a fourth measurement signal, wherein the third measurement signal is the measurement signal corresponding to the first thickness in the reference piecewise function, and the fourth measurement signal is the measurement signal corresponding to the second thickness in the reference piecewise function.

[0015] In one optional implementation, the calibration module includes: a first determining unit, configured to determine a signal offset function based on a first signal offset value and a second signal offset value; and a calibration unit, configured to calibrate a reference piecewise function based on the signal offset function.

[0016] In one optional embodiment, the apparatus further includes: a detection determination module for determining a detection range, wherein the detection range is the range of acquisition positions of the eddy current sensor on the calibration wafer; and a signal determination module including: a second determination unit for determining the average of multiple measurement signals obtained by the eddy current sensor in the detection range as a first measurement signal when the metal film thickness of the calibration wafer is a first thickness; and a third determination unit for determining the average of multiple measurement signals obtained by the eddy current sensor in the detection range as a second measurement signal when the metal film thickness of the calibration wafer is a second thickness.

[0017] In one alternative implementation, the diameter of the calibration wafer is 300 mm, and the detection range is 60 mm to 110 mm with the center of the calibration wafer as the origin.

[0018] In one alternative implementation, the first thickness is the maximum value of the metal film thickness of the calibration wafer, and the second thickness is...

[0019] In one optional embodiment, the apparatus further includes: a thickness acquisition module for acquiring the metal film thicknesses of multiple different calibration wafers; a measurement module for determining measurement signals corresponding one-to-one with the multiple metal film thicknesses using an eddy current sensor; and a generation module for generating a reference piecewise function based on the multiple metal film thicknesses and the multiple measurement signals.

[0020] Thirdly, the present invention provides a computer device, comprising: a memory and a processor, the memory and the processor being communicatively connected to each other, the memory storing computer instructions, and the processor executing the computer instructions to perform the metal film thickness calibration method of the first aspect or any corresponding embodiment described above.

[0021] Fourthly, the present invention provides a computer-readable storage medium storing computer instructions for causing a computer to perform the metal film thickness calibration method of the first aspect or any corresponding embodiment described above.

[0022] Fifthly, the present invention provides a computer program product, including computer instructions for causing a computer to execute the metal film thickness calibration method of the first aspect or any corresponding embodiment described above. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the specific embodiments or related technologies of the present invention, the drawings used in the description of the specific embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 This is a linear relationship graph between the signal values ​​and thickness measurements of wafers with different metal film thicknesses;

[0025] Figure 2 This is a schematic flowchart of a method for calibrating the thickness of a metal film according to an embodiment of the present invention;

[0026] Figure 3 This is a schematic diagram of the reference piecewise function and the target piecewise function according to an embodiment of the present invention;

[0027] Figure 4 This is a schematic flowchart of another method for calibrating the thickness of a metal film according to an embodiment of the present invention;

[0028] Figure 5 This is a schematic diagram of the detection range of a calibration wafer according to an embodiment of the present invention;

[0029] Figure 6This is a schematic flowchart of another method for calibrating the thickness of a metal film according to an embodiment of the present invention;

[0030] Figure 7 According to an embodiment of the present invention, the thickness of the metal film is... A schematic diagram of the process for updating reference calibration data on a calibration wafer;

[0031] Figure 8 The average film thickness according to an embodiment of the present invention is A schematic diagram comparing the calculated film thickness and the measured thickness at various locations on the calibration wafer;

[0032] Figure 9 The average film thickness according to an embodiment of the present invention is A schematic diagram comparing the calculated film thickness and the measured thickness at various locations on the calibration wafer;

[0033] Figure 10 The average film thickness according to an embodiment of the present invention is A schematic diagram comparing the calculated film thickness and the measured thickness at various locations on the calibration wafer;

[0034] Figure 11 The average film thickness according to an embodiment of the present invention is A schematic diagram comparing the calculated film thickness and the measured thickness at various locations on the calibration wafer;

[0035] Figure 12 This is a structural block diagram of a metal film thickness calibration device according to an embodiment of the present invention;

[0036] Figure 13 This is a schematic diagram of the hardware structure of a computer device according to an embodiment of the present invention. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0038] During wafer fabrication, various films, including metal films, are formed on the wafer's surface. Metal films are indispensable key structures in integrated circuit manufacturing. They can be used to form metal wires, enabling electrical connections within the chip; they can also be patterned as electrodes or pads, serving as interfaces between the chip and external circuits; and they can perform shielding, protection, and manufacturing support functions. In integrated circuit manufacturing, real-time feedback on the thickness of the metal film (often referred to as metal film thickness or film thickness) allows for precise control of the film thickness, ensuring the chip's electrical performance, reliability, and yield.

[0039] Specifically, during the chemical mechanical polishing (CMP) process on the metal film on the wafer surface, it is necessary to monitor the thickness of the metal film in real time to precisely control its thickness and provide a substrate that meets the accuracy requirements for subsequent processes (such as photolithography and deposition). CMP on the metal film on the wafer surface is one of the core processes for achieving high-precision, multi-level metal interconnects. Its purpose is to achieve global planarization of the metal film surface through the synergistic effect of chemical etching and mechanical polishing, while simultaneously removing excess material.

[0040] As mentioned in the background section, online measurement of metal film thickness typically employs non-contact eddy current sensors integrated into the process equipment. Eddy current sensor technology for measuring metal film thickness works by applying an alternating voltage of a certain frequency to the sensor coil, causing the LC circuit at the sensor end to form an oscillating loop and generate an alternating magnetic field. This alternating magnetic field creates an eddy current effect on the surface of the metal film being measured, forming a magnetic field opposite to that of the sensor coil. This alters the apparent impedance of the sensor coil, and by correlating the metal film thickness with relevant electrical parameters, the metal film thickness can be measured. By calibrating the metal film thickness corresponding to different sensor output signal values, a linear relationship between the signal value and the metal film thickness is established.

[0041] In actual measurements, factors such as temperature, the distance between the eddy current sensor and the metal film, and the accuracy drift of the eddy current sensor itself can affect the correspondence between the signal value and the actual film thickness, leading to inaccurate measurements. Therefore, calibration based on the sensor's signal value is necessary. Existing calibration methods involve calibrating the metal film thickness to its maximum (e.g., ...) The wafer signal value and metal film thickness are minimized (e.g.) The wafer signal value is used to generate a linear relationship between the signal value and the thickness. The same method is used to update the linear relationship when updating the calibration data.

[0042] The above method assumes a linear relationship between the metal film thickness and the sensor signal value, but the actual linearity is not necessarily 1. Except for the wafers with the maximum and minimum thicknesses, the actual thickness data for other wafers are not based on this linear relationship. Figure 1The graph shows the linear relationship between the signal value and the thickness measurement value for wafers with different metal film thicknesses. The relationship between the signal value and the metal film thickness obtained by the above calibration method may be as follows: Figure 1 As shown by the dashed line, the actual measurement result may be as follows: Figure 1 As shown by the solid line in the middle, from Figure 1 It can be seen that the thickness calculated by the above calibration method has an error compared with the actual measurement data, resulting in inaccurate real-time detection of the wafer metal film thickness during the polishing process. The inaccurate wafer film thickness leads to unreasonable process parameter settings, affecting the wafer processing results.

[0043] In view of this, the present invention provides a method, apparatus, computer equipment, medium and product for calibrating metal film thickness, which characterizes the correspondence between metal film thickness and signal value (measurement signal) output by eddy current sensor in the form of a piecewise function, which can more accurately describe the metal film thickness corresponding to the measurement signal, thereby enabling more accurate monitoring of the thickness change of metal film during the manufacturing process.

[0044] The metal film thickness calibration method provided by this invention can be applied to scenarios where CMP processing is performed on the metal film on the wafer surface.

[0045] The method for calibrating the thickness of a metal film provided by the present invention will now be described with reference to the accompanying drawings. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0046] This embodiment provides a method for calibrating the thickness of a metal film, which can be used in a calibration device for the thickness of a metal film. The calibration device for the thickness of a metal film can be a computer device or a processor in a computer device. Figure 2 This is a schematic flowchart of a method for calibrating the thickness of a metal film according to an embodiment of the present invention, as shown below. Figure 2 As shown, the method includes the following steps:

[0047] Step S201: Obtain the baseline piecewise function.

[0048] The reference piecewise function is used to characterize the correspondence between the metal film thickness and the measurement signal in different metal film thickness ranges, and the measurement signal is the signal value output by the eddy current sensor.

[0049] The minimum value among all metal film thickness ranges can be Alternatively, the target stop thickness set by the designer (i.e., the thickness of the metal film that the wafer needs to retain) can be the maximum value of all metal film thickness ranges, which can be the precise sampling upper limit of the eddy current sensor or the maximum film thickness that the designer needs to monitor.

[0050] For example, the fitted curve of the benchmark piecewise function can be as follows: Figure 3 As shown by the solid line in the image, Figure 3 The reference piecewise function is divided into four metal film thickness intervals, the first of which is... The second metal film thickness range is The third metal film thickness range is The fourth metal film thickness range is

[0051] Specifically, the reference piecewise function is the original scale for the eddy current sensor to measure the film thickness, reflecting the correspondence between the measured signal and the metal film thickness under specific conditions (such as the same eddy current sensor and the same CMP equipment).

[0052] The reference piecewise function can be obtained by fitting multiple different standard metal film thicknesses and multiple standard measurement signals. The multiple standard metal film thicknesses and multiple standard measurement signals correspond one-to-one. The standard metal film thickness is the metal film thickness of the standard wafer. The standard metal film thickness is a known value. The standard measurement signal is the signal value output by the eddy current sensor when measuring the corresponding standard metal film thickness. The multiple standard measurement signals are acquired by the same eddy current sensor, which is integrated on the process equipment (such as CMP).

[0053] The fitted reference piecewise function can be pre-configured in memory, and the metal film thickness calibration device can retrieve the reference piecewise function from memory.

[0054] It should be noted that after replacing the eddy current sensor installed on the process equipment, the reference piecewise function needs to be redefined and updated in the memory. This is because even eddy current sensors of the same model can have slight differences in sensitivity and signal output characteristics. Updating the reference piecewise function synchronously after updating the eddy current sensor can eliminate measurement errors caused by individual differences in eddy current sensors.

[0055] Step S202: Determine the first measurement signal corresponding to the first thickness of the metal film on the calibration wafer, and determine the second measurement signal corresponding to the second thickness of the metal film on the calibration wafer.

[0056] The first thickness is greater than the second thickness, and the values ​​of both thicknesses range from 0 to the maximum value of the metal film thickness on the calibration wafer. For example, the first thickness can be the maximum value of the metal film thickness on the calibration wafer, such as... The second thickness can be

[0057] Specifically, the calibration wafer with the metal film is placed in a CMP device for polishing. During the polishing process, the measurement signal output by the eddy current sensor is collected in real time. The measurement signal obtained when the metal film thickness is a first thickness is determined as the first measurement signal, and the measurement signal obtained when the metal film thickness is a second thickness is determined as the second measurement signal.

[0058] Step S203: calibrate the reference piecewise function based on the first signal offset value between the first measurement signal and the third measurement signal, and the second signal offset value between the second measurement signal and the fourth measurement signal.

[0059] The third measurement signal is the measurement signal corresponding to the first thickness in the reference piecewise function, and the fourth measurement signal is the measurement signal corresponding to the second thickness in the reference piecewise function. The first signal offset value is the difference between the first and third measurement signals, and the second signal offset value is the difference between the second and fourth measurement signals.

[0060] For example, after determining the first signal offset value and the second signal offset value, a signal offset function can be determined based on the first and second signal offset values. Then, based on the signal offset function, the signal offset values ​​corresponding to other metal film thicknesses can be predicted. Afterwards, the reference piecewise function is calibrated according to the signal offset values ​​of all thicknesses to obtain the updated reference piecewise function (i.e., the target piecewise function). For example, the curve of the target piecewise function can be as follows: Figure 3 As shown by the dashed line in the image.

[0061] Specifically, the target piecewise function characterizes the correspondence between the metal film thickness and the measurement signal in actual process scenarios (such as polishing scenarios). When monitoring the metal film thickness of a wafer, the current film thickness of the wafer can be determined by the updated benchmark piecewise function, which can eliminate the influence of environmental and other factors on the measurement results and improve the accuracy of the monitoring results.

[0062] In some embodiments, when determining the first signal offset value and the second signal offset value, the average value of the first signal offset value and the second signal offset value can be determined as the signal offset value corresponding to other metal film thicknesses. Then, the reference piecewise function is calibrated based on all thickness signal offset values ​​to obtain the target piecewise function.

[0063] The metal film thickness calibration method provided in this embodiment, after obtaining the reference piecewise function, determines the first measurement signal corresponding to the first thickness of the metal film on the calibration wafer, and the second measurement signal corresponding to the second thickness of the metal film on the calibration wafer. Then, based on the first signal offset value between the first and third measurement signals and the second signal offset value between the second and fourth measurement signals, the reference piecewise function is calibrated, and the metal film thickness is monitored in real time based on the calibrated reference piecewise function. This embodiment characterizes the correspondence between the metal film thickness and the measurement signal through a piecewise function, which can more accurately determine the metal film thickness corresponding to the measurement signal obtained during the processing. This allows for more accurate monitoring of the metal film thickness change during the process, effectively improving the accuracy of wafer surface metal film thickness monitoring in related integrated circuit manufacturing technologies.

[0064] In this embodiment, another method for calibrating the thickness of a metal film is also provided, which can be used in a device for calibrating the thickness of a metal film. Figure 4 This is a schematic flowchart of another method for calibrating the thickness of a metal film according to an embodiment of the present invention, as shown below. Figure 4 As shown, the method includes the following steps:

[0065] Step S401: Obtain the baseline piecewise function.

[0066] For example, before obtaining the reference piecewise function, the calibration method for the metal film thickness includes: obtaining the metal film thickness of multiple different calibration wafers; determining a measurement signal corresponding one-to-one with the multiple metal film thicknesses using an eddy current sensor; and generating a reference piecewise function based on the multiple metal film thicknesses and the multiple measurement signals.

[0067] Specifically, the metal film thickness of the calibrated wafer is a known value. The calibration device can input the metal film thickness by the user. After obtaining multiple metal film thicknesses and multiple measurement signals from the eddy current sensor, the multiple metal film thicknesses and corresponding measurement signals can be input into the fitting software. The fitting software generates a benchmark piecewise function, and then the metal film thickness calibration device can obtain the benchmark piecewise function from the fitting software.

[0068] Step S402: Determine the detection range.

[0069] The detection range is the range of the acquisition position of the eddy current sensor on the calibration wafer.

[0070] Specifically, after the calibration wafer is placed on the process equipment (such as CMP equipment) with integrated eddy current sensors, the metal on the process equipment may interfere with the signal value output by the eddy current sensor, or the signal value output by the eddy current sensor in some areas where the calibration wafer is located may have a large attenuation. Based on this, the area in the calibration wafer with no interference signal and signal value with basically no attenuation (attenuation less than the preset attenuation value) can be determined as the detection range. The detection range can be determined experimentally and input into the calibration device for the metal film thickness by the designer.

[0071] The size of the calibration wafer affects the setting of the detection range. Alternatively, a model can be established to establish the correspondence between the size of the calibration wafer and the detection range. Then, the size of the calibration wafer can be input into the model, and the output of the model can be used to determine the detection range.

[0072] For example, such as Figure 5 As shown, the diameter of the calibration wafer is 300mm. When the center of the calibration wafer is the origin (0mm), the detection range can be 60mm to 110mm.

[0073] Step S403: Determine the first measurement signal corresponding to the first thickness of the metal film on the calibration wafer, and determine the second measurement signal corresponding to the second thickness of the metal film on the calibration wafer.

[0074] Specifically, step S403 includes:

[0075] Step S4031: When the metal film thickness of the calibrated wafer is the first thickness, the average value of multiple measurement signals obtained by the eddy current sensor in the detection range is determined as the first measurement signal.

[0076] Specifically, when the metal film thickness of the calibration wafer is set to a first thickness, the eddy current sensor is controlled to move within the detection range to acquire multiple measurement signals, and then the average value of the multiple measurement signals is determined as the first measurement signal.

[0077] In step S4032, when the metal film thickness of the calibrated wafer is the second thickness, the average value of multiple measurement signals obtained by the eddy current sensor in the detection range is determined as the second measurement signal.

[0078] Specifically, when the metal film thickness of the calibration wafer is set to the second thickness, the eddy current sensor is controlled to move within the detection range to acquire multiple measurement signals. Then, the average value of the multiple measurement signals is determined as the second measurement signal.

[0079] For example, the first thickness can be the maximum value of the metal film thickness of the calibration wafer, and the second thickness can be...

[0080] Step S404: calibrate the reference piecewise function based on the first signal offset value between the first measurement signal and the third measurement signal, and the second signal offset value between the second measurement signal and the fourth measurement signal.

[0081] Specifically, step S404 above may include:

[0082] Step S4041: Determine the signal offset function based on the first signal offset value and the second signal offset value.

[0083] The signal offset function is used to characterize the relationship between the metal film thickness and the signal offset value.

[0084] Specifically, after determining the first signal offset value and the second signal offset value, the linear function obtained based on the first signal offset value and the second signal offset value can be determined as the signal offset function.

[0085] Step S4042: Calibrate the reference segmentation function according to the signal offset function.

[0086] Specifically, after determining the signal offset function, the signal offset value corresponding to each metal film thickness can be determined based on the signal offset function. Then, the reference piecewise function is updated based on the signal offset values ​​corresponding to all metal film thicknesses to obtain the target piecewise function.

[0087] The metal film thickness calibration method provided in this embodiment first determines a detection range. Then, when the metal film thickness of the calibrated wafer is a first thickness, the average of multiple measurement signals obtained by the eddy current sensor within the detection range is determined as the first measurement signal. When the metal film thickness of the calibrated wafer is a second thickness, the average of multiple measurement signals obtained by the eddy current sensor within the detection range is determined as the second measurement signal. The detection range eliminates interference signals and reduces attenuation, ensuring the accuracy of the determined first and second measurement signals, thereby improving the accuracy of the subsequently determined signal offset function. This embodiment improves the calibration accuracy by calibrating the reference piecewise function through the signal offset function.

[0088] The calibration process for the metal film thickness will be explained in detail below with reference to the accompanying drawings, taking a calibrated wafer with a diameter of 300 mm as an example.

[0089] Specifically, this invention employs a piecewise linear calibration method, measuring the signal values ​​and thicknesses of calibration wafers of different thicknesses to generate a piecewise fitting curve of signal value and thickness, which is then used as the baseline calibration data. During calibration updates, the piecewise fitting curve is used as the baseline, and the calibration data is updated using the signal values ​​of the wafers with the maximum and minimum thicknesses and their corresponding thicknesses. The baseline calibration wafer thicknesses are, respectively, the maximum thickness, the linear inflection point thickness, the upper limit of the precise sampling thickness, and the target stopping thickness. The wafer thickness required to update calibration data is the maximum thickness.

[0090] like Figure 6 As shown, the specific procedure for calibrating the thickness of the metal film is as follows:

[0091] First, calibration wafers with uniform film thickness and different thicknesses were selected, and the signal values ​​S output by the eddy current sensors at different locations were obtained by fixed-point measurement. R and measuring film thickness T R The fixed-point measurement location is 60mm to 110mm, and the wafer thickness is uniform and the eddy current signal output value is accurate in the 60mm to 110mm position.

[0092] Then, based on the average value of the received signals from the 60mm to 110mm position and the average value of the measured wafer film thickness, a reference signal value-film thickness piecewise fitting curve is generated. The film thickness is denoted as T, the signal value as S, and the fitting curve is T = f(S). This reference signal value-film thickness piecewise fitting curve serves as the reference calibration data and is only performed after replacing the eddy current sensor.

[0093] Subsequently, upon determining that the calibration data needed to be updated, a metal film thickness of [thickness value missing] was prepared. The calibration wafers were then measured.

[0094] For metal film thickness of The calibration wafer is polished until all metal film layers are removed, and the signal value output by the eddy current sensor is collected in real time during the polishing process.

[0095] After obtaining the signal value, the reference calibration data is updated based on the film thickness of the calibration wafer before polishing, the corresponding signal value of the calibration wafer before polishing, the film thickness of the calibration wafer after polishing, and the corresponding signal value of the calibration wafer after polishing.

[0096] Specifically, a metal film with a thickness of [missing information] is used. The process for updating the reference calibration data on the calibration wafer can be as follows: Figure 7 As shown, the specific steps are as follows:

[0097] First, prepare a metal film with a thickness of... The calibrated wafer was measured, and the average thickness at a position of 60mm to 110mm on the wafer was taken as the wafer metal film thickness, denoted as T. pre .

[0098] For metal film thickness of The calibration wafer is polished until all metal film layers are removed, and the eddy current sensor signal value is collected in real time during the polishing process.

[0099] Calculate the average signal value at the 60mm–110mm position on the wafer before and after polishing. The signal value corresponding to the thickness is denoted as S. pre , The signal value corresponding to the thickness is denoted as S. post .

[0100] Based on the benchmark calibration data, the following calculations were performed. The reference signal value S corresponding to the thickness pre_base and The reference signal value S corresponding to the thickness post_base .

[0101] After obtaining the reference signal values ​​before and after polishing, the thickness is calculated. and thickness The signal offset value is denoted as D. pre and D post D pre =S pre -S Spre_base D post =S post -S post_base .

[0102] Determine the signal offset value D pre and D post Then, based on the signal offset value D pre and D post The fitting signal offset function is D = f(T), where T is the thickness.

[0103] After determining the signal offset function, the signal offset values ​​for other thicknesses are predicted based on the signal offset function.

[0104] Then, the signal value thickness fitting curve is updated based on the reference signal value-thickness piecewise fitting curve and all calculated thickness signal offset values.

[0105] Based on the updated signal value thickness fitting curve, the metal film thickness of different wafers was calculated, and the comparison with the measured thickness is shown in the figure below. Figures 8 to 11 As shown. From Figures 8 to 11 As can be seen, the piecewise fitting curve can accurately describe the thickness of the metal film on different wafer surfaces, and can accurately detect the real-time thickness of the wafer during the polishing process.

[0106] This embodiment also provides a metal film thickness calibration device, which is used to implement the above embodiments and preferred embodiments, and will not be repeated as already described. As used below, the term "module" can be a combination of software and / or hardware that implements a predetermined function. Although the device described in the following embodiments is preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0107] This embodiment provides a calibration device for the thickness of a metal film, such as... Figure 12 As shown, it includes:

[0108] The acquisition module 1201 is used to acquire a reference piecewise function, wherein the reference piecewise function characterizes the correspondence between the metal film thickness and the measurement signal in various metal film thickness ranges, and the measurement signal is the signal value output by the eddy current sensor.

[0109] The signal determination module 1202 is used to determine a first measurement signal when the metal film thickness of the calibration wafer is a first thickness, and to determine a second measurement signal when the metal film thickness of the calibration wafer is a second thickness, wherein the first thickness is greater than the second thickness, and the values ​​of the first thickness and the second thickness range from 0 to the maximum value of the metal film thickness of the calibration wafer.

[0110] The calibration module 1203 is used to calibrate a reference piecewise function based on a first signal offset value between a first measurement signal and a third measurement signal, and a second signal offset value between a second measurement signal and a fourth measurement signal, wherein the third measurement signal is the measurement signal corresponding to the first thickness in the reference piecewise function, and the fourth measurement signal is the measurement signal corresponding to the second thickness in the reference piecewise function.

[0111] In some alternative implementations, the calibration module 1203 includes:

[0112] The first determining unit is used to determine a signal offset function based on the first signal offset value and the second signal offset value;

[0113] The calibration unit is used to calibrate the reference piecewise function based on the signal offset function.

[0114] In some alternative embodiments, the apparatus further includes:

[0115] The detection determination module is used to determine the detection range, which is the range of the acquisition positions of the eddy current sensor on the calibration wafer;

[0116] Signal determination module 1202 includes:

[0117] The second determining unit is used to determine the average of multiple measurement signals obtained by the eddy current sensor in the detection range as the first measurement signal when the metal film thickness of the calibrated wafer is a first thickness.

[0118] The third determining unit is used to determine the average of multiple measurement signals obtained by the eddy current sensor in the detection range as the second measurement signal when the metal film thickness of the calibrated wafer is the second thickness.

[0119] In some alternative implementations, the diameter of the calibration wafer is 300 mm, and the detection range is 60 mm to 110 mm with the center of the calibration wafer as the origin.

[0120] In some alternative implementations, the first thickness is the maximum value of the metal film thickness of the calibration wafer, and the second thickness is...

[0121] In some alternative embodiments, the apparatus further includes:

[0122] The thickness acquisition module is used to acquire the metal film thickness of multiple different calibration wafers;

[0123] The measurement module is used to determine measurement signals that correspond one-to-one with the thickness of multiple metal films using an eddy current sensor;

[0124] The generation module is used to generate a reference piecewise function based on multiple metal film thicknesses and multiple measurement signals.

[0125] Further functional descriptions of the above modules and units are the same as those in the corresponding embodiments described above, and will not be repeated here.

[0126] In this embodiment, the metal film thickness calibration device is presented in the form of a functional unit. Here, a unit refers to an application-specific integrated circuit (ASIC), a processor and memory that execute one or more software or fixed programs, and / or other devices that can provide the above functions.

[0127] This invention also provides a computer device, such as... Figure 13 As shown, the computer device includes one or more processors 1310, a memory 1320, and interfaces for connecting the components, including high-speed interfaces and low-speed interfaces. The components are interconnected via different buses and can be mounted on a common motherboard or otherwise installed as needed. The processor can process instructions executed within the computer device, including instructions stored in or on memory to display graphical information of a GUI on external input / output devices (such as display devices coupled to the interfaces).

[0128] Processor 1310 may be a central processing unit, a network processor, or a combination thereof. Processor 1310 may further include a hardware chip. The hardware chip may be an application-specific integrated circuit (ASIC), a programmable logic device (PLD), or a combination thereof. The programmable logic device may be a complex programmable logic device (CAMP), a field-programmable gate array (FPGA), a general-purpose array logic (GPA), or any combination thereof.

[0129] The memory 1320 stores instructions executable by at least one processor 1310 to cause at least one processor 1310 to perform the method shown in the above embodiments.

[0130] The memory 1320 may include a program storage area and a data storage area. The program storage area may store the operating system and application programs required for at least one function. The data storage area may store data created based on the use of the computer device. Furthermore, the memory 1320 may include high-speed random access memory and may also include non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device.

[0131] The memory 1320 may include volatile memory, such as random access memory; the memory may also include non-volatile memory, such as flash memory, hard disk or solid-state drive; the memory 1320 may also include a combination of the above types of memory.

[0132] The computer device also includes a communication interface 1330 for communicating with other devices or communication networks.

[0133] This invention also provides a computer-readable storage medium. The methods described above according to embodiments of the invention can be implemented in hardware or firmware, or implemented as recordable on a storage medium, or implemented as computer code originally stored on a remote storage medium or a non-transitory machine-readable storage medium and subsequently stored on a local storage medium after being downloaded via a network. Thus, the methods described herein can be processed by software stored on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. The storage medium can be a magnetic disk, optical disk, read-only memory, random access memory, flash memory, hard disk, or solid-state drive, etc.; further, the storage medium may also include combinations of the above types of memory. It is understood that computers, processors, microprocessor controllers, or programmable hardware include storage components capable of storing or receiving software or computer code, which, when accessed and executed by the computer, processor, or hardware, implements the methods shown in the above embodiments.

[0134] A portion of this invention can be applied to computer program products, such as computer program instructions, which, when executed by a computer, can invoke or provide the methods and / or technical solutions according to the invention through the operation of the computer. Those skilled in the art will understand that the forms in which computer program instructions exist in a computer-readable medium include, but are not limited to, source files, executable files, installation package files, etc. Correspondingly, the ways in which computer program instructions are executed by a computer include, but are not limited to: the computer directly executing the instructions, or the computer compiling the instructions and then executing the corresponding compiled program, or the computer reading and executing the instructions, or the computer reading and installing the instructions and then executing the corresponding installation program. Here, the computer-readable medium can be any available computer-readable storage medium or communication medium accessible to a computer.

[0135] In the description of this specification, the references to terms such as "this embodiment," "an embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0136] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0137] Although embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the present invention.

Claims

1. A method for calibrating the thickness of a metal film, characterized in that, The method includes: Obtain a reference piecewise function, wherein the reference piecewise function is used to characterize the correspondence between the metal film thickness and the measurement signal in various metal film thickness ranges, and the measurement signal is the signal value output by the eddy current sensor; A first measurement signal is determined when the metal film thickness of the calibration wafer is a first thickness, and a second measurement signal is determined when the metal film thickness of the calibration wafer is a second thickness, wherein the first thickness is greater than the second thickness, and the values ​​of the first thickness and the second thickness range from 0 to the maximum value of the metal film thickness of the calibration wafer; The reference piecewise function is calibrated based on the first signal offset value between the first and third measurement signals and the second signal offset value between the second and fourth measurement signals, wherein the third measurement signal is the measurement signal corresponding to the first thickness in the reference piecewise function, and the fourth measurement signal is the measurement signal corresponding to the second thickness in the reference piecewise function.

2. The method according to claim 1, characterized in that, The step of calibrating the reference piecewise function based on the first signal offset value between the first and third measurement signals and the second signal offset value between the second and fourth measurement signals includes: The signal offset function is determined based on the first signal offset value and the second signal offset value; The reference piecewise function is calibrated based on the signal offset function.

3. The method according to claim 1, characterized in that, Before determining the first measurement signal corresponding to the first thickness of the metal film on the calibration wafer, the method further includes: Determine the detection range, wherein the detection range is the range of the acquisition positions of the eddy current sensor on the calibration wafer; The first measurement signal corresponding to determining that the metal film thickness of the calibration wafer is a first thickness, and the second measurement signal corresponding to determining that the metal film thickness of the calibration wafer is a second thickness, include: When the metal film thickness of the calibration wafer is the first thickness, the average of the multiple measurement signals obtained by the eddy current sensor in the detection range is determined as the first measurement signal; When the metal film thickness of the calibration wafer is the second thickness, the average of the multiple measurement signals obtained by the eddy current sensor in the detection range is determined as the second measurement signal.

4. The method according to claim 3, characterized in that, The diameter of the calibration wafer is 300 mm, and the detection range is 60 mm to 110 mm when the center of the calibration wafer is the origin.

5. The method according to claim 3, characterized in that, The first thickness is the maximum value of the metal film thickness of the calibration wafer, and the second thickness is...

6. The method according to any one of claims 1 to 5, characterized in that, Prior to obtaining the benchmark piecewise function, the method further includes: Obtain the metal film thickness of multiple different calibration wafers; Using an eddy current sensor, a measurement signal corresponding one-to-one with the thickness of multiple metal films is determined; The reference piecewise function is generated based on multiple metal film thicknesses and multiple measurement signals.

7. A calibration device for the thickness of a metal film, characterized in that, The device includes: The acquisition module is used to acquire a reference piecewise function, wherein the reference piecewise function is used to characterize the correspondence between the metal film thickness and the measurement signal in various metal film thickness ranges, and the measurement signal is the signal value output by the eddy current sensor; The signal determination module is used to determine a first measurement signal when the metal film thickness of the calibration wafer is a first thickness, and a second measurement signal when the metal film thickness of the calibration wafer is a second thickness, wherein the first thickness is greater than the second thickness, and the values ​​of the first thickness and the second thickness range from 0 to the maximum value of the metal film thickness of the calibration wafer; The calibration module is used to calibrate the reference piecewise function based on a first signal offset value between the first measurement signal and the third measurement signal and a second signal offset value between the second measurement signal and the fourth measurement signal, wherein the third measurement signal is the measurement signal corresponding to the first thickness in the reference piecewise function, and the fourth measurement signal is the measurement signal corresponding to the second thickness in the reference piecewise function.

8. A computer device, characterized in that, include: A memory and a processor are communicatively connected, the memory storing computer instructions, and the processor executing the computer instructions to perform the calibration method for the metal film thickness according to any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions for causing a computer to perform the calibration method for the thickness of the metal film according to any one of claims 1 to 6.

10. A computer program product, characterized in that, Includes computer instructions for causing a computer to perform the calibration method for the thickness of the metal film as described in any one of claims 1 to 6.

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