WO2019051998A1

WO2019051998A1 - Method, apparatus and system for detecting spectrum end point in chemo-mechanical polishing, and computer-readable storage medium

Info

Publication number: WO2019051998A1
Application number: PCT/CN2017/111916
Authority: WO
Inventors: 王东辉; 井海石; 柳滨; 张为强; 王嘉琪
Original assignee: 北京半导体专用设备研究所（中国电子科技集团公司第四十五研究所）
Priority date: 2017-09-18
Filing date: 2017-11-20
Publication date: 2019-03-21
Also published as: CN107520740A

Abstract

Disclosed are a method, apparatus and system for detecting a spectrum end point in chemo-mechanical polishing. The method comprises: according to spectrum detection data of a polished thin film on a surface of a wafer, determining smooth spectrum detection data of the polished thin film; according to associated reflectivity data and detection wavelength data in the smooth spectrum detection data, determining extreme points in the smooth spectrum detection data and a wavelength value corresponding to each extreme point; according to the wavelength values of at least two adjacent extreme points and the optical refractive index of the polished thin film, determining the remaining thickness of the polished thin film; and when it is detected that the thickness of the polished thin film reaches a set thickness threshold value, determining that the thickness of the polished thin film is a polishing end point so that a chemo-mechanical polishing device stops polishing at the polishing end point. By means of the detection method, the detection accuracy of the spectrum end point is improved, and the work efficiency of the chemo-mechanical polishing device is improved.

Description

Method, device, system and computer readable storage medium for detecting spectral end point in chemical mechanical polishing

The present application claims priority to Chinese Patent Application No. CN2017108395811, entitled "Detecting Method, Apparatus and System for Spectral End Point in Chemical Mechanical Polishing", filed on September 18, 2017, the entire contents of which is hereby incorporated by reference. This is incorporated herein by reference.

Technical field

The present invention relates to the field of polishing detection technology, and in particular to a method, device, system and computer readable storage medium for detecting spectral endpoints in chemical mechanical polishing.

Background technique

With the rapid development of the semiconductor industry, the size of electronic devices is gradually shrinking, which requires the wafer surface flatness to reach the nanometer level. In order to meet this requirement, the surface of the wafer is currently polished by chemical mechanical polishing (ie, CMP) technology, and the chemical mechanical polishing technology can simultaneously meet the processing requirements of the graphic wafer from the processing performance and speed.

Among them, CMP is to smooth the wafer or other substrate material during processing by chemical etching and mechanical force, that is, to smooth the film on the surface of the wafer, which is currently determined by the application process of CMP, and the polishing process is pre-processed. The polishing time is set. After the processing time for polishing the surface of the wafer reaches the set polishing time, the surface of the wafer is stopped and the processed wafer is obtained.

However, the above CMP processing method determines the polishing end point based on the set polishing time, and it is impossible to determine whether the polished wafer surface meets the standard requirement, and it is easy to terminate the processing when the wafer surface flatness does not meet the standard requirement, thereby causing the actual The flatness is much different from the standard requirement.

Summary of the invention

In view of this, an object of embodiments of the present invention is to provide a method, a device, a system, and a computer readable storage medium for detecting a spectral end point in chemical mechanical polishing, which can improve the detection accuracy of a spectral end point.

In a first aspect, an embodiment of the present invention provides a method for detecting a spectral endpoint in chemical mechanical polishing, including:

Determining smooth spectral detection data of the polished film according to spectral detection data of the wafer surface being polished, the spectral detection data including associated reflectance data and detection wavelength data;

Determining an extreme point in the smoothed spectral detection data and a wavelength value corresponding to each extreme point according to the correlated reflectance data and the detected wavelength data in the smoothed spectral detection data;

Determining the remaining thickness of the film to be polished according to the wavelength values of the at least two adjacent extreme points and the optical refractive index of the film being polished;

Upon detecting that the remaining thickness of the film being thrown reaches a set thickness threshold, the remaining thickness is determined to be a polishing end point to cause the chemical mechanical polishing apparatus to stop polishing at the polishing end point.

With reference to the first aspect, the embodiment of the present invention provides a first possible implementation manner of the first aspect, wherein in the method for detecting a spectral end point in the chemical mechanical polishing, the spectrum according to the surface of the wafer is polished Detecting data to determine smooth spectral detection data of the polished film, including:

Obtaining spectral detection data of the wafer surface being polished;

Performing one-dimensional fast Fourier transform on the spectral detection data to obtain transformed spectral detection data;

Filtering the transformed spectral detection data to eliminate interference data in the transformed spectral detection data;

The inverse Fourier transform is performed on the filtered spectral detection data to obtain smooth spectral detection data.

With reference to the first possible implementation manner of the first aspect, the embodiment of the present invention provides a second possible implementation manner of the first aspect, wherein the transforming the spectral detection data is filtered, and the transformed Interference data in spectral detection data, including:

Performing an absolute value operation on the transformed spectral detection data to obtain positive real spectrum detection data;

The positive real-spectrum detection data smaller than the set threshold value is removed from the positive real-spectrum detection data according to the set threshold value, and the remaining spectral detection data is obtained.

With reference to the first aspect, the embodiment of the present invention provides a third possible implementation manner of the first aspect, wherein the determining the smoothing according to the correlated reflectivity data and the detected wavelength data in the smoothed spectral detection data The extreme points in the spectral detection data and the wavelength values corresponding to each extreme point, including:

Comparing the reflectance data in the smoothed spectral detection data to determine an extreme point in the spectral detection data and detection wavelength data corresponding to the extreme point;

In the spectral detection data, a set number of detection wavelength data in a set range is selected centering on the detection wavelength data, and curve matching is performed on the selected detection wavelength data and reflectance data corresponding to the wavelength data. Processing to obtain a quadratic function;

Using a numerical analysis method, determining a fitting coefficient of the quadratic function;

A wavelength value corresponding to each extreme point is determined according to the quadratic function and the fitting coefficient of the quadratic function.

With reference to the first aspect, the embodiment of the present invention provides a fourth possible implementation manner of the first aspect, wherein the extreme point includes a peak extremum point and a trough extreme point; the according to the at least two adjacent poles The wavelength value of the value point and the optical refractive index of the film being polished determine the remaining thickness of the film to be polished, including:

The thickness of the film to be polished is calculated based on the optical refractive index of the film being thrown and any two adjacent peak extreme points or two adjacent valley extreme points or adjacent peak extreme points and valley extreme points.

With reference to the first aspect, the embodiment of the present invention provides the fifth possible implementation manner of the first aspect, wherein the extreme point includes: a peak extremum point and a trough extreme point; the according to at least two neighbors The wavelength value of the extreme point and the optical refractive index of the film being thrown determine the remaining thickness of the film to be polished, including:

According to the optical refractive index of the film being thrown and every two adjacent peak extreme points or every two adjacent valley extreme points Or calculating the thickness of the film to be polished by the extreme point of each adjacent peak and the extreme point of the valley;

The thickness of all the resulting film to be polished is averaged to obtain the thickness of the final film to be polished.

In a second aspect, an embodiment of the present invention further provides a device for detecting a spectral end point in chemical mechanical polishing, including:

An acquisition module configured to determine smooth spectral detection data of the polished film according to spectral detection data of a wafer surface being polished, the spectral detection data including associated reflectance data and detection wavelength data;

a first determining module, configured to determine an extreme point in the smoothed spectral detection data and a wavelength value corresponding to each extreme point according to the correlated reflectance data and the detected wavelength data in the smoothed spectral detection data ;

a second determining module configured to determine a remaining thickness of the film to be polished according to a wavelength value of the at least two adjacent extreme points and an optical refractive index of the film to be polished;

The third determining module is configured to determine the remaining thickness as a polishing end point when the remaining thickness of the film being thrown reaches a set thickness threshold, so that the chemical mechanical polishing apparatus stops polishing at the polishing end point.

With reference to the second aspect, the embodiment of the present invention provides a first possible implementation manner of the second aspect, where the acquiring module includes:

An acquisition unit configured to acquire spectral detection data of a wafer surface being polished;

a filter processing unit configured to perform one-dimensional fast Fourier transform on the spectral detection data to obtain transformed spectral detection data; perform filtering processing on the transformed spectral detection data, and cull the transformed spectral detection data Interference data; inverse Fourier transform of the filtered spectral detection data to obtain smooth spectral detection data.

With reference to the first possible implementation manner of the second aspect, the embodiment of the present invention provides the second possible implementation manner of the second aspect, wherein the filtering processing unit is specifically configured to perform the transformed spectral detection data. Absolute value calculation processing is performed to obtain positive real-spectrum detection data; and positive real-spectrum detection data smaller than the set threshold value is removed from the positive real-spectrum detection data according to a set threshold value, and residual spectral detection data is obtained.

In a third aspect, an embodiment of the present invention provides a detection system for a spectral endpoint in chemical mechanical polishing, including: a light source, an optical sensor, and a server;

The light source is configured to emit light waves to the wafer surface by a thin film;

The optical sensor is configured to receive a reflected light wave that is reflected by a film on a surface of the wafer, and send the reflected light wave to the server; the reflected light wave carries spectral detection data;

The server is configured to receive the reflected light wave, extract spectral detection data of the wafer surface from the reflected light wave, and determine a smooth spectral detection of the polished film according to the spectral detection data Data, the spectral detection data includes associated reflectance data and detected wavelength data; determining extremum points in the smoothed spectral detection data based on the associated reflectance data and detected wavelength data in the smoothed spectral detection data And a wavelength value corresponding to each extreme point; a wavelength value according to at least two adjacent extreme points and an optical folding of the film to be polished a firing rate, determining a remaining thickness of the film to be polished; determining that the remaining thickness is a polishing end point when the remaining thickness of the film to be thrown reaches a set thickness threshold, so that the chemical mechanical polishing device stops polishing at the polishing end point .

In a fourth aspect, an embodiment of the present invention further provides a computer readable storage medium having stored thereon a computer program that, when executed, implements the above-described method for detecting a spectral endpoint in chemical mechanical polishing.

A method, device and system for detecting spectral endpoints in chemical mechanical polishing according to embodiments of the present invention include: determining spectrally smoothed spectral detection data of a film to be polished according to spectral detection data of a wafer surface being polished; Correlation reflectance data and detected wavelength data in the spectral detection data, determining extreme values in the smoothed spectral detection data and wavelength values corresponding to each extreme point; according to wavelength values of at least two adjacent extreme points Determining the optical refractive index of the film to determine the remaining thickness of the film to be polished; when detecting the thickness of the film to reach the set thickness threshold, determining the thickness of the film to be polished, so that the chemical mechanical polishing device is at the polishing end Stop polishing. Compared with the prior art, the CMP processing method cannot accurately detect whether the polished wafer surface meets the standard requirement, thereby causing the expected flatness of the wafer surface to be greatly deviated from the actual flatness after processing; The provided detection method, device, system and computer readable storage medium determine the thickness of the polished film as the polishing end point by calculating the remaining thickness of the wafer surface being polished, thereby improving the detection accuracy of the spectral end point.

The above described objects, features, and advantages of the invention will be apparent from the description and appended claims appended claims

DRAWINGS

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly described below. It should be understood that the following drawings show only certain embodiments of the present invention, and therefore It should be seen as a limitation on the scope, and those skilled in the art can obtain other related drawings according to these drawings without any creative work.

FIG. 1 is a flow chart showing a method for detecting a spectral endpoint in chemical mechanical polishing according to an embodiment of the present invention.

2 is a flow chart showing another method for detecting a spectral endpoint in chemical mechanical polishing provided by an embodiment of the present invention.

FIG. 3 is a flow chart showing another method for detecting a spectral endpoint in chemical mechanical polishing according to an embodiment of the present invention.

FIG. 4 is a schematic structural view of a device for detecting a spectral end point in chemical mechanical polishing according to an embodiment of the present invention.

FIG. 5 is a schematic structural view of an acquisition module and a first determination module in a detection device for a spectral end point in chemical mechanical polishing according to an embodiment of the present invention.

FIG. 6 is a schematic structural view of a detection system for spectral end points in chemical mechanical polishing according to an embodiment of the present invention.

7 is a schematic diagram showing the complete spectral detection data X collected by the spectrometer provided by the embodiment of the present invention; and FIG. 7 is a right diagram showing the spectrum of the wavelength range of 400-950 nm collected by the spectrometer provided by the embodiment of the present invention. A schematic diagram of the detection data X1.

The left diagram of Fig. 8 shows a schematic diagram of spectral detection data after one-dimensional fast Fourier transform (FFT); the right diagram of Fig. 8 shows a schematic diagram of data A (FFTA1) of absolute value operation.

Fig. 9 is a diagram showing the data FFTX2 in which AFFTX1 is smaller than the set threshold value, and the data FFTX2 is shown in Fig. 9. The right diagram of Fig. 9 shows the data X3 after FFTX2 performs inverse Fourier transform.

Fig. 10 is a left side view showing a schematic diagram of a single point optical detection schematic; Fig. 10 is a right side view showing a schematic view of a thin film reflection.

Fig. 11 is a view showing a dispersion curve of a silicon dioxide film.

Fig. 12 shows a schematic diagram of a similar cosine relationship between the wavelength λ and the light intensity I.

Detailed ways

The technical solutions in the embodiments of the present invention are clearly and completely described in the following with reference to the accompanying drawings in the embodiments of the present invention. It is a partial embodiment of the invention, and not all of the embodiments. The components of the embodiments of the invention, which are generally described and illustrated in the figures herein, may be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the invention in the claims All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts are within the scope of the present invention.

Considering the method of determining the polishing end point based on the set polishing time in the prior art CMP processing method, it is impossible to accurately detect whether the polished wafer surface meets the standard requirement, which may result in the expected flatness of the wafer surface and the processed surface. The problem of large deviation in actual flatness. Based on this, an embodiment of the present invention provides a method, a device and a system for detecting a spectral end point in chemical mechanical polishing. The thickness of the film to be polished is determined by calculating the remaining thickness of the film on the surface of the wafer, and the polishing end point is improved. The detection accuracy of the spectral endpoint is described below by way of examples.

The left diagram of Fig. 10 shows the schematic diagram of single point optical detection. As shown in the left figure of Fig. 10, the polishing of transparent oxide usually uses optical end point detection. According to the interference principle of light, the incident beam I _inc is projected at the incident angle α _{1 .} To the first surface, a portion of the incident beam reflects I ₁ at point A, another portion enters the transparent layer, a reflection occurs at substrate B, and refracts into air I ₂ at point C.

In the left diagram of Fig. 10, the two reflection lines have different phases due to the difference in path, forming interference. In the embodiment of the present invention, the photosensor device is disposed at I ₁ and I ₂ , and an electrical signal is generated from the light intensity, and data, or a pattern is formed by detection, filtering, shaping, and amplification to determine the position of the spectral end point (ie, the polishing end point).

When determining the end point of the spectrum by the above method, the wafer film thickness can be first calibrated (that is, the transparent film thickness calibration method), and the following two methods can be selected:

First, the extremum method: According to the position calculation of two or more extreme points on the reflection spectrum of the film, the calculation process is simple and the speed is fast.

Second, the full spectrum fitting method: a mathematical model of the relative light intensity distribution function with the dispersion refractive index, film thickness and absorption coefficient as independent variables is constructed by introducing a simplified dispersion refractive index formula, and the full spectrum data is fitted by a nonlinear model. The optical constant and thickness of the film can be measured simultaneously.

In the above two methods of calibrating the transparent film thickness, the second method of full-spectrum fitting can only use a simplified model in practical applications and the calculation speed is slow, which cannot meet the requirements of fast calculation, and is not suitable for real-time testing. The extreme value method is preferably used in the embodiment of the present invention.

Referring to the schematic diagram of the film reflection shown in the right figure of Fig. 10, the light beam 1 and the light beam 2 are respectively reflected light on the upper and lower surfaces of the film, and the film thickness is d and the refractive index is n. The optical path difference between beam 1 and beam 2 is:

Δ = 2ndcosi'; where i' is the angle of refraction.

At normal incidence, the two reflected light intensity distributions of the film are:

Assuming that the intensity of the two beams reflected I ₁ and I ₂ are approximately equal, the above equation is simplified as:

The above equation shows that when the initial value of Δ is um (micrometer), the relationship between I and λ in the above equation is a cosine-like relationship, and the shape is much like the cosine, as long as the λ increases, the period of the signal The exhibition will be wide.

The specific solution method of the extremum method is as follows:

Referring to Figure 12, a, c, and e are three upper points, and b, d, and f are three lower extreme points. First, the extreme points a, b, c, d, e, and f are found, and the extreme points are obtained. Corresponding wavelength values λ _a , λ _b ..., and then using two or more extreme points near the wavelength value corresponding to the extreme point and the wavelength value corresponding to the extreme point, the value of the film thickness is calculated according to the following formula .

In this way, the order at a, b, ... is 2m, (2m-1), ... the order is decremented because as λ increases, 1/λ decreases, so the order is decreasing. The column equations are as follows:

For a given wavelength λ _a and λ _b values, solving the above two equations in parallel, it is not necessary to calculate the value of the end m to find the film thickness d.

A method for detecting a spectral endpoint in chemical mechanical polishing is provided by an embodiment of the present invention. The method is performed by a detection system. Referring to FIG. 1, the method includes:

S11. Determine smooth spectral detection data of the polished film according to spectral detection data of the wafer surface being polished, and the spectral detection data includes associated reflectance data and detection wavelength data.

In the embodiment of the present invention, the spectrometer is used to collect spectral detection data of the wafer surface being polished, and the spectral detection data includes reflectance data and detection wavelength data, and the reflectance data and the detected wavelength data have corresponding mapping relationships, as shown in the figure. 11 is shown. In the embodiment of the present invention, the wavelength range of the spectrometer used is 350 nm-1100 nm, and the wavelength range of the light source is 360 nm-2000 nm, and the complete spectrum detection data collected is shown in the left diagram of FIG. 7 (wherein the oxidation in the left diagram of FIG. 7 is shown) In the spectrum detection data of non-metal CMP such as silicon), in practice, the edge optical signal in the wavelength range of the spectrometer is weak, and the detection interference is large. In the collected spectral detection data, the edge data needs to be first removed, and only the wavelength range is taken. For the 400nm-950nm interval detection data, see Figure 7 right, these data are used as valid spectral detection data to participate in subsequent calculations.

Then, the collected effective spectral detection data is filtered to obtain smooth spectral detection data, so as to determine an extreme point in the smoothed spectral detection data and a wavelength value corresponding to each extreme point according to the smoothed spectral detection data. . Among them, the smooth spectral detection data can initially form a smooth curve.

S12. Determine, according to the reflectance data and the detected wavelength data in the smoothed spectral detection data, an extreme value point in the smoothed spectral detection data and a wavelength value corresponding to each extreme point.

Specifically, the plurality of reflectance data in the smoothed spectral detection data are respectively compared, the first largest reflectance data in the smooth curve is determined as a peak, or the first minimum reflectance data in the smooth curve is determined as a trough, and The detection wavelength data corresponding to the peak or the trough is recorded, and the set number of detection wavelength data is selected with the set length as the center of the detection wavelength data. Here, as the wavelength increases, the number of detection wavelength data also increases.

After the detection wavelength data is selected, since there is a certain deviation between the detected wavelength data and the accurate value, in the embodiment of the present invention, the relatively accurate actual wavelength corresponding to the first peak or trough is calculated according to the selected detection wavelength data. value.

Then, continue to compare the multiple reflectance data in the smoothed spectral detection data, determine the second largest reflectance data in the smooth curve as the peak, or determine the second smallest reflectance data in the smooth curve as the trough And continue to calculate the relatively accurate actual wavelength value corresponding to the second peak or the second trough according to the calculation method after the first peak or trough, and so on, until there is no uncalculated peak in the detected smooth curve or The trough, or until the calculation of all peaks or troughs in the smooth curve is completed, yields multiple peaks or troughs and the actual wavelength values corresponding to each peak or trough.

S13. Determine a remaining thickness of the film to be polished according to wavelength values of at least two adjacent extreme points and an optical refractive index of the film to be polished.

Specifically, according to the formula

Calculate the thickness of the transparent film (ie, the remaining thickness of the film to be polished), where d is the remaining thickness of the film being thrown, n is the optical refractive index of the film being thrown, and λ _a and λ _b are the wavelengths of adjacent extreme points. value.

S14. When it is detected that the remaining thickness of the polished film reaches a set thickness threshold, determine the remaining thickness as a polishing end point, so that the chemical mechanical polishing device stops polishing at the polishing end point.

Specifically, the detection system compares the remaining thickness of the polished film with a set thickness threshold, and when the remaining thickness is greater than or equal to the set thickness threshold, no processing is performed. At this time, the control system continues to polish the film. When the remaining thickness is less than the set thickness threshold, determining the remaining thickness as the polishing end point, and sending the prompt information with the remaining thickness as the polishing end point to the control system, and the control system controls the chemical mechanical polishing device to perform the polishing according to the prompt information. The end point stops polishing.

Further, referring to FIG. 2, in the method for detecting the spectral end point in chemical mechanical polishing provided by the embodiment of the present invention, step 11 determines the smooth spectral detection data of the polished film according to the spectral detection data of the wafer surface being polished. ,include:

S111. Obtain spectral detection data of the wafer surface being polished.

When the wafer begins to polish, the spectrometer is used to acquire spectral detection data of the wafer surface being polished. In the embodiment of the present invention, only the detection data of the wavelength range of 400 nm to 950 nm is taken.

S112. Perform one-dimensional fast Fourier transform on the spectral detection data to obtain transformed spectral detection data.

Specifically, a one-dimensional fast Fourier transform (FFT) is performed on the spectral detection data in the wavelength range of 400 nm to 950 nm, and the obtained transformed spectral detection data FFTX1 is shown in the left diagram of FIG. Here, the data is processed by Fourier transform to obtain a smooth curve, and the trend is basically the same as the detected data X1.

S113: Perform filtering processing on the transformed spectral detection data, and reject interference data in the transformed spectral detection data;

Specifically, the step includes performing absolute value operation processing on the transformed spectral detection data to obtain positive real spectrum detection data. According to the set threshold, the positive real-spectrum detection data smaller than the set threshold is removed from the positive real-spectrum detection data, and the remaining spectral detection data is obtained, as shown in the right figure of FIG.

Here, the filtering process performs absolute value calculation on the transformed spectral detection data FFTX1 to obtain a set of positive real numbers AFFTX1, as shown in the right figure of FIG. Then, the data AFFTX1 obtained by the absolute value calculation is determined. If the filtered data is less than the set threshold, the data FFTX1 is recorded as zero (ie, the data is eliminated), and if the filtered data is greater than the set threshold, Then keep the data unchanged. The resulting data is recorded as FFTX2, as shown in the left figure of Figure 9.

S114. Perform inverse Fourier transform on the filtered spectral detection data to obtain smooth spectral detection data.

Referring to the right diagram of FIG. 9, the spectral detection data is subjected to Fourier transform processing and filtering processing to obtain a smooth curve (including data X3), and the smooth curve includes data X3 whose trend is substantially consistent with the spectral detection data X1.

Further, in the method for detecting a spectral end point in the chemical mechanical polishing provided by the embodiment of the present invention, referring to FIG. 3, step 12 determines the smoothed according to the correlated reflectance data and the detected wavelength data in the smoothed spectral detection data. The extreme values in the spectral detection data and the wavelength values corresponding to each extreme point, including:

S121. Compare the reflectance data in the smoothed spectral detection data, and determine an extreme point in the spectral detection data and detection wavelength data corresponding to the extreme point.

Specifically, the smooth spectral detection data may initially form a smooth curve, and the plurality of reflectance data in the smooth spectral detection data are respectively compared, and the reflectance data in the smooth curve that is greater than the adjacent reflectance data respectively is determined as The peaks, or the reflectance data in the smooth curve which is smaller than the adjacent reflectance data, respectively, are determined as the troughs, and a plurality of peaks or troughs are obtained, that is, the extreme points in the spectral detection data are determined.

Then, based on the mapping relationship between the reflectance data and the wavelength, the detection wavelength data corresponding to the reflectance data corresponding to the peak or the trough is determined.

S122. In the spectrum detection data, select a set number of detection wavelength data in a set range centering on the detection wavelength data, and perform curve on the selected detection wavelength data and reflectance data corresponding to the wavelength data. The fitting process is performed to obtain a quadratic function.

S123. Determine a fitting coefficient of the quadratic function by using a numerical analysis method.

Here, the detection wavelength data corresponding to the peak or the trough is centered near the center, specifically, N data are respectively taken on the left side and the right side of the center (the data includes reflectance data and detection corresponding to the reflectance data) Wavelength data), as the wavelength increases, the number of acquisitions also increases; then the curve fitting is performed on the obtained 2N+1 data, and the Lagrange polynomial interpolation method is used to determine the fitting coefficient.

Wherein, the curve fitting process is performed on the selected detection wavelength data, and the quadratic function is obtained as follows:

f(x)=p ₁ x ² +p ₂ x+p ₃ ;

Using the Lagrangian polynomial interpolation method, the fitting coefficient p ₁ =0.01455, p ₂ =-23.03, p ₃ =9123;

S124. Determine a wavelength value corresponding to each extreme point according to the quadratic function and a fitting coefficient of the quadratic function.

Specifically, after determining the quadratic function and the fitting coefficient of the quadratic function, the quadratic function having the fitting coefficient corresponding to each peak or trough is derivatively obtained.

f'(x)=2p ₁ x+p ₂ ,

Bring the fit coefficient to get f' ^(x) = 2 * 0.01455 * x-23.03;

Let f'(x) = 0, by deriving: x = 791.47; similarly, by cubic curve fitting, we find: x = 791.77.

Further, in the method for detecting a spectral end point in the chemical mechanical polishing provided by the embodiment of the present invention, the extreme point includes a peak extreme point and a valley extreme point; and the step 13 includes two implementation manners, the first one:

In this way, the thickness of the film to be polished can be calculated according to any two adjacent peak extreme points; the thickness of the film to be polished can be calculated according to any two adjacent valley extreme points; or according to the adjacent peak value Point, trough extreme point, calculate the thickness of the film being thrown.

Second: Calculate the film to be polished according to the optical refractive index of the film being thrown and every two adjacent peak extreme points or every two adjacent valley extreme points or each adjacent peak extreme point and valley extreme point The thickness of each of the resulting film to be polished is averaged to obtain the thickness of the final film to be polished.

In this way, the thickness of the film to be polished is calculated according to any two adjacent peak extreme points; the thickness of the film to be polished is calculated according to any two adjacent valley extreme points; and the extreme points according to adjacent peaks The peak value of the trough is calculated, and the thickness of the film to be polished is calculated. The thickness of the plurality of films to be polished can be obtained by the above calculation, and finally the thicknesses of all the films to be polished are averaged to obtain the thickness of the final film to be polished.

The following three different methods are tried in the embodiments of the present invention:

1. Calculate the calculated value of the one-dimensional fast Fourier transform on the spectral detection data, as shown in Table 1.

It can be seen from the above table that the average film thickness calculated by one-dimensional fast Fourier transform is 1519.4 nm, and the absolute error is 10.4 nm compared with the standard film thickness, and the relative error is 0.68%.

2, quadratic fitting detection calculated value

It can be seen from the above table that the average film thickness calculated by one-dimensional fast Fourier transform and quadratic fitting is 1519.8 nm, and the absolute error is 10.8 nm and the relative error is 0.72% compared with the standard film thickness.

2, three fitting test calculation value

It can be seen from the above table that after one-dimensional fast Fourier transform and three-time fitting, the calculated average film thickness is 1525.0 nm, and the absolute error is 16 nm compared with the standard film thickness, and the relative error is 1.06%.

Based on the above three methods, one of the maximum value and the minimum value in the calculated data is eliminated, and then the average value is calculated to eliminate the interference error. With this method, the calculation is available:

FFT method: detected value: 1526.08 nm; optimized error: 17.08 nm; error before optimization: 10.4 nm.

Quadratic fitting method: detection value: 1516.91 nm; error after optimization: 7.91 nm; error before optimization: 10.8 nm;

Three-fitting method: detection value: 1521.53 nm; error after optimization: 12.53 nm; error before optimization: 16 nm.

According to the above method, after the data optimization is performed, the detection data of the FFT is deteriorated, and the detection data of the polynomial fitting is improved.

Considering the accuracy and accuracy of the detection, using the one-dimensional fast Fourier transform and the quadratic polynomial fitting method, and using the error reduction optimization algorithm, the detection data with higher precision can be obtained.

Embodiments of the present invention provide a method for detecting a spectral end point in chemical mechanical polishing, by performing fast Fourier transform (FFT) on the collected raw spectral data, obtaining a set of smooth spectral curves, and then performing a lattice on the spectral curve. The quadratic polynomial fitting of the Lange polynomial interpolation method determines the remaining thickness of the wafer surface film by deriving the wavelength value corresponding to the extreme point of the spectral curve, and finally determines the polishing end point of the chemical mechanical polishing. The advantage of this method is that compared with the traditional Fourier transform method, the fast Fourier transform shortens the processing time of spectral data, increases the number of effective wafer inspection points collected in the same time, and improves the efficiency of wafer end point detection. The method can better judge the polishing end point of wafer chemical mechanical polishing; secondly, the method reduces the influence of the light source intensity on the end point detection brought by chemical mechanical polishing, and the device user does not need to frequently correct the light source, thereby improving the working efficiency of the device. .

In another aspect, the detecting method provided by the embodiment of the present invention determines the remaining thickness of the film to be polished according to the wavelength value of at least two adjacent extreme points and the optical refractive index of the film to be polished, that is, when the polishing end point is reached. The flatness also meets the requirements.

In addition, if the wafer polishing end point is determined by pattern comparison, it does not reflect the throwing of the wafer surface film well. The method determines the flatness of the wafer surface film by real-time calculation of the thickness of the wafer surface film during the polishing process, thereby determining the polishing end point of the wafer.

Embodiments of the present invention provide a detecting device for a spectral end point in chemical mechanical polishing, which is used to perform a method for detecting a spectral end point in the above chemical mechanical polishing. Referring to FIG. 4, the device includes:

The obtaining module 20 is configured to determine the smoothed spectral detection data of the polished film according to the spectral detection data of the wafer surface being polished, the spectral detection data including the associated reflectance data and the detected wavelength data;

The first determining module 30 is configured to determine an extreme point in the smoothed spectral detection data and a wavelength corresponding to each extreme point according to the correlated reflectance data and the detected wavelength data in the smoothed spectral detection data. value;

a second determining module 40 configured to determine a remaining thickness of the film to be polished according to a wavelength value of the at least two adjacent extreme points and an optical refractive index of the film to be polished;

The third determining module 50 is configured to determine the remaining thickness as a polishing end point when the remaining thickness of the film being thrown reaches a set thickness threshold, so that the chemical mechanical polishing apparatus stops polishing at the polishing end point.

Further, referring to FIG. 5, in the apparatus for detecting a spectral end point in chemical mechanical polishing according to an embodiment of the present invention, the obtaining module 20 includes:

The acquiring unit 201 is configured to acquire spectral detection data of the wafer surface being polished;

The filter processing unit 202 is configured to perform one-dimensional fast Fourier transform on the spectral detection data to obtain transformed spectral detection data, and perform filtering processing on the transformed spectral detection data to eliminate the transformed spectral detection data. Interference data; inverse Fourier transform of the filtered spectral detection data to obtain smooth spectral detection data.

Further, in the apparatus for detecting the spectral end point in the chemical mechanical polishing according to the embodiment of the present invention, the filter processing unit 202 is specifically configured to perform absolute value operation processing on the converted spectral detection data to obtain positive real spectrum detection data; The threshold value is set, and positive real-spectrum detection data smaller than the set threshold value is excluded from the positive real-spectrum detection data to obtain remaining spectral detection data.

Further, referring to FIG. 5, in the apparatus for detecting a spectral end point in the chemical mechanical polishing provided by the embodiment of the present invention, the first determining module 30 includes:

The comparing unit 301 is configured to compare the reflectance data in the smoothed spectral detection data, and determine an extreme point in the spectral detection data and detection wavelength data corresponding to the extreme point;

The curve fitting processing unit 302 is configured to select, in the spectral detection data, a set number of detection wavelength data within a set range, centering on the detection wavelength data, and the selected detection wavelength data and the wavelength The reflectance data corresponding to the data is subjected to curve fitting processing to obtain a quadratic function;

The first determining unit 303 is configured to determine a fitting coefficient of the quadratic function by using a numerical analysis method;

The second determining unit 304 is configured to determine a wavelength value corresponding to each extreme point according to the quadratic function and the fitting coefficient of the quadratic function.

Further, in the apparatus for detecting a spectral end point in chemical mechanical polishing according to an embodiment of the present invention, the extreme point includes a peak extreme point and a valley extreme point; and the second determining module 40 is specifically configured to be according to a film to be polished. The optical refractive index and any two adjacent peak extreme points or two adjacent valley extreme points or adjacent peak extreme points, trough extreme points, calculate the thickness of the film being thrown.

Further, in the apparatus for detecting a spectral end point in chemical mechanical polishing according to an embodiment of the present invention, the extreme point includes: a peak extreme point and a valley extreme point; and the second determining module 40 is specifically configured to be thrown according to the Calculate the thickness of the film being thrown by the optical refractive index of the film and every two adjacent peak extreme points or every two adjacent valley extreme points or each adjacent peak extreme point, trough extreme point; The thickness of the film to be polished is averaged to obtain the thickness of the final film to be polished.

Embodiments of the present invention provide a detection device for a spectral end point in chemical mechanical polishing, which performs a Fast Fourier Transform (FFT) on the acquired raw spectral data to obtain a set of smooth spectral curves, and then performs a lattice on the spectral curve. The quadratic polynomial fitting of the Lange polynomial interpolation method determines the remaining thickness of the wafer surface film by deriving the wavelength value corresponding to the extreme point of the spectral curve, and finally determines the polishing end point of the chemical mechanical polishing. The advantage of this method is that compared with the traditional Fourier transform method, the fast Fourier transform shortens the processing time of spectral data, increases the number of effective wafer inspection points collected in the same time, and improves the efficiency of wafer end point detection. The method can better judge the polishing end point of wafer chemical mechanical polishing; secondly, the method reduces the influence of the light source intensity on the end point detection brought by chemical mechanical polishing, and the device user does not need to frequently correct the light source, thereby improving the working efficiency of the device. .

Embodiments of the present invention provide a detection system for spectral end points in chemical mechanical polishing, with reference to FIG. 6, including: a light source 1, an optical sensor 2, and a server 3;

The light source 1 is configured to emit light waves to the wafer surface by a thin film;

The optical sensor 2 is configured to receive a reflected light wave that is reflected by the film on the surface of the wafer, and send the reflected light wave to the server; the reflected light wave carries spectral detection data;

The server 3 is configured to receive the reflected light wave, extract spectral detection data of the wafer surface from the reflected light wave, and determine smooth spectral detection data of the polished film according to the spectral detection data. The spectral detection data includes associated reflectance data and detected wavelength data; determining extremum points in the smoothed spectral detection data according to the correlated reflectance data and the detected wavelength data in the smoothed spectral detection data; a wavelength value corresponding to each extreme point; determining a remaining thickness of the film to be polished according to a wavelength value of at least two adjacent extreme points and an optical refractive index of the film to be polished; and detecting a remaining thickness of the film to be polished When the set thickness threshold is reached, the remaining thickness is determined to be the polishing end point so that the chemical mechanical polishing apparatus stops polishing at the polishing end point.

Embodiments of the present invention provide a detection system for spectral end points in chemical mechanical polishing. By performing fast Fourier transform (FFT) on the collected raw spectral data, a set of smooth spectral curves is obtained, and then the spectral curves are latticed. The quadratic polynomial fitting of the Lange polynomial interpolation method determines the remaining thickness of the wafer surface film by deriving the wavelength value corresponding to the extreme point of the spectral curve, and finally determines the polishing end point of the chemical mechanical polishing. The advantage of this method is that compared with the traditional Fourier transform method, the fast Fourier transform shortens the processing time of spectral data, increases the number of effective wafer inspection points collected in the same time, and improves the efficiency of wafer end point detection. The method can better judge the polishing end point of wafer chemical mechanical polishing; secondly, the method reduces the influence of the light source intensity on the end point detection brought by chemical mechanical polishing, and the device user does not need to frequently correct the light source, thereby improving the working efficiency of the device. .

The detecting device for the spectral end point in the chemical mechanical polishing provided by the embodiment of the present invention may be specific hardware on the device or software or firmware installed on the device. The implementation principle and the technical effects of the device provided by the embodiments of the present invention are the same as those of the foregoing method embodiments. For a brief description, where the device embodiment is not mentioned, reference may be made to the corresponding content in the foregoing method embodiments. A person skilled in the art can clearly understand that for the convenience and brevity of the description, the specific working processes of the foregoing system, the device and the unit can refer to the corresponding processes in the foregoing method embodiments, and details are not described herein again.

An embodiment of the present invention further provides a computer readable storage medium having stored thereon a computer program that, when executed, implements the above-described method for detecting a spectral endpoint in chemical mechanical polishing.

In the embodiments provided by the present invention, it should be understood that the disclosed apparatus and method may be implemented in other manners. The device embodiments described above are merely illustrative. For example, the division of the unit is only a logical function division. In actual implementation, there may be another division manner. For example, multiple units or components may be combined or Can be integrated into another system, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection through some communication interface, device or unit, and may be electrical, mechanical or otherwise.

The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, may be located in one place, or may be distributed to multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of the embodiment.

In addition, each functional unit in the embodiment provided by the present invention may be integrated into one processing unit, or may be Each unit may exist physically separately, or two or more units may be integrated into one unit.

The functions may be stored in a computer readable storage medium if implemented in the form of a software functional unit and sold or used as a standalone product. Based on such understanding, the technical solution of the present invention, which is essential or contributes to the prior art, or a part of the technical solution, may be embodied in the form of a software product, which is stored in a storage medium, including The instructions are used to cause a computer device (which may be a personal computer, server, or network device, etc.) to perform all or part of the steps of the methods described in various embodiments of the present invention. The foregoing storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk, and the like. .

It should be noted that similar reference numerals and letters indicate similar items in the following figures. Therefore, once an item is defined in a drawing, it is not necessary to further define and explain it in the subsequent drawings. Moreover, the terms "first", "second", "third", and the like are used merely to distinguish a description, and are not to be construed as indicating or implying a relative importance.

Finally, it should be noted that the above-mentioned embodiments are merely specific embodiments of the present invention, and are used to explain the technical solutions of the present invention, and are not limited thereto, and the scope of protection of the present invention is not limited thereto, although reference is made to the foregoing. The present invention has been described in detail, and those skilled in the art should understand that any one skilled in the art can still modify the technical solutions described in the foregoing embodiments within the technical scope disclosed by the present invention. The changes may be easily conceived, or equivalents may be substituted for some of the technical features. The modifications, variations, and substitutions of the present invention do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention. All should be covered by the scope of the present invention. Therefore, the scope of the invention should be determined by the scope of the appended claims.

Industrial applicability

The method, device, system and computer readable storage medium for detecting the spectral end point in the chemical mechanical polishing of the present invention, according to the spectral detection data of the wafer surface being polished, by calculating the remaining thickness of the wafer surface being polished, determining the The thickness of the polishing film is the polishing end point, which improves the detection accuracy of the spectral end point, and thus can more accurately detect whether the polished wafer surface meets the standard requirements.

Claims

A method for detecting a spectral endpoint in chemical mechanical polishing, comprising:

Determining smooth spectral detection data of the polished film according to spectral detection data of the wafer surface being polished, the spectral detection data including associated reflectance data and detection wavelength data;

Determining an extreme point in the smoothed spectral detection data and a wavelength value corresponding to each extreme point according to the correlated reflectance data and the detected wavelength data in the smoothed spectral detection data;

Determining the remaining thickness of the film to be polished according to the wavelength values of the at least two adjacent extreme points and the optical refractive index of the film being polished;

Upon detecting that the remaining thickness of the film being thrown reaches a set thickness threshold, the remaining thickness is determined to be a polishing end point to cause the chemical mechanical polishing apparatus to stop polishing at the polishing end point.
The method for detecting a spectral endpoint in chemical mechanical polishing according to claim 1, wherein the determining the smooth spectral detection data of the polished film according to the spectral detection data of the wafer surface being polished, comprises:

Obtaining spectral detection data of the wafer surface being polished;

Performing one-dimensional fast Fourier transform on the spectral detection data to obtain transformed spectral detection data;

Filtering the transformed spectral detection data to eliminate interference data in the transformed spectral detection data;

The inverse Fourier transform is performed on the filtered spectral detection data to obtain smooth spectral detection data.
The method for detecting a spectral endpoint in chemical mechanical polishing according to claim 2, wherein the filtering the transformed spectral detection data to eliminate interference data in the transformed spectral detection data comprises:

Performing an absolute value operation on the transformed spectral detection data to obtain positive real spectrum detection data;

The positive real-spectrum detection data smaller than the set threshold value is removed from the positive real-spectrum detection data according to the set threshold value, and the remaining spectral detection data is obtained.
The method for detecting a spectral end point in chemical mechanical polishing according to any one of claims 1 to 3, wherein the determining the said reflectance data and the detected wavelength data in the smoothed spectral detection data Extreme points in smooth spectral detection data, including:

Forming a smooth curve according to the smoothed spectral detection data, comparing the plurality of reflectance data in the smoothed spectral detection data, and determining reflectance data in the smooth curve that is greater than the adjacent reflectance data respectively as The peaks, or the reflectance data in the smooth curve which is smaller than the adjacent reflectance data, respectively, are determined as the troughs, and a plurality of peaks or troughs are obtained, that is, the extreme points in the spectral detection data are determined.
The method for detecting a spectral endpoint in chemical mechanical polishing according to any one of claims 1 to 4, wherein said determining said said data based on said reflectance data and said detected wavelength data in said smoothed spectral detection data The wavelength values corresponding to each extreme point in the smoothed spectral detection data, including:

Comparing the reflectance data in the smoothed spectral detection data to determine detection wavelength data corresponding to the extreme point in the spectral detection data;

In the spectral detection data, a set number of detection wavelength data in a set range is selected centering on the detection wavelength data, and curve matching is performed on the selected detection wavelength data and reflectance data corresponding to the wavelength data. Processing to obtain a quadratic function;

Using a numerical analysis method, determining a fitting coefficient of the quadratic function;

A wavelength value corresponding to each extreme point is determined according to the quadratic function and the fitting coefficient of the quadratic function.
The method for detecting a spectral endpoint in chemical mechanical polishing according to claim 5, wherein the manner of determining the fitting coefficient of the quadratic function comprises:

N data are respectively taken on the left and right sides of the center centering on the detection wavelength data corresponding to the peak or the trough; then the curve fitting is performed on the obtained 2N+1 data, and the Lagrangian polynomial interpolation method is adopted. The fitting coefficient is determined, where N is a natural number greater than or equal to 1, and the value of N is positively correlated with the wavelength.
The method for detecting a spectral endpoint in chemical mechanical polishing according to any one of claims 1 to 6, wherein said extreme point comprises a peak extreme point and a valley extreme point; said according to at least two adjacent The wavelength value of the extreme point and the optical refractive index of the film being thrown determine the remaining thickness of the film to be polished, including:

The thickness of the film to be polished is calculated based on the optical refractive index of the film being thrown and any two adjacent peak extreme points or two adjacent valley extreme points or adjacent peak extreme points and valley extreme points.
The method for detecting a spectral endpoint in chemical mechanical polishing according to any one of claims 1 to 7, wherein said extreme point comprises: a peak extreme point and a valley extreme point; said according to at least two phases The wavelength value of the adjacent extreme point and the optical refractive index of the film being polished determine the remaining thickness of the film to be polished, including:

Calculating the thickness of the film to be polished according to the optical refractive index of the film to be polished and every two adjacent peak extreme points or every two adjacent valley extreme points or each adjacent peak extreme point and valley extreme point;

The thickness of all the resulting film to be polished is averaged to obtain the thickness of the final film to be polished.
A device for detecting a spectral end point in chemical mechanical polishing, comprising:

An acquisition module configured to determine smooth spectral detection data of the polished film according to spectral detection data of a wafer surface being polished, the spectral detection data including associated reflectance data and detection wavelength data;

a first determining module, configured to determine an extreme point in the smoothed spectral detection data and a wavelength value corresponding to each extreme point according to the correlated reflectance data and the detected wavelength data in the smoothed spectral detection data ;

a second determining module configured to determine a remaining thickness of the film to be polished according to a wavelength value of the at least two adjacent extreme points and an optical refractive index of the film to be polished;

The third determining module is configured to determine the remaining thickness as a polishing end point when the remaining thickness of the film being thrown reaches a set thickness threshold, so that the chemical mechanical polishing apparatus stops polishing at the polishing end point.
The apparatus for detecting a spectral endpoint in chemical mechanical polishing according to claim 9, wherein the acquisition module comprises:

An acquisition unit configured to acquire spectral detection data of a wafer surface being polished;

a filter processing unit configured to perform one-dimensional fast Fourier transform on the spectral detection data to obtain transformed spectral detection data; perform filtering processing on the transformed spectral detection data, and cull the transformed spectral detection data Interference data; inverse Fourier transform of the filtered spectral detection data to obtain smooth spectral detection data.
The apparatus for detecting a spectral end point in chemical mechanical polishing according to claim 10, wherein the filter processing unit is specifically configured to perform absolute value calculation processing on the converted spectral detection data to obtain positive real spectrum detection data. And subtracting the positive real-spectrum detection data smaller than the set threshold from the positive real-spectrum detection data according to the set threshold, to obtain the remaining spectral detection data.
The apparatus for detecting a spectral end point in chemical mechanical polishing according to any one of claims 9 to 11, wherein the first determining module determines an extreme point and each extreme value in the smoothed spectral detection data. Ways to point, including:

Forming a smooth curve according to the smoothed spectral detection data, comparing the plurality of reflectance data in the smoothed spectral detection data, and determining reflectance data in the smooth curve that is greater than the adjacent reflectance data respectively as The peaks, or the reflectance data in the smooth curve which is smaller than the adjacent reflectance data, respectively, are determined as the troughs, and a plurality of peaks or troughs are obtained, that is, the extreme points in the spectral detection data are determined.
The apparatus for detecting a spectral endpoint in chemical mechanical polishing according to any one of claims 9 to 12, wherein the first determining module determines a wavelength value corresponding to each extreme point in the smoothed spectral detection data. Ways to include:

Comparing the reflectance data in the smoothed spectral detection data to determine detection wavelength data corresponding to the extreme point in the spectral detection data;

In the spectral detection data, a set number of detection wavelength data in a set range is selected centering on the detection wavelength data, and curve matching is performed on the selected detection wavelength data and reflectance data corresponding to the wavelength data. Processing to obtain a quadratic function;

Using a numerical analysis method, determining a fitting coefficient of the quadratic function;

A wavelength value corresponding to each extreme point is determined according to the quadratic function and the fitting coefficient of the quadratic function.
The apparatus for detecting a spectral endpoint in chemical mechanical polishing according to claim 13, wherein the manner of determining the fitting coefficient of the quadratic function comprises:

N data are respectively taken on the left and right sides of the center centering on the detection wavelength data corresponding to the peak or the trough; then the curve fitting is performed on the obtained 2N+1 data, and the Lagrangian polynomial interpolation method is adopted. The fitting coefficient is determined, where N is a natural number greater than or equal to 1, and the value of N is positively correlated with the wavelength.
The apparatus for detecting a spectral end point in chemical mechanical polishing according to any one of claims 9 to 14, wherein the extreme point includes a peak extreme point and a valley extreme point;

The second determining module is configured to be configured according to an optical refractive index of the film to be polished and any two adjacent peak extreme points or two adjacent valley extreme points or adjacent peak extreme points and valley extreme points. Calculate the thickness of the film being thrown.
The apparatus for detecting a spectral end point in chemical mechanical polishing according to any one of claims 9 to 15, wherein the extreme point includes a peak extreme point and a valley extreme point;

The second determining module is configured to be configured according to an optical refractive index of the film to be polished and every two adjacent peak extreme points or every two adjacent valley extreme points or each adjacent peak extreme point, a valley extreme value Point, calculate the thickness of the film to be polished; average the thickness of all the films to be polished to obtain the thickness of the final film to be polished.
A detection system for spectral end points in chemical mechanical polishing, comprising: a light source, an optical sensor and a server;

The light source is configured to emit light waves to the wafer surface by a thin film;

The optical sensor is configured to receive a reflected light wave that is reflected by a film on a surface of the wafer, and send the reflected light wave to the server; the reflected light wave carries spectral detection data;

The server is configured to receive the reflected light wave, extract spectral detection data of the wafer surface from the reflected light wave, and determine a smooth spectral detection of the polished film according to the spectral detection data Data, the spectral detection data includes associated reflectance data and detected wavelength data; determining extremum points in the smoothed spectral detection data based on the associated reflectance data and detected wavelength data in the smoothed spectral detection data And a wavelength value corresponding to each extreme point; determining a remaining thickness of the film to be polished according to a wavelength value of at least two adjacent extreme points and an optical refractive index of the film to be polished; and detecting the remaining of the film to be polished When the thickness reaches the set thickness threshold, it is determined that the remaining thickness is the polishing end point, so that the chemical mechanical polishing apparatus stops polishing at the polishing end point.
A computer readable storage medium having stored thereon a computer program, wherein the computer program, when executed, implements the method of detecting a spectral endpoint in chemical mechanical polishing according to any one of claims 1-8.