Reflectivity spectrum acquisition method, end point detection method and device and polishing device

Abstract

The invention relates to a reflectivity spectrum obtaining method, an end point detection method and device and a polishing device.The reflectivity spectrum obtaining method comprises the steps that an influence factor distribution curve representing light intensity measured value volatility under different light intensity light source conditions is obtained, a critical light intensity value corresponding to the dominant light source factor is determined based on the influence factor distribution curve, and the critical light intensity value is calculated according to the critical light intensity value. The source light beam is split according to a preset proportion beta to obtain a required measurement light beam and a reference light beam, and the measurement light beam enters a sample to form a reflection light beam; the reflected light intensity is calibrated based on the reference light intensity to generate a target reflected light intensity. And calculating the reflectivity spectrum of the sample based on the target reflection light intensity. Wherein the measuring light beam and the reference light beam have the same light intensity volatility, so that when the reflected light intensity is calibrated based on the reference light intensity, the accuracy and the stability of reflectivity spectrum measurement are effectively improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of chemical mechanical polishing, and in particular to a reflectivity spectrum acquisition method, an endpoint detection method and device, and a polishing device. BACKGROUND

[0002] Chemical mechanical polishing (CMP) is an important process step in the manufacturing process of semiconductor integrated circuit chips. The chemical mechanical polishing process uses a polishing pad and a polishing liquid to grind a wafer or a thin film, and realizes the planarization of the surface topography of the wafer or the thin film through a combination of mechanical and chemical methods. An important problem in chemical mechanical polishing is the endpoint determination problem of the polishing process, that is, determining whether the polishing process is complete and whether the target layer of the wafer or the thin film has been planarized to the desired flatness and thickness. Therefore, an endpoint detection (EPD) system capable of determining the thickness of the film layer during the polishing process is very important for chemical mechanical polishing. The endpoint detection based on spectral detection technology mainly uses the optical interference principle. A wide-spectrum light source capable of covering the visible light band range is used to emit a light beam as a measurement light to the surface of the thin film. The reflected light from the upper interface of the thin film will interfere with the reflected light from the lower interface of the thin film to form a reflected spectrum. Finally, a detector with spectral detection capability is used to obtain the reflected spectrum information related to the thickness of the thin film. When the dispersion model of the dielectric constant of the given thin film material and the model of the thin film layer structure are given, the reflected spectrum is only related to the wavelength and the thickness of the thin film. Therefore, in a given wide-spectrum wavelength range, the thickness of the thin film can be calculated by using the inverse algorithm of the measured reflected spectrum. In actual application, the spectral characteristics of the light source will seriously affect the shape of the reflected spectrum. Therefore, the reflected spectrum is divided by the light source spectrum to eliminate the influence of the light source spectrum characteristics, and a normalized reflectivity spectrum is obtained. During the measurement process, different thicknesses of the thin film will correspond to different reflectivity spectra. Therefore, the thickness of the thin film can be calculated by using the inverse algorithm of the obtained reflectivity spectrum, or the reflectivity spectrum can be directly used to determine whether the grinding of the wafer or the thin film in the chemical mechanical polishing has reached the endpoint.

[0003] At present, in the endpoint detection process of chemical mechanical polishing based on spectral detection technology, in order to meet the system life and dense sampling requirements, the system light source often uses a wide-spectrum light source that can realize high-frequency pulse flashing. In order to ensure the stability of the output light of the flashing wide-spectrum light source, a reference system for detecting light intensity fluctuations is applied in the endpoint detection. The reference light intensity fluctuations detected by the reference system are mainly used to feed back to the controller, and then the controller adjusts the voltage of the light source to ensure the stability of the measurement light intensity. However, the measurement light intensity and the reference light intensity fluctuations are inconsistent, which leads to poor accuracy of the light intensity calibration, and further affects the accuracy of the endpoint detection. SUMMARY

[0004] To overcome the problems in the prior art, the present application provides a reflectivity spectrum acquisition method, an endpoint detection method and device, and a polishing device.

[0005] According to a first aspect of an embodiment of the present application, a reflectivity spectrum acquisition method is provided, comprising:

[0006] An influence factor distribution curve is acquired, which characterizes the fluctuation of light intensity measurement values under different light intensity light source conditions, and the influence factor distribution curve comprises a detector factor distribution curve and a light source factor distribution curve;

[0007] Based on the influence factor distribution curve, a critical light intensity value I critical (λ) corresponding to a situation in which the light source factor is dominant is determined, wherein λ is any one wavelength value in the wavelength range of the light source;

[0008] The light source is subjected to homogenization and convergence processing to obtain a source light beam in which the light intensity fluctuation at each position of the light emitting surface is consistent;

[0009] The source light beam is split according to a preset proportion β to obtain a required measurement light beam and a reference light beam, the measurement light beam forms a reflected light beam after being incident on a sample, and the reference light intensity I reference (t, λ) and the reflected light intensity I reflecton (t, λ) of the reflected light beam satisfy the relationship: I reflecton (t, λ) ≥ I reference (t, λ) ≥ I critical (λ), wherein t is a light intensity collection time;

[0010] Based on the reference light intensity I reference (t, λ), the reflected light intensity I reflecton (t, λ) is calibrated to generate a target reflected light intensity I' reflecton (t, λ);

[0011] Based on the target reflected light intensity I' reflecton (t, λ), the reflectivity spectrum R meas (t, λ) of the sample is calculated.

[0012] In some embodiments, the detector factor distribution curve is acquired, comprising:

[0013] A reference test light beam is provided, and the reference test light beam is a wide-band light beam;

[0014] The output light intensity of the reference test light beam at different wavelengths is collected by a detector multiple times;

[0015] acquiring output light intensity noise of the reference test light beam and output light intensity average value of the reference test light beam at different wavelengths, or acquiring output light intensity signal-to-noise ratio of the reference test light beam and output light intensity average value of the reference test light beam at different wavelengths;

[0016] establishing a first relationship curve of the output light intensity noise of the reference test light beam and the output light intensity average value of the reference test light beam, or establishing a second relationship curve of the output light intensity signal-to-noise ratio of the reference test light beam and the output light intensity average value of the reference test light beam;

[0017] acquiring a light source factor distribution curve, comprising:

[0018] using the detector to collect output light intensity of the source light beam at different wavelengths in the wavelength range multiple times;

[0019] acquiring output light intensity noise of the light source and output light intensity average value of the light source at different wavelengths, or acquiring output light intensity signal-to-noise ratio of the light source and output light intensity average value of the light source at different wavelengths;

[0020] establishing a third relationship curve of the output light intensity noise of the light source and the output light intensity average value of the light source, or establishing a fourth relationship curve of the output light intensity signal-to-noise ratio of the light source and the output light intensity average value of the light source.

[0021] In some embodiments, the determining of the critical light intensity value I critical (λ) when the light source factor is dominant based on the factor distribution curve comprises:

[0022] acquiring a first intersection of the first relationship curve and the third relationship curve, determining a first light intensity value corresponding to the first intersection, and selecting any light intensity value greater than or equal to the first light intensity value as the critical light intensity value I critical (λ); or

[0023] acquiring a second intersection of the second relationship curve and the fourth relationship curve, determining a second light intensity value corresponding to the second intersection, and selecting any light intensity value greater than or equal to the second light intensity value as the critical light intensity value I critical (λ).

[0024] In some embodiments, the splitting of the source light beam according to the preset proportion β comprises:

[0025] using a fiber beam splitter or a beam splitter to split light at each position on the light emitting surface of the source light beam according to the preset proportion β.

[0026] In some embodiments, the preset ratio β is a preset ratio of a measurement light intensity I reflecton (t, λ) of the measurement light beam to a reference light intensity I reflecton (t, λ) of the reference light beam.

[0027] The preset ratio β satisfies:

[0028]

[0029] Wherein, S is a light source intensity, α is a loss coefficient of the measurement light beam in the transmission process, I critical (λ) is the critical light intensity value.

[0030] The loss coefficient α is obtained based on a measurement light intensity I measure (t, λ) and a reflected light intensity I reflecton (t, λ) of the reference light beam.

[0031]

[0032] In some embodiments, the reflected light intensity I reference (t, λ) is calibrated based on the reference light intensity I reflecton (t, λ) to generate a target reflected light intensity I’ reflecton (t, λ).

[0033] A time point t0 in the acquisition time period is selected, and the reference light intensity I reference (t0, λ) at t0 is set as a reference initial value.

[0034] The I reflecton (t, λ) is corrected according to the following formula to obtain the target reflected light intensity I’ reflecton (t, λ).

[0035]

[0036] In some embodiments, the reflectivity spectrum R reflecton (t, λ) of the sample is calculated based on the target reflected light intensity I’ meas (t, λ), comprising:

[0037] The reflectivity spectrum R meas (t, λ) is obtained based on the following formula:

[0038]

[0039] Wherein, R S i(λ) is a known reflectivity spectrum of a reference bare silicon sample, ISi(λ) is a reflected light intensity of the reference bare silicon sample, and I black(λ) is the stray light intensity of the measuring system.

[0040] According to a second aspect of the embodiments of the present application, there is provided a method for endpoint detection, comprising: meas (t, λ) is obtained by the method for obtaining reflectance spectrum according to any one of the first aspect of the embodiments of the present application; meas (t, λ) is obtained by the method for obtaining reflectance spectrum according to any one of the first aspect of the embodiments of the present application;

[0041] a film thickness d of the sample is calculated based on the reflectance spectrum R meas (t, λ);

[0042] a chemical mechanical polishing endpoint is determined based on the film thickness d.

[0043] According to a third aspect of the embodiments of the present application, there is provided an endpoint detection device, comprising:

[0044] a light source for emitting a light source beam;

[0045] a light beam homogenization and convergence processor for processing the light source beam to obtain a source light beam with consistent light intensity fluctuation at each position of a light emitting surface;

[0046] a light beam splitter for splitting the source light beam according to a preset proportion β to obtain a measurement light beam and a reference light beam, the measurement light beam forms a reflected light beam after being incident on a sample, and the reference light intensity I reference (t, λ) and the reflected light intensity I reflecton (t, λ) of the reflected light beam satisfy the relationship: I reflecton (t, λ) ≥ I reference (t, λ) ≥ I critical (λ), I critical (λ) is a critical light intensity value corresponding to a case where the light source factor dominates;

[0047] a detector module for obtaining the reflected light intensity I reflecton (t, λ) of the reflected light beam and the reference light intensity I reference (t, λ) of the reference light beam;

[0048] a control processor, the control processor being electrically connected with the detector module;

[0049] the control processor is further configured to:

[0050] calibrate the reflected light intensity I reference (t, λ) according to the reference light intensity I reflecton (t, λ) to generate a target reflected light intensity I’ reflecton (t, λ);

[0051] based on the target reflected light intensity I reflecton (t, λ), calculate the reflectivity spectrum R meas (t, λ) of the sample.

[0052] based on the reflectivity spectrum R meas (t, λ) collected in real time, calculate the film thickness d of the sample at the corresponding time point t, and determine the chemical mechanical polishing endpoint based on the film thickness d.

[0053] According to a fourth aspect of the embodiments of the present application, a polishing device is provided, which comprises the endpoint detection device according to the third aspect.

[0054] The technical scheme provided by the embodiments of the present application can have the following beneficial effects: The reflectivity spectrum acquisition method of the embodiments of the present application can homogenize the light intensity fluctuations at different positions of the light emitting surface of the light source at the convergence point through homogenization and convergence processing of the light source, that is, make the different fluctuations at different positions or regions of the original light emitting surface of the light source uniformly distributed at each position or region of the converged light emitting surface, so as to obtain a source light beam in which the light intensity fluctuations and fluctuation components at each position or region of the converged light emitting surface are consistent. Based on the source light beam, the measurement light beam and the reference light beam are obtained by splitting light, so that the measurement light beam and the reference light beam have the same light intensity fluctuation, that is, the problem of inconsistent light intensity fluctuations of the measurement light beam and the reference light beam caused by the light intensity distribution of the light source is solved.

[0055] By setting the splitting ratio β split, the reference light intensity I reference (t, λ) of the reference light beam, the reflected light intensity I reflecton (t, λ) of the reflected light beam and the critical light intensity value I critical (λ) satisfy the relationship: I reflecton (t, λ) ≥ I reference (t, λ) ≥ I critical (λ), so that the dominant influencing factors of the reflected light intensity I reflecton (t, λ) and the reference light intensity I reference (t, λ) are both light source factors, the influence of the detector factor in the reflected light intensity I reflecton (t, λ) and the reference light intensity I reference (t, λ) is weakened, and because the fluctuation of the measurement light beam and the reference light beam after homogenization is consistent, the fluctuation of the reflected light intensity I reflecton (t, λ) and the reference light intensity I reference (t, λ) caused by the light source factor is also consistent.

[0056] Therefore, the reflectivity spectrum acquisition method of the present embodiment can obtain the reflected light intensity I reflecton (t, λ) and the reference light intensity I reference(t, λ), and then the reference light intensity I reference (t, λ) to the reflected light intensity I reflecton (t, λ) to the reflected light intensity I BRIEF DESCRIPTION OF DRAWINGS

[0057] The accompanying drawings, which are incorporated herein and form a part of the specification, illustrate embodiments consistent with the present application and, together with the description, further serve to explain the principles of the application.

[0058] Figure 1 is a flow chart of a reflectance spectrum acquisition method according to an exemplary embodiment.

[0059] Figure 2a is a distribution curve of factors affecting light intensity measurement value fluctuation according to an exemplary embodiment.

[0060] Figure 2b is a distribution curve of factors affecting light intensity measurement value fluctuation according to another exemplary embodiment.

[0061] Figure 3a is a diagram showing reflected light intensity fluctuation and reference light intensity fluctuation in the related art.

[0062] Figure 3b is a diagram showing reflected light intensity fluctuation and reference light intensity fluctuation according to an exemplary embodiment.

[0063] Figure 4 is a comparison diagram of reflected light intensity stability before and after correction according to an exemplary embodiment.

[0064] Figure 5 is a diagram of an endpoint detection device according to an exemplary embodiment.

[0065] Figure 6 is a diagram of a polishing device according to an exemplary embodiment. DETAILED DESCRIPTION

[0066] The exemplary embodiments will be described in detail herein below with reference to the drawings. In the following description, the same drawings reference numbers are used to denote the same elements throughout the several views. The embodiments described in the following exemplary embodiments are not representative of all embodiments consistent with the present application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of the present application as detailed in the appended claims.

[0067] To solve the above technical problems, according to a first aspect of an embodiment of the present application, a reflectance spectrum acquisition method is provided, as shown in the formula (1), the reflectance spectrum acquisition method comprises the following steps: Figure 1

[0068] An influence factor distribution curve is acquired, which characterizes fluctuation of the light intensity measurement value under different light intensity light source conditions, and the influence factor distribution curve comprises a detector factor distribution curve and a light source factor distribution curve.

[0069] Based on the influence factor distribution curve, a critical light intensity value I critical (λ) corresponding to a situation in which the light source factor is dominant is determined, wherein λ is an arbitrary wavelength value in a light source wavelength range.

[0070] The light source is subjected to homogenization and convergence processing, so as to acquire a source light beam in which light intensity fluctuation is consistent at each position of a light emitting surface.

[0071] The source light beam is split according to a preset proportion β, so as to obtain a required measurement light beam and a reference light beam, the measurement light beam forms a reflected light beam after being incident on a sample, and the reference light intensity I reference (t, λ) and the reflected light intensity I reflecton (t, λ) of the reflected light beam satisfy the relationship: I reflecton (t, λ) ≥ I reference (t, λ) ≥ I critical (λ), wherein t is a light intensity collection time.

[0072] Based on the reference light intensity I reference (t, λ), the reflected light intensity I reflecton (t, λ) is calibrated, so as to generate a target reflected light intensity I' reflecton (t, λ).

[0073] Based on the target reflected light intensity I' reflecton (t, λ), a reflectance spectrum R meas (t, λ) of the sample is calculated.

[0074] The reflectance spectrum acquisition method of the embodiment of the present application can homogenously distribute light intensity fluctuation at different positions of a light emitting surface of a light source at a convergence point through homogenization and convergence processing of the light source, that is, different fluctuations of different positions or regions of an original light emitting surface of the light source are homogenously distributed at each position or region of a converged light emitting surface, so as to obtain a source light beam in which light intensity fluctuation and fluctuation components of each position or region of the converged light emitting surface are consistent, and the measurement light beam and the reference light beam are obtained based on the source light beam, so that the measurement light beam and the reference light beam have the same light intensity fluctuation, that is, the problem that light intensity distribution factors of the light source cause light intensity fluctuation of the measurement light beam and the reference light beam to be inconsistent is solved.

[0075] ​The reference light intensity I reference (t, λ) of the reference light beam and the reflected light intensity I reflecton (t, λ) of the reflected light beam satisfy the relationship: I critical (t, λ) ≥ I reflecton (t, λ) ≥ I reference (t, λ) ≥ I critical (λ), the reflected light intensity I reflecton (t, λ) and the reference light intensity I reference (t, λ) are mainly affected by the light source factor, and the influence of the detector factor in the reflected light intensity I reflecton (t, λ) and the reference light intensity I reference (t, λ) is weakened, and at the same time, because the fluctuation of the measurement light beam and the reference light beam after the homogenization treatment is consistent, the fluctuation of the reflected light intensity I reflecton (t, λ) and the reference light intensity I reference (t, λ) caused by the light source factor is also consistent.

[0076] Based on this, the reflectivity spectrum acquisition method of the embodiment can obtain the reflected light intensity I reflecton (t, λ) and the reference light intensity I reference (t, λ) with consistent light intensity fluctuations, and further can use the reference light intensity I reference (t, λ) to accurately correct and calibrate the light intensity fluctuation of each wavelength in the reflected light intensity I reflecton (t, λ), so as to obtain a reflectivity spectrum with high stability, improve the precision of spectral detection, and thus improve the stability and accuracy of EPD in CMP.

[0077] It can be understood that the fluctuation of light intensity is evaluated by the light intensity measurement value collected by the detector, which is affected by two factors: the fluctuation of the light source itself and the intrinsic characteristics of the detector. In the embodiment, the detector factor distribution curve and the light source factor distribution curve are obtained respectively to represent the influence of the light source and the detector on the light intensity fluctuation.

[0078] For example, the detector factor distribution curve is used to represent the influence of the background signal fluctuation of the detector on the light intensity measurement value under different light intensities, and the detector factor distribution curve is obtained by the following method:

[0079] A reference test light beam is provided, which is a wide-band light beam.

[0080] The output light intensity of the reference test light beam at different wavelengths is collected by the detector multiple times.

[0081] The output light intensity noise of the reference test light beam corresponding to different wavelengths and the output light intensity average value of the reference test light beam corresponding to different wavelengths are obtained, or the output light intensity signal-to-noise ratio of the reference test light beam corresponding to different wavelengths and the output light intensity average value of the reference test light beam corresponding to different wavelengths are obtained.

[0082] A first relationship curve of the output light intensity noise of the reference test light beam corresponding to different wavelengths and the output light intensity average value of the reference test light beam corresponding to different wavelengths is established, or a second relationship curve of the output light intensity signal-to-noise ratio of the reference test light beam corresponding to different wavelengths and the output light intensity average value of the reference test light beam corresponding to different wavelengths is established, and the first relationship curve or the second relationship curve is the detector factor distribution curve.

[0083] Preferably, the reference test light beam refers to the light beam emitted by a high-stability light source, such as a tungsten lamp, and the stability of the self-emission light intensity of the reference test light beam is higher than the stability of the background signal acquisition value of the detector, so that in the output light intensity detected by the detector, the self-generated fluctuation of the emission light intensity is covered by the fluctuation of the background signal of the detector, and thus the fluctuation of the output light intensity is the fluctuation of the background signal of the detector.

[0084] The detector is a spectrometer with spectral detection capability, which can detect the light intensity value of the reference test light beam corresponding to a certain wavelength. The output light intensity of the reference test light beam at different wavelengths is collected by the detector multiple times. Specifically, the emission light intensity of the reference test light beam is first adjusted to reach the maximum light intensity value that can be detected by the detector, and the output light intensity of the reference test light beam at different wavelengths is collected by the detector multiple times. Since the reference test light beam is a wide-band light source, it has different emission light intensities at different wavelengths, so the output light intensity collected by the detector is actually a range of light intensities rather than a single light intensity value. The reason for first adjusting the emission light intensity of the reference test light beam to reach the maximum light intensity value that can be detected by the detector is to make the emission light intensity range of the reference test light beam cover the light intensity measurement range of the detector, so as to obtain the background signal fluctuation under the complete light intensity measurement range of the detector, which is beneficial to more accurately obtaining the critical light intensity value I critical (λ).

[0085] The output light intensity noise of the reference test light beam corresponding to different wavelengths and the output light intensity average value of the reference test light beam corresponding to different wavelengths are obtained, specifically, after the detector obtains multiple output light intensity values at a certain wavelength, the standard deviation of the multiple output light intensity values is taken as the output light intensity noise of the reference test light beam corresponding to different wavelengths, and the average value of the multiple output light intensity values is taken as the output light intensity average value of the reference test light beam corresponding to different wavelengths, and then the output light intensity noise and the output light intensity average value corresponding to different wavelengths are calculated in the same way.

[0086] A first relationship curve between the output light intensity noise of the reference test light beam and the output light intensity average value of the reference test light beam is established. Specifically, after the output light intensity noise and the output light intensity average value corresponding to different wavelengths are obtained, the output light intensity noise and the output light intensity average value corresponding to each wavelength are respectively substituted into a plane rectangular coordinate system, and the first relationship curve is fitted.

[0087] The output light intensity signal-to-noise ratio of the reference test light beam and the output light intensity average value of the reference test light beam corresponding to different wavelengths are obtained. Specifically, after the detector obtains a plurality of output light intensity values at a certain wavelength, the average value of the plurality of output light intensity values is taken as the output light intensity average value of the reference test light beam, and the ratio of the average value of the plurality of output light intensity values to the standard deviation of the plurality of output light intensity values is taken as the output light intensity signal-to-noise ratio of the reference test light beam. Then, in the same way, the output light intensity signal-to-noise ratio and the output light intensity average value corresponding to different wavelengths are sequentially calculated.

[0088] A second relationship curve between the output light intensity signal-to-noise ratio of the reference test light beam and the output light intensity average value of the reference test light beam is established. Specifically, after the output light intensity signal-to-noise ratio and the output light intensity average value corresponding to different wavelengths are obtained, the output light intensity signal-to-noise ratio and the output light intensity average value corresponding to each wavelength are respectively substituted into a plane rectangular coordinate system, and the second relationship curve is fitted.

[0089] For example, the light source factor distribution curve is used to represent the influence of the fluctuation of the light source itself on the light intensity measurement value under different light intensity light sources. The light source factor distribution curve is obtained by the following method:

[0090] The detector collects the output light intensity of the light source at different wavelengths within the wavelength range of the light source multiple times.

[0091] The output light intensity noise of the light source and the output light intensity average value of the light source corresponding to different wavelengths are obtained, or the output light intensity signal-to-noise ratio of the light source and the output light intensity average value of the light source corresponding to different wavelengths are obtained.

[0092] A third relationship curve between the output light intensity noise of the light source and the output light intensity average value of the light source is established, or a fourth relationship curve between the output light intensity signal-to-noise ratio of the light source and the output light intensity average value of the light source is established.

[0093] The output light intensity noise of the light source and the output light intensity average value of the light source corresponding to different wavelengths are obtained. Specifically, after the detector obtains a plurality of output light intensity values at a certain wavelength, the standard deviation of the plurality of output light intensity values is taken as the output light intensity noise of the light source, and the average value of the plurality of output light intensity values is taken as the output light intensity average value of the light source. Then, in the same way, the output light intensity noise and the output light intensity average value corresponding to different wavelengths are sequentially calculated.

[0094] A third relationship curve is established between the corresponding output light intensity noise and the corresponding average output light intensity of the light source. Specifically, after obtaining the output light intensity noise and the average output light intensity for different wavelengths, the output light intensity noise and the average output light intensity for each wavelength are substituted into a Cartesian coordinate system and fitted to obtain the third relationship curve.

[0095] To obtain the signal-to-noise ratio (SNR) of the corresponding output light intensity of the reference test beam and the average output light intensity of the light source at different wavelengths, the detector acquires multiple output light intensity values ​​at a certain wavelength, takes the average of the multiple output light intensity values ​​as the average output light intensity of the light source, and takes the ratio of the average output light intensity to the standard deviation of the multiple output light intensity values ​​as the SNR of the corresponding output light intensity of the light source. Then, the SNR and average output light intensity of the light source at different wavelengths are calculated in the same way.

[0096] A fourth relationship curve is established between the corresponding output light intensity signal-to-noise ratio and the corresponding average output light intensity of the light source. Specifically, after obtaining the output light intensity signal-to-noise ratio and the average output light intensity for different wavelengths, the output light intensity signal-to-noise ratio and the average output light intensity for each wavelength are substituted into a Cartesian coordinate system and fitted to obtain the fourth relationship curve.

[0097] In this embodiment, the critical light intensity value I critical (λ) is obtained in the following way:

[0098] Obtain the first intersection point of the first relationship curve and the third relationship curve, determine the first light intensity value corresponding to the first intersection point, and select any light intensity value greater than or equal to the first light intensity value as the critical light intensity value I. critical (λ).

[0099] like Figure 2a As shown, the first light intensity value corresponding to the first intersection point of the first relationship curve and the third relationship curve is 3000. In this embodiment, this critical light intensity value I is defined. critical (λ) is 3000. This can be understood as defining the critical light intensity value I. critical (λ) of 3000 is just one example; any light intensity value greater than 3000 can also be selected as the critical light intensity value I. critical (λ).

[0100] Alternatively, the critical light intensity value I critical (λ) can also be obtained in the following way:

[0101] Obtain the second intersection point of the second and fourth relationship curves, determine the second light intensity value corresponding to this second intersection point, and select any light intensity value greater than or equal to the first light intensity value as the critical light intensity value I.critical (λ).

[0102] like Figure 2b As shown, the second light intensity value corresponding to the second intersection point of the second and fourth relationship curves is 3000. In this embodiment, this critical light intensity value I is defined. critical (λ) is 3000. Of course, any light intensity value greater than 3000 can also be selected as the critical light intensity value I. critical (λ).

[0103] Determine the critical light intensity value I critical The meaning of (λ) is as follows: when measuring light intensity I... measure (t,λ) and reference light intensity I reference Both (t, λ) are greater than the critical light intensity value I. critical When (λ), the light intensity fluctuation factors of both the test beam and the reference beam are dominated by the light source factor, so that the light intensity fluctuation of the test beam and the reference beam are more consistent.

[0104] In some embodiments, homogenizing and converging the light source to obtain a source beam with consistent light intensity fluctuations at each position of the emitting surface includes: homogenizing and converging the light source using a beam homogenization and converging processor.

[0105] By using a beam homogenization and focusing processor, the light intensity fluctuations at different locations on the light-emitting surface of the light source can be homogenized and distributed at the focusing point. This ensures that the different fluctuations at different locations or regions on the light-emitting surface of the light source are evenly distributed at every location or region on the converged light-emitting surface, thus ensuring that the light intensity fluctuations and their components are consistent at every location or region on the converged light-emitting surface.

[0106] In some embodiments, if the source beam is transmitted using a spatial optical path, the source beam is split into beams by a beam splitter according to a preset ratio β. The beam splitter includes optical splitting devices such as beam splitters.

[0107] The beam splitting of the source beam according to a preset ratio β, as mentioned here, refers to using a beam splitter to split the energy at each point on the propagation surface of the source beam according to a preset ratio β. This avoids beam splitting based on geometric division on the propagation surface of the source beam, where the light energy of one area is divided into the measurement beam and the light energy of another area is divided into the reference beam. This helps maintain the consistency of the intensity fluctuations between the measurement beam and the reference beam.

[0108] In some embodiments, if the source beam is transmitted via optical fiber, the beam splitter is an optical fiber beam splitter, which can split the transmitted light in each fiber into a measurement beam and a reference beam according to a preset ratio β. Common optical fiber beam splitters include 1-to-2 fiber couplers. If the transmission optical path consists of multiple optical fibers, multiple 1-to-2 fiber couplers with the same splitting ratio should be used to uniformly split the transmitted light in each fiber into a measurement beam and a reference beam.

[0109] In some embodiments, the preset ratio β is the measured light intensity I of the measurement beam. measure (t,λ) and the reference intensity I of the reference beam reference The ratio of (t,λ), that is:

[0110]

[0111] The preset ratio β satisfies:

[0112]

[0113] Where S is the light intensity of the light source, α is the loss coefficient of the measurement beam during transmission, and I critical (λ) is the critical light intensity value.

[0114] The loss coefficient α is affected by factors including the polishing slurry, polishing pad, and the mutual conversion and coupling during the beam's transmission from the optical fiber to space. The loss coefficient α is determined by the measured light intensity I. measure (t,λ) and reflected light intensity I reflecton (t,λ) is obtained based on the following formula:

[0115]

[0116] By setting this preset ratio β, the reference light intensity I of the reference beam can be adjusted. reflecton (t,λ), the reflected light intensity I of the reflected beam reflecton (t,λ) and critical light intensity value I critical (λ) satisfies the relation: I reflecton (t,λ)≥I reference (t,λ)≥I critical (λ). Thus, when the detector module respectively acquires the reference light intensity I of the reference beam... reference (t,λ) and the reflected light intensity I of the reflected beam reflecton At (t,λ), the light source factor dominates the influence factors on the intensity fluctuation of both the reference beam and the reflected beam.

[0117] It should be noted here that the preset ratio β needs to be set so that the reflected light intensity I reflecton (t,λ) and reference light intensity I referenceThe light intensity at each wavelength value λ within the light source wavelength range (t, λ) is greater than the critical light intensity value I. critical (λ), thereby ensuring the reflected light intensity I reflecton (t,λ) and reference light intensity I reference The consistency of fluctuations (t,λ) at each wavelength value λ is ensured to avoid calibration failure of the reference system due to inconsistencies in the intensity fluctuations between the reflected beam and the reference beam.

[0118] Figure 3b This is a diagram showing the fluctuations in reflected light intensity and the fluctuations in reference light intensity after spectral dispersion based on the preset ratio β. Figure 3a The diagram shown illustrates the fluctuations in reflected light intensity and the fluctuations in reference light intensity in existing related technologies. It can be seen that the reflected light intensity I in this invention... reflecton (t,λ) and reference light intensity I reflecton The fluctuation consistency of (t,λ) is better than that of existing related technologies.

[0119] In this embodiment, the reference light intensity I of the reference beam reference (t,λ) and the reflected light intensity I of the reflected beam reference (t,λ) can be acquired using the same detector module, or by using two detector modules with identical performance parameters to acquire data separately.

[0120] In this embodiment, based on the reference light intensity I reference (t,λ) represents the reflected light intensity I reflecton (t,λ) is calibrated, including: selecting a certain time point t0, and setting the reference light intensity I at t0. reference (t0,λ) is defined as the baseline initial value. I is then calculated according to the following formula. reflecton (t,λ) is corrected to obtain the target reflected light intensity I' reflecton (t,λ):

[0121]

[0122] For example, when the reference light intensity I at t0 is... reflecton After setting (t0,λ) as the reference initial value, based on the reference initial value, the reflected light intensity I at t1 is... reflecton Calibration is performed using (t1, λ). Here, t1 represents the data acquisition time point of the detector module after t0; that is, the time when the detector module acquires the reference light intensity I at time t1. reflecton (t1,λ) and reflected light intensity I reflecton Given two data points (t1, λ), the target reflected light intensity I' at time t1 is obtained using equation (5). reflecton (t1,λ):

[0123]

[0124] Therefore, during the light intensity acquisition period after t0, the reflected light intensities I collected by the detector module are sequentially... reflecton The target reflected light intensity I' is obtained by calibration using (t,λ). reflecton (t,λ).

[0125] Figure 4 This is a comparison diagram of reflected light stability before and after correction, according to an exemplary embodiment, such as... Figure 4 As shown, calibration using the above method effectively reduces the fluctuation of reflected light intensity (standard deviation of light intensity value), making the reflected light intensity of the target more stable.

[0126] In this embodiment of the invention, based on the target reflected light intensity I' reflecton (t,λ) Calculate the reflectance spectrum R of the sample. meas When (t,λ), based on the following formula:

[0127]

[0128] Among them, R Si (λ) represents the known reflectivity spectrum of the reference bare silicon sample, I Si (λ) represents the reflected light intensity of the reference bare silicon sample, I black (λ) represents the stray light intensity of the measurement system. In the process of acquiring the reflectance spectrum, in addition to the reflection from the sample, there is also stray light, including various end-face reflections and ambient background light, which exist simultaneously in the transmission optical path. These stray lights will affect the accuracy of the reflectance spectrum calculation. Therefore, in the actual measurement process, a step is also included to remove the stray light intensity of the system.

[0129] The step of removing stray light intensity from the system includes: illuminating a black sample with a reflectivity of 0 under the same measured light intensity to obtain the system stray light intensity I. black .

[0130] This invention also provides an endpoint detection method, which involves real-time acquisition of the reflectance spectrum R of a sample during chemical mechanical polishing. meas (t,λ), reflectance spectrum R meas (t,λ) is obtained using any of the reflectance spectrum acquisition methods described above. Based on the reflectance spectrum R meas (t,λ) Calculate the film thickness d of the real-time sample. Determine the endpoint of chemical mechanical polishing based on the film thickness d.

[0131] The film thickness d is obtained as follows: given the complex refractive index of each layer in the sample thin film structure, the reflectance spectrum R... meas The relationship between (t,λ) and the film thickness d of the sample is a transcendental function, which can be expressed as:

[0132] R meas=f(λ,d) (7)

[0133] Using equation (8) and the obtained reflectance spectrum R meas (t,λ) can be used to deduce the film thickness d of the sample at the current moment, and then determine whether the chemical mechanical polishing endpoint has been reached.

[0134] In the endpoint detection method of this invention, the reflectance spectrum R obtained by any of the aforementioned reflectance spectrum acquisition methods is... meas (t,λ), where by homogenizing and converging the light source, the light intensity fluctuations at different positions on the light-emitting surface of the light source can be homogenized and distributed at the convergence point, thereby obtaining a source beam with consistent light intensity fluctuations and fluctuation components at each position or region of the light-emitting surface after convergence. Based on the source beam, the measurement beam and the reference beam are obtained by further splitting the beam, so that the measurement beam and the reference beam have the same light intensity fluctuation, thus solving the problem that the light intensity distribution factors of the light source cause inconsistent light intensity fluctuations between the measurement beam and the reference beam.

[0135] The measurement beam illuminates the sample and is reflected by the sample to obtain the reflected beam. The reference beam intensity I is then determined by a preset ratio β for beam splitting. reference (t,λ), the reflected light intensity I of the reflected beam reflecton (t,λ) and critical light intensity value I critical (λ) satisfies the relation: I reflecton (t,λ)≥I reference (t,λ)≥I critical (λ) can make the reflected light intensity I reflecton (t,λ) and reference light intensity I reference The dominant influencing factors of (t,λ) are all light source factors, which weaken the reflected light intensity I. reflecton (t,θ), reference light intensity I reference The influence of detector factors in (t,θ), and because the wave characteristics of the homogenized measurement beam and the reference beam are consistent, the reflected light intensity I caused by the light source factors... reflecton (t,λ) and reference light intensity I reference The wave nature of (t,λ) is also consistent. Using the reference light intensity I... reference (t,θ) represents the reflected light intensity I reflecton By precisely correcting and calibrating the intensity fluctuations at each wavelength in (t,λ), a highly stable reflectance spectrum R of the sample can be obtained. meas (t,θ), thereby effectively improving the detection accuracy of the film thickness d of the sample during the endpoint detection process.

[0136] This invention also provides an endpoint detection device 100, such as... Figure 5As shown, the endpoint detection device 100 includes: a light source 110 for emitting a light beam; a beam homogenization and focusing processor 170 for processing the light beam to obtain a source beam with consistent intensity fluctuations at each position of the emitting surface; and a beam splitter 120 for splitting the source beam according to a preset ratio β to obtain a measurement beam and a reference beam. The measurement beam forms a reflected beam after being incident on the sample, and the reference beam has a reference intensity I. reflecton (t,λ) and the reflected light intensity I of the reflected beam reference (t,λ) satisfy the relation: I reflecton (t,λ)≥I reference (t,θ)≥I critical (λ), I critical (λ) represents the critical light intensity value when the light source factor dominates. The detector module is used to acquire the reflected light intensity I of the reflected beam. reflecton (t,λ) and the reference intensity I of the reference beam reference (t,λ). A control processor 160 is electrically connected to the detector module. The control processor is also used to: determine the reference light intensity I... reference (t,λ) represents the reflected light intensity I reflecton (t,λ) is calibrated to generate the target reflected light intensity I' reflection (t,λ). Based on the target reflected light intensity I' reflection (t,λ), calculate the reflectance spectrum R of the sample. meas (t,λ). Based on the real-time acquired reflectance spectrum R meas (t,λ) is used to calculate the film thickness d of the sample at the corresponding time point t, and the chemical mechanical polishing endpoint is determined based on the film thickness d.

[0137] In some embodiments, the light source 110 employs a high-frequency scintillation broadband light source to provide a broadband beam encompassing the visible light band. The stability of the output light intensity of this high-frequency scintillation broadband light source is independent of the magnitude of the light intensity. The light intensity distribution on the light-emitting surface of the light source is also non-uniform, with the light source at the center of the arc exhibiting the strongest light. Furthermore, the light intensity fluctuations at different locations on the light-emitting surface are also unevenly and randomly distributed. Therefore, the beam homogenization and focusing processor 170 homogenizes and focuses the broadband beam, homogenizing and distributing the light intensity fluctuations at different locations on the light-emitting surface of the light source at the focusing point. This ensures that the different fluctuations at different locations or regions of the light-emitting surface are uniformly distributed at each location or region of the focused light-emitting surface, thereby ensuring that the light intensity fluctuations and their components are consistent at each location or region of the focused light-emitting surface.

[0138] In some embodiments, the beam splitter 120 splits the entire source beam according to a preset ratio β. Specifically, the beam splitter 120 splits the energy at each point on the propagation surface of the source beam according to the preset ratio β, thereby avoiding beam splitting based on geometric division on the propagation surface of the source beam, where the light energy of one area is divided into the measurement beam and the light energy of another area is divided into the reference beam. This helps to maintain the consistency of the light intensity fluctuations between the measurement beam and the reference beam.

[0139] In some embodiments, the source beam is transmitted via optical fiber, and the beam splitter 120 includes an optical fiber beam splitter with the same splitting ratio, which can uniformly split the source beam in each optical fiber into a measurement beam and a reference beam according to a preset splitting ratio, avoiding the use of multiple optical fibers in the optical fiber cable to transmit the measurement beam and the reference beam separately.

[0140] In some embodiments, the source beam is transmitted through a spatial optical path, and the beam splitter 120 includes a beam splitter that can split the source beam as a whole according to a preset splitting ratio.

[0141] In some embodiments, the detector module includes a measuring detector 140 and a reference detector 150, which are respectively used to acquire the reflected light intensity I of the reflected beam. reflecton (t,λ) and the reference intensity I of the reference beam reference (t,λ).

[0142] The endpoint detection device 100 of this embodiment of the invention obtains a source beam with consistent light intensity fluctuations and fluctuation components at every position or region of the emitting surface of the light source 110 through a beam homogenization and focusing processor 170. Based on this source beam, a measurement beam and a reference beam are obtained through further beam splitting. This ensures that the measurement beam and the reference beam have the same light intensity fluctuation characteristics, thus solving the problem of inconsistent light intensity fluctuations between the measurement beam and the reference beam caused by the light intensity distribution factors of the light source. By using a preset ratio β for beam splitting, the reference light intensity I of the reference beam is... reference (t,λ), the reflected light intensity I of the reflected beam reflecton (t,λ) and critical light intensity value I critical (λ) satisfies the relation: I reflecton (t,λ)≥I reference (t,λ)≥I critical (λ) can make the reflected light intensity I reflecton (t,λ) and reference light intensity I reference The dominant influencing factors of (t,λ) are all light source factors, which weaken the reflected light intensity I. reflecton (t,λ), reference light intensity I referenceThe influence of detector module factors in (t,λ), and because the wave characteristics of the homogenized measurement beam and the reference beam are consistent, the reflected light intensity I caused by the light source factors... reflecton (t,λ) and reference light intensity I reference The fluctuation of (t,λ) is also consistent. Based on this, the endpoint detection device 100 of this embodiment can obtain reflected light intensity I with consistent light intensity fluctuation. reflecton (t,λ) and reference light intensity I reference (t,λ), thereby enabling the control processor 160 to utilize the reference light intensity I reference (t,λ) represents the reflected light intensity I reflecton By precisely correcting and calibrating the light intensity fluctuations at each wavelength in (t,λ), a highly stable reflectance spectrum can be obtained, improving the accuracy of spectral detection, increasing the measurement accuracy of film thickness d, and enhancing the stability and accuracy of endpoint detection in chemical mechanical polishing using the endpoint detection device 100 of this embodiment.

[0143] This invention also provides a polishing apparatus, such as... Figure 6 As shown, the polishing apparatus includes any of the aforementioned endpoint detection devices 100.

[0144] In some embodiments, a grinding stage 200 is further included. The grinding stage 200 has a cavity inside, and the endpoint detection device 100 is located inside the cavity of the grinding stage 200. A grinding pad 210 is provided on the upper surface of the grinding stage 200. The grinding pad 210 is used to grind the sample 500. A through hole is provided on the grinding stage 200 and the grinding pad 210, which can vertically penetrate the grinding stage 200 and the grinding pad 210. A window 220 is used to close the through hole, and the upper surface of the window 220 is flush with the grinding pad 210.

[0145] The probe 130 of the endpoint detection device 100 faces the window 220 and is used to illuminate the sample 500 with measuring light through the window 220 and to receive the reflected light reflected by the sample 500 through the window 220. The clamping unit 300 is used to clamp the sample 500 so that the sample 500 can be ground on the grinding pad 210.

[0146] In some embodiments, the grinding table 200 is provided with a first driving device for driving the grinding table 200 to rotate, and its rotation axis is perpendicular to the plane of the side of the grinding pad 210 used for grinding. When the grinding table 200 rotates, the endpoint detection device 100 in its cavity rotates together with the grinding table 200. When the window 220 rotates to the sample 500, the endpoint detection device 100 measures the thickness of the sample 500 to determine whether the sample to be measured has been ground to the endpoint.

[0147] In some embodiments, a polishing slurry sprayer 400 is also included, the nozzle of which is directed toward the upper surface of the polishing pad 210 for polishing, the nozzle being used to spray polishing slurry onto the polishing pad 210.

[0148] In some embodiments, the clamping unit 300 includes a bearing head 310 for clamping a sample 500. A second driving device 330 is connected to the bearing head 310 via a rotating shaft and is used to drive the bearing head 310 to rotate. A support portion 320 is used to support the second driving device 330, the rotating shaft, and the bearing head 310, positioning them on the grinding side of the grinding pad 210.

[0149] In some embodiments, the support portion 320 is provided with a third driving device, which is used to drive the support portion 320 to make linear movements. The movement plane of the support portion 320 is parallel to the plane of the grinding side of the grinding pad 210, that is, it drives the sample 500 to move on the grinding pad 210 for grinding.

[0150] In the polishing apparatus of this embodiment of the invention, during the grinding process, each time the sample 500 passes through the window 220, the endpoint detection device 100 measures the current reflectance spectrum of the sample 500. The endpoint detection device 100 utilizes the consistent reflected light intensity I... reflecton (t,λ) and reference light intensity I reference (t,λ), through the reference light intensity I reference (t,λ) represents the reflected light intensity I reflecton The light intensity fluctuations of each wavelength in (t,λ) are precisely corrected and calibrated, thereby giving the current reflectance spectrum of sample 500 better stability and accuracy, which in turn improves the measurement accuracy of the current film thickness d of sample 500, and makes the endpoint detection of the polishing device in the grinding of sample 500 more accurate.

[0151] It is understood that in this invention, "multiple" refers to two or more, and other quantifiers are similar. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. The character " / " generally indicates that the preceding and following related objects have an "or" relationship. The singular forms "a," "the," and "the" are also intended to include the plural forms unless the context clearly indicates otherwise.

[0152] It is further understood that the terms "first," "second," etc., are used to describe various types of information, but this information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another, and do not indicate a specific order or degree of importance. In fact, the expressions "first," "second," etc., are completely interchangeable. For example, without departing from the scope of this invention, first information can also be referred to as second information, and similarly, second information can also be referred to as first information.

[0153] It is further understood that the terms “center,” “longitudinal,” “lateral,” “front,” “rear,” “up,” “down,” “left,” “right,” “vertical,” “horizontal,” “top,” “bottom,” “inner,” and “outer,” etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this embodiment and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation.

[0154] It can be further understood that, unless otherwise specified, "connection" includes both direct connections where no other components exist between the two parties and indirect connections where other components exist between them.

[0155] It is further understood that although the operations are described in a specific order in the accompanying drawings in the embodiments of the present invention, this should not be construed as requiring these operations to be performed in the specific order or serial order shown, or requiring all the operations shown to obtain the desired result. In certain environments, multitasking and parallel processing may be advantageous.

[0156] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention described herein. This application is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not invented herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the following claims.

[0157] It should be understood that the present invention is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A method for obtaining reflectance spectrum, characterized in that, include: Obtain the distribution curves of influencing factors characterizing the fluctuation of light intensity measurement values ​​under different light source conditions. The distribution curves of influencing factors include detector factor distribution curves and light source factor distribution curves. Based on the distribution curves of the influencing factors, determine the critical light intensity value I corresponding to when the light source factor is dominant. critical (λ), where λ is any wavelength value within the light source band; The light source is homogenized and focused to obtain a source beam with consistent light intensity fluctuations at every position on the emitting surface; The source beam is split according to a preset ratio β to obtain the desired measurement beam and reference beam. The measurement beam forms a reflected beam after being incident on the sample, and the reference intensity I of the reference beam is... refernce (t,λ) and the reflected light intensity I of the reflected beam reflection (t,λ) satisfy the relation: I reflecton (t,λ)≥I refernce (t,λ)≥I critical (λ), where t is the light intensity acquisition time; Based on the reference light intensity I reference (t,λ) represents the reflected light intensity I reflecton (t,λ) is calibrated to generate the target reflected light intensity I' reflection (t,λ); Based on the target reflected light intensity I' reflecton (t,λ) Calculate the reflectance spectrum R of the sample. meas (t,λ).

2. The method for obtaining reflectance spectrum according to claim 1, characterized in that: Obtaining the detector factor distribution curve includes: A reference test beam is provided, wherein the reference test beam is a broadband beam; The detector was used to repeatedly collect the output light intensity of the reference test beam at different wavelengths; Obtain the corresponding output light intensity noise and the corresponding average output light intensity of the reference test beam at different wavelengths; or, obtain the corresponding output light intensity signal-to-noise ratio and the corresponding average output light intensity of the reference test beam at different wavelengths. Establish a first relationship curve between the output light intensity noise of the reference test beam and the average output light intensity of the reference test beam, or establish a second relationship curve between the output light intensity signal-to-noise ratio of the reference test beam and the average output light intensity of the reference test beam. Obtain the distribution curve of light source factors, including: The detector was used to repeatedly collect the output light intensity of the source beam at different wavelengths within the specified band. Obtain the corresponding output light intensity noise and the corresponding average output light intensity of the light source at different wavelengths; or, obtain the corresponding output light intensity signal-to-noise ratio and the corresponding average output light intensity of the light source at different wavelengths. Establish a third relationship curve between the corresponding output light intensity noise and the corresponding average output light intensity of the light source, or establish a fourth relationship curve between the corresponding output light intensity signal-to-noise ratio and the corresponding average output light intensity of the light source.

3. The method for obtaining reflectance spectrum according to claim 2, characterized in that, Based on the distribution curve of the influencing factors, the critical light intensity value I corresponding to the dominant light source factor is determined. critical (λ), including: Obtain the first intersection point of the first relationship curve and the third relationship curve, determine the first light intensity value corresponding to the first intersection point, and select any light intensity value greater than or equal to the first light intensity value as the critical light intensity value I. critical (λ); or Obtain the second intersection point of the second relationship curve and the fourth relationship curve, determine the second light intensity value corresponding to the second intersection point, and select any light intensity value greater than or equal to the second light intensity value as the critical light intensity value I. critical (λ).

4. The method for obtaining reflectance spectrum according to claim 1, characterized in that: The step of splitting the source beam according to a preset ratio β includes: The source beam is split at each position on the emitting surface using a fiber optic beam splitter or beam splitter according to the preset ratio β.

5. The method for obtaining reflectance spectrum according to claim 4, characterized in that: The preset ratio γ is the measured light intensity I of the measurement beam. measure (t,λ) and the reference light intensity I reference The ratio of (t,λ), The preset ratio β satisfies: Where S is the light intensity of the light source, α is the loss coefficient of the measurement beam during transmission, and I critical (λ) is the critical light intensity value; The loss coefficient α is determined by the measured light intensity I. reference (t,λ) and the reflected light intensity I reflecton (t,λ) is obtained based on the following formula:

6. The method for obtaining reflectance spectrum according to claim 1, characterized in that, The reference light intensity I reference (t,λ) represents the reflected light intensity I reflecton (t,λ) is calibrated to generate the target reflected light intensity I' reflecton (t,λ) includes: Select a specific time point t0 within the data acquisition period, and set the reference light intensity I at t0. reference (t0,λ) is set as the baseline initial value; According to the following formula, I... reflecton (t,λ) is corrected to obtain the target reflected light intensity I' reflecton (t,λ):

7. The method for obtaining reflectance spectrum according to claim 6, characterized in that, The target reflected light intensity I' reflecton (t,λ) Calculate the reflectance spectrum R of the sample. meas (t,λ), including: The reflectance spectrum R is obtained based on the following formula. meas (t,λ): Among them, R Si (λ) represents the known reflectivity spectrum of the reference bare silicon sample, I Si (λ) represents the reflected light intensity of the reference bare silicon sample, I black (λ) represents the stray light intensity of the measurement system.

8. An endpoint detection method, characterized in that: The reflectance spectrum R of the sample was acquired in real time during the chemical mechanical polishing process. meas (t,λ), the reflectance spectrum R meas (t,λ) is obtained by the reflectance spectrum acquisition method as described in any one of claims 1 to 7; Based on the reflectance spectrum R meas (t,λ) Calculate the film thickness d of the sample in real time; The endpoint of the chemical mechanical polishing is determined based on the film thickness d.

9. An endpoint detection device, characterized in that, include: A light source, used to emit a beam of light; A beam homogenization and focusing processor is used to process the light source beam to obtain a source beam with consistent light intensity fluctuations at each position of the emitting surface. A beam splitter splits the source beam according to a preset ratio β to obtain a measurement beam and a reference beam. The measurement beam is incident on the sample and forms a reflected beam, while the reference beam has a reference intensity I. reference (t,λ) and the reflected light intensity I of the reflected beam reflection (t,λ) satisfy the relation: I reflecton (t,λ)≥I reference (t,λ)≥I critical (λ), I critical (λ) is the critical light intensity value when the light source factor is dominant; Detector module, used to acquire the reflected light intensity I of the reflected beam. reflecton (t,λ) and the reference light intensity I of the reference beam reference (t,λ); A control processor, which is electrically connected to the detector module; The control processor is also used for: According to the reference light intensity I reflecton (t,λ) represents the reflected light intensity I reflecton (t,λ) is calibrated to generate the target reflected light intensity I' reflecton (t,λ); Based on the target reflected light intensity I' reflecton (t,λ), calculate the reflectance spectrum R of the sample. meas (t,λ); Based on the real-time acquired reflectance spectrum R meas (t,λ) is used to calculate the film thickness d of the sample at the corresponding time point t, and the chemical mechanical polishing endpoint is determined based on the film thickness d.

10. A polishing apparatus, characterized in that: Includes the endpoint detection device as described in claim 9.

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