Online monitoring device for chemical mechanical polishing

Abstract

The present invention discloses an online monitoring device for chemical mechanical polishing, which is installed within the polishing pad and can rotate with the polishing pad. The device includes a light source, an optical lens set, a reflecting unit, a detection probe, and a detector. The optical lens set receives the light beam emitted by the light source and generates a collimated beam. The reflecting unit receives the collimated beam and reflects it to form an incident light path. The detection probe is installed below the light-transmitting window of the polishing pad and includes a quartz light guide and a single-core optical fiber. The detector is connected to the single-core optical fiber and receives the output light path, obtaining corresponding spectral information and determining the endpoint of wafer polishing. The light source light path from the light source to the detection probe in the present invention uses free-space propagation, and the signal light path from the detection probe to the detector uses optical fiber propagation. The propagation modes of the two types of light beams are smoothly transitioned by the design of the detection probe, achieving high-precision detection.

Description

Technical Field

[0001] The present invention belongs to the field of chemical mechanical polishing technology, and particularly relates to an on-line monitoring device for chemical mechanical polishing.

Background Art

[0002] In the current manufacturing process of semiconductor integrated circuit chips, chemical mechanical polishing (CMP) is one of the important process steps. The chemical mechanical planarization process uses a polishing pad and polishing liquid to polish the wafer, and realizes the planarization of the wafer surface shape by a method combining mechanical means and chemical means. In the process, it is very important to judge the end point of polishing, that is, to achieve the desired removal amount or the desired thickness and judge whether the process is completed.

[0003] In the initial chemical mechanical polishing process, the process end point was controlled using polishing time, but the accuracy was low and the reliability was also low. To adapt to the process, a series of end point detection methods have been developed. End point detection based on mechanics mainly monitors the change in motor torque caused by the change in the frictional force of the material in the polishing process. However, it requires two types of medium layers with very different friction coefficients, so the applicable range is relatively narrow. End point detection based on electromagnetism mainly monitors the eddy current generated by the metal layer on the wafer surface and is applied to the detection of the metal film thickness and cannot be applied to insulating materials. End point detection based on optics mainly measures the intensity of the light reflected from the wafer and uses a monochromatic laser to monitor the change in the material reflectivity in the polishing process. Therefore, it requires two types of medium layers with very different reflectivities. For a transparent medium layer, the intensity of the reflected light is the intensity of the interference light of the light reflected from each medium surface. Although the removal amount information can be obtained from the change in the intensity of the interference light, the thin film thickness information cannot be obtained. End point detection based on spectrum is a method developed from optical methods. It uses light sources such as multi-color light, wide-spectrum light, and white light, receives the spectrum information reflected from the wafer, monitors the change in the film thickness from the correspondence between the spectrum information and the thin film thickness, and is applied to the detection of the film thickness of the transparent medium film. [Overview of the Initiative]

[0004] To address the challenges of conventional technologies, the present invention provides an online monitoring device for chemical mechanical polishing, which combines two types of light beam propagation methods, free-space propagation and optical fiber propagation, to achieve high-precision detection.

[0005] The technical solution employed by the present invention to solve the technical problem is as follows: an online monitoring device for chemical mechanical polishing, which is installed in a polishing disc and can rotate together with the polishing disc, and includes the following: light source. This is an optical lens set used to receive a light beam emitted from a light source and to generate a collimated beam. A reflective unit used to receive a collimated beam and reflect the collimated beam to form an incident light path. A detection probe is provided below the light-passing window of a polishing pad and includes at least a quartz optical guide tube and a single-core optical fiber. The quartz optical guide tube is used to receive the incident optical path and to emit the incident optical path from one end of the detection probe closer to the wafer, and the single-core optical fiber is used to receive the emitted optical path after reflection from the wafer surface. A detector is connected to the single-core optical fiber and used to receive the output optical path, acquire corresponding spectral information, and determine the endpoint of wafer polishing.

[0006] Furthermore, the detection probe also includes a housing. The quartz optical guide tube covers the outer circumference of the single-core optical fiber, the housing covers the outer circumference of the quartz optical guide tube, and the housing, the quartz optical guide tube, and the single-core optical fiber are installed concentrically. Alternatively, the quartz optical guide tube and the single-core optical fiber may be installed adjacent to each other, and the housing may cover the outer circumferences of the quartz optical guide tube and the single-core optical fiber.

[0007] Furthermore, the end face of the quartz optical guide tube closest to the wafer and the end face of the single-core optical fiber closest to the wafer may be flat, and the end face of the quartz optical guide tube closest to the wafer may have a chamfer.

[0008] Furthermore, the chamfer may be a straight chamfer with an inclination angle of 0 to 45°. Alternatively, the chamfer may be a circular chamfer with a fillet curvature of 0 to 2 mm. 1 That's fine.

[0009] Furthermore, the single-core optical fiber may protrude from the quartz optical guide tube at one end far from the wafer of the quartz optical guide tube.

[0010] Furthermore, the outer diameter of the quartz optical guide tube may be 1 to 4 mm, and the outer diameter of the single-core optical fiber may be 0.1 to 2 mm.

[0011] Furthermore, the light source is a broadband light source with a wavelength of 200 to 2000 nm. Additionally, the diameter of the collimated beam may be 1 to 10 mm.

[0012] Furthermore, the detector may be a spectrometer. The detector may acquire corresponding spectral information, convert it into thickness information of the medium film on the wafer surface, and determine the endpoint of wafer polishing.

[0013] Furthermore, it may also include a reference light sampling unit, which is placed between the optical lens set and the detection probe and used to monitor the light intensity of the light source.

[0014] Furthermore, the reference light sampling unit may include a first beam splitter and a second beam splitter, wherein the collimated beam passes through the first beam splitter to form signal light and reference light, and the signal light passes through the first beam splitter to enter the detection probe.

[0015] The beneficial effects of this invention are as follows: 1) It employs an innovative detection optical path system. Free-space propagation is used for the light source optical path from the light source to the detection probe, and optical fiber propagation is used for the signal optical path from the detection probe to the detector. The two types of optical beam propagation methods are smoothly transitioned through the special design of the detection probe, so that the entire detection optical path system combines the advantages of each type of optical beam propagation method to achieve high-precision detection. 2) Since most of the light intensity from the light source can reach the detection probe, it is possible to solve the relatively large coupling loss in the light beam that exists from the light source to the optical fiber. 3) By using optical fibers in the signal path to collect effective signals and by positioning the signal collection point close to the wafer surface, the stable transmission of the optical fibers ensures that the signal reaches the detector reliably. 4) The light emitted from the end face of the quartz light guide can be focused, further increasing the intensity of the signal light by concentrating the detected light energy, improving detection accuracy, and limiting the detection range of the detection probe on the wafer by reducing the detection area, allowing for more precise positioning of the detection location. 5) The innovative design of the detection optical path system and probe offers advantages such as high precision, accurate positioning, and low noise, making it more adaptable to current technological demands. 6) Online monitoring of chemical mechanical polishing can be achieved. The monitoring device is part of the chemical mechanical polishing system and depends on the polishing module of the CMP. It rotates with the polishing disc, performs detection during the polishing process, and provides a reference point for when to end the polishing process. Once the polishing endpoint is reached, polishing can be stopped immediately. 7) The overall dimensions are compact. 8) By employing a signal control method to adjust the light source and monitoring the light intensity in real time, the stability of the measurement signal can be ensured, detection accuracy can be improved, and the service life of the light source can be extended. [Brief explanation of the drawing]

[0016] [Figure 1]It is a schematic structural diagram of a chemical mechanical polishing system according to the present invention. [Figure 2] It is a plan view of a chemical mechanical polishing system according to the present invention. [Figure 3] It is a perspective view of the linkage structure between an online monitoring device and a chemical mechanical polishing system in Embodiment 1 of the present invention. [Figure 4] It is a schematic structural diagram of a portion where a detection probe is arranged in Embodiment 1 of the present invention. [Figure 5] It is a cross-sectional view in the lateral direction of a detection probe in Embodiment 1 of the present invention. [Figure 6] It is a longitudinal sectional view of a detection probe in Embodiment 1 of the present invention, and the chamfer is a straight chamfer. [Figure 7] It is a longitudinal sectional view of a detection probe in Embodiment 1 of the present invention, and the chamfer is a circular chamfer. [Figure 8] It is a schematic diagram of the light collection of a detection probe in Embodiment 1 of the present invention, where a is a detection probe with a chamfer and b is a detection probe without a chamfer. [Figure 9] It is a spectroscopic reflectance curve of different film thicknesses. [Figure 10] It is contrast information between a background spectrum (dotted line) and a signal spectrum (solid line). [Figure 11] It is a perspective view of the linkage structure between an online monitoring device and a chemical mechanical polishing system in Embodiment 2 of the present invention.

Modes for Carrying Out the Invention

[0017] For those skilled in the art to better understand the aspects of the present invention, hereinafter, referring to the drawings in the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. However, it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative labor should belong to the protection scope of the present invention.

[0018] Embodiment 1 As shown in Figure 1, in the chemical mechanical polishing (CMP) process, a polishing pad 2 is fixed to a polishing plate 1, a polishing head 5 supports a wafer 8, and the wafer 8 is brought into close contact with the polishing pad 2. The polishing plate 1 rotates on its own, and the polishing head 5 rotates on its own and moves back and forth relative to the polishing plate 1, generating friction between the wafer 8 and the polishing pad 2 and performing a mechanical polishing action. The polishing liquid spray arm 3 sprays polishing liquid through a nozzle, and the polishing liquid, via the rotation of the polishing plate 1, reaches the polishing head 5 and comes into contact with the wafer 8 through the groove structure on the polishing pad 2, performing a chemical polishing action. The trimmer 6 trims the polishing pad 2, maintaining its flatness and roughness.

[0019] As shown in Figures 2 to 5, the online monitoring device for chemical mechanical polishing is installed in the internal space of the polishing disc 1 and can rotate with the polishing disc 1, and includes a light source 9, an optical lens set 10, a reflection unit 12, a detection probe 13, and a detector 11.

[0020] Light source 9 is a broad-spectrum white light source with a wavelength of 200-2000 nm. The light beam emitted by light source 9 enters the optical lens set 10.

[0021] The optical lens set 10 receives the light beam emitted from the light source 9 and generates a collimated beam with a diameter of 1 to 10 mm. Specifically, the optical lens set 10 consists of a series of optical lenses that collect the light beam, reduce its diameter, and collimate it. The light beam that enters the optical lens set 10, through the action of the optical lens set 10, forms a collimated small spot parallel light emission, which reaches the reflection unit 12 in the form of spatial light. The optical lens set 10 achieves coupling of the light emitted from the light source 9 using a light beam focusing and collimation method, solving the problem of low utilization rate of light intensity from the light source with conventional optical fiber coupling, allowing a larger proportion of the light energy to be involved in detection, improving measurement accuracy, and reducing the power required by the light source 9.

[0022] The reflective unit 12 receives the collimated light beam and reflects it to form the incident light path. In this embodiment, the reflective unit 12 is a reflective mirror.

[0023] The detection probe 13 is positioned below the light-passing window 4 of the polishing pad 2 and includes a quartz optical guide tube 131, a single-core optical fiber 132, and a housing 133. The quartz optical guide tube 131 is provided to receive the incident optical path and emit the incident optical path from the proximal end 134 of the detection probe 13 (the end of the detection probe 13 on the wafer 8 side is defined as the proximal end), and the single-core optical fiber 132 is provided to receive the emitted optical path reflected from the wafer 8 surface.

[0024] Specifically, as shown in Figure 5, the quartz optical guide tube 131 covers the outer circumference of the single-core optical fiber 132, the housing 133 covers the outer circumference of the quartz optical guide tube 131, and the housing 133, quartz optical guide tube 131, and single-core optical fiber 132 are arranged concentrically. The outer diameter of the quartz optical guide tube 131 is 1 to 4 mm, i.e., D1 = 1 to 4 mm in the figure. The outer diameter of the single-core optical fiber 132 is 0.1 to 2 mm, i.e., D2 = 0.1 to 2 mm in the figure. The inner diameter of the quartz optical guide tube 131 matches the outer diameter of the single-core optical fiber 132, and the single-core optical fiber 132 is located in the central inner hole of the quartz optical guide tube 131, and the two are concentric. The inner diameter of the housing 133 matches the outer diameter of the quartz optical guide tube 131.

[0025] Of course, in other embodiments, the quartz optical guide tube 131 and the single-core optical fiber 132 may be provided adjacent to each other, and the housing 133 may cover the outer circumference of the quartz optical guide tube 131 and the single-core optical fiber 132; in other words, the three may not be arranged concentrically.

[0026] Detector 11 is a spectrometer that receives the output light path described above; that is, it receives the signal light reflected by the wafer 8, thereby acquiring the corresponding spectral information, which is used to determine the end point of the wafer 8 polishing. Detector 11 is connected to a single-core optical fiber 132. Specifically, as shown in Figure 10, the difference between the signal spectrum and the background spectrum represents spectral information, including the film thickness.

[0027] As shown in Figures 6 and 7, the quartz optical guide tube 131 and the single-core optical fiber 132 have flattened end faces at one end closest to the wafer 8, that is, the end face of the proximal end 134 of the detector 11 is also flat. At the end of the quartz optical guide tube 131 closest to the wafer 8, the end face has a chamfer 136. This chamfer may be a straight chamfer with a tilt angle of 0 to 45°, that is, the α angle in Figure 6 is 0 to 45°. As shown in Figure 7, this chamfer has a fillet curvature of 0 to 2 mm - 1 The chamfered edge may also be rounded. At one end of the quartz optical guide tube 131 and the single-core optical fiber 132 away from the wafer 8, i.e., at the distal end 135 of the detector 11, the single-core optical fiber 132 protrudes from the quartz optical guide tube 131.

[0028] The quartz optical guide tube 131 itself acts as a transition medium for the free-space propagation and medium propagation of the light beam, ensuring the airtightness and stability of the entire detection system. While the proximal end 134 of the detector 11 in Figure 8b has a flat structure, as shown in Figure 8a, the proximal end 134 of the detector 11 has a chamfer 136, which focuses the light emitted from the end face of the quartz optical guide tube 131. The angle and curvature of the end face of the quartz optical guide tube are designed by the thickness of the light passage window, focusing the light spot onto the wafer 8 detection surface. This concentration of detection light energy further increases the intensity of the signal light and improves detection accuracy. Reducing the detection area limits the detection range of the detection probe 13 on the wafer 8, allowing for more precise positioning of the detection location, avoiding signal shielding by existing patterns and microdevices on the wafer 8, and increasing the effective detection points. Compared to current conventional multi-core optical fiber probes, which typically have a divergence angle of 20-30 degrees and also have the diameter of the optical fiber itself, the detection area often reaches several millimeters. This invention can limit the size of the detection light spot to the order of tens to hundreds of micrometers, and eliminates the need to add structures such as focusing mirrors in front of the detection probe, thus avoiding increased structural complexity and surface reflection noise caused by lenses. With the further development of current wafer processes, the complexity of patterns on wafers is increasing, and the size of elements is becoming smaller, making it impossible to meet the detection accuracy of conventional large light spots. The detection system proposed by this invention, through the ingenious design of the detection light path system and probe, has advantages such as high precision, accurate positioning, and low noise, and is further adapted to the demands of current processes.

[0029] After the detector 11 acquires the corresponding spectral information, it converts it into thickness information of the medium film on the wafer 8 surface to determine the endpoint of wafer 8 polishing. In other embodiments, the determination may be made based on whether signals such as feature spectral lines and feature points have reached a target value, and is not limited to film thickness information, depending on the endpoint detection algorithm employed. As shown in Figure 9, the spectral reflectance curve differs depending on the film thickness, and the polishing endpoint can be determined based on this.

[0030] The operation process of this invention is as follows: A light beam emitted from a light source 9 is collected and collimated by an optical lens set 10, reflected by a reflection unit 12 to a detection probe 13, and emitted from the proximal end 134 of the detection probe 13 via a quartz light guide tube 131, passing through a light-passing window 4 on the polishing pad 2 and irradiating the surface of a wafer 8 pressed onto the polishing pad 2. After the reflected light from the wafer 8 surface passes through the light-passing window 4, it is received by a single-core optical fiber 17 on the detection probe 16 and reaches a detector 11. The detector 11 is a spectrometer that receives the signal light reflected from the wafer 8 and obtains the corresponding spectral information.

[0031] This invention employs an original detection optical path system. Free-space propagation is used for the light source optical path from the light source 9 to the detection probe 16, and fiber propagation is used for the signal optical path from the detection probe 16 to the detector 11. The two types of light beam propagation methods are smoothly transitioned through the special design of the detection probe 16, so the entire detection optical path system combines the advantages of each of the two types of light beam propagation methods, enabling high-precision detection. Compared to conventional technical solutions that employ Y-type fiber guides, this invention employs free-space propagation for the light source optical path and uses a lens set to collect and collimate the light beam. The reflection unit 12 adjusts the direction of the light beam, ensuring that most of the light intensity from the light source 9 reaches the detection probe 13. This solves the problem of relatively large coupling loss present in the light beam from the light source 9 to the fiber, and by making full use of the power of the xenon lamp light source, detection demands can be met using a low-power light source, or higher intensity light can be involved in detection at the detection probe 13. This invention uses optical fibers in the signal path to collect effective signals, brings the signal collection point and the detection target (i.e., the wafer surface) close together, and ensures that the signal reaches the detector reliably through stable transmission via optical fibers. This invention combines the advantages of both free space and optical fiber transmission to improve the detection accuracy of the entire system.

[0032] Embodiment 2 As shown in Figure 11, this embodiment is based on Embodiment 1 and further includes a reference light sampling unit 14, which is located between the optical lens set 10 and the detection probe 13 and is used to monitor the light intensity of the light source 9 and includes a light intensity detector.

[0033] The reference light sampling unit 14 includes a beam splitter 141. Light rays emitted from the light source 9 are collimated by the optical lens set 10, and the resulting collimated beam reaches the reference light sampling unit 14. There, it is split into two beams by the beam splitter 141, that is, after passing through the beam splitter 141, it forms signal light and reference light. Of these, the transmitted beam is the signal light, which passes through the beam splitter 141 and enters the reflection unit 12. The reflected beam is the reference light, which reaches the light intensity detector, and the light intensity value of the reference light is obtained.

[0034] Furthermore, this embodiment further includes a controller for controlling the blinking and light intensity of the light source 9 and for calculating the polishing endpoint of the wafer 8 based on spectral information acquired by the detector 11. The controller is connected to the light source 9, the detector 11, and the light intensity detector. The controller may be located inside the polishing disc 1, or it may be connected to the light source 9, the detector 11, and the light intensity detector outside the polishing disc 1 by means of a conductive slip ring or the like.

[0035] The controller directly or indirectly transmits a control signal to the light source 9, the controller transmits a control signal to the detector 11, and the detector 11 transmits a control signal to the light source 9, the control signal including a first control signal and a second control signal.

[0036] The first control signal is a pulse voltage value signal, with a pulse width of generally 10-100us and a pulse frequency of 100-1000Hz, used to control the on / off state of the light source 9. The light source 9 receives the pulse signal, turns on after a certain delay, and turns off after a certain period of time. The light source 9 turns on and off according to the frequency of the pulse signal, and the detector 11 also performs sampling detection according to the frequency of the pulse signal, maintaining synchronization between the light source 9 and the detector 11.

[0037] The second control signal is a level signal, which is a variable voltage signal, typically between 0 and 5V, and is used to control the light intensity of the light source 9. The light source 9 receives the level signal and amplifies the voltage according to a certain ratio to brighten the light source 9; the higher the voltage, the greater the light intensity of the light source 9. Therefore, the magnitude of the level signal is positively correlated with the brightness of the light source 9.

[0038] To illustrate with an example of monitoring film thickness information, during the polishing process, the polishing plate 1 and the polishing pad 2 fixed on it rotate at a set speed, and the light-transmitting window 4 on the polishing pad 2 also rotates accordingly, forming a light-transmitting window path 7. When the light-transmitting window 4 passes beneath the wafer 8 supported on the polishing head 5, the spectral information reflected by the wafer 8 is acquired by the detector 11 via the reflection unit 12 and the detection probe 13. By comparing the spectral information with the surface film thickness of the wafer 8, online measurement of the film thickness information on the surface of the wafer 8 can be performed. Depending on the rotation speed of the polishing plate 1, the time it takes for the light-transmitting window 4 to pass beneath the wafer 8 supported on the polishing head 5 differs, and the signal sampling frequency can be adjusted by the first control signal to ensure sufficient sampling points and sufficient signal data. As the polishing process progresses, the degree of wear of the light-transmitting window 4 gradually changes, and because the concentration components of each type of process polishing solution differ and the signal optical path state differs, it causes changes in signal intensity. By controlling the magnitude of the voltage value of the second control signal, the light intensity of the signal light can be kept within the appropriate range of the detector 11, thereby improving the accuracy and precision of film thickness measurement.

[0039] During the polishing process, a light intensity detector can continuously monitor and measure the reference light beam, allowing for the acquisition of the reference light intensity. The reference light reflects the state of the light source 9, and the reference light spectral information and light intensity values ​​can be used to correct for fluctuations in the light intensity of the light source 9 caused by factors such as degradation of the light source 9 and voltage instability. By controlling the magnitude of the voltage value of the second control signal, the light intensity of the light source 9 can be maintained in a stable state, improving the accuracy and precision of film thickness measurement.

[0040] The specific embodiments described above are for illustrative purposes only and do not limit the present invention. Any modifications and changes made to the present invention within the spirit and scope of the claims are also included within the scope of protection of the present invention. [Explanation of symbols]

[0041] 1 Polishing machine 2 polishing pads 3. Polishing liquid spray arm 4. Light-transmitting window 5 Polishing heads 6 Trimmers 7 Light-transmitting window path 8 wafers 9 light source 10 Optical Lens Set 11 detectors 12 Reflection Units 13 Detection probe 131 Quartz light guide tube 132 Single-core optical fiber 133 Housing 134 Proximal end of the detection probe 135 Distal end of detection probe 136 Beveling of quartz light guide tubes 14. Reference light sampling unit 141 Beam Splitter

Claims

1. An online monitoring device for chemical mechanical polishing, which is installed inside the polishing disc and can rotate together with the polishing disc. Light source and An optical lens set used to receive a light beam emitted from a light source and generate a collimated beam, A reflective unit used to receive a collimated beam and reflect the collimated beam to form an incident light path, A detection probe is provided below the light passage window of the polishing pad and includes at least a quartz optical guide tube and a single-core optical fiber, wherein the quartz optical guide tube is used to receive the incident optical path and to emit the incident optical path from one end of the detection probe closer to the wafer, and the single-core optical fiber is used to receive the outgoing optical path reflected from the wafer surface. An online monitoring device for chemical mechanical polishing, characterized by including a detector connected to the single-core optical fiber and used to receive the output optical path, acquire corresponding spectral information, and determine the endpoint of wafer polishing.

2. The detection probe further includes a housing, The quartz optical guide tube covers the outer circumference of the single-core optical fiber, the housing covers the outer circumference of the quartz optical guide tube, and the housing, the quartz optical guide tube, and the single-core optical fiber are installed concentrically. Alternatively, the online monitoring device for chemical mechanical polishing according to claim 1, characterized in that the quartz optical guide tube and the single-core optical fiber are installed adjacent to each other, and the housing covers the outer circumference of the quartz optical guide tube and the single-core optical fiber.

3. The online monitoring apparatus for chemical mechanical polishing according to claim 1 or 2, characterized in that the end face of the quartz optical guide tube closest to the wafer and the end face of the single-core optical fiber closest to the wafer are flat, and the end face of the quartz optical guide tube closest to the wafer has a chamfer.

4. The aforementioned chamfer is a straight chamfer, and its angle of inclination is greater than 0° and less than or equal to 45°. Alternatively, the chamfer is a circular chamfer, and its fillet curvature is 0 < k ≤ 2 mm, where k is the fillet curvature. -１ The online monitoring device for chemical mechanical polishing according to claim 3.

5. The online monitoring apparatus for chemical mechanical polishing according to claim 1, characterized in that the single-core optical fiber protrudes from the quartz optical guide tube at one end far from the wafer and the quartz optical guide tube.

6. The online monitoring device for chemical mechanical polishing according to claim 1, characterized in that the outer diameter of the quartz optical guide tube is 1 to 4 mm and the outer diameter of the single-core optical fiber is 0.1 to 2 mm.

7. The online monitoring device for chemical mechanical polishing according to claim 1, characterized in that the light source is a broadband light source with a wavelength of 200 to 2000 nm, and the diameter of the collimated beam is 1 to 10 mm.

8. The online monitoring apparatus for chemical mechanical polishing according to claim 1, characterized in that the detector is a spectrometer, the detector acquires corresponding spectral information, converts it into thickness information of the medium film on the wafer surface, and determines the endpoint of wafer polishing.

9. The online monitoring apparatus for chemical mechanical polishing according to claim 1, further comprising a reference light sampling unit, which is installed between the optical lens set and the detection probe and is used to monitor the light intensity of the light source.

10. The online monitoring apparatus for chemical mechanical polishing according to claim 9, wherein the reference light sampling unit includes a first beam splitter and a second beam splitter, the collimated beam passes through the first beam splitter to form signal light and reference light, and the signal light passes through the first beam splitter to enter a detection probe.

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