Method and system for detecting the surface condition of a polishing pad online

Abstract

The present invention discloses a method for detecting the surface condition of a polishing pad online, which includes the steps of: moving an optical sensor above the polishing pad to obtain distance information between the optical sensor and the surface of the polishing pad; classifying the distribution state of liquid on the surface of the polishing pad based on the measured distance information, and calculating and obtaining the value of the groove depth on the surface of the polishing pad using different correction calculation formulas; and comparing the corrected groove depth value on the surface of the polishing pad with a preset threshold value to judge the groove depth state of the polishing pad and determine whether the polishing pad needs to be replaced. The present invention further discloses an online detection system for the surface condition of a polishing pad. The present invention relies on an optical sensor to non-contact measure the surface condition of the polishing pad online, thereby preventing the possibility of damage to the surface of the polishing pad caused by contact detection, and the online measurement can timely monitor the surface condition of the polishing pad, and accurately and efficiently realize the detection of the surface condition of the polishing pad, with stronger timeliness of detection and precise measurement.

Description

Technical Field

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[0001] The present invention belongs to the field of manufacturing apparatuses for semiconductor integrated circuit chips, and particularly relates to a method and a detection system for on-line detecting the surface state of a polishing pad.

Background Art

[0006] 3. A method that indirectly determines the condition from the thickness of the polishing pad. This method employs methods such as measuring the position of structures such as dressers that come into contact with the polishing pad to obtain thickness information of the polishing pad, or measuring the transmittance of the polishing pad to obtain thickness information of the polishing pad. However, the information on the condition of the polishing pad obtained by this method is relatively simple, and only local thickness information of the polishing pad is obtained, and it is not possible to obtain information on the actual groove depth. Due to the influence on the grooves by factors unrelated to the overall wear of the polishing pad, and errors in the depth of the polishing pad grooves themselves, the judgment of this method is prone to errors. [Overview of the project]

[0007] To solve the problems of the prior art, the present invention provides an online method and system for detecting the surface condition of a polishing pad, which can detect the surface condition of the polishing pad online in real time, acquire information such as groove depth, polishing pad thickness, and surface liquid state, and improve the efficiency and yield of the chemical mechanical polishing process.

[0008] The technical solution employed by the present invention to solve this technical problem is a method for detecting the surface condition of a polishing pad online, and includes the following steps. To obtain distance information from the optical sensor to the surface of the polishing pad, the optical sensor is moved above the polishing pad.

[0009] Based on the measured distance information, the distribution state of the surface liquid of the polishing pad is distinguished, and the groove depth value of the surface of the polishing pad is calculated and obtained using different correction formulas.

[0010] The depth of the grooves on the polishing pad surface after correction is compared to a preset threshold value to determine the condition of the groove depth of the polishing pad and to determine whether or not the polishing pad needs to be replaced.

[0011] Furthermore, determining the groove depth status involves determining whether the number of grooves with a depth value smaller than a predetermined threshold has reached a set number, or whether the average groove depth within a predetermined range is smaller than a predetermined threshold.

[0012] Furthermore, during the movement process of the optical sensor, the distance from the optical sensor to the surface of the polishing pad is acquired as the first piece of information.

[0013] And / or, during the movement of the optical sensor, the distance from the optical sensor to the liquid surface on the polishing pad is acquired as second information.

[0014] And / or, during the movement process of the optical sensor, the distance to the bottom surface of the optical sensor groove is acquired as a third piece of information.

[0015] And / or, during the movement of the optical sensor, the distance from the optical sensor to the liquid surface in the groove is acquired as a fourth piece of information.

[0016] Furthermore, the distribution of liquid on the surface of the polishing pad includes one or two of the following three states, or a combination of more. A first state in which there is liquid in the groove and the liquid overflows from the groove and covers the surface of the polishing pad. A second state in which there is liquid in the groove, and the liquid does not fill the groove. The third state is when there is no liquid in the groove.

[0017] Furthermore, the optical sensor distinguishes the distribution state of the liquid on the surface of the polishing pad based on the distance information it detects and acquires.

[0018] In the first state, the first information, the second information, the third information, and the fourth information are detected.

[0019] In the second state, the first information, the third information, and the fourth information are detected.

[0020] In the third state, the first information and the third information are detected.

[0021] Furthermore, in the first state, the modified groove depth = original groove depth × liquid refractive index.

[0022] In the second state, the modified groove depth = original groove depth + (distance from the optical sensor to the bottom of the groove on the polishing pad - distance from the optical sensor to the liquid surface on the polishing pad) × (liquid refractive index - 1).

[0023] In the third state, the modified groove depth = original groove depth.

[0024] Furthermore, repeat the above steps to detect the state of the groove depth, and when the state of the groove depth reaches the set state, issue a reminder to prompt the replacement of the polishing pad.

[0025] Furthermore, the above optical sensor is parallel to and above the polishing pad, moves along the radial direction of the polishing pad, and the moving range is from the end of the polishing pad to the center of the polishing pad.

[0026] The present invention further provides a system for on-line detecting the surface state of a polishing pad, including the following. An optical sensor including at least an optical unit, a sensor probe, and a control unit. The above optical unit is used to emit a light beam towards the surface of the polishing pad.

[0027] The above sensor probe is used to focus the light beam emitted from the optical unit and irradiate the polishing pad, and receive the reflected light and transmit it to the optical unit.

[0028] The control unit is used to obtain the distance between the sensor probe and each location on the surface of the polishing pad.

[0029] The processing unit is connected to the optical sensor, analyzes the distance information obtained by the control unit, and is used to calculate and obtain the value of the depth of the groove on the surface of the polishing pad corresponding to different correction calculation formulas.

[0030] The movable support structure is used to drive the optical sensor to move above the polishing pad.

[0031] Furthermore, the correction calculation formula is for different distribution states of the liquid on the surface of the polishing pad, and the distribution state includes the following. A first state where there is liquid in the groove and the liquid covers the surface of the polishing pad after overflowing from the groove. A second state where there is liquid in the groove and the liquid does not fill the groove. A third state where there is no liquid in the groove.

[0032] Furthermore, the optical sensor adopts the spectral confocal technology.

[0033] Furthermore, the movable support structure drives the optical sensor to move along a direction parallel to the polishing pad, and the moving range is from the end of the polishing pad to the center of the polishing pad, and the height of the movable support structure is adjustable.

[0034] Furthermore, the movable support structure is a polishing head, or a polishing arm, or a polishing liquid dispenser arm, or a trimming head, or a trimming arm, or an independent support structure.

[0035] Furthermore, a transparent protective layer is provided on the outer cover of the sensor probe, and a cleaning unit for cleaning the sensor probe or the transparent protective layer is further included.

[0036] Furthermore, it includes a warning unit that issues a warning if the average depth of grooves within a predetermined range is less than a set value, or if the number of grooves with a depth value less than a preset threshold reaches a set number.

[0037] The advantageous effects of the present invention are as follows: 1) The proposed system and method for detecting the surface condition of a polishing pad online relies on an optical sensor to measure the surface condition of the polishing pad online without contact. The optical non-contact method prevents the possibility of damage to the surface of the polishing pad due to contact detection. Online measurement allows for timely monitoring of the surface condition of the polishing pad. Compared to inefficient manual detection and inaccurate experience-based time detection, this detection system can accurately and efficiently detect the surface condition of the polishing pad. 2) Based on the measurement of the distance between the polishing pad and the bottom of the groove, a quantitative and accurate value of the groove depth can be obtained. Furthermore, the optical sensor can move across the entire polishing pad by a movable support structure, allowing for accurate measurement of the depth of all grooves on the polishing pad. Compared to localized detection of the thickness of the polishing pad, the present invention can achieve accurate measurement of the overall and localized surface condition of the polishing pad. 3) The distance detection method of the present invention measures the distance to the liquid surface, determines whether or not a liquid surface exists on the polishing pad, detects the depth of the grooves of the polishing pad, simultaneously detects the liquid state on the surface of the polishing pad, determines the amount of liquid on the surface of the polishing pad, and can correct the detected groove depth of the polishing pad based on the liquid state on the surface of the polishing pad. 4) Based on the liquid distribution state on different areas of the surface of the polishing pad, the groove depth values ​​of different areas can be obtained in accordance with the distance information, resulting in more accurate depth values ​​and more accurate judgments. 5) The movable support structure can move the optical sensor in real time to detect the polishing pad, resulting in more timely detection and more timely replacement of the polishing pad. [Brief explanation of the drawing]

[0038] [Figure 1] This is a schematic perspective view of the polishing system of the present invention. [Figure 2]This is a schematic diagram of the matching structure between the system for detecting the surface condition of the polishing pad of the present invention online and a chemical mechanical polishing apparatus. [Figure 3] This is a schematic diagram of the structure of a system for detecting the surface condition of a polishing pad online according to the present invention. [Figure 4] This diagram shows the surface characteristics of the polishing pad and a schematic diagram of its detection when the liquid level covers the surface of the polishing pad. [Figure 5] This is a schematic diagram showing the state where the liquid level covers the surface of the polishing pad. [Figure 6] This is a schematic diagram showing a state where the liquid level is only within the groove. [Figure 7] This is a schematic diagram showing the polishing pad surface without any liquid. [Figure 8] This is a step block diagram of a method for detecting the surface condition of a polishing pad online according to the present invention. [Modes for carrying out the invention]

[0039] To enable those skilled in the art to better understand the methods of the present invention, the technical solutions in the embodiments of the invention will be clearly and completely described below, together with the drawings of the embodiments. Clearly, the embodiments described are only a part of the embodiments of the present invention, not all embodiments. All other embodiments that can be obtained by those skilled in the art without requiring any creative effort based on the embodiments of the present invention should all fall within the scope of the claims of the present invention.

[0040] A system for detecting the surface condition of a polishing pad online, comprising an optical sensor 1, a processing unit 3, a movable support structure 4, and a warning unit, as shown in Figure 3.

[0041] As shown in Figures 1 and 2, the polishing pad 2 is mounted on the surface of the polishing table 20 and rotates with the polishing table 20. Above the polishing table 20, a polishing head 41, a polishing arm 42, a polishing fluid dispenser arm 43, a trimming head 44, and a trimming arm 45 are mounted. The polishing head 41 fixes the wafer and brings it into sufficient contact with the polishing pad 2, moving and rotating it relative to the polishing table 20. The polishing arm 42 fixes the polishing head 41. The polishing fluid dispenser arm 43 supplies polishing fluid to the surface of the polishing pad 2. The trimming head 44 contacts the polishing pad 2 and trims the surface of the polishing pad 2. The polishing arm 42 fixes the polishing head 41. Figure 1 shows only one of the polishing configurations, but of course, other embodiments may use other conventional polishing configurations.

[0042] The optical sensor 1 is used to detect its target distance from the surface features of the polishing pad 2 online and includes at least an optical unit 11, a sensor probe 12, and a control unit 13. In this embodiment, the optical sensor 1 employs spectral confocal technology.

[0043] The optical unit 11 described above is used to emit a light beam onto the surface of the polishing pad 2.

[0044] The sensor probe 12 described above is used to focus the light beam emitted from the optical unit 11 and irradiate the polishing pad 2 with it, and to receive the reflected light and transmit it to the optical unit 11. The sensor probe 12 can be provided integrally with the optical sensor 1, or it can exist independently of the optical sensor 1.

[0045] A cleaning unit is mounted above the polishing table 20 to clean the sensor probe 12 and prevent the possibility of liquid crystallization. To improve the protective effect of the sensor probe 12, a transparent protective layer is provided to cover the outside of the sensor probe 12, preventing the possibility of liquid contamination and corrosion, and so that the cleaning unit cleans the transparent protective layer.

[0046] The control unit 13 is used to obtain the distance between the sensor probe 12 and each point on the surface of the polishing pad 2.

[0047] The processing unit 3 is connected to the optical sensor 2, analyzes the distance information acquired by the control unit 13, and calculates and obtains the depth value of the grooves 21 on the surface of the polishing pad 2 in accordance with different correction calculation formulas.

[0048] The above modified calculation formula applies to different distribution states of liquid on the surface of the polishing pad 2, and the distribution states include the following three states: The first state is when there is liquid in the groove 21 and the liquid overflows from the groove 21 and covers the surface of the polishing pad 2, i.e., both the polishing surface of the polishing pad 2 and the liquid surface above the groove 21 exist, as shown in Figure 5. The second state is when there is liquid in the groove 21, but the liquid does not fill the groove 21, i.e., the liquid surface exists above the groove 21 and there is no liquid surface above the polishing surface of the polishing pad 2, as shown in Figure 6. The third state is when there is no liquid in the groove 21, and neither the liquid surface above the polishing surface of the polishing pad 2 nor the liquid surface above the groove 21 exists, as shown in Figure 7.

[0049] The movable support structure 4 is used to drive the optical sensor 1 to move it above the polishing pad 2. That is, the optical sensor 1 moves in accordance with the movable support structure 4 and along a direction parallel to the polishing pad 2, with the range of movement from the edge of the polishing pad 2 to the center of the polishing pad 2.

[0050] The optical sensor 1 measures the distance from the sensor probe 12 to the surface of the polishing pad 2. Depending on this distance, the movable support structure 4 drives the sensor probe 12, which is fixed thereto, to move perpendicularly to the polishing pad 2. The distance from the sensor probe 12 to the surface of the polishing pad 2 is adjusted to the optimal working distance for the optical sensor 1. At the optimal working distance, the focal point of the light beam emitted from the sensor probe 12 is minimized, allowing measurement to be taken in narrower grooves. For this reason, the movable support structure 4 is designed to be height-adjustable and moves vertically vertically to the surface of the polishing pad 2 when adjusting the height.

[0051] The movable support structure 4 may be a polishing head 41, a polishing arm 42, a polishing fluid dispenser arm 43, a trimming head 44, a trimming arm 45, or an independent support structure, and is not particularly limited.

[0052] The warning unit issues a warning to the user prompting them to replace the polishing pad 2 if the average depth of the grooves 21 within a predetermined range is less than a set value, or if the number of grooves 21 with a depth value less than a preset threshold reaches a set number.

[0053] When using a system to detect the surface condition of a polishing pad online, the sensor probe 12 is mounted at a certain distance from the polishing pad 2, which is within the detection range of the optical sensor 1. The optical unit 11 of the optical sensor 1 emits a light beam, which passes through the sensor probe 12. The light beam is focused to a minute point and irradiates the polishing pad 2. After reflection from the surface features of the polishing pad 2, the reflected light beams from each feature are received by the sensor probe 12 and transmitted back to the optical unit 11, where information such as the wavelength, intensity, and spot position of the reflected light beam is detected. The control unit 13 controls the optical unit 11 to emit, receive, and detect the light beam. Based on the detected information, it obtains distance information from the sensor probe 12 to various liquid level distribution areas on the polishing pad 2, completing the distance measurement function of the optical sensor 1. The processing unit 3 receives the distance information measured from the optical sensor 1 and uses it for subsequent analysis of the surface condition of the polishing pad 2.

[0054] The movable support structure 4 drives the sensor probe 12 fixed thereto, moving it parallel to the polishing pad 2 according to a predetermined movement path, and measures surface feature distance information for each corresponding partial or overall area of ​​the polishing pad 2 along the movement path, and the distance from the sensor probe 12 to the liquid surface on the polishing pad 2, and the distance from the sensor probe 12 to the polishing pad 2 polished surface The distance to the bottom surface of the groove 21 of the polishing pad 2, and the distance from the sensor probe 12 to the bottom surface of the groove 21 of the polishing pad 2. distance from the sensor probe 12 to the liquid surface in the groove 21 of the polishing pad 2 The movable support structure 4's movement path includes the entire range from the end to the center of the polishing pad 2, and the optical sensor 1 fixed to it can measure characteristic distance information for each point on the entire polishing pad 2.

[0055] As shown in Figure 8, the method for detecting the surface condition of a polishing pad online includes the following steps: The optical sensor 1 is moved above the polishing pad 2, specifically parallel to and above the polishing pad 2, along the radial direction of the polishing pad 2, with the movement range being from the edge of the polishing pad 2 to the center of the polishing pad 2, to acquire surface condition information of the polishing pad 2 and distance information between the optical sensor 1 and the surface of the polishing pad 2.

[0056] Based on the distribution of surface liquid in the polishing pad 2, and in conjunction with the measured distance information, the depth value of the grooves 21 on the surface of the polishing pad 2 is calculated and obtained, corresponding to the use of different correction formulas.

[0057] The depth of the grooves 21 on the surface of the polishing pad 2 after correction is compared with a preset threshold value to determine the condition of the groove depth of the polishing pad 2, thereby determining whether or not the polishing pad 2 needs to be replaced.

[0058] If the initial assessment indicates that replacement is not necessary, the above steps are repeated to detect the depth state of the groove 21. When the depth state of the groove 21 reaches the set state, the warning unit issues a reminder prompting the replacement of the polishing pad 2.

[0059] The determination of the depth state of the grooves 21 on the polishing pad 2 involves determining whether the number of grooves 21 with a depth value smaller than a preset threshold has reached a set number, or whether the average depth of the grooves 21 within a predetermined range is smaller than a preset threshold. This predetermined range may be any size area on the polishing pad 2.

[0060] Specifically, the optical sensor 1 is moved above the polishing pad 2 to acquire surface condition information of the polishing pad 2, including the first information, the second information, the third information, and the fourth information.

[0061] As shown in Figure 4, the first piece of information is transmitted from the optical sensor 1 to the polishing pad 2. polished surface This is the distance to [the destination].

[0062] The second piece of information is the distance from the optical sensor 1 to the liquid surface on the polishing pad 2.

[0063] In other words, when the sensor probe 12 is positioned above the polishing pad 2, the optical sensor 1 determines whether there is a liquid surface on the polishing pad 2 and measures the distance from the sensor probe 12 to the liquid surface on the polishing pad 2. At the same time, the optical sensor 1 determines whether the polishing pad 2 is present and measures the distance from the sensor probe 12 to the polishing pad 2.

[0064] The third piece of information is the distance from the optical sensor 1 to the bottom surface of the groove 21.

[0065] The fourth piece of information is the distance from the optical sensor 1 to the liquid surface in the groove 21.

[0066] In other words, the optical sensor 1 determines whether there is a liquid surface on the polishing pad 2 when the sensor probe 12 is positioned above the groove 21 of the polishing pad 2, and measures the distance from the sensor probe 12 to the liquid surface on the polishing pad 2. At the same time, the optical sensor 1 determines whether there is a bottom surface of the groove 21 of the polishing pad 2, and measures the distance from the sensor probe 12 to the bottom surface of the groove 21.

[0067] The formula for calculating the depth of groove 21 is: Groove depth = Distance from the sensor probe to the bottom surface of the groove on the polishing pad - Distance from the sensor probe to the surface of the polishing pad (in this case, the polishing surface of the polishing pad).

[0068] Polishing fluid accumulates on the surface of the polishing pad 2, and the amount of polishing fluid accumulated differs depending on the area. Therefore, the surface condition information of the polishing pad 2 is generally one of the following three: , or two or three This includes combinations of the above. Optical sensor 1 distinguishes the distribution state of the liquid on the surface of polishing pad 2 based on the distance information it detects and acquires.

[0069] The first state is as shown in Figure 5, where there is liquid in the groove 21, and after the liquid overflows from the groove 21, the polishing pad 2 polished surfaceThe objective is to cover the first information, second information, third information, and fourth information, and the corresponding correction formula is: corrected groove depth = original groove depth × liquid refractive index.

[0070] The second state is, as shown in Figure 6, when there is liquid in the groove 21, but the liquid does not fill the groove 21. In the second state, the optical sensor 1 detects and acquires the first information, the third information, and the fourth information, and the corresponding correction formula is the corrected groove depth = Before correction Groove depth h1 + (distance from optical sensor to bottom surface of polishing pad groove h2 - Distance from the optical sensor to the liquid surface in the groove The formula is h³ × (refractive index of liquid - 1).

[0071] The third state is that there is no liquid in the groove 21, as shown in Figure 7. In the third state, the optical sensor 1 detects and acquires the first and third information, and the corresponding correction formula is: corrected groove depth = original groove depth.

[0072] The specific embodiments described above are for interpretive and illustrative purposes only and do not limit the present invention. Any modifications or changes made to the present invention within the spirit or scope claimed by the claims are included within the scope of the claims.

Claims

1. A method for detecting the surface condition of a polishing pad online, The steps include: moving the optical sensor above the polishing pad using a movable support structure, and acquiring distance information between the optical sensor and each point on the surface of the polishing pad, either partially or entirely, using a control unit included in the optical sensor; The processing unit distinguishes the distribution state of the liquid on the surface of the polishing pad based on the distance information acquired by the control unit, and calculates and obtains the value of the groove depth on the surface of the polishing pad using different correction formulas. The processing unit includes the step of comparing the depth of the corrected groove on the surface of the polishing pad with a preset threshold value to determine the groove depth state of the polishing pad and to determine whether or not the polishing pad needs to be replaced. The distinction of the liquid distribution state on the surface of the polishing pad by the processing unit is to distinguish between one, two, or a combination of three states: a first state in which there is liquid in the grooves and the liquid overflows from the grooves before covering the polishing surface of the polishing pad; a second state in which there is liquid in the grooves but the liquid does not fill the grooves; and a third state in which there is no liquid in the grooves. A method for detecting the surface condition of a polishing pad online, characterized in that, in the first state, the depth of the corrected groove = the depth of the groove before correction × the liquid refractive index; in the second state, the depth of the corrected groove = the depth of the groove before correction + (distance from the optical sensor to the bottom surface of the groove of the polishing pad - distance from the optical sensor to the liquid surface in the groove) × (liquid refractive index - 1); and in the third state, the depth of the corrected groove = the depth of the groove before correction.

2. The method for detecting the surface state of a polishing pad online according to claim 1, characterized in that the processing unit determines the groove depth state by determining whether the number of grooves with a depth value smaller than a preset threshold has reached a set number, or by determining whether the average value of the groove depths within a predetermined range is smaller than a preset threshold.

3. The distance information between each point on the surface of the polishing pad acquired by the control unit is a first piece of information acquired during the movement of the optical sensor, which is the distance between the optical sensor and the polishing surface of the polishing pad, and / or a second piece of information which is the distance between the optical sensor and the liquid surface on the polishing pad, and / or a third piece of information which is the distance between the optical sensor and the bottom surface of the groove, and / or a fourth piece of information which is the distance between the optical sensor and the liquid surface in the groove. The processing unit distinguishes the distribution state of liquid on the surface of the polishing pad based on the distance information detected and acquired during the movement process of the optical sensor, and in the first state, it detects and acquires the first information, the second information, the third information, and the fourth information; in the second state, it detects and acquires the first information, the third information, and the fourth information; and in the third state, it detects and acquires the first information and the third information, characterized in that it is a method for detecting the surface state of a polishing pad online according to claim 1.

4. A method for detecting the surface condition of a polishing pad online, characterized in that the above step is repeated to detect the depth of the groove, and when the depth of the groove reaches a set state, a reminder is issued to prompt the replacement of the polishing pad.

5. The method for detecting the surface state of a polishing pad online according to claim 1, characterized in that the optical sensor moves parallel to and above the polishing pad, along the radial direction of the polishing pad, and the range of movement is from the edge of the polishing pad to the center of the polishing pad.

6. A system for detecting the surface condition of a polishing pad online, An optical sensor including at least an optical unit, a sensor probe, and a control unit, A processing unit connected to the optical sensor analyzes distance information acquired by the control unit, distinguishes the distribution state of liquid on the surface of the polishing pad, and calculates and acquires the value of the groove depth on the surface of the polishing pad using different correction formulas corresponding to the result of the distinction. The optical sensor includes a movable support structure for driving the optical sensor above the polishing pad, The optical unit is used to emit a light beam toward the surface of the polishing pad. The sensor probe is used to focus the light beam emitted from the optical unit and irradiate the polishing pad with it, and to receive the reflected light and transmit it to the optical unit. The control unit is used to obtain the distance between the sensor probe and each point on the surface of the polishing pad, either partially or entirely. The distinction of the liquid distribution state on the surface of the polishing pad by the processing unit is to distinguish between one, two, or a combination of three states: a first state in which there is liquid in the grooves and the liquid overflows from the grooves before covering the polishing surface of the polishing pad; a second state in which there is liquid in the grooves but the liquid does not fill the grooves; and a third state in which there is no liquid in the grooves. In the first state, the depth of the corrected groove = the depth of the groove before correction × the liquid refractive index; in the second state, the depth of the corrected groove = the depth of the groove before correction + (distance from the optical sensor to the bottom surface of the groove of the polishing pad - distance from the optical sensor to the liquid surface in the groove) × (liquid refractive index - 1); and in the third state, the depth of the corrected groove = the depth of the groove before correction. A system for detecting the surface condition of a polishing pad online, characterized by comparing the corrected depth of the grooves on the surface of the polishing pad with a preset threshold value to determine the groove depth state of the polishing pad and to determine whether or not the polishing pad needs to be replaced.

7. The system for detecting the surface state of a polishing pad online according to claim 6, wherein the correction calculation formula is for different distribution states of liquid on the surface of the polishing pad, and the distribution states include a first state in which there is liquid in the groove and the liquid overflows from the groove and covers the polishing surface of the polishing pad; a second state in which there is liquid in the groove but the liquid does not fill the groove; and a third state in which there is no liquid in the groove.

8. The system for detecting the surface condition of a polishing pad online, characterized in that the optical sensor employs spectral confocal technology.

9. The system for detecting the surface condition of a polishing pad online, as described in claim 6, wherein the movable support structure is driven by the optical sensor to move along a direction parallel to the polishing pad, the range of movement is from the edge of the polishing pad to the center of the polishing pad, and the height of the movable support structure is adjustable.

10. The system for detecting the surface condition of a polishing pad online, as described in claim 6, characterized in that the movable support structure is a polishing head, or a polishing arm, or a polishing fluid dispenser arm, or a trimming head, or a trimming arm, or an independent support structure.

11. The system for detecting the surface condition of a polishing pad online according to claim 6, further comprising a transparent protective layer on the outer cover of the sensor probe and a cleaning unit for cleaning the sensor probe or the transparent protective layer.

12. The system for detecting the surface condition of an abrasive pad online, further comprising a warning unit that issues a warning when the average value of the groove depths within a predetermined range is less than a set value, or when the number of grooves whose groove depths are less than a preset threshold reaches a set number.

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