Grinding protection device and CMP machine table

Abstract

The utility model provides a grinding protection device and a CMP machine table. N cleaning assemblies are arranged in a cavity of the CMP machine table; each cleaning assembly comprises a nozzle and a fixing rod; the nozzle is connected with the cavity through the fixing rod, and M airflow channels are formed in the fixing rod and communicated with the nozzle. The nozzle is arranged towards a target device in the cavity; the nozzles are used for blowing the surface of the target device after the first gas is introduced into any P gas flow channels, N, M and P are positive integers, and P is smaller than or equal to M. The gas is blown to the surface of the target device by using the nozzle, so that a low-oxygen environment can be maintained in the chemical mechanical polishing process of a wafer, and oxidation of a copper wire and related performance reduction are reduced; and when the CMP machine gives an alarm and the wafer is idle in the cavity, the residual slurry on the surface of the wafer can be cleaned by the gas blown by the nozzle, so that excessive corrosion is avoided, and the rejection rate of the wafer is reduced.

Description

Technical Field

[0001] The utility model relates to the field of semiconductor equipment, in particular to a grinding protection device and a CMP machine. Background Art

[0002] Chemical Mechanical Polishing (CMP) equipment is an important equipment in the production process of semiconductor wafers. CMP is a processing technology that combines chemical corrosion and mechanical removal. It is the only technology that can achieve global surface flattening in the mechanical processing process. According to the grinding materials, it is mainly divided into metal chemical mechanical polishing and oxide chemical mechanical polishing. Due to the different grinding objects, the mechanisms are also quite different, and the materials used are also different. CMP machines are roughly divided into polishing units (Polish) and cleaning units (Clean). The main components of the polishing unit are polishing pads (Pad), diamond grinding discs (Disk) and polishing heads (Head), which cooperate with each other to provide a stable process environment for wafers (wafer); the cleaning unit cleans the wafers processed by the polishing unit, removes the residual particles (Particle) on the wafer surface and the complexes produced by the reaction, and finally leaves the machine after drying (Dry). Among them, the polishing unit is the place where the global flattening of the wafer surface is carried out, so it is the most important.

[0003] At present, in the CU CMP process, since the polishing object is pure copper (CU), and pure copper is very sensitive to the processing time inside the machine (such as the wafer is idle for too long inside the machine, such as more than 10 minutes) and many other factors (such as the wafer is not cleaned in time after the process), the wafer is prone to defects (such as copper oxide (CUO), copper (CU) damage, etc.). On the one hand, pure copper is very easy to oxidize in a humid environment. During the chemical mechanical polishing process, if the environmental humidity is not properly controlled, copper oxide (CUO) is easily generated on the copper wire. This oxide adheres to the surface of the copper wire and will seriously affect the electrical parameters such as Rc / Rs, thereby reducing the chip performance (CP) and reliability (RE) of the product. The slurry (slurry) used in the CU CMP process has strong oxidizing properties. On the other hand, if the slurry attached to the wafer is not cleaned off in time after the chemical mechanical polishing is completed, it will cause serious copper damage (CU damage). This defect is usually large in area and can easily exceed the scrap standard, resulting in wafer scrap.

[0004] Therefore, during the CU CMP process, defects such as copper oxide (CUO) and copper (CU) damage on the wafer are likely to affect the results of wafer acceptance test (WAT) and chip performance (CP), and even cause the wafer to be scrapped, which is a significant loss for semiconductor factories. Therefore, it is very important to reduce the wafer scrap rate.

[0005] Therefore, there is an urgent need for a polishing protection device and a CMP machine to improve the above problems. Utility Model Content

[0006] The utility model aims to provide a grinding protection device and a CMP machine, which can reduce the scrap rate of wafers.

[0007] In a first aspect, the utility model provides a polishing protection device, which is applied to a CMP machine, comprising: N cleaning components arranged in a cavity of the CMP machine;

[0008] Each of the cleaning assemblies comprises a nozzle and a fixing rod;

[0009] The nozzle is connected to the cavity through the fixing rod, and M air flow channels are provided in the fixing rod and communicate with the nozzle;

[0010] The nozzle is disposed toward a target device in the cavity;

[0011] The nozzle is used to purge the surface of the target device after the first gas is introduced into any P gas flow channels, wherein N, M and P are all positive integers, and P is less than or equal to M.

[0012] The beneficial effects of the protective device of the utility model are as follows: N cleaning components are arranged in the CMP machine chamber; each of the cleaning components includes a nozzle and a fixing rod; the nozzle is connected to the chamber through the fixing rod, and M airflow channels are arranged in the fixing rod and communicated with the nozzle; the nozzle is arranged toward the target device in the chamber; the nozzle is used to purge the surface of the target device after the first gas is introduced into any P airflow channels, wherein N, M and P are all positive integers, and P is less than or equal to M. Using the nozzle to purge the surface of the target device with gas can not only maintain a low-oxygen environment for the wafer during the chemical mechanical polishing process, reduce the oxidation of the copper wire and the related performance degradation; but also, when an alarm occurs in the CMP machine and the wafer is idle in the chamber, the gas purged by the nozzle can clean the slurry remaining on the surface of the wafer, avoid excessive corrosion of the wafer surface by the slurry, and thus reduce the scrap rate of the wafer.

[0013] Optionally, the target device is a grinding disc or a grinding head of a CMP machine;

[0014] The surface of the target device is the upper surface of the grinding disc or the lower surface of the wafer adsorbed by the bottom of the grinding head. The beneficial effect is that by setting the surface of the target device as the upper surface of the grinding disc, the wafer can maintain a low oxygen environment during the chemical mechanical polishing process, reducing the oxidation of the copper wire and related performance degradation, and setting the surface of the target device as the lower surface of the wafer adsorbed by the bottom of the grinding head, the slurry remaining on the wafer surface can be cleaned to prevent the slurry from excessively corroding the wafer surface.

[0015] Optionally, the cleaning component further includes a rotating shaft;

[0016] The nozzle is rotatably connected to the fixed rod via the rotating shaft;

[0017] The nozzle is used to purge gas toward the upper surface of the grinding disc after gas is introduced into any P gas flow channels, and after the grinding head is lifted, the nozzle is rotated toward the bottom of the grinding head through the rotating shaft, and purge gas toward the lower surface of the wafer adsorbed by the bottom of the grinding head after gas is introduced into any P gas flow channels. The beneficial effect is that by adding a rotating shaft and setting the nozzle to be rotatable, the nozzle can be adjusted in direction according to actual needs, and gas can be purged toward the upper surface of the grinding disc or the lower surface of the wafer adsorbed by the bottom of the grinding head, thereby improving the utilization rate of the nozzle and reducing the space occupied by the protective device in the CMP machine chamber.

[0018] Optionally, the rotating shaft is a multi-directional regulator, which is used to control and adjust the direction of the nozzle, so that the rotating shaft rotates around the fixed rod in several different directions. The beneficial effect is that the rotating shaft is set as a multi-directional regulator, so that the nozzle can rotate around the fixed rod through the rotating shaft in several different directions, which can not only improve the range of maintaining the low oxygen environment, but also improve the cleaning effect of the slurry on the wafer surface.

[0019] Optionally, a controller is also included;

[0020] The controller is electrically connected to the multidirectional regulator;

[0021] The controller is used to control the nozzle to rotate along a set track through the multidirectional regulator. The beneficial effect is that by setting a controller and using the controller to control the nozzle to rotate along a set track through the multidirectional regulator, the target device can be fully covered, thereby further reducing the oxygen content in the area where the wafer is located, and the slurry in various areas of the wafer surface can be fully and targetedly cleaned, thereby improving the cleaning effect.

[0022] Optionally, monitors and valves are also included;

[0023] The monitor and the valve are electrically connected to the controller respectively;

[0024] The valve is used to control the opening and closing of each gas flow channel and the gas flow rate;

[0025] The controller is also used to control the opening and closing of the valve and the flow rate of the gas in each air flow channel according to the signal of the monitor. Its beneficial effect is that by setting the monitor and the valve, and using the controller to control the opening and closing of the valve and the flow rate of the gas in each air flow channel according to the signal of the monitor, not only can the nozzle spray different gases according to different process characteristics, assisting and optimizing the grinding process, but also by setting the gas flow rate adjustable, not only can the appropriate gas flow rate range be adjusted according to the required low-oxygen environment, but the constantly changing airflow can also further improve the cleaning effect on the wafer surface.

[0026] Optionally, when blowing toward the surface of the target device, the angle between the straight line where the center line of the nozzle is located and the horizontal plane where the surface of the target device is located is in the range of 10-80 degrees. The beneficial effect is that by setting the angle between the straight line where the center line of the nozzle is located and the horizontal plane where the surface of the target device is located in the range of 10-80 degrees, the coverage range can be increased, which is conducive to maintaining a low-oxygen environment. In addition, the cleaning range can be increased, thereby improving the cleaning effect on the wafer surface.

[0027] Optionally, the first gas is one or more inert gases. The beneficial effect is that by setting the first gas to be one or more inert gases, the needs of different processes can be met and the application range is wide.

[0028] In a second aspect, a CMP machine comprises a protective device of any possible combination of the first aspect, a chamber and a target device disposed in the chamber;

[0029] The target device is used to grind the wafer;

[0030] The nozzle of the protection device is arranged toward the target device in the cavity, and is used to purge the surface of the target device after the first gas is introduced into any P gas flow channels.

[0031] The beneficial effects of the CMP machine of the utility model are as follows: by adding a protective device in the CMP machine and setting the nozzle of the protective device toward the target device in the chamber, it is used to purge the surface of the target device after the first gas is introduced into any P gas flow channels, which can not only maintain a low-oxygen environment for the wafer during the chemical mechanical polishing process and reduce the oxidation of the copper wire and related performance degradation; but also when an alarm occurs in the CMP machine and the wafer is idle in the chamber, the gas purged by the nozzle can clean the slurry remaining on the surface of the wafer to avoid excessive corrosion of the wafer surface by the slurry.

[0032] Optionally, the target device is a grinding disc and a grinding head of a CMP machine;

[0033] The grinding head is arranged above the grinding disc via a lifter;

[0034] The lifter is used to drive the grinding head to descend or rise;

[0035] After the lifter drives the grinding head to descend, the grinding head and the grinding disc cooperate with each other to grind the lower surface of the wafer adsorbed by the bottom of the grinding head;

[0036] The nozzle is arranged toward the upper surface of the grinding disc or toward the lower surface of the wafer adsorbed by the bottom of the raised grinding head;

[0037] The nozzle is used to purge gas toward the upper surface of the grinding disk after the first gas is introduced into any P gas flow channels, or to purge gas toward the lower surface of the wafer adsorbed by the bottom of the grinding head after the first gas is introduced into any P gas flow channels after the grinding head is lifted. The beneficial effect is that by setting the surface of the target device as the upper surface of the grinding disk, the wafer can maintain a low oxygen environment during the chemical mechanical polishing process, reducing the oxidation of the copper wire and related performance degradation, and by setting the surface of the target device as the lower surface of the wafer adsorbed by the bottom of the grinding head, the slurry remaining on the wafer surface can be cleaned to prevent the slurry from excessively corroding the wafer surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A schematic diagram of the structure of a grinding protection device provided by an embodiment of the utility model;

[0039] Figure 2 A schematic diagram of the internal structure of a cleaning component of a grinding protection device provided by an embodiment of the utility model;

[0040] Figure 3 A schematic structural diagram of another grinding protection device provided by an embodiment of the utility model;

[0041] Figure 4 A schematic structural diagram of another grinding protection device provided in an embodiment of the utility model;

[0042] Figure 5 A schematic diagram of the principle of grinding protection provided by an embodiment of the utility model.

[0043] Description of reference numerals:

[0044] 1. Cleaning assembly; 2. Grinding disc; 3. Grinding head; 4. Diamond grinding disc; 5. Lifter; 6. Multi-directional regulator; 7. Controller; 8. Monitor; 9. Valve;

[0045] 11. Nozzle; 12. Fixed rod; 13. Rotating shaft;

[0046] 121. Air flow channel. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical solution and advantages of the utility model clearer, the technical solution in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings of the utility model. Obviously, the described embodiment is a part of the embodiment of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the utility model. Unless otherwise defined, the technical terms or scientific terms used herein should be understood by people with general skills in the field to which the utility model belongs. "Including" and similar words used in this article mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects.

[0048] like Figure 1 and Figure 2As shown, the utility model provides a grinding protection device, which is applied to a CMP machine, comprising: a cleaning component 1 arranged in a cavity (not shown) of the CMP machine; each of the cleaning components 1 comprises a nozzle 11 and a fixing rod 12; the nozzle 11 is connected to the cavity through the fixing rod 12 (for example, a fixed connection method such as welding or integral molding, or a detachable connection method such as threading or snap-fitting, and a rotation connection method can be adopted. When the nozzle 11 is not working, the cleaning component 1 is stored, thereby reducing the space occupied by the protection device in the cavity, and the nozzle 11 needs to face the target device when working), and three air flow channels 121 are arranged in the fixing rod 12 and are connected to the nozzle 11; the nozzle 11 is arranged to face the target device (such as a grinding disc 2 or a grinding head 3) in the cavity; The nozzle 11 is used to purge gas to the surface of the target device (such as the upper surface of the grinding disc 2 or the lower surface of the wafer adsorbed at the bottom of the grinding head 3) after the first gas is introduced into any P gas flow channels 121, wherein 1≤P≤3, the first gas is one or more inert gases, such as one or more of nitrogen, argon or ammonia, which can meet the needs of different processes and have a wide range of applications; during the CMP process, the nozzle 11 can be used to purge gas to the upper surface of the grinding disc 2, so that the wafer can maintain a low oxygen environment during the chemical mechanical polishing process, reduce the oxidation of the copper wire and related performance degradation; and when the CMP machine alarm causes the wafer to be idle in the chamber, the gas purged by the nozzle 11 can clean the slurry remaining on the surface of the wafer, avoid excessive corrosion of the wafer surface by the slurry, and thus reduce the wafer scrap rate. It should be understood that the number of cleaning components 1 and the number of gas flow channels 121 can be adjusted according to actual needs. It is worth noting that the gas introduced to maintain the low oxygen environment and the gas introduced during cleaning can be the same or different, and the gases introduced into different air flow channels 121 can be the same (for example, nitrogen is introduced into all three air flow channels 121) or different (for example, nitrogen is introduced into the first air flow channel 121, argon is introduced into the second air flow channel 121, and ammonia is introduced into the third air flow channel 121, or nitrogen is introduced into the first and second air flow channels 121, and argon is introduced into the third air flow channel 121).

[0049] In some embodiments, in order to improve the utilization rate of the nozzle 11 and reduce the space occupied by the protective device in the CMP machine chamber, the cleaning component 1 also includes a rotating shaft 13; the nozzle 11 is rotatably connected to the fixed rod 12 through the rotating shaft 13; the nozzle 11 is used to purge gas toward the upper surface of the grinding disk 2 after gas is introduced into any P air flow channels 121, and after the grinding head 3 is lifted, it rotates toward the bottom of the grinding head 3 through the rotating shaft 13, and after gas is introduced into any P air flow channels 121, purge gas toward the lower surface of the wafer adsorbed by the bottom of the grinding head 3. The nozzle 11 can adjust its direction according to actual needs, and can purge gas to the upper surface of the grinding disk 2 to maintain a low oxygen environment, and can also purge gas to the lower surface of the wafer adsorbed by the bottom of the grinding head 3 to clean the slurry remaining on the wafer surface to avoid excessive corrosion of the wafer surface by the slurry. It should be understood that when multiple cleaning components 1 are provided, some of the cleaning components 1 can be provided to face the grinding disc 2 when in operation, and other cleaning components 1 can be provided to face the bottom of the raised grinding head 3 when in operation. It is worth noting that the cleaning components 1 provided to face the grinding disc 2 can be provided not only at the bottom of the cavity, but also at the side wall or top of the cavity, while the cleaning components 1 provided to face the grinding head 3 are preferably provided at the bottom or side wall of the cavity.

[0050] In some specific embodiments, Figure 5 As shown, in order to improve the range of maintaining the low oxygen environment and improve the cleaning effect of the slurry on the wafer surface, the rotating shaft 13 is a multi-directional regulator 6 (which can be composed of multiple rotating shafts with different rotation directions, or a damping rotating shaft, or a gear combination), which is used to control and adjust the direction of the nozzle 11, so that the rotating shaft 13 rotates around the fixed rod 12 in several different directions.

[0051] In some other specific embodiments, Figure 5 As shown, in order to further reduce the oxygen content in the area where the wafer is located and to achieve comprehensive and targeted cleaning of the slurry in various areas on the surface of the wafer to improve the cleaning effect, the protection device also includes a controller 7; the controller 7 is electrically connected to the multi-directional regulator 6; the controller 7 is used to control the nozzle 11 to rotate along a set trajectory through the multi-directional regulator 6. The specific trajectory can be adjusted according to actual conditions, but it is necessary to ensure that the gas purged by the nozzle 11 can fully cover or clean the grinding disc or the wafer at the bottom of the grinding head.

[0052] In some specific embodiments, Figure 5As shown, in order to enable the nozzle 11 to spray different gases according to different process characteristics, assist and optimize the grinding process, and adjust the appropriate gas flow rate range according to the required low-oxygen environment, and the constantly changing airflow can further improve the cleaning effect on the wafer surface, the protection device also includes a monitor 8 (such as a timer or sensor) and a valve 9; the monitor 8 and the valve 9 are electrically connected to the controller 7 respectively; the valve 9 is used to control the opening and closing of each airflow channel 121 and the gas flow rate; the controller 7 is also used to control the opening and closing of the valve 9 and the flow rate of the gas in each airflow channel 121 according to the signal of the monitor 8.

[0053] In some embodiments, Figure 3 and Figure 4 As shown, in order to facilitate maintaining a low oxygen environment and improve the cleaning effect on the wafer surface, when blowing toward the surface of the target device, the angle between the straight line where the center line of the nozzle 11 is located and the horizontal plane where the surface of the target device is located is in the range of 10-80 degrees. Among them, the center line of the nozzle 11 can be determined by the center point on the end faces of both ends of the nozzle, that is, the straight line where the connecting line of the center point of the end face of the air inlet end and the center point of the end face of the air outlet end is located. It is worth mentioning that the angle between the straight line where the center line of the nozzle 11 is located and the horizontal plane where the surface of the target device is located is set to 10-80 degrees in order to ensure a better low oxygen environment and a cleaning effect on the wafer surface. In some embodiments, the following method can also be adopted. Figure 1 The parallel manner shown means that the straight line where the center line of the nozzle 11 is located is parallel to the grinding disc 2 or the grinding head 3.

[0054] like Figure 1-5As shown, based on the above-mentioned grinding protection device, the utility model also provides a CMP machine, including the above-mentioned protection device, as well as a cavity (not shown) and a target device (such as a grinding disc 2 or a grinding head 3) and a diamond grinding disc 4 arranged in the cavity; the target device is used to grind the wafer; the nozzle 11 of the protection device is arranged toward the target device in the cavity, and is used to purge the surface of the target device after the first gas is introduced into any P gas flow channels 121. By adding a protection device to the CMP machine and setting the nozzle 11 of the protection device toward the target device in the cavity, and being used to purge the surface of the target device after the first gas is introduced into any P gas flow channels, not only can the wafer maintain a low oxygen environment during the chemical mechanical polishing process, and reduce the oxidation of the copper wire and related performance degradation; but also when an alarm occurs in the CMP machine and the wafer is idle in the cavity, the gas purged by the nozzle 11 can clean the slurry remaining on the surface of the wafer to avoid excessive corrosion of the wafer surface by the slurry. The CMP machine usually also includes a grinding pad (not shown), which is adhered to the upper surface of the grinding disk 1, rotates with the grinding disk 2, and grinds the wafer adsorbed on the bottom of the grinding head 3 by continuous rotation; an air bag is provided under the grinding head 3 to pressurize the wafer so that the wafer contacts the grinding pad below for grinding; a diamond grinding disc 4 is used to rotate continuously during the grinding process, tidy up the grinding pad and remove by-products produced by grinding on the surface of the grinding pad.

[0055] In some embodiments, the target device is a grinding disc 2 and a grinding head 3 of a CMP machine; the grinding head 3 is arranged above the grinding disc 2 through a lifter 5; the lifter 5 is used to drive the grinding head 3 to descend or ascend; after the lifter 5 drives the grinding head 3 to descend, the grinding head 3 and the grinding disc 2 cooperate with each other to grind the lower surface of the wafer adsorbed by the bottom of the grinding head 3; the nozzle 11 is arranged toward the upper surface of the grinding disc 2 or toward the lower surface of the wafer adsorbed by the bottom of the raised grinding head 3; Figure 3 As shown, the nozzle 11 is used to purge gas toward the upper surface of the grinding disc 2 after the first gas is introduced into any P gas flow channels 121, or as shown in FIG. Figure 4 As shown, the nozzle 11 is used to purge gas toward the lower surface of the wafer adsorbed at the bottom of the grinding head 3 after the grinding head 3 is lifted and the first gas is introduced into any P air flow channels 121, so that the wafer can maintain a low oxygen environment during the chemical mechanical grinding process, reduce the oxidation of the copper wire and related performance degradation, or clean the slurry remaining on the wafer surface to avoid excessive corrosion of the wafer surface by the slurry.

[0056] Although the embodiments of the present invention are described in detail above, it is obvious to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations are within the scope and spirit of the present invention as described in the claims. Moreover, the present invention described herein may have other embodiments and may be implemented or realized in a variety of ways.

Claims

1. A grinding protection device, applied to a CMP machine, characterized in that: include: N cleaning components are disposed in the chamber of the CMP machine; Each of the cleaning assemblies comprises a nozzle and a fixing rod; The nozzle is connected to the cavity through the fixing rod, and M air flow channels are provided in the fixing rod and communicate with the nozzle; The nozzle is disposed toward a target device in the cavity; The nozzle is used to purge the surface of the target device after the first gas is introduced into any P gas flow channels, wherein N, M and P are all positive integers, and P is less than or equal to M.

2. The device according to claim 1, characterized in that The target device is a grinding disc or a grinding head of a CMP machine; The surface of the target device is the upper surface of the grinding disc or the lower surface of the wafer adsorbed by the bottom of the grinding head.

3. The device according to claim 2, characterized in that The cleaning assembly also includes a rotating shaft; The nozzle is rotatably connected to the fixed rod via the rotating shaft; The nozzle is used to purge gas toward the upper surface of the grinding disk after gas is introduced into any P air flow channels, and to purge gas toward the lower surface of the wafer adsorbed at the bottom of the grinding head after the grinding head is lifted by rotating toward the bottom of the grinding head through the rotating shaft. After gas is introduced into any P air flow channels, the nozzle is used to purge gas toward the lower surface of the wafer adsorbed at the bottom of the grinding head.

4. The device according to claim 3, characterized in that The rotating shaft is a multi-directional regulator, which is used to control and adjust the direction of the nozzle, so that the rotating shaft rotates around the fixed rod in several different directions.

5. The device according to claim 4, characterized in that Also includes a controller; The controller is electrically connected to the multidirectional regulator; The controller is used to control the nozzle to rotate along a set trajectory through the multi-directional regulator.

6. The device according to claim 5, characterized in that Also includes monitors and valves; The monitor and the valve are electrically connected to the controller respectively; The valve is used to control the opening and closing of each gas flow channel and the gas flow rate; The controller is also used to control the opening and closing of the valve and the flow rate of the gas in each air flow channel according to the signal of the monitor.

7. The device according to claim 1, characterized in that When blowing toward the surface of the target device, the angle between the straight line where the center line of the nozzle is located and the horizontal plane where the surface of the target device is located is in the range of 10-80 degrees.

8. The device according to any one of claims 1 to 6, characterized in that: The first gas is one or more inert gases.

9. A CMP machine, characterized in that: A protective device comprising any one of claims 1 to 8, and a cavity and a target device disposed in the cavity; The target device is used to grind the wafer; The nozzle of the protection device is arranged toward the target device in the cavity, and is used to purge the surface of the target device after the first gas is introduced into any P gas flow channels.

10. The CMP machine according to claim 9, characterized in that: The target device is a grinding disc and a grinding head of a CMP machine; The grinding head is arranged above the grinding disc via a lifter; The lifter is used to drive the grinding head to descend or rise; After the lifter drives the grinding head to descend, the grinding head and the grinding disc cooperate with each other to grind the lower surface of the wafer adsorbed by the bottom of the grinding head; The nozzle is arranged toward the upper surface of the grinding disc or toward the lower surface of the wafer adsorbed by the bottom of the raised grinding head; The nozzle is used to purge gas toward the upper surface of the grinding disk after the first gas is introduced into any P air flow channels, or to purge gas toward the lower surface of the wafer adsorbed at the bottom of the grinding head after the grinding head is lifted and the first gas is introduced into any P air flow channels.

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