Wafer stage device and method for cleaning polishing head

Abstract

The invention provides a wafer carrying table device and a method for cleaning a polishing head. The wafer carrying table device comprises a carrying table base body, a bearing disc and a cleaning pipeline, and the carrying table base body is provided with a containing cavity with an upward opening; the bearing disc is horizontally arranged in the containing cavity, and a plurality of upward jet orifices are formed in the bearing disc; the cleaning pipeline penetrates through the carrying table base body and communicates with the jet orifice, the cleaning pipeline is connected with a first liquid inlet pipe and a second liquid inlet pipe, the first liquid inlet pipe is used for supplying a weak acid cleaning agent, and the second liquid inlet pipe is used for supplying deionized water. According to the wafer carrying table device provided by the invention, the weak acid cleaning agent is matched with the deionized water, so that the polishing head is cleaned in all directions, and the cleaning effect of the polishing head is ensured; and meanwhile, compared with traditional chemical flushing, the mode of combining the weak acid cleaning agent and the deionized water is more environmentally friendly, the use cost of the cleaning agent can be reduced, the cleaning quality can be guaranteed, and the production and maintenance cost can be reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of wafer polishing, and more specifically, relates to a wafer carrier device and a method for cleaning a polishing head. Background Art

[0002] As a representative of the third-generation compound semiconductor materials, silicon carbide (SiC) has the characteristics of high thermal conductivity, high critical breakdown electric field, high saturated electron drift rate, high bonding energy and wide bandgap. It is the preferred material for high-frequency, high-temperature, high-power, radiation-resistant electronic devices and sensor devices, and has important application prospects in aviation, aerospace exploration, nuclear energy development, new energy vehicles, radar and communications.

[0003] Due to the high hardness of silicon carbide materials, polishing liquid containing oxidant components, large downward pressure, high polishing disc (polishing pad) rotation speed, and long operation time are often required during the polishing process, which easily leads to more and more stubborn residues on the wafer surface. These residues will accumulate on the surface of the polishing head and flexible film, and then block the groove of the retaining ring. In addition, the above residues may also be transferred to the wafer when the polishing head absorbs the wafer or fall onto the polishing disc during the polishing process, resulting in micro scratches on the wafer surface, affecting the polishing quality.

[0004] In the prior art, commonly used polishing head cleaning methods include dry cleaning, wet rinsing, chemical cleaning, and ultrasonic / megasonic cleaning. Among them, dry cleaning is simple and quick to operate, but the cleaning effect is limited and can only remove loose particles and dust. Wet rinsing can remove larger residues, but the cleaning effect is limited for stubborn chemical residues or embedded tiny particles. Chemical cleaning can effectively dissolve and remove stubborn organic and inorganic residues, but it increases the cleaning cost. Ultrasonic / megasonic cleaning can remove tiny particles in hard-to-reach areas, but the technology is more complicated and the energy consumption is higher, which increases the cleaning cost. Summary of the invention

[0005] The object of the present invention is to provide a wafer stage device that can effectively remove residues on the surface and gaps of the polishing head, ensure the cleanliness of the polishing head, ensure the yield of the wafer, and reduce the cleaning cost.

[0006] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: in the first aspect, a wafer carrier device is provided, including a carrier base, a carrying plate and a cleaning pipeline, the carrier base has a accommodating cavity opening upward; the carrying plate is horizontally arranged in the accommodating cavity, the carrying plate is used to support the wafer, and a plurality of upwardly arranged injection nozzles are provided on the carrying plate; the cleaning pipeline runs through the carrier base and is connected with the injection nozzles, the cleaning pipeline is connected with a first liquid inlet pipe and a second liquid inlet pipe, the first liquid inlet pipe is used to supply a weak acid cleaning agent, the second liquid inlet pipe is used to supply deionized water, and the cleaning pipeline is used to successively deliver the weak acid cleaning agent and deionized water to the injection nozzles to rinse the polishing head located above the carrier base.

[0007] As another embodiment of the present invention, a nozzle is provided in the injection port, and the top end of the nozzle is flush with or lower than the top surface of the supporting plate.

[0008] As another embodiment of the present invention, a guide cavity connected to the cleaning pipeline is provided in the carrier plate, and a plurality of nozzles are respectively connected to the guide cavity.

[0009] As another embodiment of the present invention, the injection port is arranged to penetrate the carrier plate, the cleaning pipeline is arranged below the carrier plate, and the plurality of nozzles are respectively connected to the cleaning pipeline.

[0010] As another embodiment of the present invention, the injection ports are arranged in a circular array on the horizontal plane of the carrier plate or in a linear array along the radial direction of the carrier plate.

[0011] As another embodiment of the present invention, an annular water retaining platform is provided on the upper edge of the carrier base.

[0012] The beneficial effect of a wafer carrier device provided by the present invention is that: compared with the prior art, the wafer carrier device of the present invention, the carrier plate located in the accommodating chamber can reliably support the wafer, which is convenient for realizing the transfer buffering of the wafer; in addition, when the polishing head needs to be cleaned, the first liquid inlet pipe and the second liquid inlet pipe can be opened to supply weak acid cleaning agent and deionized water to the injection port on the carrier plate respectively, so as to rinse the polishing head located above the carrier plate; the weak acid cleaning agent can react chemically with the chemical residue on the polishing head to achieve the purpose of effectively removing the residue on the surface and gap of the polishing head; the deionized water is used to rinse off the residual cleaning agent and other particulate matter; the accommodating chamber can receive and discharge the waste liquid after rinsing to avoid splashing of the waste liquid. Through the combination of weak acid cleaning agent and deionized water, the polishing head can be cleaned in all directions, ensuring the cleaning effect of the polishing head, effectively preventing problems such as polishing abnormalities and scratches, and significantly improving the surface quality and yield rate of the wafer; at the same time, compared with traditional chemical washing, the combination of weak acid cleaning agent and deionized water is more environmentally friendly, can reduce the cost of using cleaning agents, and can ensure cleaning quality, which helps to reduce production and maintenance costs.

[0013] In a second aspect, an embodiment of the present invention further provides a method for cleaning a polishing head using the aforementioned wafer stage device, the method for cleaning a polishing head comprising the following steps: S1. Move the carrier base upward so that the lower surface of the polishing head enters the receiving cavity and is located above the injection port, while the polishing head rotates; S2. Open the first liquid inlet pipe to deliver weak acid cleaning agent to the injection port; S3. Close the first liquid inlet pipe, open the second liquid inlet pipe, and deliver deionized water to the injection port; S4. Close the second liquid inlet pipe, the carrier base moves down and resets, and the polishing head stops rotating.

[0014] As another embodiment of the present invention, in step S2, the time for delivering the weak acid cleaning agent to the injection port through the first liquid inlet pipe is 4-8s; in step S3, when the polishing rate of the polishing head is 3.9μm / h, 4.7μm / h, 5.2μm / h, and 5.3μm / h, the time for the second liquid inlet pipe to deliver deionized water to the injection port is correspondingly selected from 10-15s, 15-25s, 25-35s, and 35-45s.

[0015] As another embodiment of the present invention, in step S2, the duration of delivering the weak acid cleaning agent to the injection port through the first liquid inlet pipe is 1-3 seconds.

[0016] As another embodiment of the present invention, the flow rate of the weak acid cleaning agent in the first liquid inlet pipe and the flow rate of the deionized water in the second liquid inlet pipe are both 1-5 ml / min.

[0017] The beneficial effect of a method for cleaning a polishing head provided by the present invention is that: compared with the prior art, the method for cleaning a polishing head of the present application, by moving the carrier base upward, allows the lower surface of the polishing head to enter the accommodating cavity and be located above the injection port, so that the weak acid cleaning agent and deionized water sprayed from the injection port can accurately act on the part of the polishing head that needs to be cleaned, making the cleaning more comprehensive and thorough. At the same time, with the self-rotation of the polishing head, the weak acid cleaning agent and deionized water can cover the lower surface of the polishing head more evenly, avoiding the occurrence of cleaning dead corners, and further improving the cleaning effect; by first using a weak acid cleaning agent to remove chemical residual stains on the surface of the polishing head, and then rinsing with deionized water, the weak acid cleaning agent remaining on the polishing head and the impurity particles washed off can be effectively removed, avoiding the secondary pollution or corrosion of the polishing head by the above-mentioned residual substances, and ensuring the safety and thoroughness of the cleaning. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0019] Figure 1 A schematic diagram of the structure of a wafer stage device in use according to an embodiment of the present invention; Figure 2 A schematic structural diagram of another embodiment of a wafer stage device provided by an embodiment of the present invention; Figure 3 A schematic diagram of the top view of the carrier plate provided in an embodiment of the present invention; Figure 4 A schematic structural diagram of another embodiment of a carrier plate provided in an embodiment of the present invention; Figure 5 The figure is a schematic diagram comparing the effects of cleaning a polishing head using the method for cleaning a polishing head provided by an embodiment of the present invention.

[0020] Among them, the reference numerals in the figure are: 1. Carrier base; 11. Accommodating cavity; 12. Water retaining platform; 13. Cavity; 2. Carrier plate; 21. Injection port; 22. Diversion cavity; 3. Cleaning pipeline; 4. First liquid inlet pipe; 41. First valve; 5. Second liquid inlet pipe; 51. Second valve; 6. Nozzle; 10. Polishing head; 101. Rotating axis. DETAILED DESCRIPTION

[0021] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0022] It should be noted that when an element is referred to as being "disposed on" another element, it may be directly on another element or indirectly on another element. It should be understood that the orientation or positional relationship indicated by the terms "length", "width", "upper", "lower", "front", "back", "top", "bottom", "inside", "outside", etc. is based on the orientation or positional relationship shown in the accompanying drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. The terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "several" is two or more, unless otherwise clearly and specifically defined.

[0023] Please also read Figures 1 to 5 Now, a wafer stage device provided by the present invention is described. A wafer stage device comprises a stage base 1, a carrier plate 2 and a cleaning pipeline 3. The stage base 1 has a receiving cavity 11 opening upward; the carrier plate 2 is horizontally arranged in the receiving cavity 11, the carrier plate 2 is used to support the wafer, and a plurality of upwardly arranged injection ports 21 are arranged on the carrier plate 2; the cleaning pipeline 3 is arranged through the stage base 1 and is connected with the injection ports 21, the cleaning pipeline 3 is connected with a first liquid inlet pipe 4 and a second liquid inlet pipe 5, the first liquid inlet pipe 4 is used to supply a weak acid cleaning agent, the second liquid inlet pipe 5 is used to supply deionized water, and the cleaning pipeline 3 is used to successively deliver the weak acid cleaning agent and deionized water to the injection ports 21 to rinse the polishing head 10 located above the stage base 1.

[0024] A wafer carrier device provided in this embodiment, compared with the prior art, has a carrier plate 2 located in the accommodating chamber 11 that can reliably support the wafer, thereby facilitating the transfer buffering of the wafer; in addition, when the polishing head 10 needs to be cleaned, the first liquid inlet pipe 4 and the second liquid inlet pipe 5 can be opened to supply a weak acid cleaning agent and deionized water to the injection port 21 on the carrier plate 2, respectively, so as to rinse the polishing head 10 located above the carrier plate 2; the weak acid cleaning agent can react chemically with the chemical residues on the polishing head 10 to effectively remove the residues on the surface and gaps of the polishing head 10; the deionized water is used to rinse off the residual cleaning agent and other particulate matter; the accommodating chamber 11 can receive and discharge the waste liquid after rinsing to avoid splashing of the waste liquid. Through the combination of weak acid cleaning agent and deionized water, the polishing head 10 can be cleaned in all directions, ensuring the cleaning effect of the polishing head 10, effectively preventing problems such as polishing abnormalities and scratches, and significantly improving the surface quality and yield rate of the wafer; at the same time, compared with traditional chemical washing, the combination of weak acid cleaning agent and deionized water is more environmentally friendly, can reduce the cost of using cleaning agents, and can ensure cleaning quality, which helps to reduce production and maintenance costs.

[0025] It should be understood that the CMP (chemical mechanical polishing) process is a technology used to flatten the surface of semiconductor wafers. It combines the dual effects of chemical corrosion and mechanical grinding to achieve high-precision flattening of the wafer surface. The CMP equipment mainly includes a polishing head 10, a grinding disc, a polishing pad, a liquid supply system and a control system. The polishing head 10 is used to fix the wafer and apply a certain pressure to make the wafer in close contact with the polishing pad. The polishing liquid is generally composed of deionized water, abrasive particles, chemical additives, etc. The abrasive particles provide mechanical grinding, and commonly used ones are silicon dioxide, aluminum oxide, etc. The chemical additives are used to adjust the pH, redox potential, etc. of the polishing liquid to control the rate of the chemical reaction. Due to the ultra-high hardness of silicon carbide (SiC) substrate wafers, it is often necessary to add a strong oxidant to the polishing liquid to achieve the effect of oxidizing the silicon carbide wafer, which is more likely to leave more and more stubborn residues on the wafer surface or the polishing head 10. Therefore, silicon carbide substrate wafers require more frequent cleaning cycles. Before polishing each wafer, the polishing head 10 is cleaned by the wafer stage device of the present invention, which can ensure that the polishing head 10 always remains in a clean and stable state. In addition, the wafer stage device provided by the present invention can also play a temporary buffering role for the wafer when the polishing head 10 is not cleaned, thereby improving the practicality of the wafer stage device.

[0026] Specifically, the carrier base 1 is connected to a lifting device, which can drive the carrier base 1 to move up and down under the control of the air path. A accommodating chamber 11 is set in the carrier base 1, and the carrier plate 2 is set in the accommodating chamber 11. When the wafer is temporarily stored, the wafer is placed on the carrier plate 2. The upper edge of the accommodating chamber 11 can be higher than the upper surface of the wafer, thereby protecting the wafer. On the other hand, when the polishing head 10 is cleaned by using the wafer carrier device, the lower surface of the polishing head 10 enters the accommodating chamber 11, and the cleaning liquid sprayed upward from the injection port 21 rinses the polishing head 10 to form waste liquid, which can be confined in the accommodating chamber 11 and will not splash around and pollute other areas. Furthermore, a cavity 13 connected to the accommodating chamber 11 and extending downward is also provided in the carrier base 1, which is convenient for draining the waste liquid in the accommodating chamber 11 from the bottom of the carrier base 1. More specifically, the bottom of the carrier plate 2 is connected to the bottom wall of the accommodating cavity 11 through a plurality of connecting blocks. This structure enables a gap to be formed between the bottom surface of the carrier plate 2 and the bottom wall of the accommodating cavity 11, which ensures the connection between the accommodating cavity 11 and the cavity 13 to achieve the diversion of the waste liquid, and facilitates the connection of the cleaning pipeline 3. The plurality of connecting blocks are arranged in a circular array along the main axis of the carrier plate 2 to ensure the stability of the carrier plate 2.

[0027] By using the first liquid inlet pipe 4 and the second liquid inlet pipe 5 to respectively deliver weak acid cleaning agent and deionized water to the cleaning pipeline 3, cross contamination between different cleaning liquids can be avoided, the purity of the cleaning process can be ensured, and secondary contamination of the wafer and the polishing head 10 can be reduced. Specifically, a first valve 41 is provided on the first liquid inlet pipe 4, a second valve 51 is provided on the second liquid inlet pipe 5, and flow meters are provided on the first liquid inlet pipe 4 and the second liquid inlet pipe 5. The first valve 41 and the second valve 51 are respectively used to control the opening and closing of the first liquid inlet pipe 4 and the second liquid inlet pipe 5, and the flow meters are respectively used to display the flow of weak acid cleaning agent and deionized water, so as to accurately control the flow and flushing time of the two cleaning liquids, thereby optimizing the flushing efficiency of the polishing head 10.

[0028] In this embodiment, the weak acid cleaning agent can be citric acid, oxalic acid or acetic acid. In addition to silicon carbide substrate wafers, the wafer stage device can also be used to clean various substrate wafers such as single crystal silicon, lithium niobate, lithium tantalate, gallium nitride and gallium arsenide, as well as the above substrate wafer polishing heads 10.

[0029] As a specific implementation of the embodiment of the present invention, please refer to Figure 1 or Figure 2 A nozzle 6 is disposed in the injection port 21 , and a top end of the nozzle 6 is flush with or lower than the top surface of the carrier plate 2 .

[0030] In this embodiment, the nozzle 6 can make the cleaning liquid in the injection port 21 spray out in a fan shape, which not only increases the flushing area of ​​the polishing head 10, but also increases the flushing pressure to ensure the flushing effect. The nozzle 6 is hidden inside the injection port 21, which can keep the top surface of the carrier plate 2 flat, ensuring that the wafer is stably and reliably supported when the wafer is temporarily stored.

[0031] As a specific implementation of the embodiment of the present invention, please refer to Figure 1 A guide cavity 22 connected to the cleaning pipeline 3 is provided in the carrier plate 2, and a plurality of nozzles 6 are respectively connected to the guide cavity 22.

[0032] In this embodiment, the outlet end of the cleaning pipeline 3 is connected to the center position of the bottom surface of the carrier plate 2 and communicates with the guide cavity 22 to ensure that the cleaning liquid is evenly supplied to the multiple nozzles 6 .

[0033] As a specific implementation of the embodiment of the present invention, please refer to Figure 2 The injection port 21 is arranged through the carrier plate 2 , the cleaning pipeline 3 is arranged below the carrier plate 2 , and the plurality of nozzles 6 are respectively connected to the cleaning pipeline 3 .

[0034] In this embodiment, the cleaning pipeline 3 includes a first branch pipe located below the carrier plate 2 and a second branch pipe connected between the first branch pipe and the first liquid inlet pipe 4 and the second liquid inlet pipe 5. The layout of the first branch pipe is determined according to the layout of the injection port 21. The nozzle 6 is connected to the outer wall of the first branch pipe and extends upward along the injection port 21. The above structure simplifies the processing operation of the carrier plate 2 and reduces the processing difficulty.

[0035] As a specific implementation of the embodiment of the present invention, please refer to Figure 3 and Figure 4 The injection ports 21 are arranged in a circular array on the horizontal plane of the carrier plate 2 or in a linear array along the radial direction of the carrier plate 2 .

[0036] In this embodiment, the layout shape of the injection ports 21, the diameter of the injection ports 21 and the spacing between adjacent injection ports 21 are determined according to actual processing requirements, and accordingly, the shape of the guide cavity 22 or the shape of the cleaning pipeline 3 is also determined accordingly. It should be noted that when multiple injection ports 21 are arranged in a linear array along the radial direction of the carrier plate 2 (such as Figure 4 ) when the polishing head 10 is cleaned, the self-rotation of the polishing head 10 can be combined to achieve a comprehensive flushing of the polishing head 10, and the cleaning effect can also be guaranteed.

[0037] As a specific implementation of the embodiment of the present invention, please refer to Figure 1 An annular water retaining platform 12 is provided on the upper edge of the carrier base 1.

[0038] In this embodiment, when cleaning the polishing head 10, after the lower surface of the polishing head 10 enters the accommodating cavity 11, the height of the water retaining platform 12 is higher than the lower surface of the polishing head 10, so that when the cleaning liquid is sprayed onto the lower surface of the polishing head 10, it can effectively prevent the cleaning liquid from splashing everywhere, thereby avoiding contamination of other areas outside the carrier base 1, thereby ensuring the stable progress of the cleaning process.

[0039] Based on the same inventive concept, an embodiment of the present invention further provides a method for cleaning a polishing head using the aforementioned wafer stage device, the method for cleaning a polishing head comprising the following steps: S1. Move the carrier base 1 upward so that the lower surface of the polishing head 10 enters the accommodating cavity 11 and is located above the injection port 21, and the polishing head 10 rotates at the same time; S2. Open the first liquid inlet pipe 4 to deliver a weak acid cleaning agent to the injection port 21; S3. Close the first liquid inlet pipe 4, open the second liquid inlet pipe 5, and deliver deionized water to the injection port 21; S4. The second liquid inlet pipe 5 is closed, the carrier base 1 is moved downward and reset, and the polishing head 10 stops rotating.

[0040] The beneficial effect of a method for cleaning a polishing head provided by the present invention is that: compared with the prior art, the method for cleaning a polishing head of the present application, by moving the carrier base 1 upward, allows the lower surface of the polishing head 10 to enter the accommodating cavity 11 and be located above the injection port 21, so that the weak acid cleaning agent and deionized water sprayed by the injection port 21 can accurately act on the part of the polishing head 10 that needs to be cleaned, so that the cleaning is more comprehensive and thorough. At the same time, with the self-rotation of the polishing head 10, the weak acid cleaning agent and deionized water can cover the lower surface of the polishing head 10 more evenly, avoiding the occurrence of cleaning dead corners, and further improving the cleaning effect; by first using a weak acid cleaning agent to remove the chemical residual stains on the surface of the polishing head 10, and then rinsing with deionized water, the weak acid cleaning agent remaining on the polishing head 10 and the impurity particles washed off can be effectively removed, avoiding the secondary pollution or corrosion of the polishing head 10 by the above-mentioned residual substances, and ensuring the safety and thoroughness of the cleaning.

[0041] It should be understood that the polishing head 10 in the CMP device is connected to the lower end of the rotating shaft 101 , and the rotating shaft 101 is connected to a rotating driving member for driving the polishing head 10 to rotate.

[0042] When the wafer stage device is used to clean the polishing head 10, the polishing head 10 is first driven to move to the top of the stage base 1 by the rotating shaft 101, and then the stage base 1 is controlled to move upward by the gas path until the lower surface of the polishing head 10 enters the accommodating cavity 11 and approaches the top surface of the carrier plate 2. The rotary drive member is turned on to make the polishing head 10 rotate at a speed of 5-20 rpm, and the first valve 41 is opened at the same time to make the weak acid cleaning agent enter the cleaning pipeline 3 through the first liquid inlet pipe 4, and spray upward through the spray port 21 on the carrier plate 2 to wash the lower surface of the polishing head 10. While the polishing head 10 rotates, the weak acid cleaning agent is sprayed on the polishing head 10 to achieve an all-round cleaning effect on the polishing head 10, ensuring that the surface and gaps of the polishing head 10 can be cleaned in place.

[0043] When the weak acid cleaning agent is rinsed to the set time, the first valve 41 is closed to stop the supply of the weak acid cleaning agent, and the second valve 51 is opened at the same time, so that the deionized water enters the cleaning pipeline 3 through the second liquid inlet pipe 5, and the deionized water is sprayed to the polishing head 10 through the injection port 21. The weak acid cleaning agent can react chemically with the chemical residues accumulated on the polishing head 10, thereby achieving the effect of cleaning the polishing head 10, but after being rinsed with the weak acid cleaning agent, the residue of the weak acid cleaning agent will inevitably be left on the polishing head 10, and the acid residue will interact with the polishing liquid in the subsequent polishing process, reducing the polishing effect. Therefore, in the above step S3, the polishing head 10 is rinsed with deionized water for a set time, which can not only rinse off the particles on the polishing head 10, but also effectively remove the acid cleaning liquid remaining on the polishing head 10 in step S2, effectively ensuring the cleaning state of the polishing head 10.

[0044] It should be noted that in step S2, when the first valve 41 is opened to supply the weak acid cleaning agent into the cleaning pipeline 3, the second valve 51 can also be opened to supply deionized water into the cleaning pipeline 3. At this time, the weak acid cleaning agent can be diluted by adding deionized water to adapt to the cleaning of the polishing head 10 in different states. After the amount of weak acid cleaning agent reaches the cleaning requirement, the first valve 41 is closed, and the deionized water flushing in step S3 can be directly performed.

[0045] After the deionized water flushing reaches the set time, the second valve 51 is closed, the carrier base 1 moves downward and resets under the control of the air circuit, the rotating drive part is closed, and the polishing head 10 stops rotating. At this time, the polishing head 10 is in a completely clean state and can be driven by the rotating shaft 101 to move to the polishing station for subsequent polishing work.

[0046] As a specific implementation of an embodiment of the present invention, in step S2, the time for conveying the weak acid cleaning agent to the injection port 21 through the first liquid inlet pipe 4 is 4-8s; in step S3, when the polishing rate of the polishing head 10 is 3.9μm / h, 4.7μm / h, 5.2μm / h, and 5.3μm / h, the time for conveying deionized water to the injection port 21 by the second liquid inlet pipe 5 is selected from 10-15s, 15-25s, 25-35s, and 35-45s respectively.

[0047] In this embodiment, the relationship between the rinsing time and the polishing rate of different cleaning solutions is shown in the following table:

[0048] Table 1 Relationship between rinsing time and polishing rate It can be seen from the results in Table 1 that by rinsing the polishing head 10 for 4-8 seconds with a weak acid cleaning agent, the chemical residues on the polishing head 10 can be effectively removed. The longer the deionized water rinsing time is, the more thorough the removal effect of the residues of the weak acid cleaning agent and the particle residues is, and the greater the polishing rate. During the cleaning process, according to the data in Table 1, the rinsing time of each cleaning liquid is accurately controlled so that the cleaning liquid can achieve the best cleaning effect while avoiding excessive use. In this way, on the basis of ensuring that the polishing head 10 is thoroughly cleaned to meet the stringent requirements of the subsequent CMP process, the effective saving of the amount of cleaning liquid is achieved, which not only reduces the production cost, but also reduces the potential pollution to the environment caused by the discharge of the cleaning liquid, which helps to promote the CMP process cleaning process to develop in a green and efficient direction.

[0049] As a specific implementation of the embodiment of the present invention, in step S2, the duration of delivering the weak acid cleaning agent to the injection port 21 through the first liquid inlet pipe 4 is 1-3 seconds.

[0050] In this embodiment, considering that silicon carbide (SiC) substrate wafers often require more frequent cleaning cycles, the inventors further optimized the rinsing time of the weak acid cleaning agent through experiments: if it can be ensured that the polishing head 10 is cleaned using the method for cleaning the polishing head in the present invention before polishing each wafer, the residual amount of polishing liquid on the polishing head 10 will be relatively reduced, and the rinsing time of the weak acid cleaning agent can be shortened to 1-3s, and the clean state of the polishing head 10 can still be ensured. Figure 5 A comparison diagram of the state of the polishing head 10 after the polishing head 10 is rinsed with a weak acid cleaning agent for 1-3 seconds is shown. It can be seen from the figure that the residual substances on the flexible film and the retaining ring of the polishing head 10 are significantly reduced.

[0051] As a specific implementation of the embodiment of the present invention, the flow rate of the weak acid cleaning agent in the first liquid inlet pipe 4 and the flow rate of the deionized water in the second liquid inlet pipe 5 are both 1-5 ml / min, which can meet the cleaning requirements of the polishing head 10.

[0052] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A wafer stage device, characterized in that: include: The carrier base (1) has a receiving cavity (11) opening upward; A carrier plate (2) is horizontally arranged in the accommodating cavity (11), the carrier plate (2) is used to support the wafer, and a plurality of injection ports (21) arranged upward are provided on the carrier plate (2); and A cleaning pipeline (3) is arranged through the carrier base (1) and is in communication with the injection port (21); the cleaning pipeline (3) is connected to a first liquid inlet pipe (4) and a second liquid inlet pipe (5); the first liquid inlet pipe (4) is used to supply a weak acid cleaning agent, and the second liquid inlet pipe (5) is used to supply deionized water; the cleaning pipeline (3) is used to successively deliver the weak acid cleaning agent and deionized water to the injection port (21) to rinse the polishing head (10) located above the carrier base (1).

2. A wafer stage device as claimed in claim 1, characterized in that: A nozzle (6) is provided in the injection port (21), and the top end of the nozzle (6) is flush with the top surface of the carrier plate (2) or lower than the top surface of the carrier plate (2).

3. A wafer stage device as claimed in claim 2, characterized in that: A flow guide cavity (22) connected to the cleaning pipeline (3) is provided in the carrier plate (2), and the plurality of nozzles (6) are respectively connected to the flow guide cavity (22).

4. A wafer stage device as claimed in claim 2, characterized in that: The injection port (21) is arranged to penetrate the carrier plate (2), the cleaning pipeline (3) is arranged below the carrier plate (2), and the plurality of nozzles (6) are respectively connected to the cleaning pipeline (3).

5. A wafer stage device according to any one of claims 1 to 4, characterized in that: The injection ports (21) are arranged in a circular array on a horizontal plane of the carrier plate (2) or in a linear array along a radial direction of the carrier plate (2).

6. A wafer stage device as claimed in claim 5, characterized in that: An annular water retaining platform (12) is provided on the upper edge of the carrier base (1).

7. A method for cleaning a polishing head, characterized in that: A polishing head is cleaned using a wafer stage device as described in any one of claims 1 to 6, wherein the method for cleaning the polishing head comprises the following steps: S1. Move the carrier base (1) upward so that the lower surface of the polishing head (10) enters the accommodating cavity (11) and is located above the injection port (21), and the polishing head (10) rotates at the same time; S2. Open the first liquid inlet pipe (4) to deliver a weak acid cleaning agent to the injection port (21); S3. close the first liquid inlet pipe (4), open the second liquid inlet pipe (5), and deliver deionized water to the injection port (21); S4. The second liquid inlet pipe (5) is closed, the carrier base (1) moves downward and resets, and the polishing head (10) stops rotating.

8. A method for cleaning a polishing head as claimed in claim 7, characterized in that: In the step S2, the duration of conveying the weak acid cleaning agent to the injection port (21) through the first liquid inlet pipe (4) is 4-8 seconds; in the step S3, when the polishing rate of the polishing head (10) is 3.9 μm / h, 4.7 μm / h, 5.2 μm / h, or 5.3 μm / h, the duration of conveying deionized water to the injection port (21) through the second liquid inlet pipe (5) is selected from 10-15 seconds, 15-25 seconds, 25-35 seconds, or 35-45 seconds, respectively.

9. A method for cleaning a polishing head according to claim 7, characterized in that: In the step S2, the duration of delivering the weak acid cleaning agent to the injection port (21) through the first liquid inlet pipe (4) is 1-3 seconds.

10. A method for cleaning a polishing head according to claim 8, characterized in that: The flow rate of the weak acid cleaning agent in the first liquid inlet pipe (4) and the flow rate of the deionized water in the second liquid inlet pipe (5) are both 1-5 ml / min.

Images