Device and method for pre-cleaning wafer surface

Abstract

The present invention belongs to the technical field of wafer processing equipment, and mainly relates to a device and method for pre-cleaning the surface of a wafer. The device for pre-cleaning the surface of a wafer comprises a main body, a cavity inlet pipe and a mixing assembly. The main body has a processing chamber connected to the cavity inlet pipe; the mixing assembly comprises a plurality of mixing elements, the mixing element comprises two fixed rings and a plurality of guide plates, the guide plates are formed by twisting a straight plate around the central axis of the fixed ring at a set angle, the guide plate has end planes located at the upper and lower ends and parallel to each other, and a spiral surface located between the two end planes, and a mixing guide channel for mixing and flowing process gases is formed between any two adjacent guide plates in the mixing element, and between the guide plates located on both sides and the tube wall of the cavity inlet pipe, and an angle α is formed between the end planes of the two corresponding guide plates in two adjacent mixing elements. Through the mixing action of the two adjacent mixing elements, uniform mixing of multiple process gases is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of wafer processing equipment, and mainly relates to a device and method for pre-cleaning a wafer surface. Background Art

[0002] In the semiconductor process, before performing the epitaxial process on the wafer surface, it is necessary to remove the oxide of the conductive layer on the wafer surface. Therefore, a wafer pre-cleaning device is needed to clean the wafer surface so that the wafer can be further epitaxially processed. This process of cleaning the wafer surface is the wafer pre-cleaning process.

[0003] In the pre-cleaning process, process gas needs to be introduced into the processing chamber of the plasma processing equipment, and then sprayed onto the wafer surface after mixing. The process gas reacts with the oxide of the conductive layer on the surface of the wafer to achieve the effect of removing the oxide.

[0004] In the prior art, multiple mixed process gases are often used to etch wafers, but they are all simply mixed with multiple substances. For example, the Chinese patent document with the authorization announcement number CN220121783U discloses a wafer pre-cleaning device, which includes a processing chamber, a gas shower head disposed on the upper part of the processing chamber, and a base disposed in the processing chamber. The base is used to carry the wafer during the pre-cleaning process, and the gas shower head is used to pass the mixed process gas into the processing chamber, and the process gas is used to etch and remove the oxide on the wafer.

[0005] The above-mentioned wafer pre-cleaning equipment simply mixes the process gases. The mixed gas is not uniform. The concentration of the process gas in the middle is high, and the concentration of the process gas in the periphery is low. The uneven process gas will affect the etching effect of the wafer, thereby affecting the quality and performance of subsequent wafer devices. Summary of the invention

[0006] The present invention provides a wafer surface pre-cleaning device and method, so as to solve the problem in the prior art that the wafer surface pre-cleaning equipment is prone to uneven mixing of process gases, thereby affecting the wafer etching effect.

[0007] To solve the above problems, the present invention adopts the following technical solutions:

[0008] A wafer surface pre-cleaning device comprises a main body, a cavity inlet pipe arranged on the main body and a mixing assembly installed in the cavity inlet pipe, wherein the main body has a processing chamber for placing wafers, the cavity inlet pipe is connected with the processing chamber and the axis extends in the up-down direction, and the cavity inlet pipe faces the wafer in the processing chamber;

[0009] The mixing assembly includes a plurality of mixing elements arranged in the cavity inlet tube, each mixing element includes two fixed rings spaced apart in the up-down direction and a plurality of equally spaced guide plates fixedly assembled between the two fixed rings, each guide plate is formed by twisting a straight plate around the central axis of the fixed ring at a set angle, the guide plate has end planes located at the upper and lower ends and parallel to each other, and a spiral surface located between the two end planes, a mixing guide channel for mixing and flowing of process gases is formed between any two adjacent guide plates in the same mixing element and between the guide plates on both sides and the tube wall of the cavity inlet tube, an angle α is formed between the end planes of two corresponding guide plates in two adjacent mixing elements, and the angle α is greater than 0° and less than 180°.

[0010] The invention has the following beneficial effects: a plurality of process gases pass through the plurality of mixing guide channels of the first mixing element, are mixed under the guidance of the guide plate, and when entering the plurality of mixing guide channels of the next mixing element, the process gas passing through each mixing guide channel of the previous mixing element is divided into multiple parts, which respectively enter different mixing guide channels of the next mixing element, so that a uniform mixing of the plurality of process gases is achieved through the mixing action of two adjacent mixing elements.

[0011] Furthermore, the mixing assembly further comprises two fixing plates disposed at upper and lower sides of the inlet tube, the plurality of mixing elements are located between the two fixing plates, and both fixing plates have through holes;

[0012] Each of the mixing elements comprises a rotating shaft coaxial with the central axis of the fixed ring, the rotating shaft is fixedly mounted on the guide plate at the middle position, adjacent rotating shafts are coaxially rotatably connected, the fixed plates on the corresponding sides are rotatably connected to the corresponding rotating shafts, and the number of the guide plates is an odd number;

[0013] The spiral extension directions of the guide plates in two adjacent mixing elements are opposite.

[0014] The invention has the following beneficial effects: the rotating shaft drives the multiple guide plates in the mixing element to rotate under the action of the flowing process gas, and the rotation of the guide plates will increase the Reynolds coefficient of the flow of multiple process gases and improve the mixing degree of the multiple process gases; at the same time, because the spiral extension directions of two adjacent mixing elements are different, the rotation directions of the guide plates are also different, which can also increase the Reynolds coefficient of the flow of multiple process gases, improve the mixing degree of multiple process gases, and achieve uniform mixing of multiple process gases.

[0015] Furthermore, the mixing assembly further comprises a tube shell disposed in the inlet tube, two fixing plates are fixedly assembled on two tube openings of the tube shell, and a plurality of mixing elements are disposed in the tube shell;

[0016] A step is arranged on the lower side of the cavity inlet tube, and the fixing plate located on the lower side is placed on the step.

[0017] The invention has the following beneficial effects: a plurality of mixing components are arranged in the tube shell by two fixing plates, so that the mixing assembly can become an independent component. When in use, the mixing assembly can be directly placed in the cavity inlet tube. When replacing, the entire mixing assembly can be directly taken out and replaced with a new one, which facilitates maintenance and saves maintenance time.

[0018] Furthermore, each of the guide plates has a plurality of mixing holes, and the mixing holes connect two adjacent mixing guide channels.

[0019] The invention has the following beneficial effects: when the process gas flows in the mixing guide channel, the process gas will enter the adjacent mixing guide channel from the mixing hole, thereby improving the mixing degree of the various process gases. At the same time, the mixing hole will also change the flow path of the process gas, causing turbulence in the process gas, thereby improving the Reynolds coefficient of the flow of the various process gases, improving the mixing degree of the various process gases, and achieving uniform mixing of the various process gases. At the same time, because the mixing element needs to rotate, the dynamic balance of the mixing element can be more easily achieved by increasing or reducing the mixing holes.

[0020] Furthermore, each of the guide plates is spirally extended by 180°.

[0021] Furthermore, the extension directions of the end surfaces of the adjacent guide plates in two adjacent mixing elements have an angle α of 90°.

[0022] Furthermore, the main body is provided with an outlet pipe connected to the processing chamber, the outlet pipe is used to discharge residual process gas and to draw vacuum, a carrier is provided in the processing chamber, the wafer is used to be placed on the carrier, and the main body is provided with a wafer transfer port connected to the processing chamber, the wafer transfer port is used for the wafer to enter and exit.

[0023] Furthermore, a heating component is provided on the carrier, and the carrier is connected to a radio frequency bias electric field.

[0024] Furthermore, the main body is provided with an annular permanent magnet, which is axially arranged around the outer side of the inlet tube. A gas distribution disk is provided in the processing chamber, and the gas distribution disk is located between the inlet tube and the carrier. A through hole is provided on the gas distribution disk.

[0025] A method for pre-cleaning a wafer surface, applied to the above-mentioned device for pre-cleaning a wafer surface, comprises the following steps:

[0026] Step 1: Place the wafer in the processing chamber;

[0027] Step 2: Multiple RPS-treated process gases are introduced into the inlet tube, and the mixing component mixes the multiple process gases evenly;

[0028] Step 3: Multiple process gases contact the oxide on the wafer to remove the oxide on the wafer.

[0029] The invention has the following beneficial effects: a plurality of process gases pass through the plurality of mixing guide channels of the first mixing element, are mixed under the guidance of the guide plate, and when entering the plurality of mixing guide channels of the next mixing element, the process gas passing through each mixing guide channel of the previous mixing element is divided into multiple parts, which respectively enter different mixing guide channels of the next mixing element, so that a uniform mixing of the plurality of process gases is achieved through the mixing action of two adjacent mixing elements. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] By reading the following detailed description with reference to the accompanying drawings, the above and other objects, features and advantages of the exemplary embodiments of the present invention will become readily understood. In the accompanying drawings, several embodiments of the present invention are shown in an exemplary and non-limiting manner, and the same or corresponding reference numerals represent the same or corresponding parts, wherein:

[0031] Figure 1 It is a structural schematic diagram of the present invention;

[0032] Figure 2 is an internal view of the present invention;

[0033] Figure 3 This is a schematic structural diagram of a mixing assembly from a first viewing angle in Example 1 of the present invention;

[0034] Figure 4 This is a schematic diagram of the structure of the mixing component in Embodiment 1 of the present invention from a second viewing angle;

[0035] Figure 5 is a cross-sectional view of a mixing assembly in Example 1 of the present invention;

[0036] Figure 6 This is a schematic structural diagram of a mixing element in a spiral extension direction in Example 1;

[0037] Figure 7 This is a schematic structural diagram of another mixing element with a spiral extension direction in Example 1;

[0038] Figure 8 is an exploded view of the mixing element in Example 1 from a first viewing angle;

[0039] Fig. 9 is an exploded view of the mixing element in Example 1 from a second viewing angle;

[0040] Fig.10 A schematic diagram of the structure of a mixing element with a 45° spiral extension;

[0041] Fig.11 A schematic diagram of the structure of a mixing element extending in a 90° spiral;

[0042] Fig.12A schematic diagram of the structure of a mixing element with a 135° spiral extension;

[0043] Fig.13 is a schematic diagram of the structure of the mixing assembly in Example 2;

[0044] Fig.14 is a schematic diagram of the structure of the mixing assembly in Example 3;

[0045] Fig.15 This is an exploded view of the mixing assembly in Example 3.

[0046] Description of reference numerals:

[0047] 1. Main body; 2. Inlet tube; 3. Outlet tube; 4. Annular permanent magnet; 5. Film transfer port; 6. Mixing assembly; 7. Processing chamber; 8. Carrier; 9. Wafer; 10. Gas distribution disk; 11. Mixing element; 12. Guide plate; 13. Mixing guide channel; 14. Fixed ring; 15. Mixing hole; 16. Rotating shaft; 17. Fixed plate; 18. Tube shell; 19. Through hole. DETAILED DESCRIPTION

[0048] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Those skilled in the art should know that the embodiments described below are part of the embodiments of the present disclosure, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0049] Various non-limiting embodiments of the present invention are described in detail below. Any number of elements in the accompanying drawings is for illustration and not for limitation, and any naming is only for distinction and does not have any limiting meaning. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0050] Wafer surface pre-cleaning device embodiment 1

[0051] like Figure 1-Figure 2 As shown, a wafer surface pre-cleaning device includes a main body 1, an inlet tube 2 and an outlet tube 3 arranged on the main body 1, and a mixing component 6 installed in the inlet tube 2.

[0052] The main body 1 has a processing chamber 7, and a carrier 8 is provided in the processing chamber 7. The carrier 8 is used to place a wafer 9. The axis of the inlet tube 2 extends in the up-down direction. The inlet tube 2 is connected to the upper part of the processing chamber 7. The inlet tube 2 faces the wafer 9 in the processing chamber 7. The outlet tube 3 is connected to the processing chamber 7, and the outlet tube 3 is located at the lower part of the processing chamber 7. The process gas is processed by RPS and enters the processing chamber 7 through the inlet tube 2, so as to etch the oxide of the conductive layer on the surface of the wafer 9 to achieve the purpose of cleaning. The residual process gas is discharged from the outlet tube 3, and the vacuum of the processing chamber 7 can also be extracted through the outlet tube 3. RPS refers to a remote plasma source.

[0053] Specifically, Figure 3-Figure 9 As shown, the mixing assembly 6 includes four mixing elements 11 fixedly assembled in the inlet tube 2, each mixing element 11 includes two fixed rings 14 arranged at intervals in the up-down direction and five equally spaced guide plates 12 fixedly assembled between the two fixed rings 14, that is, the distances between the five guide plates 12 are the same, and the intervals between the two fixed rings 14 on each mixing element 11 are equal. The planes where the two fixed rings 14 are located are parallel to each other, and the mixing element 11 is fixed in the inlet tube 2 by the two fixed rings 14, and the two fixed rings 14 also play the role of fixing the five guide plates 12. Each guide plate 12 is formed by twisting a straight plate around the central axis of the fixed ring 14, and is spirally shaped, that is, the two ends of the guide plate 12 are respectively planes, and the middle is a spiral curved surface extending spirally along the central axis of the fixed ring 14. In this way, a mixing guide channel 13 for the process gas to flow is formed between any two adjacent guide plates 12. Both ends of the five guide plates 12 are connected to two fixing rings 14 respectively, and the end surfaces of the same side of the five guide plates 12 are arranged at equal intervals in the fixing ring 14, so that the spatial dimensions of any two adjacent mixing guide channels 13 are also the same.

[0054] In this embodiment, the number of the mixing guide channels 13 is six. The mixing guide channels 13 are used for mixing and circulating multiple process gases. Each guide plate 12 has two end faces fixed on the corresponding side fixing ring 14. The end faces of the multiple guide plates 12 on the same side are distributed in parallel. The extension direction of the end faces of the adjacent guide plates 12 in two adjacent mixing elements 11 has an angle α, such as Figure 5 As shown, the angle α is greater than 0°, and the angle α is less than 180°. In this embodiment, the angle α is 90°. In this embodiment, the multiple process gases refer to two gases. In this embodiment, each guide plate 12 is a 180° spiral extension (such as Figure 6 , Figure 7 as shown).

[0055] Multiple process gases pass through multiple mixing guide channels 13 of the first mixer 11, and are mixed under the guidance of the guide plate 12. When entering the multiple mixing guide channels 13 of the next mixer 11, the process gases passing through each mixing guide channel 13 of the previous mixer 11 are divided into multiple parts, and enter different mixing guide channels 13 of the next mixer 11 respectively, so that the multiple process gases are evenly mixed through the mixing action of two adjacent mixers 11. The process gas originally at the edge can be mixed with the process gas in the middle position, and the process gas originally in the middle position can be mixed with the process gas at the edge, which enhances the uniformity of mixing of the multiple process gases.

[0056] In other embodiments, the number of the mixing elements 11 is two, three, or more than five, and the specific number of the mixing elements 11 can be determined based on actual conditions.

[0057] In other embodiments, the plurality of process gases is more than three gases.

[0058] In other embodiments, the number of the guide plates 12 is one, three, seven, or other suitable numbers. The specific number of the guide plates 12 can be determined based on actual conditions, and the number of the guide plates 12 needs to be an odd number.

[0059] In other embodiments, the guide plate 12 may be a 45° spiral extension (eg Fig.10 ), or a 90° spiral extension (as Fig.11 ), or a 135° helical extension (as Fig.12 As shown), or 360° spiral extension, or spiral extension at other suitable degrees.

[0060] In other embodiments, the angle α between the extension directions of the end surfaces of adjacent guide plates 12 in two adjacent mixing elements 11 may be 10°, 20°, 30°, 40°, 50°, 60°, 70°, 80° or other angles α.

[0061] Specifically, Figure 5 As shown, each guide plate 12 has a plurality of mixing holes 15, and the mixing holes 15 are connected to two adjacent mixing guide channels 13. When the process gas flows in the mixing guide channel 13, the process gas will enter the adjacent mixing guide channel 13 from the mixing hole 15, thereby improving the mixing degree of the various process gases. At the same time, the mixing hole 15 will also change the flow path of the process gas, causing the process gas to flow turbulently, thereby improving the Reynolds coefficient of the flow of the various process gases, improving the mixing degree of the various process gases, and realizing uniform mixing of the various process gases.

[0062] like Figure 1-Figure 2As shown, the main body 1 is provided with a wafer transfer port 5 communicating with the processing chamber 7, and the wafer transfer port 5 is used for the entry and exit of the wafer 9. When in use, a mechanical gripper can be used to grab the wafer 9, so that the wafer 9 can enter and exit from the wafer transfer port 5.

[0063] The carrier 8 is provided with a heating component, which can realize temperature control in the range of 25°C-300°C, achieve faster response speed, and adjust process processing uniformity.

[0064] The carrier 8 is simultaneously connected to a radio frequency bias electric field with a frequency of 13.56 MHz. The plasma from the RPS will be affected by the electric field and pulled to the surface of the wafer 9. At the same time, different electric field powers can be used to adjust the bombardment of ions on the surface of the wafer 9, affecting the etching rate and selectivity.

[0065] like Figure 1-Figure 2 As shown, the main body 1 is provided with an annular permanent magnet 4, which is arranged axially around the outer side of the cavity tube 2. The annular permanent magnet 4 forms a magnetic field, which can be used to constrain the plasma, prevent it from diffusing to unnecessary areas, expand the effective range of the process gas, especially at the edge of the wafer 9, and improve the uniformity of the process. Because the plasma coming out of the RPS will be gradually consumed during the movement, the plasma density at the outlet will be higher, and the presence of the magnetic field increases the plasma density at the edge of the wafer 9, making the density distribution of the plasma more uniform before passing through the uniform gas disk.

[0066] like Figure 2 As shown, a gas distribution plate 10 is provided in the processing chamber 7, and the gas distribution plate 10 is located between the chamber inlet pipe 2 and the carrier 8, and a through hole is provided on the gas distribution plate 10. The gas distribution plate 10 ensures that the process gas is evenly distributed on the surface of the wafer 9, thereby achieving a uniform etching effect.

[0067] The working process of the present invention is as follows:

[0068] The two process gases treated by RPS enter the processing chamber 7 from the chamber inlet tube 2, and then process the oxide of the conductive layer on the surface of the wafer 9. Among them, when the two process gases enter the chamber inlet tube 2, they enter the six mixing guide channels 13 respectively, and the two process gases are mixed in the mixing guide channels 13. When the two process gases enter the next mixing element 11, the two process gases in each mixing guide channel 13 will be divided into multiple portions, and these portions of process gases enter different mixing guide channels 13 in the next mixing element 11 respectively, so that the process gases can be evenly mixed through the cooperation of two adjacent mixing elements 11.

[0069] When the process gas flows and mixes in the mixing guide channel 13, the mixing holes 15 on the guide plate 12 will cause the process gases in two adjacent mixing guide channels 13 to mix, thereby increasing the Reynolds coefficient of the process gas flow and improving the degree of mixing.

[0070] Wafer surface pre-cleaning device embodiment 2

[0071] The difference between this embodiment and embodiment 1 is that Fig.13 As shown, the mixing assembly 6 in this embodiment further includes two fixed plates 17 fixedly disposed on the upper and lower sides of the inlet tube 2, and the plurality of mixing elements 11 are located between the two fixed plates 17. Both of the two fixed plates 17 have through holes 19 for the process gas to flow through. The fixing ring 14 in this embodiment is not fixedly connected to the inlet tube 2.

[0072] Each mixing element 11 includes a rotating shaft 16 coaxial with the central axis of the fixing ring 14, and the rotating shaft 16 is fixedly assembled on the guide plate 12 at the middle position of this embodiment, and multiple rotating shafts 16 are coaxial and adjacent rotating shafts 16 are coaxially connected and rotated, and the fixing plate 17 on the corresponding side is rotatably connected to the corresponding rotating shaft 16, that is, multiple mixing elements 11 are rotatably assembled between two fixing plates 17. In this embodiment, the spiral extension directions of two adjacent mixing elements 11 are opposite. In this embodiment, the number of guide plates 12 is an odd number.

[0073] The rotating shaft 16 drives the multiple guide plates 12 in the mixing element 11 to rotate under the action of the flowing process gas. The rotation of the guide plates 12 will increase the Reynolds coefficient of the flow of multiple process gases and improve the mixing degree of the multiple process gases. At the same time, because the spiral extension directions of two adjacent mixing elements 11 are different, the rotation directions of the guide plates 12 are also different, which can also increase the Reynolds coefficient of the flow of multiple process gases, increase the mixing degree of multiple process gases, and achieve uniform mixing of multiple process gases.

[0074] Because the mixer 11 in this embodiment needs to rotate, the dynamic balance of the mixer 11 can be more easily achieved by increasing or decreasing the number of mixing holes 15. The number of mixing holes 15 in this embodiment can be determined according to the dynamic balance situation.

[0075] Wafer surface pre-cleaning device embodiment 3

[0076] The difference between this embodiment and embodiment 2 is that Fig.14 , Fig.15As shown, the mixing assembly 6 in this embodiment further includes a tube shell 18 disposed in the cavity inlet tube 2, the tube shell 18 is clearance-matched with the inner wall of the cavity inlet tube 2, two fixing plates 17 are fixedly assembled on two tube openings of the tube shell 18, and a plurality of mixing elements 11 are disposed in the tube shell 18. The fixing plates 17 in this embodiment are not fixedly connected to the cavity inlet tube 2, and the lower side of the interior of the cavity inlet tube 2 has a step, and one of the fixing plates 17 is placed on the step, so as to prevent the mixing assembly 6 from falling.

[0077] Multiple mixing elements 11 are arranged in the tube shell 18 through two fixing plates 17, so that the mixing assembly 6 can become an independent component. When in use, the mixing assembly 6 can be directly placed in the cavity tube 2. When replacing, the entire mixing assembly 6 can be directly taken out and replaced with a new one, which facilitates maintenance and saves maintenance time.

[0078] Wafer surface pre-cleaning method embodiment

[0079] A method for pre-cleaning a wafer surface, applied to the above-mentioned device for pre-cleaning a wafer surface, specifically comprises the following steps:

[0080] Step 1: Use a mechanical gripper to place the wafer 9 on the carrier 8 in the processing chamber 7. Turn on the heating component to control the temperature of the carrier 8 between 25 and 300°C. The specific temperature can be determined according to the actual situation. Turn on the RF bias electric field, and the power of the RF bias electric field is controlled at 50 to 800W.

[0081] Step 2: Multiple process gases treated by RPS are introduced into the inlet tube 2, the flow rate of each process gas is controlled at 5-200 sccm, and the mixing component 6 mixes the multiple process gases evenly. The power of RPS is 50-3000W.

[0082] Step 3: A plurality of process gases are brought into contact with the oxide on the wafer 9 to remove the oxide on the wafer 9 .

[0083] Two processes will occur on the surface of wafer 9:

[0084] Physical bombardment: The process gas acquires high energy under the action of the electric field, and when they bombard the surface of the metal oxide film, physical sputtering occurs. This physical bombardment can remove atoms on the surface of the oxide, thereby achieving oxide cleaning on the surface of the wafer 9.

[0085] Reduction reaction: The process gas has reducing properties in the plasma state and can react chemically with metal oxides to reduce them to metal and water. The reducing process gas is hydrogen.

[0086] Physical bombardment can quickly remove materials, while chemical reactions can further promote the decomposition of oxides. The combination of the two can significantly increase the etching rate. By adjusting the ratio of the two process gases, the selectivity of the etching process can be optimized and the damage to the underlying material can be reduced.

[0087] A variety of process gases pass through the multiple mixing guide channels 13 of the first mixer 11, and are mixed under the guidance of the guide plate 12. When entering the multiple mixing guide channels 13 of the next mixer 11, the process gases passing through each mixing guide channel 13 of the previous mixer 11 are divided into multiple parts, which respectively enter different mixing guide channels 13 of the next mixer 11. In this way, the uniform mixing of the multiple process gases is achieved through the mixing action of two adjacent mixers 11.

Claims

1. A wafer surface pre-cleaning device, characterized in that: The invention comprises a main body, a cavity inlet pipe arranged on the main body and a mixing assembly installed in the cavity inlet pipe, wherein the main body has a processing chamber for placing wafers, the cavity inlet pipe is connected with the processing chamber and the axis thereof extends in the up-down direction, and the cavity inlet pipe faces the wafers in the processing chamber; The mixing assembly includes a plurality of mixing elements arranged in the inlet tube, each mixing element includes two fixed rings spaced apart in the up-down direction and a plurality of equally spaced guide plates fixedly assembled between the two fixed rings, each guide plate is formed by twisting a straight plate around the central axis of the fixed ring at a set angle, the guide plate has end planes located at the upper and lower ends and parallel to each other, and a spiral surface located between the two end planes, a mixing guide channel for mixing and flowing process gases is formed between any two adjacent guide plates in the same mixing element, and between the guide plates on both sides and the tube wall of the inlet tube, and an angle α is formed between the end planes of the two corresponding guide plates in two adjacent mixing elements, and the angle α is greater than 0° and less than 180°; The mixing assembly also includes two fixing plates disposed at the upper and lower sides of the inlet tube, and the plurality of mixing elements are located between the two fixing plates, and both fixing plates have through holes; Each mixing element includes a rotating shaft coaxial with the central axis of the fixed ring, the rotating shaft is fixedly assembled on the guide plate at the middle position, adjacent rotating shafts are coaxially connected for rotation, the fixed plates on the corresponding sides are rotatably connected to the corresponding rotating shafts, and the number of guide plates is an odd number; The spiral extension directions of the guide plates in two adjacent mixing elements are opposite.

2. A wafer surface pre-cleaning device according to claim 1, characterized in that: The mixing assembly also includes a tube shell arranged in the inlet tube, two fixing plates are fixedly assembled on two tube openings of the tube shell, and a plurality of mixing elements are arranged in the tube shell; A step is arranged on the lower side of the cavity inlet tube, and the fixing plate located on the lower side is placed on the step.

3. The device for pre-cleaning a wafer surface according to claim 1, characterized in that: Each guide plate has a plurality of mixing holes, and the mixing holes are connected to two adjacent mixing guide channels.

4. The device for pre-cleaning a wafer surface according to claim 1, characterized in that: Each of the guide plates is extended in a 180° spiral.

5. The device for pre-cleaning a wafer surface according to claim 1, characterized in that: The extension directions of the end surfaces of the adjacent guide plates in two adjacent mixing elements have an included angle α of 90°.

6. A wafer surface pre-cleaning device according to any one of claims 1 to 5, characterized in that: The main body is provided with an outlet pipe connected to the processing chamber, the outlet pipe is used to discharge residual process gas and to draw vacuum, the processing chamber is provided with a carrier, the wafer is used to be placed on the carrier, the main body is provided with a wafer transfer port connected to the processing chamber, the wafer transfer port is used for the wafer to enter and exit.

7. The device for pre-cleaning a wafer surface according to claim 6, characterized in that: The carrier is provided with a heating component, and the carrier is connected to a radio frequency bias electric field.

8. The device for pre-cleaning a wafer surface according to claim 7, characterized in that: The main body is provided with an annular permanent magnet, which is axially arranged around the outer side of the inlet tube. A gas distribution disk is provided in the processing chamber, which is located between the inlet tube and the carrier, and a through hole is provided on the gas distribution disk.

9. A method for pre-cleaning a wafer surface, characterized in that: A wafer surface pre-cleaning device according to any one of claims 1 to 8, comprising the following steps: Step 1: Place the wafer in the processing chamber; Step 2: Multiple RPS-treated process gases are introduced into the inlet tube, and the mixing component mixes the multiple process gases evenly; Step 3: Multiple process gases contact the oxide on the wafer to remove the oxide on the wafer.

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