Method and equipment for cleaning edge of wafer buffer layer

Abstract

The present application provides a method and device for cleaning the edge of a wafer buffer layer. The cleaning method includes: rotating the wafer, spraying a first cleaning liquid onto the surface of the wafer to remove the buffer layer at the edge of the wafer, and forming a byproduct mark on the surface of the wafer; obtaining the position of the byproduct mark, which is recorded as a marked position; keeping the wafer rotating, spraying a second cleaning liquid onto the marked position to remove the byproduct mark on the surface of the wafer; spraying a rinse liquid onto the surface of the wafer to rinse the wafer. The method for cleaning the edge of a wafer buffer layer of the present application performs targeted cleaning of the byproduct marks on the surface of the wafer, thereby improving the yield of the wafer.

Description

Technical Field

[0001] The present application relates to the field of semiconductor manufacturing, and in particular to a method and device for cleaning the edge of a wafer buffer layer. Background Art

[0002] Due to the design requirements of the wafer, it is often necessary to sputter a buffer layer on the wafer to achieve buffering, increase adhesion between film layers, isolation and other functions. The buffer layer can also be called an insulating layer or an isolation layer depending on the material. At the edge (bevel) of the wafer, due to the uneven edge area of ​​the wafer, the insulating material of the buffer layer is prone to peeling off or generating particle contamination due to weak adhesion, thermal stress, back cleaning or dry etching at the edge of the wafer, which reduces the yield of the wafer. Therefore, the edge of the buffer layer needs to be cleaned.

[0003] During the edge removal of the buffer layer, due to the diversity of chemical reactions and the large number of reaction directions, when the wafer rotates at high speed, the byproducts generated by the edge area of ​​the buffer layer and the cleaning liquid are overflowed by the cleaning liquid and brought into the wafer and gathered to produce abnormal marks. The abnormal marks generated by the aggregation of byproducts have relatively weak bonding with the wafer surface, and may fall off and be contaminated during the wafer transfer or transportation process, thereby reducing the product yield of the wafer.

[0004] How to clean the byproduct marks produced during the cleaning process of the edge of the wafer buffer layer to avoid falling off and contaminating the wafer is a technical problem that technical personnel in this field urgently need to solve. Summary of the invention

[0005] In view of the problems existing in the prior art, the present application provides a method for cleaning the edge of a wafer buffer layer, comprising:

[0006] Rotating the wafer and spraying a first cleaning liquid onto the surface of the wafer to remove a buffer layer at the edge of the wafer, where a byproduct mark is formed on the surface of the wafer;

[0007] Obtaining the position of the byproduct imprint, and recording it as the marking position;

[0008] Keep the wafer rotating and spray a second cleaning solution onto the marked position to remove the byproduct mark on the surface of the wafer;

[0009] A rinse liquid is sprayed onto the surface of the wafer to rinse the wafer.

[0010] According to a method for cleaning the edge of a wafer buffer layer provided by the present application, the marking position is determined by the distance between the byproduct mark and the edge of the wafer.

[0011] According to a method for cleaning the edge of a wafer buffer layer provided by the present application, the marking position is determined by the distance between the inner circle of the byproduct mark and the edge of the wafer.

[0012] According to a method for cleaning the edge of a wafer buffer layer provided in the present application, the landing point of the first cleaning liquid is on the cleaning line of the wafer, and the distance between the cleaning line and the edge of the wafer is the bevel width of the wafer.

[0013] According to a method for cleaning the edge of a wafer buffer layer provided in the present application, spraying the second cleaning liquid to the marked position is achieved by moving a nozzle, and in the process of moving the nozzle, the first cleaning liquid is switched to the second cleaning liquid.

[0014] According to a method for cleaning the edge of a wafer buffer layer provided by the present application, when the first cleaning liquid is sprayed onto the wafer surface and when the second cleaning liquid is sprayed onto the marked position, the rotation speed of the wafer remains unchanged.

[0015] According to a method for cleaning an edge of a wafer buffer layer provided in the present application, the flow rate of the first cleaning liquid is the same as the flow rate of the second cleaning liquid.

[0016] According to a method for cleaning the edge of a wafer buffer layer provided in the present application, the first cleaning liquid is any one of DHF, HF, SC1, SC2 or a mixture of HF and HNO3, and the second cleaning liquid is any one of DHF, HF, SC1, SC2 or a mixture of HF and HNO3.

[0017] According to a method for cleaning an edge of a wafer buffer layer provided in the present application, the first cleaning liquid and the second cleaning liquid are the same chemical liquid.

[0018] According to a method for cleaning the edge of a wafer buffer layer provided in the present application, the rinse liquid is deionized water.

[0019] According to a method for cleaning the edge of a wafer buffer layer provided in the present application, the landing point of the first cleaning liquid and / or the second cleaning liquid is closer to the edge of the wafer than the orthographic projection of the nozzle on the wafer.

[0020] According to a method for cleaning the edge of a wafer buffer layer provided in the present application, when spraying the first cleaning liquid onto the wafer surface and / or spraying the second cleaning liquid onto the marked position, the nozzle forms an inclined angle less than 90 degrees with the wafer surface.

[0021] According to a method for cleaning the edge of a wafer buffer layer provided in the present application, before spraying the first cleaning liquid onto the surface of the wafer, the first cleaning liquid is pre-sprayed at a position outside the wafer for a preset time.

[0022] The present application also provides a cleaning device for the edge of a wafer buffer layer, comprising:

[0023] A chuck, used to hold and rotate the wafer;

[0024] A nozzle, connected to an external liquid supply device, for spraying chemical liquid onto the wafer;

[0025] An acquisition unit, used for acquiring the position of the byproduct mark on the wafer surface and recording it as the mark position;

[0026] The controller is configured to: control the nozzle to spray the first cleaning liquid to the cleaning line of the wafer to remove the buffer layer at the edge of the wafer, control the acquisition unit to acquire the position of the by-product mark on the wafer surface, and control the movement of the nozzle according to the acquired mark position so that the landing point of the second cleaning liquid sprayed by the nozzle is located at the mark position, and control the nozzle to move to the rinse position to rinse the surface of the wafer.

[0027] The present application provides a method for cleaning the edge of a wafer buffer layer. First, the wafer is rotated and a first cleaning liquid is sprayed onto the surface of the wafer to remove the buffer layer at the edge of the wafer, thereby forming a circle of by-product marks on the surface of the wafer. Then, the position of the by-product mark is obtained and recorded as a marked position. The wafer is kept rotating and a second cleaning liquid is sprayed onto the marked position to remove the by-product mark at the marked position. Finally, a rinsing liquid is sprayed onto the surface of the wafer to rinse the wafer.

[0028] The by-product marks were precisely rinsed, effectively solving the problem of by-product marks generated during the cleaning process of the buffer layer edge and improving the wafer yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the present application or the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0030] Figure 1 is a structural schematic diagram of a wafer cleaning device according to an embodiment of the present application;

[0031] Figure 2 It is a schematic flow chart of a method for cleaning an edge of a wafer buffer layer according to an embodiment of the present application;

[0032] Figure 3 is a schematic diagram of a byproduct imprint of an embodiment of the present application;

[0033] Figure 4This is a schematic diagram of the nozzle landing point position of an embodiment of the present application;

[0034] Figure 5 It is a schematic diagram of the cleaning result of an embodiment of the present application. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of this application clearer, the technical solutions in this application will be clearly and completely described below in conjunction with the drawings in this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0036] The cleaning method for the edge of a wafer buffer layer provided in the present application is implemented in a single wafer cleaning chamber.

[0037] Research has found that there are generally two factors that affect the position of the by-product mark. The first is the process position required by the wafer, that is, the location of the cleaning liquid landing point. Secondly, when the cleaning liquid landing point remains unchanged, the rotation speed of the wafer itself also affects the position of the by-product mark. If the wafer rotates slowly, the centrifugal force is small, and the area of ​​the cleaning liquid overflowing to the center of the wafer increases, then the position of the by-product mark formed in the end will be closer to the center of the wafer relative to the cleaning line.

[0038] How to clean the abnormal marks on the wafer surface produced during the cleaning process of the buffer layer edge is a technical problem to be solved by this application.

[0039] The present application provides a method for cleaning the edge of a wafer buffer layer, comprising: Figure 1 The wafer cleaning device includes a chuck 101 and a nozzle 102. The chuck 101 and the nozzle 102 are arranged in a wafer cleaning chamber to clean a wafer 103.

[0040] The inventors know that the cleaning method of the edge of the wafer buffer layer is roughly divided into two parts. First, based on the wafer process requirements, the edge area of ​​the buffer layer that needs to be cleaned is removed using a cleaning liquid, and then the wafer surface is rinsed with a rinse liquid to remove residual substances on the wafer surface.

[0041] refer to Figures 2 to 4 The cleaning method for the edge of a wafer buffer layer according to an embodiment of the present application includes the following steps:

[0042] S110, removing the buffer layer at the edge of the wafer. Moving the nozzle based on the cleaning width of the wafer edge so that the landing point of the first cleaning liquid sprayed from the nozzle is located on the cleaning line to clean the edge of the wafer.

[0043] In this step, based on the process requirements of the wafer, the edge cleaning width of the wafer, that is, the distance between the cleaning line and the edge of the wafer, can be determined. The nozzle is moved for the first time so that the landing point of the first cleaning liquid sprayed from the nozzle is located on the cleaning line to clean the edge area of ​​the wafer.

[0044] During the cleaning process of the edge area of ​​the wafer buffer layer, the first cleaning liquid reacts with the buffer layer at the edge of the wafer and further hydrolyzes to form by-products. Since the nozzle position for spraying the cleaning liquid is fixed and the wafer is rotating at high speed, the by-products generated on the wafer surface will continue to move toward the center of the wafer and accumulate, and eventually appear on the wafer surface as a by-product mark with a circular line centered on the center of the wafer. Figure 3 The black line area in the figure is the local byproduct mark on the wafer surface.

[0045] S120, removing the byproduct mark on the wafer. Obtaining the marked position of the byproduct mark, moving the nozzle based on the marked position so that the landing point of the second cleaning liquid sprayed from the nozzle is located at the marked position, thereby cleaning the byproduct mark.

[0046] After the first cleaning liquid removes the buffer layer at the edge of the wafer, the marking position is obtained by obtaining the distance between the by-product mark and the edge of the wafer. Since the wafer keeps rotating during the cleaning of the by-product mark, the position of the by-product mark is the position of any point on the circular line, and the marking position is closer to the internal area of ​​the wafer relative to the process position. The process position is the position of the edge cleaning line of the wafer, that is, the position of the landing point of the first cleaning liquid during the edge cleaning process. During the cleaning process of the edge of the buffer layer, since the first cleaning liquid itself is an aqueous solution, after the first cleaning liquid reacts with the edge of the buffer layer, it is further hydrolyzed to produce by-products. As the wafer rotates and the first cleaning liquid overflows toward the center of the wafer, the by-products gather in the direction of the edge cleaning line toward the center of the wafer to produce a by-product mark. In some embodiments, the marking position of the by-product mark is obtained by an optical microscope or a measuring machine, which is not limited here.

[0047] After obtaining the mark position of the byproduct mark, the position of the nozzle 102 is moved for the second time based on the control platform of the wafer cleaning equipment. In some embodiments, the position of the nozzle 102 can be changed by changing the length of the robot arm connected to the nozzle 102.

[0048] It should be noted that, in order to avoid the second cleaning liquid from sputtering on the wafer surface, the nozzle is non-perpendicular to the wafer surface, that is, there is an inclined angle of less than 90 degrees between the nozzle and the wafer surface. At the same time, in order to make the waste liquid after cleaning flow less to the center of the wafer, the landing point of the second cleaning liquid is closer to the edge of the wafer than the orthographic projection of the nozzle on the wafer.

[0049] refer to Figure 1 In some embodiments, there is a certain inclination angle between the nozzle 102 and the surface of the wafer 103 to ensure that the landing point of the second cleaning liquid sprayed from the nozzle 102 is located at the marked position to clean the by-product mark. And because the nozzle 102 is tilted toward the edge of the wafer, if the second cleaning liquid sprayed from the nozzle is sputtered, the sputtering is biased toward the edge of the wafer and will not affect the center area of ​​the wafer. In some embodiments, there are many by-products formed on the surface of the wafer 103, and the by-product mark formed on the surface of the wafer 103 is an annular area with a certain width. Therefore, the landing point of the second cleaning liquid should be located in the inner circle of the annular mark to thoroughly clean the by-product mark.

[0050] In some embodiments, the first cleaning liquid and the second cleaning liquid are the same chemical liquid, which can not only remove the edge of the buffer layer film, but also remove the byproduct mark, such as dilute hydrofluoric acid (DHF), hydrofluoride (HF), SC1, SC2 or a mixture of HF and HNO3.

[0051] In some embodiments, during the process of moving the nozzle based on the marked position, the cleaning liquid can be directly switched, that is, the nozzle is kept continuously supplied with liquid, and the first cleaning liquid is switched to the second cleaning liquid. After the nozzle moves to the point where the second cleaning liquid is sprayed and the liquid point is located at the marked position, the fixed spray is performed, and the second cleaning liquid is used to remove the byproduct mark. Continuous liquid supply during the movement of the nozzle can ensure that the liquid film on the wafer surface is stable and more uniform, and optimize the wafer yield.

[0052] S130, rinse the wafer surface. Move the nozzle toward the center of the wafer and switch the second cleaning liquid to the rinse liquid, so that the landing point of the rinse liquid sprayed from the nozzle is located at the rinse position, and rinse the wafer surface.

[0053] After cleaning the byproduct mark with the second cleaning liquid, in order to ensure the cleanliness of the wafer surface, the wafer surface needs to be rinsed again to remove impurities on the wafer surface. In this step, the nozzle 102 is moved toward the center of the wafer for the third time, and during the movement, the cleaning liquid supplied by the nozzle 102 is switched from the second cleaning liquid to the rinsing liquid, so that the landing point of the rinsing liquid sprayed from the nozzle is located at the rinsing position. The rinsing position is closer to the center of the wafer relative to the marking position, that is, the distance between the rinsing position and the edge of the wafer is greater than the distance between the marking position and the edge of the wafer. In a specific embodiment, the rinsing position is the center of the wafer.

[0054] The nozzle is moved for the third time so that the landing point of the rinse liquid sprayed from the nozzle is located at the rinse position to rinse the wafer surface. In the previous step, the second cleaning liquid may produce some sputtered materials in the process of cleaning the byproduct mark, which fall on the surface of the wafer. In order to avoid contamination caused by overflow and ensure the cleanliness of the wafer surface, the nozzle is moved further toward the center of the wafer, and the second cleaning liquid sprayed from the nozzle is switched to the rinse liquid.

[0055] In some embodiments, the first cleaning liquid and the second cleaning liquid function as a film removal solution, i.e., the above-mentioned DHF, HF, SC1, SC2 or a mixture of HF and HNO3. The rinse liquid is deionized water, and the surface of the wafer is rinsed with deionized water to remove the residues after the by-product mark is cleaned. The method for cleaning the by-product mark of the wafer buffer layer of the present application moves the nozzle based on the wafer process requirements, and after using the first cleaning liquid to clean the edge of the buffer layer of the wafer, obtains the marked position of the by-product mark, and controls the nozzle to move for the second time based on the machine control of the wafer cleaning equipment, so that the landing point of the second cleaning liquid sprayed from the nozzle is located at the marked position, and the by-product mark is accurately removed, and then the nozzle is moved toward the center of the wafer for the third time and the second cleaning liquid is switched to the rinse liquid to rinse the wafer surface to improve the yield of the wafer.

[0056] In some embodiments, when the nozzle continuously supplies liquid during its movement, the rotation speed of the wafer needs to be controlled to remain unchanged, that is, during the movement of the nozzle, the first cleaning liquid and the second cleaning liquid are connected instantly, and there will be no blank period when the nozzle stops supplying liquid, so that the liquid film on the wafer surface is more stable, the impact of the cleaning liquid connection on the wafer surface is weakened, and the rinsing effect is optimized.

[0057] refer to Figure 4 The relative positions of the cleaning line, the marking position of the byproduct imprint and the rinsing position of wafer w on the wafer surface are as follows: Figure 3 As shown, on wafer w, the first dotted circular line 510 is the cleaning line, i.e., the landing point position of the first cleaning liquid when the nozzle moves for the first time; the black circular line 520 is the by-product mark position, i.e., the landing point position of the second cleaning liquid after the nozzle moves for the second time; the second dotted circular line 530 is the rinsing position, i.e., the landing point position of the rinsing liquid after the nozzle moves for the third time.

[0058] In some embodiments, the inclination angle between the nozzle and the wafer surface remains unchanged, that is, the nozzle is tilted toward the edge of the wafer, ensuring that the first cleaning liquid and the second cleaning liquid sprayed from the nozzle will not contaminate the central area of ​​the wafer when cleaning the cleaning line and the marking position.

[0059] In some embodiments, the flow rates of the first cleaning liquid, the second cleaning liquid, and the rinse liquid supplied by the nozzle are kept consistent to improve the uniformity of the liquid film on the wafer surface.

[0060] It should also be noted that, since the hydrolysis reaction is an endothermic reaction, the temperature of the heating plate on which the wafer is placed also has a certain influence on the strength of the byproduct mark. High temperature will promote the hydrolysis reaction. Therefore, lowering the temperature of the heating plate can inhibit the occurrence of the hydrolysis reaction and reduce the generated byproducts. Therefore, during the cleaning process of the byproduct mark of the wafer buffer layer, ensure that the temperature of the heating plate is below the preset temperature to further reduce the byproducts. In some embodiments, the preset temperature can be 30 degrees to 60 degrees.

[0061] In one embodiment, the method for cleaning byproduct marks of a wafer buffer layer of the present application is described in detail with the buffer layer composition being Ta / TaN.

[0062] In order to prevent Cu atoms from diffusing into the substrate material and affecting the performance of the wafer product, a buffer layer is usually deposited before Cu electroplating to isolate Cu from the substrate. The composition of the buffer layer is Ta / TaN. After the electroplating process is performed on the buffer layer, since the edge area will not be electroplated to form a Cu film, the buffer layer in the edge area needs to be removed, and chemical mechanical polishing (CMP) cannot remove the edge area of ​​the wafer. In the CMP process, the film in the edge area of ​​the wafer is easily peeled off due to thermal stress and mechanical stress. Therefore, Ta / TaN needs to be removed from the edge area after Cu electroplating.

[0063] In one embodiment, a mixture of HF and HNO3 is used to remove the edge of TaN / Ta. The following is an example of a cleaning step for the edge of a wafer:

[0064] First, external pre-spraying is performed. Before cleaning the wafer edge, the nozzle is located outside the wafer and the first cleaning liquid is sprayed at this position. In the early stage of the nozzle spraying the first cleaning liquid, there is an unstable flow fluctuation, which affects the process accuracy. Therefore, the wafer external pre-spraying is maintained for a preset time, and the edge cleaning is started when the flow of the first cleaning liquid sprayed from the nozzle is stable.

[0065] Then, the edge of the buffer layer is cleaned. In this embodiment, the position of the cleaning line required by the wafer process is determined by the bevel width of the wafer edge, and the distance between the cleaning line and the wafer edge is the bevel width of the wafer. The nozzle is moved for the first time so that the landing point of the first cleaning liquid sprayed from the nozzle is located on the cleaning line, where the first cleaning liquid, i.e., a mixture of HF and HNO3, is used to clean the edge of the wafer to remove the edge of the buffer layer.

[0066] During the edge cleaning process, the mixture of HF and HNO3 reacts with TaN / Ta to produce fluorotantalate or fluorotantalate, and the hydrolysis products produced by hydrolysis overflow toward the center of the wafer along with the mixture of HF and HNO3 and accumulate to form a by-product mark.

[0067] After the edge of the buffer layer is cleaned, the marking position of the by-product mark is obtained, that is, the distance between the by-product mark and the edge of the wafer is obtained, the nozzle is moved for the second time, and the nozzle continues to supply a mixture of HF and HNO3 so that the liquid landing point of the nozzle is located at the marking position, and the by-product mark position is cleaned for a period of time.

[0068] Finally, the nozzle is moved toward the center of the wafer for the third time, and during the movement, the mixture of HF and HNO3 sprayed from the nozzle is switched to deionized water, so that the landing point of the deionized water is located at the rinsing position, which is closer to the center of the wafer relative to the marked position, and the wafer surface is rinsed with deionized water.

[0069] In some embodiments, during the movement of the nozzle, it is ensured that the rotation speed of the wafer does not change, so that the liquid film formed on the surface of the wafer by the cleaning liquid sprayed from the nozzle is more stable and uniform.

[0070] refer to Figure 3 and Figure 5 , is a schematic diagram of the wafer buffer layer before byproduct mark cleaning, Figure 3 The black lines in the figure are byproduct marks. Figure 5 It is a schematic diagram of the wafer surface after using the wafer buffer layer edge cleaning method of the present application, and the byproduct mark has disappeared.

[0071] Reference again Figure 1 The present application also provides a cleaning device for the edge of a wafer buffer layer, including a chuck 101, a nozzle 102, an acquisition unit and a controller. The chuck 101 is used to carry and rotate the wafer. The nozzle 102 is connected to an external liquid supply device for spraying chemical liquid onto the wafer. The acquisition unit is used to obtain the marked position of the by-product imprint. In some embodiments, the acquisition unit can be a communication module of an optical microscope or a measuring machine, and the marked position of the by-product imprint on the wafer is obtained through the acquisition unit.

[0072] A controller is used to control the movement of the nozzle. More specifically, the controller is configured to: control the movement of the nozzle based on the process requirements so that the landing point of the first cleaning liquid sprayed from the nozzle is located on the cleaning line required by the process, and the first cleaning liquid is sprayed to the cleaning line through the nozzle to clean the edge of the wafer. In the process of cleaning the edge of the wafer, a by-product mark of a certain width is generated at a certain distance from the cleaning line to the center of the wafer. Then, the controller obtains the marked position of the by-product mark by controlling the acquisition unit, and then moves the nozzle for the second time based on the marked position, so that the landing point of the second cleaning liquid sprayed from the nozzle is located at the marked position, and the by-product mark generated on the edge of the wafer is cleaned in a targeted manner. Finally, in order to thoroughly rinse the surface of the wafer to remove all impurities, the controller controls the nozzle to move toward the center of the wafer for the third time, so that the rinsing liquid sprayed from the nozzle can rinse the surface of the wafer.

[0073] For other details of the cleaning equipment, please refer to the previous reference Figure 2 The described process will not be expanded here.

[0074] In the description of the present application, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application 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 on the present application. The terms "first" and "second" are used for descriptive purposes only, 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 application, unless otherwise specified, "multiple" means two or more.

[0075] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0076] In the description of this specification, specific features, structures, materials or characteristics may be combined in an appropriate manner in any one or more embodiments or examples.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for cleaning the edge of a wafer buffer layer, characterized in that: include: Rotating the wafer and spraying a first cleaning liquid onto the surface of the wafer to remove a buffer layer at the edge of the wafer, where a byproduct mark is formed on the surface of the wafer; Obtaining the position of the byproduct imprint, and recording it as the marking position; Keep the wafer rotating and spray a second cleaning solution onto the marked position to remove the byproduct mark on the surface of the wafer; A rinse liquid is sprayed onto the surface of the wafer to rinse the wafer.

2. The method for cleaning the edge of a wafer buffer layer according to claim 1, characterized in that: The mark position is determined by the distance between the byproduct mark and the wafer edge.

3. The method for cleaning the edge of a wafer buffer layer according to claim 2, characterized in that: The marking position is determined by the distance between the inner circle of the byproduct mark and the edge of the wafer.

4. The method for cleaning the edge of a wafer buffer layer according to claim 1, characterized in that: The landing point of the first cleaning liquid is on the cleaning line of the wafer, and the distance between the cleaning line and the edge of the wafer is the hypotenuse width of the wafer.

5. The method for cleaning the edge of a wafer buffer layer according to claim 3, characterized in that: The spraying of the second cleaning liquid onto the marked position is achieved by moving a nozzle, and in the process of moving the nozzle, the first cleaning liquid is switched to the second cleaning liquid.

6. The method for cleaning the edge of a wafer buffer layer according to claim 1, characterized in that: When the first cleaning liquid is sprayed onto the surface of the wafer and when the second cleaning liquid is sprayed onto the marked position, the rotation speed of the wafer remains unchanged.

7. The method for cleaning the edge of a wafer buffer layer according to claim 1, characterized in that: The flow rate of the first cleaning liquid is the same as the flow rate of the second cleaning liquid.

8. The method for cleaning the edge of a wafer buffer layer according to claim 1, characterized in that: The first cleaning liquid is any one of DHF, HF, SC1, SC2 or a mixture of HF and HNO3, and the second cleaning liquid is any one of DHF, HF, SC1, SC2 or a mixture of HF and HNO3.

9. The method for cleaning the edge of a wafer buffer layer according to claim 8, characterized in that: The first cleaning liquid and the second cleaning liquid are the same chemical liquid.

10. The method for cleaning the edge of a wafer buffer layer according to claim 1, characterized in that: The flushing liquid is deionized water.

11. The method for cleaning the edge of a wafer buffer layer according to claim 5, characterized in that: The landing point of the first cleaning liquid and / or the second cleaning liquid is closer to the edge of the wafer than the orthographic projection of the nozzle on the wafer.

12. The method for cleaning the edge of a wafer buffer layer according to claim 11, characterized in that: When the first cleaning liquid is sprayed onto the wafer surface and / or the second cleaning liquid is sprayed onto the marked position, the nozzle and the wafer surface form an inclined angle less than 90 degrees.

13. The method for cleaning the edge of a wafer buffer layer according to claim 1, characterized in that: Before spraying the first cleaning liquid onto the surface of the wafer, the first cleaning liquid is pre-sprayed on a position other than the wafer for a preset time.

14. A cleaning device for the edge of a wafer buffer layer, characterized in that: include: A chuck, used to hold and rotate the wafer; A nozzle, connected to an external liquid supply device, for spraying chemical liquid onto the wafer; An acquisition unit, used for acquiring the position of the byproduct mark on the wafer surface and recording it as the mark position; The controller is configured to: control the nozzle to spray the first cleaning liquid to the cleaning line of the wafer to remove the buffer layer at the edge of the wafer, control the acquisition unit to acquire the position of the by-product mark on the wafer surface, and control the movement of the nozzle according to the acquired mark position so that the landing point of the second cleaning liquid sprayed by the nozzle is located at the mark position, and control the nozzle to move to the rinse position to rinse the surface of the wafer.

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