Pre-cleaning method of wafer
By adjusting the position of the ejector pin and the gas selection, the problem of damage to the non-plated surface of single-sided electroplated wafers by plasma pre-cleaning was solved, achieving a pre-cleaning effect with high compatibility and high yield.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HUA HONG SEMICONDUCTOR MANUFACTURING (WUXI) LTD
- Filing Date
- 2026-05-14
- Publication Date
- 2026-07-31
AI Technical Summary
In existing technologies, plasma pre-cleaning processes can easily cause damage and edge film peeling defects to the non-plated side of wafers with single-sided electroplating, affecting product yield.
By adjusting the lifting height of the ejector pins in the reaction chamber, the wafer is positioned at different working positions, ensuring that the surface to be plated is exposed to the plasma, while the non-plated surface is protected by the support stage. Pre-cleaning is performed using a mixture of oxygen and argon gas, and the etching rate is controlled between 570 Å/min and 670 Å/min.
It achieves high compatibility with different types of wafers, reduces production costs, avoids damage to non-plated surfaces, and improves product yield.
Smart Images
Figure CN122497300A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of semiconductor devices and integrated circuit technology, and in particular to a pre-cleaning method for wafers. Background Technology
[0002] In semiconductor manufacturing, electroless plating is one of the core processes for preparing a conductive metal layer on the wafer surface to achieve electrical connection between the chip and external circuits. Depending on the product design and functional requirements, wafer electroless plating is divided into single-sided electroless plating and double-sided electroless plating. For example, thin wafers using the drum wafer (taiko wafer) process will prepare conductive metal layers such as Ni / Pd / Au on the front side of the wafer through single-sided electroless plating. Some products require electroless plating to be completed on both the front and back sides of the wafer to form a double-sided conductive structure.
[0003] Regardless of whether single-sided or double-sided electroplating is used, the wafer needs to undergo plasma pre-cleaning before entering the electroplating process to remove surface contaminants, photoresist residue, and other impurities from the wafer's electroplating surface. This also improves the hydrophilicity of the wafer surface, ensuring the adhesion and film quality of the subsequent electroplated metal layers.
[0004] In related technologies, a pin is typically used to lift the wafer support in the reaction chamber of the pre-cleaning equipment to the middle position for plasma pre-cleaning. During the cleaning process, the wafer does not come into contact with the support surface. However, this pre-cleaning process is only suitable for wafers that require double-sided plating. For wafers that require single-sided plating, the non-plated surface is generally pre-prepared with a metal layer (e.g., a single-sided plating wafer treated with back gold). If this process is used for pre-cleaning, oxygen-containing plasma will penetrate the non-plated surface of the wafer and react with the surface metal at the edge (e.g., oxygen plasma reacts with silver to generate silver oxide). The resulting metal oxide has poor adhesion to the underlying metal, which can easily cause edge film peeling defects, affecting the product yield. Summary of the Invention
[0005] This application provides a pre-cleaning method for wafers. For wafers that require single-sided plating, this method can take into account both the pre-cleaning of the plating surface and the protection of the non-plating surface during the pre-cleaning process, which helps to avoid damage or edge film peeling defects caused by plasma pre-cleaning to the non-plating surface.
[0006] In view of this, this application provides a pre-cleaning method for wafers, comprising:
[0007] S1, drive the ejector pin in the reaction chamber, the ejector pin carries the wafer at the first position, the wafer includes a main body and an edge portion surrounding the main body;
[0008] S2, according to the type of plating to be performed on the wafer, drive the ejector pin to move until the ejector pin drives the wafer to the second position or the third position. When the wafer is a wafer to be plated on both sides, drive the ejector pin to make the wafer reach the second position, and there is a gap between the wafer and the bearing surface of the support stage. When the wafer is a wafer to be plated on one side, drive the ejector pin to make the wafer reach the third position, and the edge of the wafer is in contact with the bearing surface.
[0009] S3, perform plasma pre-cleaning on the wafer, and after the pre-cleaning, drive the ejector pin to move the wafer to the first position and unload the wafer.
[0010] Optionally, the wafer is a wafer to be plated on one side, the thickness of the edge of the wafer is greater than the thickness of the main body, and a metal film layer is formed on its back side.
[0011] Optionally, the metal film layer includes a silver layer.
[0012] Optionally, the ejector pin abuts against the edge of the wafer.
[0013] Optionally, the ejector pins are evenly distributed around the main body of the wafer.
[0014] Optionally, the support platform includes an electrostatic chuck.
[0015] Optionally, the gas used for pre-cleaning is a mixture of oxygen and argon.
[0016] Optionally, the etching rate of the pre-cleaning is 570 Å / min - 670 Å / min.
[0017] The technical solution of this application has at least the following advantages:
[0018] This application allows adjustment of the lifting height of the ejector pins within the reaction chamber according to the type of wafer to be plated, thereby controlling the working position of the wafer during plasma pre-cleaning. Specifically, when the wafer is to be plated on both sides, driving the ejector pins to the second position (i.e., the wafer is in the first cleaning position) creates a gap between the wafer and the support surface of the stage, exposing both sides of the wafer to be plated to the plasma, thus achieving double-sided plasma pre-cleaning. When the wafer is to be plated on one side, driving the ejector pins to the third position (i.e., the wafer is in the second cleaning position) creates a gap between the wafer and the support surface of the stage. In this position, the wafer edge is in contact with the carrier surface, and the wafer surface to be plated is exposed to the plasma, while the non-plated surface is protected by the carrier stage. The pre-cleaning method of this application has high compatibility with wafers and can be applied to the pre-cleaning of different types of wafers to be plated, which is beneficial to improving the flexibility of wafer production and reducing production costs. In addition, for wafers that need to be plated on one side, the method of this application can also take into account the pre-cleaning of the surface to be plated and the protection of the non-plated surface during the pre-cleaning process, which is beneficial to avoid damage or edge film peeling defects caused by plasma pre-cleaning to the non-plated surface. Attached Figure Description
[0019] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0020] Figure 1 This is a physical image of a drum-shaped wafer that has undergone back-gold processing in the relevant technology after plasma pre-cleaning.
[0021] Figure 2 This is a process flow diagram of a wafer pre-cleaning method provided in an exemplary embodiment of this application;
[0022] Figure 3 This is a schematic cross-sectional view of the wafer in a first position in a wafer pre-cleaning method provided by an exemplary embodiment of this application;
[0023] Figure 4 This is a schematic cross-sectional view of the wafer in a second position in a wafer pre-cleaning method provided by an exemplary embodiment of this application;
[0024] Figure 5 This is a schematic cross-sectional view of the wafer in the third position in a wafer pre-cleaning method provided by an exemplary embodiment of this application;
[0025] Figure 6This is a physical image of a drum-type wafer after pre-cleaning and unloading, which has undergone back-gold processing, in a wafer pre-cleaning method provided by an exemplary embodiment of this application.
[0026] Figure label:
[0027] 01. Reaction Chamber
[0028] 10. Support platform;
[0029] 20. Thruster; 21. First position; 22. Second position; 23. Third position;
[0030] 30. Wafer. Detailed Implementation
[0031] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0032] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.
[0033] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components; and they can refer to a wireless connection or a wired connection. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.
[0034] Furthermore, the technical features involved in the different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.
[0035] The following is combined with Figures 1 to 6 This describes an embodiment of the present application.
[0036] refer to Figure 2The illustration shows an embodiment of this application, providing a wafer pre-cleaning method, comprising:
[0037] S1, drive the ejector pin in the reaction chamber, the ejector pin carries the wafer at the first position, the wafer includes a main body and an edge surrounding the main body.
[0038] For example, the ejector pin is typically driven to rise or retract by an ejector pin drive system within the reaction chamber.
[0039] It should be noted that the first position is the wafer loading and unloading station. When loading the wafer, the ejector pin is driven to carry the wafer at the first position. When unloading the wafer, the ejector pin is driven to move the wafer to the first position for unloading.
[0040] For example, the edge thickness of the wafer can be greater than the body thickness, such as a drum wafer (a wafer with back-side thinning by the Taiko process), or the edge thickness of the wafer can be equal to the body thickness, such as a polished wafer (a wafer processed by chemical mechanical polishing (CMP)).
[0041] In some embodiments, the ejector pin abuts against the edge of the wafer. This arrangement helps to prevent the ejector pin from damaging the main body of the wafer.
[0042] In some embodiments, the ejector pins are evenly distributed circumferentially around the main body of the wafer.
[0043] S2, depending on the type of wafer to be plated, drive the ejector pin to move until the ejector pin drives the wafer to the second or third position. Wherein, if the wafer is a wafer to be plated on both sides, drive the ejector pin to make the wafer reach the second position, and there is a gap between the wafer and the bearing surface of the carrier stage. When the wafer is a wafer to be plated on one side, drive the ejector pin to make the wafer reach the third position, and the edge of the wafer is in contact with the bearing surface.
[0044] For example, when the thickness of the wafer edge is greater than the thickness of the main body and a metal film is formed on its back side, such as a drum wafer with a silver back surface film after a back-gold plating process, a conductive metal layer needs to be prepared on the front side of the wafer by single-sided electroless plating. For such wafers, if a plasma pre-cleaning process provided by related technologies is used for pre-cleaning, during the pre-cleaning process, oxygen-containing plasma easily penetrates the back side of the wafer and first reacts with the surface metal film at the edge to generate metal oxides, reducing the adhesion between the surface film and the underlying metal, thus causing edge peeling (e.g.) Figure 1(As shown). For this type of wafer, this application can drive the ejector pin to move the wafer to the third position, that is, the wafer is in the second cleaning working position. In the second cleaning working position, the edge of the wafer is in contact with the bearing surface. Therefore, when the wafer is pre-cleaned by plasma in the second cleaning working position, the metal film layer on the back of the wafer can be effectively prevented from being eroded by plasma. This can improve the problem of the back edge film layer peeling off after plasma pre-cleaning of this type of wafer and improve the yield of the product.
[0045] In some embodiments, the support stage includes an electrostatic chuck. The electrostatic attraction of the wafer by the electrostatic chuck helps to ensure that the edge of the wafer to be plated on one side fits tightly against the support surface, further enhancing the protection of the non-plated side during the pre-cleaning process.
[0046] It should be noted that for a wafer to be double-sided plated, both sides are the plated surfaces. For a wafer to be single-sided plated, the side closer to the substrate is the non-plated surface, and the opposite side is the plated surface.
[0047] S3, perform plasma pre-cleaning on the wafer. After pre-cleaning, drive the ejector pin to move the wafer to the first position and unload the wafer.
[0048] In some embodiments, the gas used for pre-cleaning is a mixture of oxygen and argon.
[0049] In some embodiments, the etching rate for pre-cleaning is 570 Å / min to 670 Å / min.
[0050] For example, the etching rate for pre-cleaning can be 570 Å / min, 600 Å / min, 630 Å / min, 670 Å / min, etc.
[0051] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this application.
Claims
1. A method of pre-cleaning a wafer, characterized by, include: S1, drive the ejector pin in the reaction chamber, the ejector pin carries the wafer at the first position, the wafer includes a main body and an edge portion surrounding the main body; S2, according to the type of plating to be performed on the wafer, drive the ejector pin to move until the ejector pin drives the wafer to the second position or the third position. When the wafer is a wafer to be plated on both sides, drive the ejector pin to make the wafer reach the second position, and there is a gap between the wafer and the bearing surface of the support stage. When the wafer is a wafer to be plated on one side, drive the ejector pin to make the wafer reach the third position, and the edge of the wafer is in contact with the bearing surface. S3, perform plasma pre-cleaning on the wafer, and after the pre-cleaning, drive the ejector pin to move the wafer to the first position and unload the wafer.
2. The method of claim 1, wherein, The wafer is a wafer to be plated on one side only. The thickness of the edge of the wafer is greater than the thickness of the main body and a metal film is formed on its back side.
3. The method of claim 2, wherein, The metal film layer includes a silver layer.
4. The method according to claim 1, characterized in that, The ejector pin abuts against the edge of the wafer.
5. The method according to claim 1, characterized in that, The ejector pins are evenly distributed around the main body of the wafer.
6. The method according to claim 1, characterized in that, The support platform includes an electrostatic chuck.
7. The method according to claim 1, characterized in that, The gas used for pre-cleaning is a mixture of oxygen and argon.
8. The method according to claim 1, characterized in that, The etching rate for the pre-cleaning is 570 Å / min - 670 Å / min.