Micro-arc oxidation treatment method for RPS complex molded surface inner cavity wall and insulation clamp

Abstract

The invention discloses a micro-arc oxidation treatment method for an RPS complex molded surface inner cavity wall and an insulation clamp, and relates to the technical field of micro-arc oxidation treatment. The micro-arc oxidation treatment method comprises the following steps: carrying out insulation protection on a non-processing surface of the RPS reaction cavity, and installing an auxiliary cathode at the center of an inner cavity of the RPS reaction cavity; placing the RPS reaction cavity in an electrolyte to serve as an anode; the raw materials of the electrolyte comprise sodium silicate, sodium aluminate, sodium oxalate and sodium hydroxide; carrying out micro-arc oxidation treatment by adopting a constant-current method, so that an oxidation film bottom layer is formed on the inner cavity wall of the RPS reaction cavity; carrying out micro-arc oxidation treatment by adopting a constant-voltage method, forming an oxidation film surface layer on the oxidation film bottom layer, and tightly combining the oxidation film bottom layer and the oxidation film surface layer to form the ceramic oxidation film. According to the micro-arc oxidation treatment method disclosed by the invention, in-situ ceramization of the complex molded surface and the micropore inner wall in the RPS reaction cavity can be realized, and the corrosion resistance and the breakdown voltage resistance of the RPS reaction cavity are greatly enhanced.

Description

Technical Field

[0001] The invention relates to the technical field of micro-arc oxidation treatment, and in particular to a micro-arc oxidation treatment method for an RPS complex-shaped inner cavity wall and an insulating clamp. Background Art

[0002] A remote plasma source (RPS) is a device used to generate plasma. It is often used to process, modify or deposit thin films on the surface of materials in a vacuum environment. In the semiconductor device manufacturing industry, RPS is widely used to etch the surface of semiconductor materials. The working principle of the remote plasma source is as follows: In a plasma generator, fluorine ions of gases such as nitrogen trifluoride (NF3) are ionized by radio frequency energy to generate plasma, and the plasma enters the reaction chamber through a transmission channel to process the workpiece.

[0003] There is a problem that has been difficult to solve when using a remote plasma source to process workpieces. After long-term use of the remote plasma source, fluorine ions will corrode the inner wall of the reaction chamber and form particles that flow into the surface of the workpiece, thereby causing defects in the workpiece. In particular, when a remote plasma source is used to process semiconductor materials (such as silicon wafers), the particles formed after the inner wall of the reaction chamber is corroded flow into the surface of the semiconductor material, and the defects caused to the semiconductor material will seriously affect the performance of the semiconductor material. In order to resist the corrosion of fluorine ions, the commonly used method at present is to perform surface treatment on the inner wall of the reaction chamber that is in contact with fluorine ions. For example, the inner wall of the reaction chamber can be treated by hard anodizing to form an anodized film on the inner surface of the reaction chamber, thereby improving the corrosion resistance of the inner wall of the reaction chamber, extending the service life of the reaction chamber, and keeping the particle level at an acceptable level in the short term.

[0004] Although the anodized film formed on the inner surface of the reaction chamber by the above method can improve the corrosion resistance of the reaction chamber to a certain extent, the reaction chamber used by the remote plasma source has extremely high requirements on the corrosion resistance and voltage breakdown resistance of its inner wall. In order to effectively improve the corrosion resistance and voltage breakdown resistance of the inner wall of the reaction chamber, the thickness of the anodized film needs to be grown above 50μm. However, when the anodized film grows to a certain thickness, longitudinal microcracks are prone to occur. Fluoride ions will invade the reaction chamber substrate through these longitudinal microcracks and corrode the reaction chamber substrate, which may easily cause the anodized film to peel off and fail. Therefore, the corrosion resistance of the reaction chamber obtained by surface treatment of the inner wall of the reaction chamber by the above method is still difficult to meet the demand. Moreover, since the shape and structure of the reaction chamber are relatively complex, there are not only long cavity holes used as reaction chambers, but also some micropores used to transmit plasma or for other functions. At present, the anodizing method can basically only perform surface treatment on the inner surface of the long cavity holes, and it is difficult to perform surface treatment on the inner surface of the micropores, that is, it is difficult to form an oxide film on the inner surface of the micropores. Therefore, during use, plasma will still corrode the reaction chamber through the micropores, thereby generating particulate matter that will cause defects to the workpiece, thereby affecting the performance of the workpiece. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to propose a micro-arc oxidation treatment method for the inner cavity wall of RPS complex surface, which can realize the in-situ ceramicization of the complex surface and the inner wall of the micropores in the RPS reaction cavity, so that the inner cavity wall and the inner wall of the micropores of the RPS reaction cavity are formed with a uniform and dense ceramic oxide film, which greatly enhances the corrosion resistance and breakdown voltage resistance of the RPS reaction cavity, and solves the problem that the corrosion resistance of the reaction cavity obtained by surface treatment of the inner wall of the reaction cavity by traditional hard anodizing is still difficult to meet the demand.

[0006] Another object of the present invention is to provide an insulating clamp, which is applied to the micro-arc oxidation treatment method of the RPS complex surface inner cavity wall mentioned above, which can ensure that the interior of the RPS reaction cavity is not affected by the electric field shielding, thereby realizing the inner cavity and micropore film formation.

[0007] In order to solve the above technical problems, the present invention provides a micro-arc oxidation treatment method for the inner wall of a complex RPS surface, comprising the following steps:

[0008] (1) Insulate and protect the non-machined surface of the RPS reaction chamber, and install an auxiliary cathode in the center of the inner cavity of the RPS reaction chamber;

[0009] (2) placing the RPS reaction chamber of step (1) in an electrolyte as an anode; the raw materials of the electrolyte include sodium silicate, sodium aluminate, sodium oxalate and sodium hydroxide;

[0010] (3) performing micro-arc oxidation treatment on the RPS reaction chamber of step (2) by a constant current method, so that an oxide film bottom layer is formed on the inner wall of the RPS reaction chamber;

[0011] (4) The RPS reaction chamber of step (3) is subjected to micro-arc oxidation treatment by a constant pressure method to form an oxide film surface layer on the oxide film bottom layer, wherein the oxide film bottom layer and the oxide film surface layer are tightly combined to form a ceramic oxide film.

[0012] As an improvement of the above technical solution, in the electrolyte, the concentration of sodium silicate is 2g / L to 15g / L, the concentration of sodium aluminate is 5g / L to 30g / L, the concentration of sodium oxalate is 2g / L to 20g / L, and the concentration of sodium hydroxide is 1g / L to 3g / L.

[0013] As an improvement of the above technical solution, two sides of the auxiliary cathode protrude from two ends of the RPS reaction chamber respectively; the material of the auxiliary cathode is stainless steel.

[0014] As an improvement of the above technical solution, a reaction chamber and microholes communicating with the reaction chamber are provided inside the RPS reaction chamber; the diameter of the microholes is 0.8 mm to 5 mm, and the depth is 30 mm to 50 mm.

[0015] As an improvement of the above technical solution, in step (3), the conditions for micro-arc oxidation treatment of the RPS reaction chamber in step (2) by constant current method are as follows:

[0016] The forward current density is 1A / dm 2 ~5A / dm 2 , the forward duty cycle is 25% to 60%, and the forward frequency is 50Hz to 500Hz;

[0017] Negative current density is 0~3A / dm 2 , the negative duty cycle is 30% to 70%, and the negative frequency is 50Hz to 500Hz;

[0018] The temperature of the electrolyte is 20°C to 80°C, and the processing time is 30min to 60min.

[0019] As an improvement of the above technical solution, in step (4), the conditions for micro-arc oxidation treatment of the RPS reaction chamber in step (3) by constant pressure method are as follows:

[0020] The forward voltage is 450V~550V, the forward duty cycle is 25%~60%, and the forward frequency is 50Hz~500Hz;

[0021] The negative voltage is 60V~150V, the negative duty cycle is 30%~70%, and the negative frequency is 50Hz~500Hz.

[0022] The temperature of the electrolyte is 20-80°C, and the treatment time is 60-300 minutes.

[0023] As an improvement of the above technical solution, an insulating clamp is used to insulate the non-machined surface of the RPS reaction chamber, and an installation cavity for installing the RPS reaction chamber is provided inside the insulating clamp, and the shape and size of the installation cavity are respectively adapted to the shape and size of the RPS reaction chamber;

[0024] The auxiliary cathode is installed inside the installation cavity along the axial direction of the installation cavity, and two sides of the auxiliary cathode are respectively connected to two sides of the insulating clamp.

[0025] Accordingly, the present invention also provides an insulating fixture, which is applied to the micro-arc oxidation treatment method of the RPS complex-shaped inner cavity wall, comprising a fixture body, a cover plate, a conductive wire, an insulating sleeve, a sealing cover and an auxiliary cathode;

[0026] The interior of the fixture body is hollow, forming an installation cavity for installing the RPS reaction chamber, the cover plates are respectively provided at both ends of the fixture body, the cover plates are detachably connected to the fixture body, an electrolyte through hole for electrolyte to pass through is provided in the middle of the cover plate, the electrolyte through hole is connected to the installation cavity, the auxiliary cathode is installed in the center of the installation cavity, and the two sides of the auxiliary cathode are respectively connected to the two cover plates;

[0027] The insulating sleeve is installed on the fixture body, and one end of the insulating sleeve passes through the fixture body and is flush with the inner wall of the installation cavity. The sealing cover is sleeved on the outside of the insulating sleeve, and the outside of the sealing cover is connected to the fixture body. The conductive wire is installed on the inside of the insulating sleeve, one side of the conductive wire is used to be electrically connected to the RPS reaction chamber, and the other side of the conductive wire is used to be electrically connected to the positive electrode of an external power supply.

[0028] As an improvement of the above technical solution, the insulating clamp also includes a sealing gasket, and a mounting groove for installing the sealing gasket is provided on the side of the cover plate facing the clamp body, the sealing gasket is installed in the mounting groove, and the sealing gasket protrudes from the end face of the cover plate on the side facing the clamp body.

[0029] As an improvement of the above technical solution, the materials of the clamp body, the cover plate, the insulating sleeve and the sealing cover are engineering plastics or ceramics respectively.

[0030] The implementation of the present invention has the following beneficial effects:

[0031] 1. A micro-arc oxidation treatment method for surface treatment of the inner wall of the RPS reaction chamber was creatively developed. By insulating the non-machined surface of the RPS reaction chamber, installing an auxiliary cathode in the inner center of the RPS reaction chamber, and using an electrolyte specially designed for the RPS reaction chamber and a two-step method for micro-arc oxidation, in-situ ceramicization of complex surfaces and microporous inner walls in the RPS reaction chamber was achieved, so that a uniform and dense ceramic oxide film was formed on the inner wall and microporous inner wall of the RPS reaction chamber, which greatly enhanced the corrosion resistance and breakdown voltage resistance of the RPS reaction chamber, so that the RPS reaction chamber has excellent corrosion resistance after long-term use, effectively extending the service life of the RPS reaction chamber.

[0032] 2. By insulating and protecting the non-machined surface of the RPS reaction chamber (i.e., the outer surface of the RPS reaction chamber) and designing an auxiliary cathode in the center of the inner cavity of the RPS reaction chamber, the inner cavity electric field of the RPS reaction chamber is enhanced, and the electrolyte can flow smoothly in the cavity, ensuring that the inner cavity and micropores of the RPS reaction chamber are not affected by the electric field shielding, which can promote the electrochemical growth process of the ceramic oxide film in the inner cavity wall and the inner wall of the micropores of the RPS reaction chamber, and ensure that the density and thickness of the formed ceramic oxide film meet the requirements of the cavity, thereby ensuring that the inner cavity of the RPS reaction chamber has excellent corrosion resistance and anti-breakdown voltage capability. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a schematic structural diagram of an insulating clamp used in Example 1 of the present invention;

[0034] Figure 2 yes Figure 1 A cross-sectional view of the interior of the insulating fixture after the RPS reaction chamber is installed;

[0035] Figure 3 is a scanning electron microscope image of the RPS reaction chamber at the micropore after being processed in Example 1 of the present invention;

[0036] Figure 4 is a scanning electron microscope image of the RPS reaction chamber at the corner after being processed in Example 1 of the present invention;

[0037] Among them, there are a conductive wire 1, an insulating sleeve 2, a sealing cover 3, a cover plate 4, a fastener 5, a fixture body 6, an auxiliary cathode 7, a sealing gasket 8, and an RPS reaction chamber 9. DETAILED DESCRIPTION

[0038] To make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0039] If no specific techniques or conditions are specified in the examples, the techniques or conditions described in the literature in the field or the product instructions are used. Raw materials used without specifying the manufacturer are all conventional products that can be obtained through commercial purchase.

[0040] This embodiment discloses a method for micro-arc oxidation treatment of the inner wall of a complex RPS surface, comprising the following steps:

[0041] (1) Insulating and protecting the non-machined surface of the RPS reaction chamber, and installing an auxiliary cathode at the center of the inner cavity of the RPS reaction chamber; specifically, the non-machined surface of the RPS reaction chamber is the outer surface of the RPS reaction chamber;

[0042] (2) placing the RPS reaction chamber of step (1) in an electrolyte as an anode; the raw materials of the electrolyte include sodium silicate, sodium aluminate, sodium oxalate and sodium hydroxide;

[0043] (3) performing micro-arc oxidation treatment on the RPS reaction chamber of step (2) by a constant current method, so that an oxide film bottom layer is formed on the inner wall of the RPS reaction chamber;

[0044] (4) The RPS reaction chamber of step (3) is subjected to micro-arc oxidation treatment by a constant pressure method to form an oxide film surface layer on the oxide film bottom layer, wherein the oxide film bottom layer and the oxide film surface layer are tightly combined to form a ceramic oxide film.

[0045] The present embodiment creatively develops a micro-arc oxidation treatment method for surface treatment of the inner wall of the RPS reaction chamber. By insulating the non-machined surface of the RPS reaction chamber, installing an auxiliary cathode at the inner center of the RPS reaction chamber, and using an electrolyte specially designed for the RPS reaction chamber and a two-step method for micro-arc oxidation, in-situ ceramicization of complex surfaces and microporous inner walls in the RPS reaction chamber is achieved, so that a uniform and dense ceramic oxide film is formed on the inner wall and microporous inner wall of the RPS reaction chamber, which greatly enhances the corrosion resistance and breakdown voltage resistance of the inner cavity of the RPS reaction chamber, so that the RPS reaction chamber has excellent corrosion resistance after long-term use.

[0046] The ceramic oxide film obtained by the micro-arc oxidation treatment method of this embodiment has high wear resistance, corrosion resistance and excellent pressure resistance, and the ceramic oxide film is evenly distributed in the inner cavity and micropores of the RPS reaction chamber, and is also evenly distributed at the corners and chamfers, with stable product quality and excellent comprehensive performance. In addition, the ceramic oxide film has a dense structure without micro cracks, and no corrosion particles (Particles) that affect semiconductor etching defects are generated after long-term installation, which greatly improves the equipment performance of the remote plasma source.

[0047] It should be noted that according to the traditional micro-arc oxidation treatment method, usually only the outer surface of the workpiece can be micro-arc oxidized to form an oxide film on the outer surface of the workpiece. The structure of the RPS reaction chamber is special, requiring the inner cavity wall and the inner wall of the micropore of the RPS reaction chamber to be corrosion-resistant and able to resist the erosion of fluoride ions, and usually requiring the outer surface of the RPS reaction chamber to maintain good conductivity. Therefore, for the RPS reaction chamber, it is necessary to perform micro-arc oxidation treatment on the inner cavity wall and the inner wall of the micropore of the RPS reaction chamber to form an oxide film on the inner cavity wall and the inner wall of the micropore, and there is no need to perform micro-arc oxidation treatment on the outer surface of the RPS reaction chamber. However, if the traditional micro-arc oxidation treatment method is used, the inner cavity and micropores of the RPS reaction chamber are shielded by the electric field, and the electrolyte cannot flow in the cavity. Therefore, it is difficult to perform micro-arc oxidation treatment on the inner cavity wall and the inner wall of the micropore of the RPS reaction chamber according to the traditional micro-arc oxidation treatment method. In this embodiment, the non-machined surface of the RPS reaction chamber (i.e., the outer surface of the RPS reaction chamber) is insulated and protected, and an auxiliary cathode is designed in the center of the inner cavity of the RPS reaction chamber, thereby enhancing the inner cavity electric field of the RPS reaction chamber, and the electrolyte can flow smoothly in the cavity, ensuring that the inner cavity and micropores of the RPS reaction chamber are not affected by the electric field shielding, promoting the electrochemical growth process of the ceramic oxide film in the inner cavity wall of the RPS reaction chamber and the inner wall of the micropores, and ensuring that the density and thickness of the ceramic oxide film meet the requirements of the cavity, thereby ensuring that the inner cavity of the RPS reaction chamber has excellent corrosion resistance and anti-breakdown voltage capability.

[0048] Further explanation: By adopting the electrolyte formula designed in this embodiment and the two-step method for micro-arc oxidation treatment, a high-quality ceramic oxide film with complete structure, high density and uniform and controllable thickness can be obtained. If only the constant current method is used for micro-arc oxidation treatment, the long and thick oxide film is loose and porous, with poor density, which will lead to poor corrosion resistance and breakdown voltage resistance of the oxide film; if only the constant voltage method is used for micro-arc oxidation treatment, the obtained oxide film has poor adhesion, is easy to fall off, and is not thick, and it is difficult to obtain an oxide film of the required thickness.

[0049] Specifically, the constant current method refers to the use of a constant current for micro-arc oxidation treatment, and the constant voltage method refers to the use of a constant voltage for micro-arc oxidation treatment.

[0050] Preferably, the material of the RPS reaction chamber is metal, which has excellent electrical and thermal conductivity and is easy to process and manufacture RPS reaction chambers with complex shapes. Specifically, the material of the RPS reaction chamber can be a single metal material or an alloy material.

[0051] More preferably, the RPS reaction chamber is made of aluminum alloy.

[0052] In one embodiment, in the electrolyte, the concentration of sodium silicate is 2g / L to 15g / L, the concentration of sodium aluminate is 5g / L to 30g / L, the concentration of sodium oxalate is 2g / L to 20g / L, and the concentration of sodium hydroxide is 1g / L to 3g / L. The use of this electrolyte formula is conducive to achieving uniform growth of ceramic oxide films on complex surfaces and micropores in the cavity, and further improving the corrosion resistance and breakdown voltage resistance of the ceramic oxide film.

[0053] The concentration of sodium silicate is exemplarily 2g / L, 3g / L, 5g / L, 8g / L, 10g / L, 13g / L, 15g / L, but is not limited thereto; the concentration of sodium aluminate is exemplarily 5g / L, 8g / L, 10g / L, 12g / L, 15g / L, 18g / L, 20g / L, 25g / L, 28g / L, 30g / L, but is not limited thereto; the concentration of sodium oxalate is exemplarily 2g / L, 5g / L, 8g / L, 10g / L, 15g / L, 18g / L, 20g / L, but is not limited thereto; the concentration of sodium hydroxide is exemplarily 1g / L, 2g / L, 3g / L, but is not limited thereto.

[0054] In one embodiment, by installing an auxiliary cathode in the center of the inner cavity of the RPS reaction cavity and making the two sides of the auxiliary cathode protrude from the two ends of the RPS reaction cavity respectively, the internal electric field distribution of the RPS reaction cavity can be ensured to be uniform, thereby achieving inner cavity and micropore film formation.

[0055] The auxiliary cathode is made of stainless steel. The auxiliary cathode made of stainless steel is more conducive to uniform distribution of the inner cavity electric field of the RPS reaction cavity.

[0056] In one embodiment, the RPS reaction chamber is provided with a reaction chamber (i.e., an inner chamber of the RPS reaction chamber) and a micropore communicating with the reaction chamber;

[0057] The diameter of the micropores is 0.8 mm to 5 mm, and the depth is 30 mm to 50 mm.

[0058] The micro-arc oxidation treatment method of this embodiment can ensure that the electric field distribution of the reaction chamber is uniform and that the electrolyte flows smoothly in the reaction chamber, thereby achieving uniform ceramic treatment of the reaction chamber and the micropores, so that a uniform and dense ceramic oxide film is formed on the inner walls of the reaction chamber and the micropores, thereby greatly enhancing the corrosion resistance and voltage breakdown resistance of the inner wall.

[0059] The diameter of the micropores is exemplarily 0.8mm, 1mm, 1.2mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, but not limited thereto; the depth of the micropores is exemplarily 30mm, 35mm, 40mm, 45mm, 50mm, but not limited thereto.

[0060] In one embodiment, in step (3), the conditions for micro-arc oxidation treatment of the RPS reaction chamber of step (2) using a constant current method are as follows:

[0061] The forward current density is 1A / dm 2 ~5A / dm 2 , the forward duty cycle is 25% to 60%, the forward frequency is 50Hz to 500Hz; the forward current density is exemplarily 1A / dm 2 , 1.5A / dm 2 , 2A / dm 2 , 2.5A / dm 2 、3A / dm 2 、3.5A / dm 2 , 4A / dm 2 , 4.5A / dm 2 , 5A / dm 2 , but not limited thereto; the forward duty cycle is exemplarily 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, but not limited thereto; the forward frequency is exemplarily 50Hz, 100Hz, 200Hz, 300Hz, 400Hz, 500Hz, but not limited thereto;

[0062] Negative current density is 0~3A / dm 2 , the negative duty cycle is 30% to 70%, the negative frequency is 50Hz to 500Hz; the negative current density is 0, 1A / dm 2 , 1.5A / dm 2 , 2A / dm 2 , 2.5A / dm 2 、3A / dm 2, but not limited thereto; the negative duty cycle is exemplarily 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, but not limited thereto; the negative frequency is exemplarily 50Hz, 100Hz, 200Hz, 300Hz, 400Hz, 500Hz, but not limited thereto;

[0063] The temperature of the electrolyte is 20°C to 80°C, exemplarily 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, and 80°C, but not limited thereto; the processing time is 30min to 60min, exemplarily 30min, 35min, 40min, 45min, 50min, 55min, and 60min, but not limited thereto.

[0064] In one embodiment, in step (4), the conditions for micro-arc oxidation treatment of the RPS reaction chamber of step (3) using a constant pressure method are as follows:

[0065] The forward voltage is 450V to 550V, the forward duty cycle is 25% to 60%, and the forward frequency is 50Hz to 500Hz; the forward voltage is exemplarily 450V, 460V, 470V, 480V, 490V, 500V, 510V, 520V, 530V, 540V, 550V, but not limited thereto; the forward duty cycle is exemplarily 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, but not limited thereto; the forward frequency is exemplarily 50Hz, 100Hz, 200Hz, 300Hz, 400Hz, 500Hz, but not limited thereto;

[0066] The negative voltage is 60V to 150V, exemplarily 60V, 70V, 80V, 90V, 100V, 110V, 120V, 130V, 140V, 150V, but not limited thereto; the negative duty cycle is 30% to 70%, exemplarily 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, but not limited thereto; the negative frequency is 50Hz to 500Hz, exemplarily 50Hz, 100Hz, 200Hz, 300Hz, 400Hz, 500Hz, but not limited thereto;

[0067] The temperature of the electrolyte is 20-80°C, exemplarily 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, and 80°C, but not limited thereto; the processing time is 60min-300min, exemplarily 60min, 100min, 150min, 180min, 200min, 240min, and 300min, but not limited thereto.

[0068] By further limiting the process parameters of the micro-arc oxidation treatment in step (3) and step (4), it is beneficial to form a ceramic oxide film with a complete and dense structure, uniform and controllable thickness, and excellent wear resistance and corrosion resistance.

[0069] In one embodiment, an insulating clamp is used to insulate the non-machined surface of the RPS reaction chamber. An installation cavity for installing the RPS reaction chamber is provided inside the insulating clamp. The shape and size of the installation cavity are respectively adapted to the shape and size of the RPS reaction chamber, so that after the RPS reaction chamber is installed in the installation cavity, the non-machined surface of the RPS reaction chamber (i.e., the outer surface of the RPS reaction chamber) can fit tightly with the inner wall of the installation cavity, thereby insulating the non-machined surface of the RPS reaction chamber.

[0070] The auxiliary cathode is installed inside the installation cavity along the axial direction of the installation cavity, and the two sides of the auxiliary cathode are respectively connected to the two sides of the insulating clamp. The specially designed insulating clamp is used to clamp the RPS reaction cavity and protect the non-processed surface of the RPS reaction cavity, which can improve the production efficiency and quality control of the micro-arc oxidation processing of the product and promote the uniform growth of the ceramic oxide film on the inner wall of the RPS reaction cavity.

[0071] Accordingly, the present invention also discloses an insulating fixture, which is applied to the micro-arc oxidation treatment method of the inner cavity wall of the RPS complex surface, such as Figure 1 and Figure 2 As shown, the insulating clamp includes a clamp body 6, a cover plate 4, a conductive wire 1, an insulating sleeve 2, a sealing cover 3 and an auxiliary cathode 7;

[0072] The interior of the fixture body 6 is hollow, forming an installation cavity for installing the RPS reaction chamber 9, the cover plates 4 are respectively provided at both ends of the fixture body 6, the cover plates 4 are detachably connected to the fixture body 6, an electrolyte through hole for electrolyte to pass through is provided in the middle of the cover plate 4, the electrolyte through hole is communicated with the installation cavity, the auxiliary cathode 7 is installed in the center of the installation cavity, and the two sides of the auxiliary cathode 7 are respectively connected to the two cover plates 4, through the cooperation of the cover plate 4 and the fixture body 6, the RPS reaction chamber 9 can be installed in the installation cavity, so as to insulate and protect the outer surface (i.e., the non-processed surface) of the RPS reaction chamber 9, and allow the electrolyte to flow in the inner cavity of the RPS reaction chamber 9, so as to perform micro-arc oxidation on the inner cavity wall and the inner wall of the micropores of the RPS reaction chamber 9;

[0073] The insulating sleeve 2 is installed on the fixture body 6, and one end of the insulating sleeve 2 passes through the fixture body 6 and is flush with the inner wall of the installation cavity. The sealing cover 3 is sleeved on the outside of the insulating sleeve 2, and the outside of the sealing cover 3 is connected to the fixture body 6. The conductive wire 1 is installed inside the insulating sleeve 2, one side of the conductive wire 1 is used to be electrically connected to the RPS reaction chamber 9, and the other side of the conductive wire 1 is used to be electrically connected to the external positive electrode of the power supply. When performing micro-arc oxidation treatment, the RPS reaction chamber is electrically connected to the positive electrode of the power supply through the conductive wire 1, so that the RPS reaction chamber serves as an anode.

[0074] Using the traditional micro-arc oxidation treatment method, the inner cavity and micropores of the RPS reaction chamber 9 are shielded by the electric field, and the electrolyte cannot flow. The RPS reaction chamber 9 is subjected to micro-arc oxidation treatment using the insulating clamp designed in this embodiment. Due to the design of the auxiliary cathode 7, the micro-arc oxidation of the inner cavity and micropores of the RPS reaction chamber 9 is ensured not to be affected by the electric field shielding, thereby ensuring that the density and thickness of the ceramic oxide film meet the requirements. In addition, since the auxiliary cathode 7 is arranged at the center of the installation cavity, after the RPS reaction chamber 9 is installed, the auxiliary cathode 7 is located at the inner cavity center of the RPS reaction chamber 9, thereby ensuring that the electric field on the inner wall of the RPS reaction chamber 9 is uniformly distributed, thereby achieving film formation in the inner cavity and micropores, and thereby obtaining a ceramic oxide film with uniform thickness.

[0075] Preferably, the insulating clamp further comprises a fastener 5 , the fastener 5 is threadedly connected to the auxiliary cathode 7 , the cover plate 4 is connected to the fastener 5 , and the two sides of the auxiliary cathode 7 and the cover plate 4 are detachably connected via the fastener 5 .

[0076] More preferably, the cover plate 4 may be provided with a clamping portion (not shown in the figure) for clamping the RPS reaction chamber 9, so that the RPS reaction chamber 9 can be more firmly fixed in the installation cavity.

[0077] In one embodiment, the insulating clamp further includes a sealing gasket 8, and a mounting groove for mounting the sealing gasket 8 is provided on the side of the cover plate 4 facing the clamp body 6, and the mounting groove is located outside the electrolyte through hole, the sealing gasket 8 is installed in the mounting groove, and the sealing gasket 8 protrudes from the end face of the cover plate 4 on the side facing the clamp body 6, so that after the RPS reaction chamber 9 is installed in the mounting cavity, the sealing gasket 8 and the side of the RPS reaction chamber 9 are abutted against each other, ensuring that the insulating clamp is liquid-proof, preventing the electrolyte from penetrating into the gap between the outer surface of the RPS reaction chamber 9 and the inner wall of the clamp body 6, thereby preventing the electrolyte from corroding the outer surface of the RPS reaction chamber 9.

[0078] Specifically, the sealing gasket 8 can be a silicone gasket.

[0079] In one embodiment, the materials of the clamp body 6, the cover plate 4, the insulating sleeve 2 and the sealing cover 3 are respectively engineering plastics or ceramics to ensure that the insulating clamp has reliable strength, good electrical insulation, and long-term high temperature resistance and acid and alkali corrosion resistance, thereby extending the service life of the insulating clamp.

[0080] More preferably, the materials of the clamp body 6, the cover plate 4, the insulating sleeve 2 and the sealing cover 3 are all engineering plastics. Engineering plastics not only have excellent comprehensive properties, high rigidity, small creep, high mechanical strength, good heat resistance, good electrical insulation, and can be used for a long time in harsh chemical and physical environments, but also have better processability than ceramic materials, and it is easier to produce insulating clamps of the required shape.

[0081] The engineering plastic is preferably any one or more combinations of PVC (polyvinyl chloride), PP (polypropylene), PET (polyethylene terephthalate) and PEEK (polyetheretherketone), all of which have good mechanical strength, insulation, heat resistance and acid and alkali resistance.

[0082] The technical solution of the present invention is further described below by way of examples.

[0083] Example 1

[0084] The micro-arc oxidation treatment method for the RPS complex surface inner cavity wall of this embodiment includes the following steps:

[0085] (1) Install the aluminum alloy RPS reaction chamber on Figure 1 In the insulating fixture shown, the non-machined surface of the RPS reaction chamber is insulated and protected, and an auxiliary cathode is installed in the center of the inner cavity (i.e., the reaction chamber) of the RPS reaction chamber, and the auxiliary cathode is made of 304 stainless steel; the fixture body 6, the cover plate 4, the insulating sleeve 2 and the sealing cover 3 in the insulating fixture are all made of PET plastic;

[0086] (2) placing the insulating fixture equipped with the RPS reaction chamber in step (1) in an electrolyte as an anode; the raw material composition of the electrolyte is: 8 g / L sodium silicate, 10 g / L sodium aluminate, 10 g / L sodium oxalate and 1 g / L sodium hydroxide;

[0087] (3) The RPS reaction chamber of step (2) was subjected to micro-arc oxidation treatment by a constant current method, wherein the forward current density was 2.5 A / dm 2 , the forward duty cycle is 50%, the forward frequency is 300Hz; the negative current density is 1.5A / dm 2, the negative duty cycle is 30%, the negative frequency is 300Hz; the electrolyte temperature is 50℃, the processing time is 60 minutes, with the increase of applied voltage, micro arc sparks gradually appear on the workpiece surface, with the extension of oxidation time, the oxide film continues to thicken, and a uniform gray-white oxide film bottom layer is obtained, the thickness of the oxide film bottom layer is 7 microns;

[0088] (4) The RPS reaction chamber of step (3) was subjected to micro-arc oxidation treatment by constant voltage method, wherein the forward voltage was 550V, the forward duty cycle was 50%, and the forward frequency was 300Hz; the negative voltage was 130V, the negative duty cycle was 30%, and the negative frequency was 300Hz; the electrolyte temperature was 50°C, and the treatment time was 240 minutes. As the oxidation time increased, the oxide film continued to thicken, and a silver-white oxide film surface layer with uniform thickness was obtained. The oxide film bottom layer and the oxide film surface layer were closely combined to form a ceramic oxide film, the thickness of the ceramic oxide film was 55.2 microns, and the surface roughness Ra was 2.13μm; the ceramic oxide film on the inner cavity wall was polished by abrasive liquid flow, so that the surface roughness Ra after polishing was ≤1μm.

[0089] Example 2

[0090] The micro-arc oxidation treatment method for the RPS complex surface inner cavity wall of this embodiment includes the following steps:

[0091] (1) Install the aluminum alloy RPS reaction chamber on Figure 1 In the insulating fixture shown, the non-machined surface of the RPS reaction chamber is insulated and protected, and an auxiliary cathode is installed in the center of the inner cavity (i.e., the reaction chamber) of the RPS reaction chamber, and the auxiliary cathode is made of 304 stainless steel; the fixture body 6, the cover plate 4, the insulating sleeve 2 and the sealing cover 3 in the insulating fixture are all made of PET plastic;

[0092] (2) placing the insulating fixture equipped with the RPS reaction chamber in step (1) in an electrolyte as an anode; the raw material composition of the electrolyte is: 15 g / L sodium silicate, 8 / L sodium aluminate, 8 g / L sodium oxalate and 2 g / L sodium hydroxide;

[0093] (3) The RPS reaction chamber of step (2) was subjected to micro-arc oxidation treatment by a constant current method, wherein the forward current density was 2.5 A / dm 2 , the forward duty cycle is 50%, the forward frequency is 300Hz; the negative current density is 0; the electrolyte temperature is 30℃, and the processing time is 60 minutes. As the applied voltage increases, micro arc sparks gradually appear on the workpiece surface. As the oxidation time increases, the oxide film continues to thicken, and a uniform gray-white oxide film bottom layer is obtained. The thickness of the oxide film bottom layer is 8 microns.

[0094] (4) The RPS reaction chamber of step (3) was subjected to micro-arc oxidation treatment by constant voltage method, wherein the forward voltage was 480V, the forward duty cycle was 50%, and the forward frequency was 300Hz; the negative voltage was 80V, the negative duty cycle was 30%, and the negative frequency was 300Hz; the electrolyte temperature was 30°C, and the treatment time was 240 minutes. As the oxidation time increased, the oxide film continued to thicken, and a silver-white oxide film surface layer with uniform thickness was obtained. The oxide film bottom layer and the oxide film surface layer were closely combined to form a ceramic oxide film, the thickness of the ceramic oxide film was 35.1 microns, and the surface roughness Ra was 2.02μm; the ceramic oxide film on the inner cavity wall was polished by abrasive liquid flow, so that the surface roughness Ra after polishing was ≤1μm.

[0095] Example 3

[0096] The micro-arc oxidation treatment method for the RPS complex surface inner cavity wall of this embodiment includes the following steps:

[0097] (1) Install the aluminum alloy RPS reaction chamber on Figure 1 In the insulating fixture shown, the non-machined surface of the RPS reaction chamber is insulated and protected, and an auxiliary cathode is installed in the center of the inner cavity (i.e., the reaction chamber) of the RPS reaction chamber, and the auxiliary cathode is made of 304 stainless steel; the fixture body 6, the cover plate 4, the insulating sleeve 2 and the sealing cover 3 in the insulating fixture are all made of PET plastic;

[0098] (2) placing the insulating fixture equipped with the RPS reaction chamber in step (1) in an electrolyte as an anode; the raw material composition of the electrolyte is: 15 g / L sodium silicate, 10 g / L sodium aluminate, 10 g / L sodium oxalate and 3 g / L sodium hydroxide;

[0099] (3) The RPS reaction chamber of step (2) was subjected to micro-arc oxidation treatment by a constant current method, wherein the forward current density was 1.5 A / dm 2 , the positive duty cycle is 30%, the positive frequency is 300Hz; the negative current density is 1, the negative duty cycle is 50%, the negative frequency is 500Hz; the electrolyte temperature is 50℃, the processing time is 60 minutes, with the increase of applied voltage, micro arc sparks are gradually generated on the surface of the workpiece, with the extension of oxidation time, the oxide film is continuously thickened, and a uniform gray-white oxide film bottom layer is obtained, and the thickness of the oxide film bottom layer is 8 microns;

[0100] (4) The RPS reaction chamber of step (3) was subjected to micro-arc oxidation treatment by constant voltage method, wherein the forward voltage was 500 V, the forward duty cycle was 30%, and the forward frequency was 300 Hz; the negative voltage was 90 V, the negative duty cycle was 50%, and the negative frequency was 500 Hz; the electrolyte temperature was 50° C., and the treatment time was 180 minutes. As the oxidation time increased, the oxide film continued to thicken, and a silver-white oxide film surface layer with uniform thickness was obtained. The oxide film bottom layer and the oxide film surface layer were closely combined to form a ceramic oxide film, and the thickness of the ceramic oxide film was 38.2 microns, and the surface roughness Ra was 1.96 μm; the ceramic oxide film on the inner cavity wall was polished by abrasive liquid flow, so that the surface roughness Ra after polishing was ≤1 μm.

[0101] Example 4

[0102] The micro-arc oxidation treatment method for the RPS complex surface inner cavity wall of this embodiment includes the following steps:

[0103] (1) Install the aluminum alloy RPS reaction chamber on Figure 1 In the insulating fixture shown, the non-machined surface of the RPS reaction chamber is insulated and protected, and an auxiliary cathode is installed in the center of the inner cavity (i.e., the reaction chamber) of the RPS reaction chamber, and the auxiliary cathode is made of 304 stainless steel; the fixture body 6, the cover plate 4, the insulating sleeve 2 and the sealing cover 3 in the insulating fixture are all made of PET plastic;

[0104] (2) placing the insulating fixture equipped with the RPS reaction chamber in step (1) in an electrolyte as an anode; the raw material composition of the electrolyte is: 5 g / L sodium silicate, 5 / L sodium aluminate, 8 g / L sodium oxalate and 2 g / L sodium hydroxide;

[0105] (3) The RPS reaction chamber of step (2) is subjected to micro-arc oxidation treatment by a constant current method, wherein the forward current density is 2 A / dm 2 , the forward duty cycle is 50%, the forward frequency is 300Hz; the negative current density is 0; the electrolyte temperature is 20℃, and the processing time is 60 minutes. As the applied voltage increases, micro arc sparks gradually appear on the workpiece surface. As the oxidation time increases, the oxide film continues to thicken, and a uniform gray-white oxide film bottom layer is obtained. The thickness of the oxide film bottom layer is 7 microns.

[0106] (4) The RPS reaction chamber of step (3) was subjected to micro-arc oxidation treatment by constant voltage method, wherein the forward voltage was 500 V, the forward duty cycle was 50%, and the forward frequency was 300 Hz; the negative voltage was 100 V, the negative duty cycle was 30%, and the negative frequency was 300 Hz; the electrolyte temperature was 20° C., and the treatment time was 240 minutes. As the oxidation time increased, the oxide film continued to thicken, and a silver-white oxide film surface layer with uniform thickness was obtained. The oxide film bottom layer and the oxide film surface layer were closely combined to form a ceramic oxide film, and the thickness of the ceramic oxide film was 43.3 microns, and the surface roughness Ra was 2.11 μm; the ceramic oxide film on the inner cavity wall was polished by abrasive liquid flow, so that the surface roughness Ra after polishing was ≤1 μm.

[0107] Specifically, the ceramic oxide film obtained in the above embodiment was tested for performance using an eddy current thickness gauge, a scanning electron microscope, a surface roughness tester, a nanoindentation test, an acid salt spray test, an insulation resistance tester, etc., and the performance was compared with that of a traditional anodized film. The analysis results are shown in Table 1.

[0108] Table 1 Analysis results

[0109]

[0110]

[0111] From the above analysis results, it can be seen that Examples 1 to 4 can not only form a ceramic oxide film on the inner wall of the reaction chamber of the RPS reaction chamber, but also form a ceramic oxide film on the inner wall of the micropores of the RPS reaction chamber, while the conventional anodizing method can only form an oxide film in the inner cavity, and cannot form an oxide film in the micropores. In addition, the Vickers hardness of the ceramic oxide film obtained in Examples 1 to 4 is 1403.1 to 1723.7 HV, while the Vickers hardness of the conventional anodized film is 505.8 HV. It can be seen that the Vickers hardness of the ceramic oxide film obtained in Examples 1-4 is about 3 times the Vickers hardness of the conventional anodized film. It can be seen that the micro-arc oxidation treatment method of this embodiment can significantly improve the wear resistance of the inner wall of the RPS reaction chamber. It can be seen from the results of the acid salt spray test that the acid salt spray resistance time of the traditional anodized film is less than 96 hours, that is, it did not pass the 96h acid salt spray test, while the acid salt spray resistance time of the ceramic oxide film obtained in Examples 1 to 4 is ≥240h, that is, the ceramic oxide films obtained in Examples 1 to 4 can all pass the 240h acid salt spray test. It can be seen that the micro-arc oxidation treatment method of Examples 1 to 4 can significantly improve the corrosion resistance of the inner cavity wall of the RPS reaction chamber, and can ensure that the RPS reaction chamber will not generate corrosion particles that affect semiconductor etching defects after long-term installation and use. From the insulation resistance test results, it can be seen that the 500V breakdown resistance of the traditional anodized film is 0, while the 500V breakdown resistance of the ceramic oxide film obtained in Examples 1 to 4 is 0.9~2.2GΩ. It can be seen that the micro-arc oxidation treatment method of Examples 1 to 4 greatly enhances the voltage breakdown resistance of the inner cavity wall of the RPS reaction chamber.

[0112] In addition, the ceramic oxide film at the micropores and corners in the RPS reaction chamber after treatment in Example 1 was characterized and analyzed, and the results were as follows: Figure 3 and Figure 4 Scanning electron microscope image of .

[0113] from Figure 3 It can be seen that the diameter of the micropores in the RPS reaction chamber is 1.5 mm and the depth is 40 mm. By analyzing the pictures, it can be seen that Example 1 forms a uniform and dense ceramic oxide film on the inner wall of the micropores, and the thickness of the ceramic oxide film is basically 47.7 μm. Figure 4 It can be seen that a dense and uniform ceramic oxide film can also be formed at the corners of the RPS reaction chamber. It can be seen that in this embodiment, the ceramic oxide film is evenly distributed in the reaction chamber and micropores of the RPS reaction chamber, and the ceramic oxide film at the corners and chamfers is also evenly distributed, which shows that the product quality is stable and the overall performance is excellent.

[0114] The above disclosure is only a preferred embodiment of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. A micro-arc oxidation treatment method for the inner wall of a complex RPS surface, characterized in that: The steps include: (1) Insulate and protect the non-machined surface of the RPS reaction chamber, and install an auxiliary cathode in the center of the inner cavity of the RPS reaction chamber; (2) placing the RPS reaction chamber of step (1) in an electrolyte as an anode; the raw materials of the electrolyte include sodium silicate, sodium aluminate, sodium oxalate and sodium hydroxide; (3) performing micro-arc oxidation treatment on the RPS reaction chamber of step (2) by a constant current method, so that an oxide film bottom layer is formed on the inner wall of the RPS reaction chamber; (4) The RPS reaction chamber of step (3) is subjected to micro-arc oxidation treatment by a constant pressure method to form an oxide film surface layer on the oxide film bottom layer, wherein the oxide film bottom layer and the oxide film surface layer are tightly combined to form a ceramic oxide film.

2. The micro-arc oxidation treatment method for the RPS complex surface inner cavity wall according to claim 1, characterized in that: In the electrolyte, the concentration of sodium silicate is 2g / L to 15g / L, the concentration of sodium aluminate is 5g / L to 30g / L, the concentration of sodium oxalate is 2g / L to 20g / L, and the concentration of sodium hydroxide is 1g / L to 3g / L.

3. The micro-arc oxidation treatment method for the RPS complex surface inner cavity wall according to claim 1, characterized in that: Both sides of the auxiliary cathode protrude from the two ends of the RPS reaction chamber respectively; The auxiliary cathode is made of stainless steel.

4. The micro-arc oxidation treatment method for the RPS complex surface inner cavity wall according to claim 3, characterized in that: The RPS reaction chamber body is provided with a reaction chamber and a microhole communicating with the reaction chamber; The diameter of the micropores is 0.8 mm to 5 mm, and the depth is 30 mm to 50 mm.

5. The micro-arc oxidation treatment method for the RPS complex surface inner cavity wall according to claim 1, characterized in that: In step (3), the conditions for micro-arc oxidation treatment of the RPS reaction chamber in step (2) by constant current method are as follows: The forward current density is 1A / dm 2 ~5A / dm 2 , the forward duty cycle is 25% to 60%, and the forward frequency is 50Hz to 500Hz; Negative current density is 0~3A / dm 2 , the negative duty cycle is 30% to 70%, and the negative frequency is 50Hz to 500Hz; The temperature of the electrolyte is 20°C to 80°C, and the processing time is 30min to 60min.

6. The micro-arc oxidation treatment method for the RPS complex surface inner cavity wall according to claim 1, characterized in that: In step (4), the conditions for micro-arc oxidation treatment of the RPS reaction chamber in step (3) by constant pressure method are as follows: The forward voltage is 450V~550V, the forward duty cycle is 25%~60%, and the forward frequency is 50Hz~500Hz; The negative voltage is 60V~150V, the negative duty cycle is 30%~70%, and the negative frequency is 50Hz~500Hz. The temperature of the electrolyte is 20-80°C, and the treatment time is 60-300 minutes.

7. The micro-arc oxidation treatment method for the RPS complex surface inner cavity wall according to claim 1, characterized in that: An insulating fixture is used to insulate the non-machined surface of the RPS reaction chamber, and an installation cavity for installing the RPS reaction chamber is provided inside the insulating fixture, and the shape and size of the installation cavity are respectively adapted to the shape and size of the RPS reaction chamber; The auxiliary cathode is installed inside the installation cavity along the axial direction of the installation cavity, and two sides of the auxiliary cathode are respectively connected to two sides of the insulating clamp.

8. An insulating clamp, characterized in that: A micro-arc oxidation treatment method for the RPS complex-shaped inner cavity wall as described in any one of claims 1 to 7, comprising a fixture body, a cover plate, a conductive wire, an insulating sleeve, a sealing cover and an auxiliary cathode; The interior of the fixture body is hollow, forming an installation cavity for installing the RPS reaction chamber, the cover plates are respectively provided at both ends of the fixture body, the cover plates are detachably connected to the fixture body, an electrolyte through hole for electrolyte to pass through is provided in the middle of the cover plate, the electrolyte through hole is connected to the installation cavity, the auxiliary cathode is installed in the center of the installation cavity, and the two sides of the auxiliary cathode are respectively connected to the two cover plates; The insulating sleeve is installed on the fixture body, and one end of the insulating sleeve passes through the fixture body and is flush with the inner wall of the installation cavity. The sealing cover is sleeved on the outside of the insulating sleeve, and the outside of the sealing cover is connected to the fixture body. The conductive wire is installed on the inside of the insulating sleeve, one side of the conductive wire is used to be electrically connected to the RPS reaction chamber, and the other side of the conductive wire is used to be electrically connected to the positive electrode of an external power supply.

9. The insulating clamp according to claim 8, characterized in that: The insulating clamp also includes a sealing gasket. A mounting groove for mounting the sealing gasket is provided on the side of the cover plate facing the clamp body. The sealing gasket is mounted in the mounting groove, and the sealing gasket protrudes from the end surface of the cover plate on the side facing the clamp body.

10. The insulating clamp according to claim 8, characterized in that: The materials of the fixture body, the cover plate, the insulating sleeve and the sealing cover are engineering plastics or ceramics respectively.

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