Method for preparing high-density yttrium oxide coating for semiconductor etching equipment by using suspension plasma spraying technology

Abstract

The invention belongs to the field of suspension plasma spraying (SPS), and discloses a method for preparing a high-density yttrium oxide coating for semiconductor etching equipment by using a suspension plasma spraying technology, which comprises the following steps of: injecting self-made low-micron yttrium oxide suspension into plasma flame flow generated by spraying equipment by using the suspension plasma spraying technology; and spraying to the surface of the inner cavity of the part of the etching equipment subjected to surface roughening to form a high-density yttrium oxide corrosion-resistant coating. According to the invention, the problems of limitation of solid powder feeding, such as low fluidity and easy caking of nano-particles, and low fluidity caused by strong interaction among low-momentum powder particles in the spraying process, are effectively overcome. And finer powder, higher spray gun power and higher plasma flame flow speed are used, more high-quality flat particles are formed, fewer gaps are generated during layer-to-layer stacking, the porosity and hardness index of the coating are effectively improved, the corrosion resistance of parts is improved, and the service life is prolonged.

Description

Technical Field

[0001] The invention belongs to the field of suspension plasma spraying (SPS), and in particular relates to a method for preparing a high-density yttrium trioxide coating for semiconductor etching equipment by using a suspension plasma spraying technology. Background Art

[0002] Semiconductor etching process is an extremely important part of integrated circuit manufacturing. Its main function is to transfer the photolithography pattern obtained by photolithography to the thin film on the surface of the wafer, and remove the material not protected by the photoresist by physical or chemical means. Due to the various chlorine-based and fluorine-based process gases used in etching, it is inevitable to corrode the inner wall of the aluminum etching equipment cavity while removing the wafer material. Therefore, most of the etching equipment parts are sprayed with dense ceramic coatings such as Y2O3 and AL2O3 to delay the corrosion of the parts by etching gas and plasma containing free radicals and free electrons, thereby improving the service life of the parts.

[0003] The current mainstream spraying process is the atmospheric plasma spraying (APS) process. However, with the continuous development of process technology, in processes below 14nm, the coatings prepared using APS are gradually unable to meet the use requirements of the equipment due to reasons such as high porosity, insufficient hardness, and poor voltage resistance. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a method for preparing a high-density yttrium trioxide coating for semiconductor etching equipment using suspended plasma spraying technology. The suspended plasma spraying (SPS) technology used in the present invention uses a suspension with low viscosity and low surface tension formed by fine oxide particles dispersed in a specific solvent as the spraying raw material, and injects it into the plasma flame flow using a specific feeding system. After the suspension and plasma undergo complex interactions, they fly and collide with the substrate surface to form a coating. Compared with traditional APS technology, it effectively overcomes the limitations of solid powder feeding, such as low fluidity of nanoparticles, easy agglomeration, and low fluidity due to interaction between low momentum powder particles during spraying, and can obtain a corrosion-resistant coating with performance far superior to APS.

[0005] The above object of the present invention is achieved through the following technical solutions:

[0006] A method for preparing a high-density yttrium trioxide coating for semiconductor etching equipment using suspended plasma spraying technology, wherein a self-made low-micron yttrium trioxide suspension is injected into a plasma flame flow generated by a spraying device using the suspended plasma spraying technology, and then sprayed onto the inner cavity surface of the etching equipment parts with roughened surface, thereby forming a high-density yttrium trioxide corrosion-resistant coating.

[0007] Furthermore, the self-made low-micron yttrium trioxide suspension is prepared by mixing yttrium trioxide powder (purity>99.9%) with a particle size of 3 μm with ultrapure water with a conductivity greater than 18.2 MΩ, and then fully stirring to form a suspension with a mass fraction of yttrium trioxide of 35%.

[0008] Furthermore, if the plasma spraying equipment used is a 100HE plasma spraying equipment produced by progressive Surface, the spraying process parameters used are: argon flow rate 140-50SLPM; nitrogen flow rate 66-70SLPM; hydrogen flow rate 60-65SLPM; spray gun power 100-102KW; spray gun moving speed 6-30mm / s; turntable speed 100-150RPM; spraying distance 75-76mm; yttrium oxide suspension injection flow rate 36-38mL / min; cooling gas pressure 2-3Bar.

[0009] Furthermore, the inner cavity surface of the etching equipment parts needs to be roughened before spraying, and the surface roughening sand material is used to roughen the surface using a gravity sandblasting machine at a pressure of 0.5 MPa. The surface roughness after roughening is Ra3.5-4 μm.

[0010] Furthermore, the surface roughening sand material includes quartz sand, white corundum, glass sand, silicon carbide, resin sand and the like.

[0011] The above parameters are the optimal solutions based on multiple comparative experiments. Changing one of the parameters may affect the overall performance by 5-15%.

[0012] The corrosion-resistant coating sprayed by the above method has a thickness of 80-120 μm, a surface roughness of 2-2.5 μm, a porosity of <1%, a withstand voltage of >6KV, and a Vickers hardness of HV0.2=470-490.

[0013] The beneficial effects of the present invention compared with the prior art are:

[0014] (1) It effectively overcomes the limitations of solid powder feeding, such as low fluidity of nanoparticles, easy agglomeration, and strong interaction between low momentum powder particles during spraying, resulting in low fluidity.

[0015] (2) Use finer powder, higher spray gun power, and faster plasma flame flow speed to form more high-quality flat particles, and produce fewer gaps when stacking layers, which effectively improves the porosity and hardness index of the coating, improves the corrosion resistance of parts, and increases service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1The figure is a powder image of yttrium trioxide with a particle size of 3 μm, i.e., the morphology of SPS suspension under a scanning electron microscope;

[0017] Figure 2 is the morphology of APS powder;

[0018] Figure 3 The cross-sectional morphology and porosity (0.98%) of the coating;

[0019] Figure 4 This is the microhardness test diagram of the coating cross section;

[0020] Figure 5 This is the surface morphology of the etching equipment parts after spraying;

[0021] Figure 6 This is a 1000x morphology image of the APS cross section;

[0022] Figure 7 This is a 1000x morphology image of the SPS cross section. DETAILED DESCRIPTION

[0023] The present invention is described in detail below by specific examples, but the protection scope of the present invention is not limited. Unless otherwise specified, the experimental methods used in the present invention are all conventional methods, and the experimental equipment, materials, reagents, etc. used can be obtained from commercial channels.

[0024] Example 1

[0025] The present invention relates to a method for preparing a high-density yttrium oxide coating for semiconductor etching equipment using a suspended plasma spraying technology, and its specific implementation method is described as follows:

[0026] (1) The inner surface of the etching equipment parts to be sprayed is roughened by using WA#80 white corundum sand and a gravity sandblasting machine at a pressure of 0.5 MPa to roughen the surface. The surface roughness after roughening is Ra3.5-4 μm.

[0027] (2) The roughened etching equipment parts are cleaned with a high-pressure water jet at 1000 psi to remove the sand and other impurities remaining on the surface. After being purged with compressed air, they are placed in an atmospheric oven and baked at 100°C for 1 hour to completely dry the surface. After cooling to room temperature, they are taken out and transferred to the spray room.

[0028] (3) Clean the spray room environment, install the fixture on the turntable bracket, and fix the etching equipment parts to be sprayed.

[0029] (4) 1 kg of yttrium trioxide powder (purity>99.9%) with a particle size of 3 μm was mixed with 1.86 L of ultrapure water (>18.2 MΩ), placed on a rotating device and rotated at 60 RPM for more than 4 hours before pouring into the feeding mechanism.

[0030] (5) Turn on the 100HE spray equipment and set the parameters as follows: argon flow rate 150SLPM; nitrogen flow rate 70SLPM; hydrogen flow rate 65SLPM; spray gun power 102KW; spray gun moving speed 20mm / s; turntable speed 100RPM; spray distance 75mm; yttrium trioxide suspension injection flow rate 38ml / min; cooling gas pressure 2Bar.

[0031] (6) The corrosion-resistant coating prepared by the above steps has a relatively smooth surface, a dense cross-sectional structure, no vertical crack structure, a porosity of <1%, a withstand voltage of >6KV, and a Vickers hardness of HV0.2 = 470-490, which can meet the requirements of high-process (below 14nm) technology.

[0032] Figure 1 This is the morphology of the SPS suspension under a scanning electron microscope. It can be seen that most of the particles are round spheres with a good particle size distribution. The round powder helps to form regular flat particles when it hits the substrate surface at high speed during the spraying process, which helps to form a denser coating with fewer pores. Figure 2 This is the morphology of APS powder. Since it is crushed rather than spheroidized, it has many irregular edges and corners.

[0033] like Figure 3 As shown, the cross-sectional morphology of the coating is mainly obtained by cutting the sprayed test block or product, grinding and polishing the cut section, using the cold mounting process to make a mosaic block, and observing it under a high-magnification microscope or scanning electron microscope at a magnification of 500-1000. The figure reflects the number of pores inside the coating, whether there are transverse / vertical cracks, etc. It is one of the detection methods for judging the performance of the coating. It can be seen that at the same magnification, the pores inside the APS coating are larger, and there are microcracks in some areas. The overall pores of the SPS are smaller and there are no obvious cracks. The large number of pores will cause some fluorine-containing process gases to enter or even penetrate the coating faster during the operation of the equipment in the semiconductor manufacturer, and begin to corrode the substrate and cause adverse reactions.

[0034] After testing, the performance indicators of the coating prepared by the present invention are shown in the following table:

[0035]

[0036] The above-described embodiments are only preferred embodiments of the present invention, but not all feasible embodiments of the present invention. For those skilled in the art, any obvious changes made thereto without departing from the principles and spirit of the present invention should be considered to be included in the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a high-density yttrium oxide coating for semiconductor etching equipment using suspended plasma spraying technology, characterized in that: The suspended plasma spraying process is used to inject a low-micron yttrium trioxide suspension into the plasma flame generated by the spraying equipment, and then sprayed onto the inner cavity surface of the etching equipment parts that have been roughened to form a highly dense yttrium trioxide corrosion-resistant coating.

2. The method for preparing a high-density yttrium oxide coating for semiconductor etching equipment using suspended plasma spraying technology according to claim 1, characterized in that: The low-micron yttrium trioxide suspension is a suspension with a mass fraction of yttrium trioxide of 35% formed by mixing yttrium trioxide powder with ultrapure water.

3. The method for preparing a high-density yttrium oxide coating for semiconductor etching equipment using suspended plasma spraying technology according to claim 2, characterized in that: The particle size of the yttrium oxide powder is 3 μm.

4. The method for preparing a high-density yttrium oxide coating for semiconductor etching equipment using suspended plasma spraying technology according to claim 1, characterized in that: The parameters of the suspended plasma spraying process are: argon flow rate 140-50SLPM; nitrogen flow rate 66-70SLPM; hydrogen flow rate 60-65SLPM.

5. The method for preparing a high-density yttrium oxide coating for semiconductor etching equipment using suspended plasma spraying technology according to claim 1, characterized in that: The parameters of the suspended plasma spraying process are: spray gun power 100-102KW; spray gun moving speed 6-30mm / s; turntable speed 100-150RPM; spraying distance 75-76mm.

6. The method for preparing a high-density yttrium oxide coating for semiconductor etching equipment using suspended plasma spraying technology according to claim 1, characterized in that: The parameters of the suspended plasma spraying process are: yttrium oxide suspension injection flow rate 36-38 mL / min; cooling gas pressure 2-3 Bar.

7. The method for preparing a high-density yttrium oxide coating for semiconductor etching equipment using suspended plasma spraying technology according to claim 1, characterized in that: The high-density yttrium oxide coating has a thickness of 80-120 μm, a surface roughness of 2-2.5 μm, and a porosity of <1%.

8. An application of using suspended plasma spraying technology to prepare a high-density yttrium trioxide coating for semiconductor etching equipment, characterized in that: Used for spraying on the inner surface of etching equipment parts, and surface roughening treatment is performed before spraying.

9. The use of the suspended plasma spraying technology to prepare a high-density yttrium oxide coating for semiconductor etching equipment according to claim 8, characterized in that: The surface is roughened using surface roughening sand material, and the surface roughness after roughening is Ra3.5-4μm.

10. The use of the suspended plasma spraying technology to prepare a high-density yttrium oxide coating for semiconductor etching equipment according to claim 9, characterized in that: Surface roughening sand materials include quartz sand, white corundum, glass sand, silicon carbide and resin sand.

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