KR20060031135A - Coating film for vacuum plasma chamber and its manufacturing method - Google Patents

Abstract

The present invention is based on the vacuum plasma chamber or a component mounted therein, the base material is immersed in the electrolyte, and a high voltage direct current is applied to the base material to form a micro arc or plasma on the surface of the base material while continuously forming an oxide coating film. It provides a coating film manufacturing method and a coating film according to the vacuum plasma chamber characterized in that it is formed. According to the present invention, compared with the conventional anodizing surface coating, the hardness is improved by 2-3 times or more, the internal pores are reduced, and the coating film can be formed with improved durability.

Micro discharge, anodizing, plasma chamber

Description

Coating film for vacuum plasma chamber and its manufacturing method {COATING LAYER FOR VACUUM PLASMA CHAMBER AND FABRICATION METHOD THEREOF}

1 is a vertical cross-sectional view of a chamber and an interior of a plasma etching equipment, which is one of semiconductor / LCD manufacturing equipment.

2A and 2B are photographs observing internal pores of the oxide film formed by anodizing.

3 is a cross-sectional photograph of a high density oxide coating film formed by the micro discharge oxide film method according to the present invention.

The present invention relates to a coating film for a vacuum plasma chamber and a method of manufacturing the same.

Vacuum plasma chambers are used in the field of processing for semiconductor / LCD manufacturing or other ultrafine shapes. For example, plasma enhanced chemical vapor deposition (PECVD) equipment for forming a deposited film by a chemical vapor deposition method on a substrate, sputtering equipment for forming a deposited film by a physical method, and etching a substrate or a coated material on the substrate in a desired pattern. Such as a vacuum plasma chamber for dry etching equipment.

In the plasma vacuum chamber, high temperature plasma is generated to shorten the lifespan of the chamber and its internal components, as well as to generate specific elements and contaminating particles from the surface of the chamber and its components, which is likely to contaminate the chamber. In particular, since the plasma etching equipment injects reactive gases including F and Cl into the plasma atmosphere, the chamber inner wall and its internal parts are placed in a very corrosive environment. This corrosion causes serious problems such as shortening the life of the chamber and its internal parts, degrading the product quality by increasing the defective rate of the final product due to the generation of contaminants and particles, and increasing the production cost due to the interruption of operation for parts replacement / cleaning. do.

The corrosion problem of the plasma vacuum chamber will be described in detail using the plasma dry etching apparatus illustrated in FIG. 1 as an example.

Plasma dry etching equipment is used to etch a specific location of a substrate such as a semiconductor wafer or glass for LCD or a thin film formed for the substrate to implement a desired circuit or shape on the substrate.

Looking at the components and the operating principle of the equipment as follows. The etching gas is introduced into the chamber through the hole 14 installed in the gas distribution plate 13. RF current is applied to the upper electrode 2 and the lower electrode 9 to generate a plasma to increase the reactivity of the introduced etching gas, and then collide with the substrate 15 placed on the substrate support 8 to thereby A portion of the coated membrane is etched. Examples of the etching gas include C4F ₈ , C ₅ H ₈ , CH ₂ F ₂ , CF, CF ₂ , CF ₃ , CF ₄ , SF ₆ , NF ₃ , F ₂ , CH ₂ F ₂ , CHF ₃ , C ₂ F Gas containing F such as ₆ and gas containing Cl such as Cl ₂ , BCl ₃ , SiCl ₄ , HCl, gas containing Br such as HBr, Br ₂ , CF ₃ Br and other SiN ₄ , O ₂ , Ar, H _The gas etc. which mixed one or more of these, etc. are mentioned.

The upper electrode 2 may take the form of a flat plate or a coil and may be installed on the upper surface of the insulating window 3, but may be installed inside the vacuum chamber. The gas distribution plate 13 may be integrally formed with a gas nozzle, a gas ring, or the like, or may be added as a heterogeneous body to evenly distribute the etching gas into the chamber. In some cases, the gas dispersion plate 13 may be provided in the substrate support 8. .

In addition, the chamber wall 1 may be provided with a liner 11 such as a cylindrical or conical inclined at an angle to prevent the chamber wall 1 from being directly exposed to the etching gas and the plasma atmosphere. In addition, the liner 11 may be manufactured in two separate parts to protect the upper chamber and the lower chamber, respectively. In order to maintain the surface temperature of the liner at a temperature above room temperature (preferably between room temperature and 300 ° C.), a liner heating device 12 is provided to heat the liner 11 to attach contaminants generated during etching to the liner. Instead, it can be removed in a gaseous state with a vacuum pump through a connection porter 7 at the bottom of the chamber or through a passage (not shown) provided separately under the chamber. In the chamber, a separate inner supporter 5 and an outer supporter 6 may be installed to fix the liner 11.

The plasma screen 10 may be provided to prevent the plasma from flowing out through the empty space between the liner 11 and the substrate support 8. The screen 10 may be provided with a plurality of holes so that the etching gas and the etching reactant can move toward the vacuum pump.

A substrate transfer passage (not shown) for transferring the substrate 15, which is an object to be etched, such as a semiconductor wafer and a glass substrate for LCD into the chamber is provided in the chamber wall 1, the inner and outer supports 5, 6, and the liner 11. Installed through one or more side surfaces, it is possible to reduce the time required to insert and remove the substrate 15.

The substrate 15 is fixed to the substrate support by the fixing chuck 16. Recently, the fixing chuck using an electrostatic force is widely used. The focus ring 17 surrounding the substrate 15 serves to uniformly irradiate the plasma generated inside the chamber over the entire substrate 15.

The above description of the operation principle of the plasma etching apparatus and the components thereof is merely an example, and it is well known that the structure of the equipment and its components may be variously modified, and the types thereof are not limited to the above components. to be. For example, although not shown in FIG. 1, components included in a vacuum plasma chamber include a substrate transfer module, a lift system, a load lock, a door system, a robot arm, and a fastener.

The chamber of the etching equipment and its internal components are subjected to chemical / physical damage by the extreme atmosphere inside the chamber during the semiconductor / LCD manufacturing process. Just as the physico-chemical impact on the part or the front surface of the substrate is damaged by the etch process and then the damaged part is removed, the chamber inner wall and the internal parts are also damaged by the same process. That is, the chamber and the internal parts are subjected to chemical attack by the reaction gas activated by the plasma. At the same time, ionized gas particles are accelerated by RF electromagnetic fields and damaged by physical attacks that bomb the surface of the part.

As such, when the chamber and the internal parts are damaged by the above process, some of the etching equipment must be replaced or cleaned / repaired first, so additional costs are required, and additionally, the process line must be stopped for replacement or cleaning / repair. The processing time of the product is increased. In addition, when the contaminants generated on the damaged chamber and the surface of the internal parts contaminate the wafer or the LCD glass substrate to be etched, the defect rate of the semiconductor and the LCD increases.

A typical method for preventing corrosion of a conventional plasma vacuum chamber and its internal components will be described below.

The plasma vacuum chamber and the internal components are selected in consideration of many characteristics such as corrosion resistance, processability, fabrication ease, price, and insulation, and generally, stainless steel or aluminum alloy is used as the chamber material. Although the chamber is preferably manufactured integrally by casting or the like, the chamber may be fabricated integrally, but may be assembled after being processed into several parts in consideration of productivity and manufacturing cost. Since metal, which is a chamber material, is generally low in corrosion resistance, in order to provide durability against plasma and chemical gases, an alumina (Al ₂ O ₃ ) coating film may be formed on the surface of the metal material by anodizing. .

Anodizing, also called anodization, is a method of immersing a coating object in an electrolyte and oxidizing the surface by applying an anode current to the object. This method has been widely adopted since it is possible to form an Al ₂ O ₃ coated film having high hardness and good corrosion resistance at low cost. Parts such as gas distribution plates (including gas rings), liners, substrate supports, screens, insulating windows, focus rings, upper and lower electrodes installed inside the chamber may be made of conductive metals (Al, Fe or their alloys) or insulating ceramics (typically Al ₂ O ₃ , SiO ₂ , SiC, BN, etc.), these parts can be formed on the surface by anodizing to form a metal oxide (eg Al ₂ O ₃ ) protective coating to extend the life of the parts and corrosion resistance Can be increased.

As described above, anodizing technology is widely adopted to form the surface protective coating film of the metal material, but the durability of the anodizing coating film is weak, so that the surface coating film is easily damaged and frequently regenerated, or the detached particles generated from the damaged surface contaminate the chamber. In addition, through the anodizing Al ₂ O ₃ coating film, F, Cl ion particles easily diffuse into the metal base material or the bottom coating film has a problem of reacting with the elements of the base material or the bottom coating film to form a reaction product. As such, the anodizing coating film does not effectively block the diffusion of reactive gas and metal atoms, and at the same time, it is not easily damaged by external physical / chemical impact, and the Al ₂ O ₃ coating film formed by the anodizing method has several micro-tensions of micro-thickness on the base material surface. This is because the pores are formed in a direction perpendicular to the inside of the coating layer, although the structure is maintained until the compact structure. 2A and 2B are enlarged photographs of the anodized Al ₂ O ₃ coating film to confirm that the reaction gas and the metal element (eg Al) can be easily diffused and can be easily damaged by external impact.

Accordingly, it is an object of the present invention to extend the life of chambers and their components which significantly reduce the incidence of contamination-causing elements and particles, and to provide a vacuum plasma chamber and its internal components.

In particular, the present invention by replacing the anodizing coating film with a high-density, high hardness, high corrosion resistance material to apply to the surface protective film formation of the chamber of the plasma vacuum equipment and its internal components, significantly improved corrosion resistance and lifespan, significantly reduced the generation rate of contaminants It is an object to provide a chamber of equipment and its internal parts.

In order to achieve the above object, the present invention uses a vacuum plasma chamber or a component mounted therein as a base material, so that the base material is immersed in the electrolyte, and a high voltage direct current is applied to the base material to continuously apply the micro arc or plasma to the surface of the base material. It provides a coating film manufacturing method and a coating film according to the vacuum plasma chamber, characterized in that to form an oxide coating film while forming a.

Anodizing Al ₂ O ₃ coatings that form part of the outermost protective film of metal materials or two or more multilayer protective films used in vacuum plasma processing equipment may be made of high density / hardness / high corrosion resistant ceramics (eg, A technique for replacing with an oxide of metal (Al ₂ O ₃ , ZrO ₂ , MgO, TiO ₂ ) or a coating film thereof is described in detail as follows.

The method for forming a high density / high hardness / high corrosion resistance ceramic coating film according to the present invention is to immerse a high voltage anode current in a coating object after immersing a vacuum plasma chamber to be coated or a component mounted therein in an electrolyte solution.

At this time, since a fine arc (or plasma) is generated by the high voltage current applied to the surface of the coating material, the coating method is anodic spark deposition, anodic oxidation by spark discharge, It is called various names such as microdischarge electrolytic oxidation technology.

The core of the microdischarge electrolytic oxidation coating technology is to form a continuous micro arc (or plasma) on the surface of the base material by applying a high voltage direct current while forming an oxide coating film on the surface of the metal material. In this case, as the coating thickness increases in the existing anodizing coating by the generated micro arc (or plasma), micropores in the vertical direction of the base material, which are inevitably formed, may be removed to form a high-density oxide film.

The oxide film according to the present invention may be an oxide of a single chemical formula, but when the base material is an alloy containing several elements, the oxide film may be a composite of oxides including its elemental elements. have. In some cases, it may be a composite containing a constituent element of the electrolyte or a compound synthesized therefrom.

In the method for forming an oxide film according to the present invention, the electrolyte includes an aqueous solution of an alkali metal hydroxide such as potassium hydroxide or sodium hydroxide and an oxyacid salt of an alkali metal, or Na ₂ SiO ₃ , NaAl ₂ , H ₂ SO ₄ , Solutions including NaF-Na ₂ CO ₃ may be used, and the constituent materials and composition ratios of these electrolyte solutions may be adjusted / modified by the type of metal material to be coated.

In addition, the current flowing to the target material to be coated may vary depending on the thickness of the target coating layer, the type of base material (or composition), and the method of forming the base material (for example, casting, forging, rolling, machining, heat treatment, etc.). However, it is preferable to flow a DC current of 200V or more. The direct current may be a full direct current, a half-wave rectified direct current, a modified direct current formed by combining direct current and alternating current, and a combination of these may supply a direct current having a step of raising or lowering the voltage signal over time. have. In some cases, the voltage signal may fall to allow a negative current to flow through the base material for a predetermined time, which is to supply Al atoms necessary for the growth of the coating layer to the coating layer. In general, when a low voltage direct current is applied, it is difficult to form a thick dense coating film due to insufficient surface micro arc (or plasma) generation. On the contrary, when a high voltage direct current is applied, a thick and dense protective film can be formed, but high power equipment is required for coating a large component, which makes it difficult to apply to an industrial scale. Therefore, in the present invention, the upper limit of the high voltage applied to the base material when forming the coating film is limited to 1500V.

3 shows a photograph of Al ₂ O ₃ metal oxide 40 coated on the surface 41 of an aluminum 7075 alloy according to an embodiment of the present invention. It can be seen that no pores were formed in a direction perpendicular to the base material observed in the anodizing oxide film as shown in FIG. 2A. As can be deduced naturally from the coating film shape of Figure 3 and Figure 2a, the hardness of the oxide film formed in accordance with the present invention was 1200 Hv ~ 1600 Hv increased by two to three times compared to the anodizing film, ASTM B117-97 As a result of evaluating the corrosion resistance of the coating film by the salt spray method, the endurance time was 2000 to 5000 hours, which was 2 to 5 times increased compared to the 1000 hours of the anodizing film. From these results, the metal oxide film formed by the micro discharge electrolytic oxidation film technology according to the present invention can be a very good protective film that can replace the anodizing oxide film applied to the chamber and its internal parts of the conventional vacuum plasma processing equipment. Able to know.

On the other hand, the micro-discharge electrolytic oxide film technology uses a high voltage of 200V or more, so that the amount of power used increases proportionally as the surface area of the base material to be coated increases. Therefore, high power is required to form a protective film on the surface of a large metal material, which may be industrially limited. Therefore, the present invention further provides a method of forming a fine discharge oxide film on the surface of a large surface area components such as vacuum plasma chamber, liner, flat plate electrode, lower substrate support, gas dispersion plate.

That is, in the present invention, a large-area part is manufactured by dividing into two or more parts to form a protective film on each surface and then reassemble. Alternatively, by sequentially masking a part of the surface of a component manufactured by coating a specific part, and then changing the position of the masking, exposing an uncoated surface to an electrolyte solution and then forming a coating film on the surface. Can also be used. In this way, in the present invention, a high density oxide protective film can be formed on the surface of a large-area plasma vacuum chamber and its internal components while using low power coating equipment.

When fabricating and coating a large-area part into two or more parts and assembling them, the joints are provided on the inner side where the gap is matched with each other, a key hole is formed, a groove is made, or the plasma and the reaction gas are contacted. A third auxiliary body may be provided to prevent the joint portion from being damaged by the reaction gas and the plasma.

The microdischarge oxide film proposed in the present invention can be applied in place of all existing anodizing oxide films. That is, it may be used as a single layer outermost protective film on the surface of the metal base material, may be formed on one or more intermediate layers, or may be applied as an intermediate layer coating material of two or more multilayer protective films.

Preferably, the thickness of the microdischarge oxide film is preferably 10 micrometers to 200 micrometers.

In addition, pretreatment (physical / chemical cleaning, surface roughness formation, etc.) to increase the adhesive strength of the micro-discharge oxide film and the base material, and post-treatment to control the surface roughness of the film and to remove defects on the film surface (polishing, blasting) The process can be applied.

On the other hand, even when the outermost protective film of the base material is formed with the micro discharge oxide film according to the present invention, it may be difficult to completely remove pores inside the film. Therefore, after the micro discharge oxide film is formed, the pores therein may be filled using heterogeneous materials (for example, metal fluoride salts, organic acid salts, Si, SiO ₂ , and polymers). If a micro-discharge oxide film is formed as part of the inner film, and the outermost film is formed by a thermal spray coating or the like on the inner film, it is preferable to seal the outermost protective film. Sealing treatment is also possible. Preferably Si or it is recommended to fill the shield pores with SiO _2, which Si or SiO ₂ is to by the reaction gas form a _{SiF 2, SiF 4, SiCl 2} , SiCl 4 , etc. Volatile product easily easily from within the chamber Because it can be removed.

On the other hand, the protective film forming method proposed in the present invention can be equally applied to the newly produced vacuum plasma chamber and its internal parts as well as the regeneration process performed in order to ensure the reliability of the parts damaged during use or after periodic cleaning.

Although the present invention has been described above with reference to specific embodiments, the present invention is not limited thereto, and various modifications and improvements may be made by those skilled in the art without departing from the scope of the following claims.

According to the present invention, the anodizing ceramic coating used in the prior art as a protective film of the vacuum plasma chamber and the internal components made of a metal material, the internal porosity is significantly reduced compared to the anodizing ceramic coating, the hardness is increased 2-3 times or more It provides a high-density / high corrosion resistance / hardness micro discharge oxide film that has a 2-5 times or more improvement in durability when salt spraying. Therefore, the protective film of the chamber and the internal parts is peeled off by internal / external mechanical / thermal / chemical impact or particles formed by surface damage are released to prevent the contamination of the chamber, and the F, Cl ions, etc. It can prevent the diffusion of metal atoms in the base or lower coating to the top coating side, thereby preventing the formation of metal chlorides or fluorides, which in turn extends the replacement and cleaning cycles of the vacuum plasma component. In addition, it is expected to reduce the incidence of internal pollutants to improve the quality and reliability of semiconductors and LCDs and to reduce manufacturing costs.

Claims (11)

The base material is immersed in the electrolyte using the vacuum plasma chamber or a component mounted therein as a base material. Applying a high voltage direct current to the base material to form an oxide coating film while continuously forming a micro arc or plasma on the surface of the base material Coating film manufacturing method for a vacuum plasma chamber. The method of claim 1, wherein the high voltage applied to the base material is 200 V or more. The method of claim 1, wherein the electrolyte is an aqueous solution of an alkali metal hydroxide such as potassium hydroxide or sodium hydroxide, a solution containing an oxyacid salt of an alkali metal, or Na ₂ SiO ₃ , NaAl ₂ , H ₂ SO ₄ , NaF-Na ₂ Coating method for a vacuum plasma chamber selected from a solution containing CO ₃ and the like. The method of claim 1, wherein the coating film is Al ₂ O ₃ , ZrO ₂ , MgO, TiO _2, or a composite containing them. The method of claim 1, wherein before the coating film is formed on the base material, performing a pretreatment process such as physical / chemical cleaning, surface roughness formation, or performing a post-treatment process such as polishing or surface roughness formation after the coating film is formed. Coating film manufacturing method for a vacuum plasma chamber characterized in that. The method of claim 1, wherein the high voltage direct current includes a fully direct current, half-wave rectified direct current, a modified direct current formed by combining direct current and alternating current. The method of claim 1, wherein when the base material is large, the coating film is formed on each of two or more parts, and then each part is joined. The method of claim 7, wherein each of the portions has a stepped portion, a groove, a keyhole, or a third protective material at the joint portion to facilitate fastening after forming the coating layer. . The method of claim 1, further comprising filling the pores in the coating film with a heterogeneous material such as metal fluoride salt, organic acid salt, Si, SiO ₂ , and polymer after forming the coating film. The coating film for a vacuum plasma chamber according to claim 1, wherein when the base material is large, the coating film is formed by a sequential method of masking a part of the base material and coating the masked part first, and coating the masked part secondly. Manufacturing method. Coating film for a vacuum plasma chamber prepared according to claim 1.

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