Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
  • C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
  • C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
  • C23C8/10—Oxidising
  • C23C8/16—Oxidising using oxygen-containing compounds, e.g. water, carbon dioxide
  • C23C8/18—Oxidising of ferrous surfaces
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
  • C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
  • C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
  • C23C8/10—Oxidising
  • C23C8/12—Oxidising using elemental oxygen or ozone
  • C23C8/14—Oxidising of ferrous surfaces

Definitions

• the present invention relates to a stainless steel material for a clean system which is useful as a component member of a semiconductor manufacturing apparatus ⁇ a component member of a high vacuum apparatus, and more particularly, to manufacturing a high quality and high performance semiconductor product. It is used as a component of the supply system, exhaust system, reaction vessel, etc. of the high-purity process gas or ultrapure water necessary for the operation, and also as a component of the ultra-vacuum equipment. It relates to a stainless steel pan with low water release.
• the development of semiconductor utilization technology has been remarkable in recent years, and accordingly, the quality and performance required of semiconductor products have been remarkably advanced.
• the wiring spacing of semiconductor storage elements is required to be a few micron or submicron accurate, so even if very fine particles or bacteria adhere to the SB line, a circuit can be formed.
• the surface of these components be smooth so that the contact surface with pure water or the like becomes as small as possible. If there is a possibility that the altered layer may remain when the material is further processed, the gas or the like may be adsorbed by the altered layer and the cleanliness may be impaired.
• the ability to form a layer is also an important requirement, and there is a great deal of expectation for electrolytically polished stainless steel rods that can meet these requirements.
• the present inventors have proposed the use of electrolytic polishing as a means for improving the above-mentioned problems remaining in the electropolished stainless steel material.
• a technology was developed to prevent the elution of metal ions and the like by oxidizing the surface and forming a passivation film (JP-A-63-169391, JP-A-63-16991). No. 3-1956, No. 64-87760, Tokuheikai 1-19898463).
• the release of gas from the inside of the component is also suppressed by the oxide film, so that the gas cleaning effect is also good.
• the degree of cleanliness required for clean system systems such as semiconductor manufacturing equipment is becoming more and more advanced, and recently, it is not limited to the above-mentioned metal compound contamination due to elution of metal ions and gas contamination due to released gas.
• even contamination of adsorbed molecules, such as moisture adsorption on the surface of wafers, etc. is becoming a problem.
• 0.1 HID level ultra-fine ⁇ In ultra-high-integration high-speed devices, the amount of water release required for stainless steel used for fluid E pipes and chambers in clean systems is It is desired to reduce the number from less than a few ppm to less than a few ppb, and furthermore, there is a need for a material having characteristics that make it harder for foreign matter to adhere. That is, even if the surface-oxidized stainless steel material has sufficient cleanliness and excellent low-moisture release property at the time of manufacture, moisture, gas, or foreign matter may be generated during the processing or handling process or during use. If they are absorbed, they will not be suitable as clean system components.
• the present invention has been made in view of such circumstances, and for the purpose thereof, has good surface smoothness and cleanliness, does not cause elution of metal ions and the like, and has good gas release resistance.
• the surface has good stain resistance and adheres to moisture and impurities.
• the aim is to provide stainless steel materials for clean systems that are less likely to be contaminated by water.
• the stainless steel pan material for the clean system of the present invention is made by oxidizing a stainless steel material with a surface roughness of Rmax: 1 ⁇ or less by electrolytic polishing in a high-temperature oxidizing gas atmosphere to obtain a film thickness: 7
• An amorphous oxide film of 5 mm or more is formed, and the gist is that the ratio of 0-H bonded oxygen atoms to all oxygen atoms in the oxide film is reduced to 30% or less by atomic ratio. It has.
• the contact angle with the water droplet measured within 30 seconds after dropping a water droplet with a diameter of 1 mm on the surface of a circle having a radius of curvature of 2 mm or more is 38 degrees or more.
• a stainless steel material having a surface roughness of R max: l / z B or less by electrolytic polishing is used as a constituent material. If the surface roughness exceeds Raax: 1 ⁇ m, the oxide film to be formed lacks dense S, and even if a thick antiglare film is formed, the elution of the constituent elements is increased. And the effect of suppressing outgassing becomes insufficient.
• the oxide film must be amorphous and have a thickness of 75 A or more. Although the theoretical basis for these requirements has not been clarified, as shown in Japanese Patent Application Laid-Open No. 64-87760, the outgassing resistance of a crystalline oxide film is not improved, and If the thickness of the amorphous oxide film is less than 75 A, it is too thin and has sufficient gas resistance. Release property cannot be obtained.
• a stainless steel material having an amorphous oxide film with a surface roughness of less than Umax: 1 m and a film thickness of 75 A or more has a smaller metal ion elution amount than conventional materials. Outgassing is also good.
• the inventors of the present application have further studied that even though such an amorphous oxide film is formed, the impurity gas fi in the clean system is reduced to several p pb levels. It has become clear that attempting to do so will cause considerable variability in water release.
• M-0 type oxides (M: Fe, Cr, Ni, etc.) are formed on the surface, but in practice, Depending on the oxygen concentration, temperature, time, etc. of the steel, or the surface properties of the steel to be treated, a considerable amount of M-0H-type hydroxide is also generated and is considered to be mixed in the oxide film. And this M- OH type hydroxide, then to release H 2 0 and Ho decomposition by condition for ⁇ used as a constituent member for a clean system, which deteriorates the water content release and considered available.
• M-0 type oxides M: Fe, Cr, Ni, etc.
• the moisture release resistance of the oxide film has a close relationship with the surface wettability represented by the contact angle ( ⁇ ) with a water droplet described later.
• ⁇ surface wettability represented by the contact angle ( ⁇ ) with a water droplet described later.
• FIG. Changed around 38 degrees, and it was clarified that by setting the contact angle (0) to 38 degrees or more, the water release of shochu could be significantly increased. .
• the reasons for these remarkable trends are considered as follows.
• a small contact angle (e) on the oxide film surface indicates that the surface has high wettability, and such an oxide film surface has moisture, foreign matter, and gas in the air or in a clean system. Etc. are easily adsorbed, and those that have been adsorbed once are difficult to separate.
• the surface properties of these oxide films are extremely important for purifying the clean system.
• the wettability of the oxide film is high, no matter how low the water release of the steel material and the oxide film is, the subsequent handling such as transportation, storage or construction
• a great deal of effort is required to remove moisture and foreign matter adhering in a difficult process, and it is not always possible to completely remove such moisture and foreign matter.
• the initial adhesion of water, etc . Even if the amount of S is very small, the amount of adhesion or adsorption of water, etc., gradually increases as the operation time becomes longer, which has a serious effect. .
• the oxide film has a low roughness and therefore has a small adsorption energy. Based on the data shown in FIG. 2, the contact angle (0)> 38 degrees j is obtained.
• the ratio of 0-H bonded oxygen atoms to the total oxygen atoms in the oxide film is 30% or less in terms of atomic number, and the contact angle (0) with water droplets is 38 degrees or more.
• an oxide film satisfying such conditions can be obtained, for example, by the following method.
• oxidation is performed in a high-temperature oxidizing gas atmosphere.
• the stainless steel material be sufficiently dried to completely remove the adhering moisture, and that the atmosphere gas be dried to + minutes to reduce the moisture S as much as possible.
• Performing vacuum heating after electropolishing is one of the preferable methods for reducing the amount of 0-H bonded oxygen: S in the oxide film. That is, when this method is carried out, the bound water and hydroxide taken into the surface of the stainless steel material in the electropolishing step are removed, so that the 0-H bound oxygen in the oxide film formed thereafter is removed. This is because the mixing amount is reduced, and the moisture release resistance of the oxide film can be further improved.
• the heating temperature during oxide film formation is preferably in the range of 220 to 580. If the temperature is less than 220 t, the oxide film formation rate is slow, and the thickness of the amorphous oxide film is 75 A or more. On the other hand, the productivity is poor because it takes a long time to perform the treatment. On the other hand, if it exceeds 580 X :, the oxide film becomes crystalline and the water release resistance intended by the present invention cannot be obtained.
• FIG. 1 is a graph showing the relationship between the ratio of the number of 0-H bonded oxygen atoms to the total number of oxygen atoms in the oxide film and the released water i.
• FIG. 2 is a graph showing the relationship between the contact angle of water droplets on the oxide film surface and the amount of released water.
• Fig. 3 is a graph showing the relationship between the analysis result of the oxide film of 0 by X-ray optical spectroscopy (XPS) and the sputtering time * in comparison with the material of the embodiment of the invention and the comparative material.
• XPS X-ray optical spectroscopy
• FIG. 4 is an explanatory diagram showing a method of measuring the contact angle (0) of a water droplet on the oxide film surface.
• H 2 S0 4 as the electrolytic polishing solution (30-fold fi%) - H 3 P0 ⁇ ( using 55-fold amount aqueous, outer diameter 9.53 mm, wall thickness 1.0 mm, length 4,000 mm AISI 316L stainless ⁇ ).
• the inner surface of the tube was electropolished, and after the electropolishing, the inner surface was washed with warm pure water before air drying, and then dried while blowing high-purity N 2 gas. Then, the inside surface was oxidized under the conditions shown in Table 1 below, and the following tests were performed on each of the obtained sample tubes.
• the stainless steel material of the present invention exhibits excellent moisture release resistance, whereas the 0-H bond oxygen atom ratio is 3%.
• Water release of the comparative material (No. 12 to 15) having a surface oxide film exceeding 0%: S is very large, indicating that the material has poor water release resistance.
• those having a 0-H-bonded oxygen atom ratio of more than 30% those with a contact angle with water droplets of more than 38%, even those with 30% or less, have better moisture resistance.
• the electropolishing treatment performed as a pretreatment for the surface treatment is a means that can relatively easily achieve a surface roughness of Rmax: 1 #m or less. ⁇ ⁇ or less is necessary to reduce the true surface area in contact with the process foam, etc. and to completely remove the work-modifying layer, but the comparative material No. 10 is electrolytically polished. Insufficient treatment resulted in a surface roughness exceeding Rmax: 1 ⁇ m.Comparative material No. l5 was not subjected to electropolishing but was subjected to mechanical polishing instead of processing. In addition, the comparative material No. l7 has a rough surface roughness of R max: 3.6 ⁇ due to normal bright annealing and therefore has a large value of 0-H bond oxygen atom ratio and a small contact angle (0). Therefore, satisfactory water extraction resistance has not been obtained.
• Comparative material No. l6 was not oxidized even though it had an extremely smooth surface roughness of Rmax: 0.2 ⁇ by electrolytic polishing. Generated It has only a 40 A oxide film, and has a large amount of released water due to a large number of 0-H-bonded oxygen atoms and a small contact angle (0) of water droplets. Also, the comparative material No. l3, which has been subjected to oxidation treatment after electrolytic polishing, has a thin film thickness of 70 A, so that the moisture release resistance is still insufficient. On the other hand, the water release of Invention Material No. 9, in which an oxide film of 80 A or more was formed, was significantly less.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Physical Vapour Deposition (AREA)
• Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
• Chemical Vapour Deposition (AREA)
• Chemical Treatment Of Metals (AREA)
• Heat Treatment Of Sheet Steel (AREA)

Priority Applications (4)

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Citations (2)

• 1989
  • 1989-09-21 WO PCT/JP1989/000957 patent/WO1991004350A1/ja active Application Filing
  • 1989-09-21 DE DE19893991748 patent/DE3991748C2/de not_active Expired - Fee Related
  • 1989-09-21 DE DE19893991748 patent/DE3991748T1/de active Pending
• 1991
  • 1991-05-21 SE SE9101526A patent/SE9101526L/ not_active Application Discontinuation

Patent Citations (2)

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