Metal treatment – Process of modifying or maintaining internal physical... – Heating or cooling of solid metal
Patent
1998-02-10
1999-06-29
Yee, Deborah
Metal treatment
Process of modifying or maintaining internal physical...
Heating or cooling of solid metal
148628, 266250, 266103, C21D 967, C21D 1773
Patent
active
059163887
ABSTRACT:
The invention includes an apparatus and associated method of increasing the pump-out efficiency of H.sub.2 O by, for example, reducing the staying time or the probability of sticking of H.sub.2 O or analogous molecules on a stainless steel surface. The method for the vacuum treatment of stainless steel surfaces includes an annealing treatment carried out under conditions of at least 500.degree. C. while maintaining an H.sub.2 O partial pressure of not more than 1.times.10.sup.-5 torr, or at least 400.degree. C. while maintaining an H.sub.2 partial pressure of at least ten times the H.sub.2 O partial pressure, or at least 300.degree. C. while maintaining an H.sub.2 partial pressure at least the same as the H.sub.2 O partial pressure and activating the H.sub.2. Furthermore, during the interval after the annealing treatment and before use, the surface is stored in an environment such that the product of the relative humidity and the number of days is not more than 500. Following the annealing treatment a baking treatment is carried out as required under conditions of H.sub.2 O partial pressure not more than 1.times.10.sup.-5 torr, or H.sub.2 partial pressure at least ten times the H.sub.2 O partial pressure, or H.sub.2 partial pressure at least the same as the H.sub.2 O partial pressure in a state where the reactivity of the H.sub.2 is increased. The associated apparatus includes a device capable of sequentially heating the stainless steel surface, such as a plurality of individually controlled wire heaters, a lamp heater with moveable reflector, or a laser oscillator with moveable reflecting mirror. The associated apparatus includes a device for increasing the partial pressure of H.sub.2, such as a low-temperature panel that releases H.sub.2 when heated, a solid that releases H.sub.2 when heated, a controlled turbomolecular pump, or a separate H.sub.2 delivery system.
REFERENCES:
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"Correlation of outgassing of stainless steel and aluminum with various surface treatments"; H.F. Dylla et al; J. Vac. Sci. Technol. A11(5), Sep./Oct. 1993.
"Thermal passivation of AISI 316 stainless steel in controlled vacuum"; G. Hulquist and C. Leygraf; J. Vac. Sci. Technol., 17(1), Jan./Feb. 1980.
"Interaction of hydrogen with the surface of type 304 stainless steel"; L.C. Beavis; J. Vac. Sci. Technol., vol. 10, No. 2, Mar./Apr. 1973.
"Effect of surface treatment on the adsorption kinetics of water vapor in a vacuumchamber"; Y. Tuzi et al; Vacuum/vol. 47/No.6-8, pp. 705 to 708/ 1996.
"Scientific Semiconductor Manufacturing Using Process Gases"; Tadahiro Ohmi; Ultra Clean Technology Vo. 9, No. 5/6, published on Dec. 10, 1997.
Anelva Corporation
Yee Deborah
LandOfFree
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