Electric heating – Heating devices – Combined with container – enclosure – or support for material...
Patent
1980-07-25
1982-08-31
Reynolds, B. A.
Electric heating
Heating devices
Combined with container, enclosure, or support for material...
148189, 373109, H05B 310
Patent
active
043474314
ABSTRACT:
A diffusion furnace (11) includes a typical process tube (12) and an outer envelope (26) which forms an annular chamber (37) with the process tube. A heating element (29) of high purity graphite substantially surrounds the process tube within the chamber (37). Inner surfaces of the chamber (37) are made of materials such as, for example, silicon, pyrolytic graphite or quartz. Such materials are essentially free of harmful impurity elements such as iron, nickel, copper calcium or gold, which have an energy level about halfway between the valence and the conduction band of a semiconductor material to be processed within the process tube. A nonoxidizing gas within the heater chamber protects the graphite elements therein from oxidation. A small gas flow within the chamber (37) is preferred to purge such harmful impurity elements as may penetrate into the chamber during the operation of the furnace.
REFERENCES:
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patent: 3180917 (1965-04-01), Morrison et al.
patent: 3409727 (1968-11-01), Hampton
patent: 3598666 (1971-08-01), Addamiano
patent: 3641249 (1972-02-01), Higgins
patent: 3698872 (1972-10-01), Reusser
patent: 3804967 (1974-04-01), Werych
patent: 4195820 (1980-04-01), Berg
Kirk-Othmer Encyclopedia of Chemical Technology, Second Edition, vol. 4, pp. 189-190, 329; 1964.
"A Neutron Activation Analysis Study of the Sources of Transition Group Metal Contamination in the Silicon Device Manufacturing Process", Schmidt, Pearce, Reprint, Journal of the Electrochemical Society, vol. 128, No. 3, Mar. 1981, pp. 630-637.
Pearce Charles W.
Schmidt Paul F.
Bell Telephone Laboratories Inc.
Reynolds B. A.
Roskoski Bernard
Schellin W. O.
Western Electric Company Inc.
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