| 摘要 |
1,266,380. Semi-conductor devices. INTERNATIONAL BUSINESS MACHINES CORP. 16 Oct., 1969 [4 Nov., 1968], No. 50865/69. Heading H1K. Impurity diffusion to a depth of less than 20 microinches is effected by preheating a semiconductor wafer in a gas which does not form a film on the surface or removes any pre-existing film, then introducing vapour of the impurity into the gas and flowing it over the wafer under continued heating to effect diffusion, and finally cooling the wafer to room temperature. Suitable gases are argon, helium, hydrogen, chlorine and hydrogen chloride. In a typical case pre-heating, to 800-1100‹ C. for Si or 650-900‹ C. for Ge and cooling both take 5 minutes. After preheating a mixture of phosphorus oxychloride and oxygen is added to the flow-and the temperature maintained-for 30 minutes. Arsenic is an alternative diffusant -in this process which yields uniform high surface concentration shallow impurity gradient junctions.
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