| 摘要 |
1,126,309. Semi-conductor devices. WESTINGHOUSE ELECTRIC CORP. 10 Aug., 1967 [19 Sept., 1966], No. 36794/67. Heading H1K. A diffusion source for providing gold recombination centres to reduce the minority carrier lifetime in the body of a semi-conductor device comprises a gold halide or cyanide. The gold halide or cyanide (e.g. AuCl or AuCl 3 ) is heated in the presence of the semi-conductor body to form elemental gold by thermal decomposition, the elemental gold then diffusing by gaseous diffusion into those parts of the semiconductor body exposed thereto. It is stated that it is known to diffuse gold into a semi-conductor device from a coating plated on to the substrate or non-active side of the device; in the present process however the gold may be diffused directly from the gaseous phase into the active side of the device through a suitable mask (e.g. of SiO 2 ), thus permitting a more precise control of the localization of the gold recombination centres within the device. In practising the invention, silicon wafers having oxide masks thereon are placed together with a quantity of gold halide or cyanide in a quartz ampoule which is then evacuated and sealed, the sealed ampoule then being heated for a period of from 5 to 120 minutes at a temperature of at least 700‹ C., preferably at least 850‹ C. The thermal decomposition of the heated gold compound creates a gold vapour pressure at the exposed surfaces of the semi-conductor devices considerably in excess of that which can be achieved by heating elemental gold to similar temperatures. In one embodiment, Fig. 1 (not shown), gold is diffused through an annular window in a silica mask into the base region of a silicon planar transistor. In a second embodiment, Fig. 2 (not shown), the whole surface of a PNPN silicon thyristor, except for the one face constituting the P-type anode emitter, is coated with a silica layer. Gold is diffused through the anode emitter and part of the way through the adjacent N-type base region, none being diffused into the gate or cathode emitter.
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