GB878764A - Improvements in and relating to manufacturing processes - Google Patents

Abstract

<PICT:0878764/III/1> In the production of a semi-conductor element by thermal decomposition of a gaseous hydride, an elevated temperature, which is at least sufficient to decompose the hydride, is maintained in the decomposition chamber by a heating element consisting of the semiconductor element being produced, which is heated by the passage of an electrical current therethrough, the temperature and pressure in the chamber are such that the thermal decomposition of the hydride is substantially wholly a gas - phase reaction, the semiconductor element produced is swept to, and deposited on, the walls of the chamber, and the temperature at which the major portion of the decomposition occurs is such that the major portion of the semi-conductor element is deposited on the walls in a sintered, readily-removable, form. Pure mono-silane prepared as described in Specification 878,763 enters at A quartz decomposition chamber B, which is sealed by water-cooled metal endblock J and metal cone R, and contains high purity silicon rods C, D, fixed in slidable clamp E1, and fixed clamp E2, respectively. Rods C, D are first heated until the conductivity is sufficient, either by directing an infra-red source by elliptical, or parabolic mirrors thereonto, or by creating an arc between the rods, when C, D are firmly contacted, and the current passed through for further heating. The silane is decomposed and silicon is deposited on the walls of B first as an amorphous layer and then as sintered flakes. Quartz protecting shield L prevents silicon deposition in the lower part, and hydrogen formed is withdrawn through F by vacuum pump. The silicon may be doped with an additive element by admitting a gaseous hydride of the additive element, e.g. arsine or diborane, to form AS or B by decomposition under the same conditions. Specification 878,765 also is referred to.