GB949649A - Improvements in or relating to methods and apparatus for forming semi-conductor materials - Google Patents

Abstract

In the formation of semi-conductor materials by passing a gaseous compound of the semiconductor material over a heated body of the same semi-conductor material to deposit semiconductor material, e.g. silicon, on the body, the semi-conductor body, e.g. a silicon body, is placed in a reaction vessel which is then filled with a gas, e.g. hydrogen, and the silicon body is heated to an intermediate temperature by a heating element situated at a first position inside the vessel. The body is then heated from this intermediate temperature to the decomposition temperature of the gaseous compound of the semi-conductor material, e.g. silicon chloroform, to be passed over the body, by means of electrical currents flowing in the body. The heating element is moved to a second position outside the vessel and then the gaseous silicon chloroform is passed over the body to deposit silicon on to the body. In Figs. 1, 2 and 3, a reaction vessel having a cover 21 is situated above a vessel 17, the dividing wall between the vessels consisting of an outer ring 12 and an inner movable plate 13 which is mounted on a shaft 14. Mounted on ring 12 is a plurality of silicon bodies in the form of rods 11 and 111, adjacent rods being connected together by a piece of semi-conductor material, see Fig. 8, in which piece 23 is the connector. The lower surface of the movable plate 13 carries a plurality of heater elements 16 and 161 and <PICT:0949649/C1/1> <PICT:0949649/C1/2> <PICT:0949649/C1/3> <PICT:0949649/C1/4> <PICT:0949649/C1/5> <PICT:0949649/C1/6> on its upper surface is a plurality of further silicon rods 15 and 151. At the beginning of the process cover 21 and plate 13 are moved from the Fig. 1 positions to the Fig. 2 positions, hydrogen is passed into the two vessels and current is applied to heater elements 16 and 161 to heat rods 11 and 111. Plate 13 is then lowered to the Fig. 3 position and a direct current is applied to rods 11 and 111 and heat radiated and conducted from 11 and 111 heats rods 15 and 151 to the intermediate temperature after which they are also heated to the decomposition temperature by direct current. Silicon chloroform is then passed over rods 11, 111, 15 and 151 under such conditions that the silicon deposited is in the monocrystalline form. In Fig. 4, the dividing wall 41 between the two vessels contains a plurality of holes through which a plurality of heater elements 16 and 161 may be lowered to heat rods 11, 111, 15 and 151 in vessel 46. In Fig. 7, a plurality of silicon rods 61 to 65 in a vessel 71 are arranged in concentric rings and a plurality of heater elements 51 in a vessel 72 are raised up through elements 51 in a vessel 72 are raised up through holes in the dividing wall between the two vessels.ALSO:Pure germanium is produced by thermal decomposition of a gaseous germanium compound, e.g. a germanium halogenide, in a reaction vessel containing a germanium body and a gas by first heating the germanium body to an intermediate temperature by means of a heater element situated inside the reaction vessel and then heating the body, by passing an electrical current therethrough, from this intermediate temperature to the decomposition temperature of the gaseous germanium compound and then passing the said gaseous compound over the body to deposit germanium on the body, the heater element being moved out of the reaction vessel before decomposition commences. Semi-conductor materials other than germanium can be prepared by this method. In Figs. 1, 2 and 3, a reaction vessel having a cover 21 is situated above a vessel 17, the dividing wall between the vessels consisting of an outer ring 12 and an inner movable plate 13 mounted on shaft 14. Mounted on ring 12 is a plurality of semi-conductor bodies in the form of rods 11 and 111, adjacent rods being connected together by a piece of semi-conductor material, see Fig. 8 in which 23 is the connector. The lower surface of movable plate 13 carries a plurality of heater elements 16 and 161 and on its upper surfaces a plurality of further semi-conductor rods 15 and 151. At the beginning of the process cover 21 and plate 13 are moved from the Fig. 1 positions to the Fig. 2 positions, hydrogen is passed into the two vessels and current is applied to heater elements 16 and 161 to heat rods 11 and 111. Plate 13 is then lowered to the Fig. 3 position and direct current is applied to rods 11 and 111 and heat radiated and conducted from these rods heats <PICT:0949649/C3/1> <PICT:0949649/C3/2> <PICT:0949649/C3/3> <PICT:0949649/C3/4> <PICT:0949649/C3/5> <PICT:0949649/C3/6> rods 15 and 151 to the intermediate temperature after which they are also heated by direct current. A gaseous compound containing the semi-conductor material, e.g. a gaseous germanium compound, is passed over rods 11, 111, 15 and 151 to deposit the material on the rods. In Fig. 4, the dividing wall 41 between the two vessels contains a plurality of holes through which a plurality of heater elements 16 and 161 may be lowered to heat rods 11, 111, 15 and 151 in vessel 46 and in Fig. 7 the rods of semi-conductor material are arranged in concentric rings in vessel 71 and a plurality of heater elements 51 in vessel 72 are raised up through holes in the dividing wall of the two vessels.