GB970456A - Improvements in or relating to processes for the preparation of semiconductor arrangements - Google Patents

Abstract

<PICT:0970456/C1/1> In a process for the preparation of a semi-conductor arrangement by the thermal decomposition of a gaseous halogen containing compound of a semi-conductor material mixed with a carrier gas, the semi-conductor material is deposited epitaxially on to a semi-conductor substrate which is in thermal contact with a heated support at least the surface of which is formed of semi-conductor material and the space between the semi-conductor substrate and the support is so enriched with an hydrogen halide gas and the temperature of the support is such that a gaseous sub halide of the semi-conductor of the support is formed in a concentration corresponding to a partial pressure of 10-6 atmospheres and said sub halide is decomposed to deposit semi-conductor material on the side of the semi-conductor substrate adjacent said support. The concentration of hydrogen halide gas may be obtained by the decomposition of the gaseous halide of the semi-conductor and reaction with an hydrogen carrier gas, or by introducing hydrogen halide gas or by a combination of both. The process may be operated using a flowing reaction gas in which case a semi-conductor layer is also deposited on the side of the substrate remote from the support, or if a deposit is not required on this side a masking cover plate of alumina, quartz or silicon carbide may be placed over this side. Alternatively the process may be operated with a static hydrogen halide and carrier gas atmosphere in which case only the underside of the substrate adjacent the support is coated by transfer of the semi-conductor material from the support. The supports may be quartz, graphite, silicon coated with a semi-conductor material such as silicon, germanium or a AIII BV or AII BVI type compounds or solid semi-conductor material. Examples are given of the formation of Si on Si, Ge on Ge, Si on Ge, GaAs on Ge, GaAs on GaAs, Ge on GaAs and different conductivity types and doped layers may also be formed. In one embodiment shown in Fig. 5 a quartz reaction vessel 30 with a gas inlet 32 and gas outlet 33 contains a silicon carbide coated graphite heater 34 which heats a support 35 of silicon. A substrate 37 of silicon is placed on support 35 and a cover of silicon carbide may be placed over substrate 37. After heating in hydrogen at 1150 DEG C. the support is heated to 1150 DEG -1300 DEG C. and HCl or SiCl3 or SiCl4 is added to the hydrogen atmosphere in a concentration of 3-10% by volume. The SiCl2 formed decomposes to produce a Si layer on the underside of substrate 37.ALSO:<PICT:0970456/C6-C7/1> In a process for the preparation of a semi-conductor arrangement by the thermal decomposition of a gaseous halogen-containing compound of a semi-conductor material mixed with a carrier gas, the semi-conductor material is deposited epitaxially on to a semi-conductor substrate which is in thermal contact with a heated support at least the surface of which is formed of semi-conductor material and the space between the semi-conductor substrate and the support is so enriched with a hydrogen halide gas and the temperature of the support is such that a gaseous sub halide of the semi-conductor of the support is formed in a concentration corresponding to a partial pressure of 10-6 atmospheres and said sub halide is decomposed to deposit semi-conductor material on the side of the semi-conductor substrate adjacent said support. The concentration of hydrogen halide gas may be obtained by the decomposition of the gaseous halide of the semi-conductor and reaction with a hydrogen carrier gas, or by introducing hydrogen halide gas or by a combination of both. The process may be operated using a flowing reaction gas in which case a semi-conductor layer is also deposited on the side of the substrate remote from the support, or if a deposit is not required on this side a masking cover plate of alumina, quartz or silicon carbide may be placed over this side. Alternatively the process may be operated with a static hydrogen halide and carrier gas atmosphere in which case only the underside of the substrate adjacent the support is coated by transfer of the semi-conductor material from the support. The supports may be quartz, graphite, silicon coated graphite or silicon carbide each coated with a semi-conductor material such as silicon, germanium or a AIII BV or AII BVI type compounds or solid semi-conductor material. Examples are given of the formation of Si on Si, Ge on Ge, Si on Ge, GaAs on Ge, GaAs on GaAs, Ge on GaAs and different conductivity types and doped layers may also be formed. In one embodiment shown in Fig. 5 a quartz reaction vessel 30 with a gas inlet 32 and gas outlet 33 contains a silicon carbide coated graphite heater 34 which heats a support 35 of silicon. A substrate 37 of silicon is placed on support 35 and a cover of silicon carbide may be placed over substrate 37. After heating in hydrogen at 1150 DEG C. the support is heated to 1150-1300 DEG C. and HCl or SiCl3 or SiCl4 is added to the hydrogen atmosphere in a concentration of 3-10% by volume. The SiCl2 formed decomposes to produce a Si layer on the underside of substrate 37.