Patent GB-1035499-A (GB)
Title: Process for the manufacture of crystalline layers from low volatility substances in the gas phase
IPC: C23C16/00
Filed: 1963-06-14
Abstract: In producing monocrystalline layers of semiconductor materials, viz:- Si, Ge, pyrographite, hard carbides and AIIIBV compounds, on a substrate is heated to a desired temperature in a vessel under sub-atmospheric pressure, a gaseous material which decomposes or reacts to give the desired semi-conductor material is introduced into the vessel, which is then sealed and a layer allowed to form on the substrate to a desired thickness, after which the vessel is evacuated and the layered substrate allowed to cool under sub-atmospheric pressure. The gaseous material is introduced into the vessel, and the vessel evacuated after layer formation at a rate which is rapid in comparison with the rate at which the layer forms, for example, the time of introduction is not more than one tenth of the layer formation time, and the withdrawal time is between one hundredth and one tenth of the layer formation time.  The walls of the reaction vessel are preferably maintained at a temperature below that of the substrate, e.g., a temperature within the range -10 to +300 DEG C., throughout the whole of the process.  If required, prior to cooling the substrate, a second different gaseous material may be introduced and a second layer formed on the first.  This second gaseous material may differ from the first only in that it either contains a different amount of doping material or a different doping material, the amount of said doping material being 0.1 to 10-10% by volume.  The pressure of the gas during layer formation is preferably between 0.1 and 5 atmospheres, whilst during the heating and cooling of the substrate and after layer formation it is less than 10-2 mm of mercury.  The carrier may be heated by infra-red radiation or high frequency inductive means.  The disclosure is primarily directed to the production of silicon layers, but the other materials are mentioned, particularly the decomposition of GaCl3 and PCl3 to give GaP, the decomposition of CH3SiCl3 to give SiC, and CH3TiCl3 to give TiC, and the production of pyrographite from methane and hydrogen.ALSO:In producing monocrystalline layers of semiconductor materials, viz.:-Si, Ge, pyrographite, hard carbides and AIIIBV compounds, on a substrate, the substrate is heated to a desired temperature in a vessel under sub-atmospheric pressure, a gaseous material which decomposes or reacts to give the desired semi-conductor material is introduced into the vessel, which is then sealed and a layer allowed to form on the substrate to a desired thickness, after which the vessel is evacuated and the layered substrate allowed to cool under subatmospheric pressure.  The gaseous material is introduced into the vessel, and the vessel evacuated afte layer formation at a rate which is rapid in comparison with the rate at which the layer forms, for example, the time of introduction is not more than one-tenth of the layer formation time, and the withdrawal time is between one-hundredth and one-tenth of the layer formation time.  The walls of the reaction vessel are preferably maintained at a temperature below that of the substrate, e.g. a temperature within the range -10 DEG  to +300 DEG  C., throughout the whole of the process.  If required, prior to cooling the substrate, a second different gaseous material may be introduced and a second layer formed on the first. This second gaseous material may differ from the first only in that it either contains a different amount of doping material or a different doping material, the amount of said doping material being 0.1 to 10-10% by volume.  The pressure of the gas during layer formation is preferably between 0.1 and 5 atmospheres, whilst during the heating and cooling of the substrate and after layer formation it is less than 10-2 mm. of mercury.  The carrier may be heated by infrared radiation or high frequency inductive means.  The disclosure is primarily directed to the production of silicon layers, but the other materials are mentioned, particularly the decomposition of GaCl3 and PCl3 to give GaP, the decomposition of CH3SiCl3 to give SiC, and CH3TiCl3 to give TiC, and the production of pyrographite from methane and hydrogen.