Method and device for producing highly pure polycrystalline silicon with a reduced dopant content

摘要

Batch production of high-purity polycrystalline silicon by principles of plasma-enhanced chemical vapor deposition comprises inserting a silicon-made U-shaped substrate into an open chemical vapor deposition reactor; hermetically sealing the reactor; heating the substrate; feeding a silicon-containing reaction gas and hydrogen into reactor; terminating the chemical vapor deposition; cooling and removing the substrate from reactor; inserting a second U-shaped substrate into the reactor; and introducing an inert carrier gas by a supply line, discharge line and the open reactor. Batch production of high-purity polycrystalline silicon by principles of plasma-enhanced chemical vapor deposition comprises inserting a U-shaped substrate made of silicon into an open chemical vapor deposition reactor and fastened to it; hermetically sealing the chemical vapor deposition reactor; heating the U-shaped substrate by means of direct electrical current; feeding a silicon-containing reaction gas and hydrogen into the chemical vapor deposition reactor by a supply line, as a result of which silicon is isolated from the reaction gas and deposited on the substrate, the diameter of the substrate grows and a waste gas develops, which is removed by a discharge line from the chemical vapor deposition reactor; terminating the chemical vapor deposition after the substrate reaches a desired diameter; cooling the substrate to room temperature; opening the chemical vapor deposition reactor; removing the substrate from the chemical vapor deposition reactor; inserting a second U-shaped substrate made of silicon into the chemical vapor deposition reactor and fastened to it; and introducing an inert carrier gas by a supply line and the discharge line and further through the open reactor from the point of time of the opening of the chemical vapor deposition reactor for dismounting the first substrate with the deposited silicon up to the point of time of closing the reactor for deposition of silicon on the second substrate. Independent claims are included for: (1) a highly-pure, polycrystalline silicon with a slope of the radial gradient of the specific electrical resistance amounts to at least 75, preferably 80-200 omega cm/mm; and (2) a device for the implementation of the above procedure comprising a supply line, which is meant for a reaction gas (1), a shut-off valve (8) and leads there over a supply opening (2) through a bottom plate (3) into a reactor (4), a discharge line (6), which is meant for a waste gas and leads into the surroundings or to a treatment process over a shut-off valve (7) through the discharge opening in the bottom plate of the reactor, an inert gas line (11), which can be regulated by a shut-off valve (10), which leads into the supply line after the shut-off valve, and an inert gas line, which can be regulated by a shut-off valve (9), leads into the discharge line before the shut-off valve.