Apparatus for producing semiconductor grade silicon and replenishing the

Abstract

A method and related apparatus are provided for producing on a semi-continuous basis polycrystalline silicon and melt replenishment for a crystal growth crucible. The silicon is deposited in low density form on the inner walls of a multi-walled reaction chamber by delivering gaseous HSiCL.sub.3, SiH.sub.4, or the like, and reducing gas if needed, through the chamber which is heated to the reaction temperature of the feed gas. After a certain amount of silicon has been produced, the chamber temperature is raised sufficiently to melt down the silicon which is then used to replenish a crystal growth crucible. The operations are then cyclically repeated. The apparatus includes a reaction chamber having a multi-walled configuration to maximize the interior surface area on which the silicon is deposited. A drain trap such as a U-shaped tube, or the like, is connected to the bottom of the reaction chamber and provided with heating elements. Silicon collected on the walls of the reaction chamber, when periodically melted, flows through the drain trap and a delivery tube to a crystal growth system. By selectively adjusting the temperature in the trap, either above or below the melting point of the silicon, the silicon is alternately liquified or solidified so that the liquid/solid transition of the silicon in the trap acts as a valve between the reaction chamber and the crystal growth system.