Production of high-purity polycrystalline silicon rod for semiconductor

Abstract

Disclosed is a process for rapidly producing large diameter, high-purity polycrystalline silicon rods for semiconductor applications, while maintaining the purity of a highly refined monosilane gas inside the reactor. The equipment includes a reactor vessel which encloses powder catchers consisting of cylindrical water jackets. Also within the vessel is a cylindrical water jacket which concentrically surrounds the powder catchers and which defines multiple reaction chambers. Control is effected in such a way that the temperature distribution in different sections inside the reactor is as follows in the ascending order: the powder catcher walls, the walls of the water jacket which defines the reaction chambers, and the lower wall of the vessel cover. Part of the monosilane gas is ejected horizontally from a plurality of gas nozzles, is agitated by a descending gas flow generated around the powder catchers, and ascends inside the reaction chambers at a uniform concentration, thereby causing polycrystalline silicon rods to be grown around silicon starter filaments in a short time. The silicon powder generated in this process adheres to the coolest wall surfaces, which are those of the powder catchers, and is thereby collected. Little of the powder adheres to the walls of the reaction chambers or the wall of the reactor ceiling section. This effect can be further enhanced by the provision of a fan to increase gas circulation.