Semiconductor deposition appts., esp. for mfg. silicon rods - has bell jar located on metal baseplate contg. two separate water cooling systems to aid sealing of appts.

摘要

Appts. consists of a bell jar, made of fused vitreous silica, glass, rotosil, or steel, and located via a gastight seal on a metal baseplate, which may be cup-shaped. The bell jar includes inlets and outlets for reaction gas, and holders for a heated substrate on which the semiconducting material is deposited. The metal baseplate contains holes which form two independent cooling systems through which a coolant flows. One system pref. cools the outer zone, and the other the inner zone, of the baseplate; and the resistance to water flow, and the water path length, are pref. identical in the two systems, which pref. flow in counter-current. Used esp. in mfg. Si rods above 3-5" in dia., where the process ensures completely effective sealing of the appts. via a rigid baseplate so no impurities reach the Si.