Ultrahigh Purification of Silane for Semiconductor Silicon

Abstract

Monosilane was purified with a newly developed ion‐exchanged zeolite A, which sorbs phosphine in silane. The phosphine content of silane was determined from electrical resistivity of silicon which was obtained by decomposing silane. Two kinds of silicon samples were used for analysis, i.e., epitaxial films on silicon substrate, and single crystal rods. The electrical resistivity of the silicon rods of p‐type ranged between at room temperature, depending on conditions of purification. A surface barrier type solid‐state detector, fabricated from this silicon, was evaluated with x‐rays and conversion electrons from 207Bi, and showed satisfactory characteristics. Characteristics of the adsorption column were studied with a simulation column by the aid of gas‐chromatographic techniques. Optimum conditions were deduced for the operation of the adsorption column.