SELECTIVE DIFFUSION METHOD OF PPTYPE IMPURITY IN INP OR INGAASP

摘要

PURPOSE:To obtain a diffusion area having a desired micro width and depth with a high precision by using a Mg3P2 single substance or a mixed substance of Mg3P2 and Inp as diffusion materials and subjecting them to vapour-phase decomposition and diffusing selectively Mg in the InP or InGaP semiconductor as P type impurity. CONSTITUTION:SiO2 film B is caused to adhere onto InP semiconductor substrate A and window 9 is provided on he diffusion area. Then, vapour phase decomposition is performed by using Mg3P2 single substance or a mixed substance of Mg3P2InP. When Mg is diffused in substrate A as P type impurity through window 9 in this manner, extending width W at the bottom part is prevented from being wide even if depth D of the diffusion area is made deep, and W is restrained below D/2. As a result, width H of the area can have a micro size, and the diffusion area can have a desired depth because the impurity concentration is not lowered gradually and is lowered rapidly at the bottom part.