SOI SUBSTRATE AND PROCESS FOR PREPARING THE SAME, AND SEMICONDUCTOR DEVICE AND PROCESS FOR PREPARING THE SAME

摘要

In growing a silicon layer on a sapphire substrate to prepare an SOS substrate, or alternatively in depositing an oxide layer or a fluoride layer as an intermediate layer on a silicon substrate followed by the growth of a silicon layer on the intermediate layer to prepare an SOI substrate, heat treatment is carried out in an oxidizing atmosphere after the growth of the silicon layer to oxidize a part of the silicon layer on its surface side followed by the removal of the silicon oxide layer by etching and the residual silicon layer is used as a seed layer to conduct homoepitaxial growth again, or heating is carried out in a hydrogen atmosphere after or in the course of the growth of the silicon layer. This process can provide an SOS substrate or an SOI substrate which is free from defects and has high crystallinity, high orientation and small surface roughness.