Issues and Problems Involved in Selective Epitaxial Growth of Silicon for SOI Fabrication

Abstract

In the epitaxial lateral overgrowth (ELO) technique an SOI layer is formed by overgrowing oxide with CVD silicon seeded at the edges of an oxide island on single‐crystal silicon. In the ELO technique conventional epitaxial reactors are used for the production of epitaxial silicon. SOI films have low defect density (compared to other SOI approaches) and wafers supporting the ELO silicon are not warped. Electrical characteristics, such as mobility and lifetime of SOI/ELO films, are similar to homoepitaxial layer grown in the same reactor. In this paper the problems related to ELO and selective epitaxial growth (SEG) are discussed. Our present knowledge will be reviewed on the topics of: defect structure, dependence of the growth rate on pattern geometry, and overgrowth ratio. We will also discuss the electrical characteristics of ELO/ SEG films, with a special emphasis on the interfacial properties (formed by CVD overgrowth). The process used to obtain SOI wafers with a continuous oxide layer underneath a silicon film will be described. The potential and the problems faced in preparing these layers will be discussed.