Handbook of Silicon Based MEMS Materials and Technologies

Chapter Seven. Thick-Film SOI Wafers - Preparation and Properties

7.1. Introduction

Silicon-on-insulator (SOI) is a semiconductor structure consisting of a layer of single crystalline silicon separated from the bulk substrate by a thin layer of insulator. In SOI wafers the insulator is almost invariably a thermal silicon oxide (SiO²) layer, and the substrate is a silicon wafer. Depending on the type of application, the silicon film can be very thin (< 50 nm for fully depleted transistors), or it can be tens of micrometers thick. Likewise, the buried oxide thickness ranges from tens of nanometers to several micrometers. Manufacturing methods of wafers vary accordingly. Silicon-on-sapphire (SOS) is another SOI technology that has some further advantages ...