TEM Analysis of Defects in Simox Silicon-On-Insulator Material

Abstract

Abstract Silicon-on-Insulator is the leading technology for VLSI fast speed processors and low voltage applications. SIMOX (Separation by Implantation of Oxygen) is a subset of SOI with a high quality top silicon layer onto which VLSI circuitry is placed. SIMOX processing begins with a high energy, high current implantation of a large dose of O+ ions to penetrate the wafer’s surface to form the buried oxide and top silicon layers. This implantation creates numerous precipitates and a large damage region. Therefore a multi-step anneal is used to improve the quality of the top silicon layer by significantly reducing precipitate and dislocation densities, to create smooth interfaces, and to remove any ion residual damage. Using TEM, this study traces the defect formations through the various processing steps, with the objective to arrive at device quality. The SIMOX wafers were implanted with an oxygen ion implant dose of 5xl017cm−2, and then subjected to multiple implantation and anneal steps, bringing the final oxygen ion dose to 1.5xl018cm−2[1].