5.1 INTRODUCTION

Silicon-on-insulator has gone far in substantiating its early promise in semiconductor technology. Mainstream computer and data processing products are available, and many more are in development [1]. SOI material continues to evolve to meet the needs of each new technology generation. Two types of starting substrate material have emerged from a larger list of early candidates: SIMOX and bonded SOI, and both continue to show great promise. Of the two, SIMOX manufacturing technology exhibits greater flexibility. The buried oxide (BOX) and superficial Si layer thicknesses are easily modified by changes in the implantation energy, the dose of implanted oxygen atoms, and the annealing atmosphere and time schedule. (Details of SIMOX development and manufacturing are discussed in Chapter 6 of this volume by D. Sadana.) However, unlike bulk silicon starting material, in which wafer to wafer, ingot to ingot, and manufacturer to manufacturer consistency and uniformity have been established by many years of development, SOI material still exhibits a great deal of variability.

This evolutionary nature of SOI development has both advantages and disadvantages. On one hand, the material can be tailored to fit the needs and requirements of each new technology node. The SIA Roadmap for Semiconductors [2] describes in detail how the Si and BOX thicknesses, surface roughness, background metal content, and many other material properties must be changed (improved) if the advances in performance, power requirements, device density etc. expected for future technology generations are to be realised. The flexibility of SOI material manufacturing...