Overview

Silicon dioxide and silicon nitride are used in a variety of ways in integrated circuit fabrication. Silicon dioxide films are used as gate dielectrics, for device isolation, as the capacitor material in DRAMs, for tunneling oxides in EPROMs and for final passivation, apart from their common use as a masking material. This chapter will focus on the manufacturing challenges for the formation of gate dielectrics such as oxide and nitride on strained layers.

It is well known that the semiconductor industry is on an aggressive scaling program and the device dimensions are expected to shrink as low as 0.18 ?m in 2001, 0.12 ?m in 2004 and 0.10 ?m in 2007. Along with this, power supply voltage has to drop to 1.5 V in 2004 as indicated in table 4.1. The gate dielectric is of key importance in this scaling effort, since it forms the "heart" of n- and p-channel MOSFETs in CMOS technology, and largely determines the performance of the transistors. Gate dielectrics are getting thinner as device dimensions shrink: now about 60 , gate thickness is expected to shrink to about 40 in the next five years.