Fabrication of a Si_1-xGe_x Channel Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) Containing High Ge Fraction Layer by Low-Pressure Chemical Vapor Deposition

Abstract

A method for growing the high-quality strained epitaxial heterostructure of Si/Si 1- x Ge x /Si by low-pressure chemical vapor deposition (CVD) and the fabrication of Si 1- x Ge x -channel metal-oxide-semiconductor field-effect transistors (MOSFET's) with a high Ge fraction layer have been investigated. It is found that lowering of the deposition temperature of the Si 1- x Ge x and Si capping layers is necessary with increasing Ge fraction in order to prevent island growth of the layers. With the use of the optimized fabrication process, Si/Si 1- x Ge x /Si heterostructures with flat surfaces and interfaces were realized, and a high-performance Si 0.5 Ge 0.5 -channel MOSFET has been achieved with a large mobility enhancement of about 70% at 300 K and over 150% at 77 K compared with that of a MOSFET without a Si 1- x Ge x channel.