FUNDAMENTALS OF CHEMICAL VAPOR DEPOSITION

This chapter discusses the fundamental aspects of the chemical vapor deposition (CVD) technology combining several scientific and engineering disciplines including thermodynamics, plasma physics, kinetics, and fluid dynamics. CVD is a synthesis process in which the chemical constituents react in the vapor phase near or on a heated substrate to form a solid deposit. A CVD reaction is governed by thermodynamics and kinetics. It may occur in the gas phase instead of at the substrate surface if the supersaturation of the reactive gases and the temperature are sufficiently high. This proves to be detrimental as the gas-phase precipitated particles, in the form of soot, become incorporated in the deposit, causing nonuniformity in the structure, surface roughness, and poor adhesion. A film is formed on a surface by CVD considering three important factors that control the nature and properties of the deposit to some degree. These factors are: epitaxy, gas-phase precipitation, and thermal expansion. The epitaxial CVD of silicon III–V and II–VI compounds is a major process in the semiconductor industry and plays an important part in improving the performance of the semiconductor and optoelectronic designs.