Fundamentals of Chemical Vapor Deposition (CVD) and Atomic Layer Deposition (ALD) and Safety Management of Chemical SubstancesPart 5 : Atomic Layer Deposition (ALD) Methods, Digital CVD Methods

Abstract

Atomic layer deposition (ALD) methods are attracting attention because these can achieve surface reactions by chemically reacting only with raw material molecules adsorbed to solid surfaces. Two highly chemically reactive raw material gases are injected alternately, and a vacuum is drawn between them to suppress spatial reactions. Because the films are fabricated by repeated adsorption and reaction of the raw materials, the film deposition rates are extremely slow. However, because the manufacture of modern functional devices requires the deposition of nanometer-level films on highly uneven substrates, the slow film deposition rates are no longer seen as a drawback, but rather as an advantage in terms of film thickness control.