Influence of Heat Treatment on Aluminum Oxide Films on Silicon

Abstract

Properties of aluminum oxide films deposited on silicon by hydrolysis of AlCl3 depend on the growth temperatures. The influence of subsequent heat treatments on the film properties and structures have been investigated in films grown at 700 and 830°C. Etch rates and electron-diffraction patterns indicated that the properties of the films grown at 700°C were not converted to those of the 830°C-grown films even after the heat treatment at 900°C in argon. The amount of residual chlorine in low-temperature films determined by MeV He+ ion backscattering technique, reduced from 2 to 0.9 at.% after the heat treatment at 900°C but still exceeded that (≲0.02 at.%) for the film deposited at 830°C. A small amount of silicon (5 at.% at the surface) diffused through the films deposited at 700°C after the heat treatment at 900°C. In contrast, the 830°C-deposited film did not change following the heat treatment at 900°C in argon atmosphere. Comparisons between the backscattering data obtained from the films treated under oxidizing conditions and those from reference standards indicated oxygen migration through aluminum oxide and growth of an oxide film underneath the aluminum oxide. In addition, at least a part of the new-formed oxide appeared to be comprised of a mixture of aluminum, silicon, and oxygen.