Channeling-Effect Analysis of Thin Films on Silicon: Aluminum Oxide

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Abstract
The stoichiometry of films of aluminum oxide deposited hydrolytically onto silicon substrates has been measured by using 2-MeV He-ion backscattering techniques. Oxygen to aluminum ratios of 1.5±0.1 are found for all films grown in the temperature range 600–830°C, despite marked differences in chlorine content and physicochemical properties. The procedures used for extracting line shapes for the two components (aluminum and oxygen) are shown to be generally applicable to many thin film systems. In the particular case of a thin amorphous film overlying a crystalline substrate, channeling effects in the substrate permit a direct determination of the individual line shapes contributing to the total backscattered particle spectrum. Examples are given for stoichiometry tests of amorphous films of aluminum oxide and silicon oxide on silicon-crystal substrates. The composition of thin films of silicon-metal alloys may be measured by the same procedure as illustrated by studies of chromium-silicide formation on silicon substrates. Alternative procedures are discussed for the case of thin films on noncrystalline substrates.