Unusual room-temperature intermixing and oxidation in copper deposited on a fluorinated amorphous silicon system

Abstract
The room‐temperature behavior of Cu thin films on crystalline and amorphous silicon (c‐Si and a‐Si) substrates was studied by Auger electron spectroscopy. All samples, except Cu/ a‐Si:F, behaved as usual metal on silicon systems. It was found that F greatly enhances Cu‐Si intermixing which proceeds up to the sample surface. After prolonged room‐temperature exposure to air, this system settles into the unusual configuration: Cu/SiO2/a‐Si:F. The effect is explained in terms of the permeability of Cu3Si to oxygen and the low solubility of Cu in SiO2.