Argon incorporation and silicon carbide formation during low energy argon-ion bombardment of Si(100)

Abstract

Argon incorporation and the formation of silicon carbide in Si(100) by low energy Ar+ ion bombardment have been studied by angle-resolved x-ray photoelectron spectroscopy (XPS). The bombardment was performed at ion energies of 1, 1.5, and 2 keV and various ion fluences in an ultrahigh vacuum chamber equipped with XPS. The XPS measurements showed that the incorporated Ar concentrations achieved saturation in the near-surface region at ion bombardment fluences ≳1016 cm−2. The surface Ar concentrations decreased with increasing bombardment energy. No Ar bubbles on the surface of Ar+-bombarded samples were observed by atomic force microscopy under these experimental conditions suggesting that Ar bubble formation was not the main Ar trapping mechanism in our study. The SiC formation was confirmed by characteristic XPS peaks of Si 2p and C 1s for SiC. The carbide formed at lower ion fluence was of a metastable structure as inferred by XPS. Bombardment at higher ion fluence yielded a stable carbide phase through continuous ion beam mixing. No strong dependence of carbide depth distribution on bombardment energy was observed suggesting that the carbide phase is probably dispersed inside the bombarded layer and that carbon is bonded to silicon at localized defect sites.