ARGON INCORPORATION AND SILICON-CARBIDE FORMATION DURING LOW-ENERGY ARGON-ION BOMBARDMENT OF SI(100)

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 ultr ahigh vacuum chamber equipped with XPS. The XPS measurements showed th at the incorporated Ar concentrations achieved saturation in the near- surface region at ion bombardment fluences >10(16) cm(-2). The surface Ar concentrations decrease with increasing bombardment energy. No Ar bubbles on the surface of Ar+-bombarded samples were observed by atomi c force microscopy under these experimental conditions suggesting that Ar bubble formation was not the main ?rr trapping mechanism it, our s tudy. The SiC formation was confirmed by characteristic XPS peaks of S i 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 f luence yielded a stable carbide phase through continuous ion beam mixi ng, No strong dependence of carbide depth distribution on bombardment energy was observed suggesting that the carbide phase is probably disp ersed inside the bombarded layer and that carbon is bonded to silicon at localized defect sites. (C) 1996 American Institute of Physics.