ETHANOL DECOMPOSITION ON SI(100) - ALTERATION OF REACTION CHANNELS WITH COADSORBED HYDROGEN

Tetraethoxysilane (TEOS) is one of the most often used sources for the low pressure chemical vapor deposition (LPCVD) of silicon dioxide fil ms in the electronics industry because it can yield conformal films ev en for highly corrugated substrates. Our previous studies have shown t hat ethanol can model, to a large extent, the adsorption and thermal d ecomposition of TEOS on both Si(100) and porous SiO2 surfaces. In part icular, on the Si(100) surface, after the initial reactive adsorption of either precursor gas, the subsequent thermal decomposition in vacuu m of both systems primarily leads to the desorption of ethylene, hydro gen, acetylene, and acetaldehyde. Using temperature programmed desorpt ion mass spectrometry (TPD), we have studied the effects of preadsorbe d H on the CH3CD2OH adsorption and decomposition on Si(100). Two major effects are observed in this coadsorption system. Firstly, the ethano l reactive adsorption level is perturbed by the preadsorption level of atomic hydrogen. Secondly, the relative yields among various desorpti on channels are altered. Specifically, at increasing level of H-preads orption, the production of acetylene and hydrogen is suppressed; while the production of acetaldehyde is enhanced.