Adsorption and Decomposition of Diethylsilane on Silicon Surfaces

Abstract

ABSTRACTDiethylsilane (DES), Si(C2H5)2H2, is a promising candidate for the atomic layer epitaxy of silicon. The adsorption and decomposition kinetics of DES on silicon surfaces were studied using laser-induced thermal desorption (LITD), temperature programmed desorption (TPD), and Fourier transform infrared (FTIR) spectroscopy. FTIR studies on porous silicon surfaces indicated that DES dissociatively adsorbs below 600 K and produces Si-H and Si-C2H5 surface species. The desorption products following DES adsorption on Si(111) 7×7 were C2H4 and H2 for all surface coverages using both LITD and TPD techniques. Ethylene and H2 desorption occurred at 700 and 810 K, respectively, during TPD experiments with a heating rate of β = 9 K/s. Ethylene desorption was consistent with a β-hydrogen elimination mechanism from the Si-C2H2 surface species. Isothermal LITD studies monitored the desorption kinetics of C2 H4 from Sl (111) 7×7 as a function of time following DES exposures. The first-order ethylene desorption kinetics were Ed = 36 kcal/mol and vd = 2.7 × 109 s−1. Additional LITD measurements determined that le initial reactive sticking coefficient of DES on Si(111) 7×7 decreased versus surface temperature. The temperature-dependent sticking coefficients suggested a precursormediated adsorption mechanism.