Monosilane adsorption and initial growth stages of silicon layers on the (100) and oxidized silicon surfaces: Ellipsometric investigation

Abstract Monosilane adsorption kinetics on (100) and oxidized silicon surfaces has been studied by means of a fast-response ellipsometer. Monosilane adsorption on the (100) silicon surface is irreversible and has no activation barrier in the temperature range 20–500°C. Condensation coefficients of SiH 4 for the closed and the flowing adsorption technique are σ = 7 × 10 − and 5 × 10 −2 , respectively. The thickness of the adsorption layer increases in the temperature range 125–350°C which is evidence for the formation of a surface supermonolayer coverage. At T > 350°C decomposition of adsorption complexes takes place, accompanied by hydrogen desorption. This process is characterized by an activation energy of E = 44 ± 2 kcal/mol. Monosilane is adsorbed reversibly on the oxidized silicon surface in the temperature range 350–490°C and at a pressure of P −2 Torr. At pressure P > 5 × 10 −2 Torr adsorption complexes decompose and amorphous silicon grows. The growth rate is directly proportional to the monosilane pressure in the gas phase and increases with increasing temperature; the activation energy of this process is E = 56 ± 6 kcal/mol. The analysis of the kinetic curves indicates that the growth of amorphous silicon is a chain process at the initial stage.