Real-time spectroscopic ellipsometric investigation of adsorption and desorption in atomic layer deposition: A case study for the strontium bis(tri-isopropylcyclopentadienyl)/water process

Abstract

The atomic layer deposition (ALD) of SrO thin films from Sr(C5iPr3H2)2 (g) and H2O (g) was studied using real-time spectroscopic ellipsometry (SE) investigations of adsorption and desorption during each half cycle. Adsorption of Sr(C5iPr3H2)2 was self-terminating at deposition temperatures of 150–350 °C and the saturated growth per cycle (GPC) highly depended on the deposition temperature, ranging from 0.05 to 0.33 nm/cycle at the lower and upper limits, respectively. Submonolayer sensitivity of SE was demonstrated by examining changes in the ellipsometric parameters and apparent thickness before and after precursor pulses. A comparison between experimental GPC and available theoretical models demonstrates that the deposition temperature has a marked effect on the reaction mechanism and indicates more than one operation regime for the ALD process of Sr(C5iPr3H2)2 and H2O.