In situ infrared spectroscopy study of the interface self-cleaning during the atomic layer deposition of HfO_2 on GaAs(100) surfaces

摘要

In situ attenuated total reflectance Fourier transform infrared spectroscopy was utilized to study the interface evolution during the atomic layer deposition (ALD) of HfO_2 on GaAs surfaces using of tetrakis (dimethylamino) hafnium and H_2O. The experiments were performed on chemical oxide and hydrogen fluoride etched GaAs(100) starting surfaces. For the deposition of HfO_2 on chemical oxide GaAs surfaces at 275 ℃, which corresponds to the optimal ALD process temperature, continuous arsenic oxide removal was observed for the first 20 ALD cycles. The oxide removal was more pronounced at the initial 1-2 cycles but nonetheless persisted, at a reduced rate, up to the 20th cycle. The substrate temperature was confirmed to affect the arsenic oxide removal; the rate was significant at temperatures above 250 ℃ while negligible below 200 ℃.