Effects of post-deposition annealing temperature and atmosphere on interface properties in ALD Al2O3/plasma oxidation GeO x /(111) and (100) n-Ge MOS structures

Abstract

In this work, the effects of post-deposition annealing (PDA) on Al2O3/GeO x /(111) and (100) n-Ge structures are experimentally studied with changing annealing temperatures from 300 °C to 650 °C in a vacuum, N2 and O2 atmosphere in order to clarify the stability of the MOS interface properties under high-temperature annealing. A decrease in D it and an increase in the oxide capacitance with increasing PDA temperature is observed up to 500 ∼ 600 °C, depending on the annealing atmosphere and surface orientation. The minimum D it of ∼3 × 1011 eV−1cm−2 is achieved for (111) Ge after PDA at 550 °C and 600 °C in N2/O2 or vacuum. This trend is similar to the (100) MOS interfaces and a similar amount of minimum D it is obtained. These results suggest that the present Al2O3/GeO x /Ge interfaces are suitable for the formation of the Ge-On-insulator (GOI) back interfaces by the wafer bonding process in the Smart-cut, where high-temperature annealing is indispensable.