Low-temperature Hf-silicate prepared with various thermal budgets

Abstract

In this study, the influence of thermal budget on preparing hafnium silicate (HfSiO) and metal–insulator–semiconductor (MIS) structures with tetragonal hafnium oxide (HfO2) films was investigated. Amorphous silicon (a-Si) was used as a sacrificial layer for HfSiO formation. Rapid thermal annealing (RTA) could efficiently drive the oxidation of a-Si with HfO2. The RTA-produced HfSiO film thicker than that produced through furnace annealing could suppress gate leakage in MIS devices, and aid in maintaining a high dielectric constant of the gate insulator. The combination of sacrificial a-Si film use and RTA application resulted in a HfSiO/HfO2 structure (named as hybrid HfO2), which demonstrated a high dielectric constant and strength (29.5 and 21.2 MV cm−1, respectively). MIS devices integrated with this hybrid HfO2 achieved a hysteresis value of only 0.11 V on a flat-band voltage measured at a 50 mV s−1 sweep rate with an applied voltage between −5 and 5 V.