Controlling interfacial reactions between HfO2 and Si using ultrathin Al2O3 diffusion barrier layer

The authors investigated the effectiveness of atomic layer deposited (ALD) aluminum oxide barrier layer in controlling the interfacial reaction between ALD HfO2 film and Si substrate. The HfO2 was observed to form silicate and silicide at its interface with Si during 5min postdeposition annealing in Ar at 800 and 1000°C. A 0.5-nm-thick Al2O3 barrier layer was found to control interfacial reactions between HfO2 and Si during annealing at 800°C, but not at 1000°C, whereas a 1.5-nm-thick barrier of Al2O3 was needed to prevent interfacial reaction up to an annealing temperature of 1000°C.