ALD Hf0.2Zr0.8O2 and HfO2 with cyclic annealing/SPA plasma treatment: reliability

Abstract

The reliability of atomic layer-deposited Hf0.2Zr0.8O2 and HfO2 on a SiON interfacial layer (IL) with cyclic deposition and annealing (DADA) and cyclic deposition and slot-plane-antenna Ar plasma exposure (DSDS) is studied. The results are compared with control, that is, As-Deposited samples, without any treatment during or after the dielectric deposition. DSDS Hf0.2Zr0.8O2 demonstrates a promising equivalent oxide thickness (EOT) downscaling ability, a reduced gate leakage current, and low mid-gap interface state density as compared to the control device, while DADA Hf0.2Zr0.8O2 has degraded the value of EOT as well as a degraded interface. When devices are subjected to a constant voltage stress in the gate injection mode, DSDS Hf0.2Zr0.8O2 showed a four times reduction in the flat-band voltage shift and a three order of magnitude reduction in the stress-induced leakage current within 100-s stress as compared to the control sample. The observed time to failure, T63%, is the highest for DSDS Hf0.2Zr0.8O2. The addition of Zr and the cyclic plasma exposure (DSDS process) seems to supress the oxide trap formation in Hf0.2Zr0.8O2 films. When DSDS Hf0.2Zr0.8O2 deposited on two different ILs, SiON and plasma oxynitride are compared, in that SiON demonstrates improved reliability as compared to plasma oxynitride.