ALD Hf_0.2Zr_0.8O₂ and HfO₂ with cyclic annealing/SPA plasma treatment: Reliability

The reliability of atomic layer-deposited Hf_0.2Zr_0.8O₂ 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 Hf_0.2Zr_0.8O₂ 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 Hf_0.2Zr_0.8O₂ 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 Hf_0.2Zr_0.8O₂ 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, T_63%, is the highest for DSDS Hf_0.2Zr_0.8O₂. The addition of Zr and the cyclic plasma exposure (DSDS process) seems to supress the oxide trap formation in Hf_0.2Zr_0.8O₂ films. When DSDS Hf_0.2Zr_0.8O₂ deposited on two different ILs, SiON and plasma oxynitride are compared, in that SiON demonstrates improved reliability as compared to plasma oxynitride.