Comparative analysis of ferroelectric domain wall motion under cycling stress of HfZrO2 fabricated by thermal and plasma-enhanced atomic layer depositions

초록

Ferroelectric HfZrO2 (HZO) formed by atomic layer deposition (ALD) has been widely studied due to its composition control of material contents and stable ferroelectric properties. However, the effect of various ALD methods on ferroelectric switching dynamics has not been thoroughly investigated. We conduct a comparative study on the differences in ferroelectric (FE) domain wall motion under electrical cycling stress between two ALD methods: thermal ALD (THALD) and plasma-enhanced ALD (PEALD). The extraction of activation energy from fatigue rate and FE switching speed analysis results shows that PEALD HZO has inherent defects during the deposition step, and the FE switching speed of PEALD HZO degraded faster under cycling stress than that of THALD HZO. XPS analysis results show that under cycling stress, oxygen vacancies are formed faster in PEALD than in THALD HZO. Furthermore, dynamic domain phase analysis shows that the electric fields required for switching in the relaxation to creep (E-1) change in THALD HZO by +46%, while the electrical fields required for the transition from creep to flow (E-2) rarely change under the cycling stress. However, E-1 and E-2 values of PEALD HZO change by +19% and -10%, respectively, depending on the cycling stress.

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