Etch characteristics of TiO ₂ etched by using an atomic layer etching technique with BCI ₃ gas and an Ar neutral beam

The etch characteristics of TiO ₂ etched by using an atomic-layer-etching technique (ALET) with a BCI ₃/Ar neutral beam were investigated. In addition, the surface composition after the etching by using the ALET was compared with that after the etching by using an inductively coupled plasma (ICP). By supplying BCI ₃ gas at partial pressures >0.16 mTorr and by using Ar beam irradiation at doses >1.49 x 10 ¹⁷ atoms/cm ²-cycle, we could obtain a saturated etch rate of 1.25 ̊/cycle (one monolayer /cycle). Therefore, by adjusting the number of etch cycles, we could control the etch depth with atomic precision. When the surface compositions of TiO ₂ after etching by using ALET and by using an ICP were compared, no change of the surface composition was observed for the sample surface after the ALET while a Ti-rich surface was observed after the ICP etching.