Thermal atomic layer etching (ALEt) of amorphous Al2O3 was performed by alternate exposures niobium pentafluoride (NbF5) and carbon tetrachloride (CCl4). The ALEt is observed at temperatures from 380 to 460 °C. etched thickness the etch rate were determined using spectroscopic ellipsometry verified X-ray reflectivity. maximum about 1.4 Å/cycle a linear increase removed film with number cycles o...