Reliability improvement of Ge pMOSFETs with Al2O3 dielectric by ozone post annealing

Al
₂
O
₃
films deposited as gate dielectrics on germanium (Ge) by atomic layer deposition (ALD) were post annealed in an ozone atmosphere at 450°C for 15, 25 and 35 minutes. The structure and chemical compound of Al
₂
O
₃
/Ge gate stacks were detected by X-ray photoelectron spectroscopy (XPS) measurements after ozone post annealing (OPA) treatments. It is confirmed by XPS measurements that this OPA treatment could significantly decreases the amount of oxygen deficiencies in Al
₂
O
₃
films, resulting in better insulating property. By using these Al
₂
O
₃
/Ge gate stacks, the Ge pMOSFETs were successfully demonstrated. The results show that OPA treatment could enhance the low field mobility and meanwhile improve the breakdown behaviors of Ge pMOSFETs.