A novel approach for leakage current reduction of LPCVD Ta₂O₅ and TiO₂ films by rapid thermal N₂O annealing

摘要

Rapid thermal N₂O annealing (RTN₂O) has beenapplied to reduce the leakage current in the Ta₂O₅and TiO₂ thin films (100-200 Å) prepared bylow-pressure chemical vapor deposition (LPCVD) for the first time. Amongthree different post-deposition annealing conditions compared: (a)800° C rapid thermal O₂ annealing (RTO) for 60 sec, (b)800° C furnace O₂ annealing for 30 min and (c) 800° CRTN₂O for 60 sec, RTN₂O has resulted the lowestleakage current and best time-dependent dielectric breakdown (TDDB)characteristics in Ta₂O₅ films. However, furnace O₂ annealing produces the lowest leakage in LPCVD-TiO₂ films. An increase in RTN₂O temperature above800° C decreases both high field leakage current and the effectivedielectric constant. It also induces a low-field leakage current due tothe reaction between high dielectric constant materials and the bottomelectrode