Rapid thermal anneal of gate oxides for low thermal budget TFT's

The performance and reliability of deposited gate oxides for thin film transistors (TFT's) has been studied as a function of rapid thermal annealing (RTA) conditions. The effect of temperature ranging from 700 to 950°C and the annealing ambients including oxygen (O₂), argon (Ar), and nitrous oxide (N₂O) is investigated. Improvement in charge to breakdown (Q_bd) is seen starting from 700°C, with marked increase at 900°C temperature and above. The N₂O and Ar ambients result in higher Q_bd compared to O₂ ambient and we attribute this to reduced interfacial stress. Fourier Transform Infrared spectroscopy (FTIR) is used to qualitatively measure the stress. The bias temperature instability is decreased by RTA. The TFT characteristics are significantly improved with RTA gate oxide. The RTA-Ar anneal at 950°C results in the lowest trap density in TFT's as measured from charge pumping technique