Process development, characterization, transient relaxation, and reliability study of hafnium oxide and hafnium silicate gate oxide for 45nm technology and beyond

In this research, process development, characterization and reliability study of HfO2 and its silicate have been performed. It has been observed that both nitrogen (N) and chlorine (Cl) have significant effect in improving the device performances. Incorporation of nitrogen by NH 3 post-deposition anneal reduced EOT (effective oxide thickness), and improved device characteristics, like Id-Vg, I d-Vd characteristics, and mobility. On the other hand, surface nitridation using NH3 was found to be an effective way to aggressively scale down the EOT. Moreover, Cl treatment using precursor, HfCl4 pulse time variation in ALD (atomic layer deposition) HfO2, and using HCl as high-k post deposition rinsing element, both mobility and bias instabilities of high-k oxides could be improved.; Reliability of Hf-based oxide could be improved by compositionally varying HfSixOy structure. Fabricating Hf-silicate with low composition of Si on top of Hf-silicate with high composition of Si not only enhanced the device performance, but also improved the reliability characteristics. Furthermore, insertion of Si in the HfOxNy dielectric was found to be an effective way to improve device performance and reliability. At the end, a novel approach in understanding the breakdown mechanism of HfO 2 has been proposed by stress-anneal experiments. It was found that accumulation of holes is primarily responsible for breakdown of HfO2 under substrate injection condition. An appropriate model has also been proposed along with supporting experimental data.; Considering all of the process development, characterization and reliability studies made in this research, it can successfully be asserted that high-k gate oxide can be proposed as a viable and promising candidate for 45nm technology and beyond. But still careful attention need to be taken to resolve remaining intrinsic and extrinsic issues in high-k gate oxide. (Abstract shortened by UMI.)...