Mechanism of Gm degradation and comparison of Vt instability and reliability of HfO2, HfSiOx and HfAlOx gate dielectrics with 80 nm poly-Si gate CMOS

To achieve a lower gate leakage in high speed devices at the same equivalent oxide thickness, a major thrust is to replace the SiO₂ with a thicker dielectric that has a higher dielectric constant. Recently, there has been much interest in hafnium dioxide as a potential high-k gate dielectric as presented in E. P Gusev et a. (2001), B. Barlage et al. (2001), G. Wilk et al. (2001), C. Hobbs et al. (2001), W. Zhu et al. (2001), W. Qi et al. (2000) and B. Lee et al. (1999) due to its high permittivity. However, the polycrystalline microstructure may be undesirable. In order to increase the crystallization temperature, SiO₂ or Al₂O₃ are added to HfO₂ to form Hf silicates atid Hf aluminates. A systematic study to compare the device characteristics of these three major candidates is needed. In this work, we have compared them in terms of the key challenges of high-K devices such as Gm degradation, Vt instability, and reliability, in devices fabricated with a conventional CMOS process technology according to A. Perera et al. (2000).