Hafnium-based high-k dielectrics

Hafnium-based high-K dielectrics such as HfO₂, HfON and HfSiON have attracted a great deal of attention because of their potential for successful integration into CMOS technology. However, channel mobility degradation, charge trapping and reliability are major concerns. In this paper, we review our recent research results, namely, the charge trapping characteristics, the effects of nitrogen on minority carrier lifetime and channel mobility, and Hf-Ti-O dielectrics. We have investigated how N affects the minority carrier lifetime in the Si substrate and how it relates to μ_eff. A new dielectric stack consists of TiO₂/HfO₂ bi-layer has shown improved thermal stability and increased K value (thus scaled EOT < 1.0nm) without the disadvantages of incorporated N.