Atomic layer deposition of HfO2 gate dielectric with surface treatments and post-metallization annealing for germanium MOSFETs

摘要

HfO₂ gate dielectric is fabricated by atomic layer deposition on an n-type germanium (Ge) substrate to form p-type Ge MOS capacitors. Three solution-based chemical treatments of the Ge surface using propanethiol, octanethiol and (NH₄)₂S solutions respectively as well as post-metallization annealing are investigated to improve the interface quality of HfO₂ gate dielectric on the Ge substrate. Experimental results show improvement in the electrical characteristics of the Ge MOS devices with a 20-nm HfO₂ gate dielectric. In particular, the gate leakage current density is improved by one order of magnitude using the straightforward processing techniques.