Atomic layer deposition of HfO 2 gate dielectric with surface treatments and post-metallization annealing for germanium MOSFETs

HfO 2 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 (NH 4 ) 2 S 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 HfO 2 gate dielectric. In particular, the gate leakage current density is improved by one order of magnitude using the straightforward processing techniques.