Effective reduction of fixed charge densities in germanium based metal-oxide-semiconductor devices

摘要

Metal-oxide-semiconductor capacitor was fabricated using in situ O_2 plasma passivation and subsequent deposition of a HfO_2 high-k gate stack on Ge. By extracting flat band voltages from capacitors with different equivalent oxide thicknesses (EOT), the effect of forming gas annealing (FGA) and O_2 ambient annealing on the fixed charge was systematically investigated. The O_2 ambient annealing is more effective than FGA as it reduced fixed charge density to 8.3×10~(11) cm~(-2) compared to 4.5×10~(12) cm~(-2) for at the same thermal budget and showed no degradation of EOT. Further, the distribution of fixed charges in gate stack was discussed in detail.