(Invited) Border Trap Density in Al2O3/InGaAs MOS: Dependence on Hydrogen Passivation and Bias Temperature Stress

Abstract

We report on the role of hydrogen (forming gas) post-metal annealing to passivate border traps in Al2O3/In0.53Ga0.47As (100) gate stacks and of bias temperature stress treatments to generate/depassivate such traps. Experiments are carried out with Pd metal gates that efficiently dissociate molecular hydrogen during forming gas annealing, and they make use of InGaAs epitaxial layer substrates that are capped with arsenic after completion of their growth, to avoid unintentional oxide formation and disorder at the channel surface prior to atomic layer deposition of the Al2O3 gate dielectric. We find that forming gas anneal (FGA) greatly reduces both the interface trap density and border trap density measured in the gate stacks, but that the effectiveness of FGA for border trap passivation saturates for anneals with thermal budgets greater than 450°C/30 min. Both negative and positive bias temperature stress treatments are found to have no effect on the extracted border trap densities compared to non-treated capacitors.