Extremely High-κ Hf0.2Zr0.8O2 Gate Stacks Integrated Into Eight Stacked Ge0.95Si0.05 Nanowires and Nanosheets nFETs to Boost ION

By taking advantage of extremely high dielectric constant ( $\kappa $ ) of 47, the Hf0.2Zr0.8O2 gate stacks are integrated into the eight stacked high mobility Ge0.95Si0.05 channels with low thermal budget ( $\leqq 450$ °C) to significantly enhance the ${I} _{ \mathrm{\scriptscriptstyle ON}}$ . Isotropic wet etching by $\text{H}_{{2}}\text{O}_{{2}}$ and HNO3 serve well during the channel release of nanowires and nanosheets, respectively. The simulated $\kappa $ versus Zr concentration in HZO can show that the $\kappa $ can have a peak value at Zr concentration around 80%. The eight stacked Ge0.95Si0.05 nanowires and nanosheets with Hf0.2Zr0.8O2 gate stacks achieve the record high ${I} _{ \mathrm{\scriptscriptstyle ON}}$ per footprint of $9200~\mu \text{A}$ and record high ${I} _{ \mathrm{\scriptscriptstyle ON}}$ per stack of $360~\mu \text{A}$ at ${V} _{\text {OV}} ={V}_{\text {DS}}$ = 0.5 V, respectively, among all Si/GeSi/Ge 3-D nFETs. Moreover, the potential gate delay improvement by combining the extremely high- $\kappa $ gate stacks and large floor number is studied by TCAD simulation using industrial device structures.