Monolithic 3-D Self-Aligned Heterogeneous Nanosheet Channel Complementary FETs With Matched <i>V</i>T by Band Alignments of Individual Channels
Wan-Hsuan Hsieh, Chien-Te Tu, Yu-Rui Chen, Bo‐Wei Huang, Wei-Jen Chen, Yi‐Chun Liu, Chun-Yi Cheng, Hung-Chun Chou, C. W. Liu
Abstract
Monolithic 3-D stacked Ge0.9Sn0.1 nanosheet and Ge0.75Si0.25 nanosheet complementary FETs with multiple P/N junction isolation by in-situ doped CVD epitaxy are experimentally demonstrated. Heterogeneous channels with common single work function metal (WFM) gate structure are fabricated as a CMOS inverter with the matched <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {T}}$ </tex-math></inline-formula> and good voltage transfer characteristics (VTCs). <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {T}}$ </tex-math></inline-formula> tuning is achieved individually by the band alignment of GeSi and GeSn for n-channel and p-channel, respectively, for the first time. The Hf0.2Zr0.8O2 gate stacks with extremely high <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\boldsymbol {\kappa } $ </tex-math></inline-formula> of 47 are integrated to enhance the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${I}_{\text {ON}}$ </tex-math></inline-formula> of complementary FET (CFET) for high performance. The monolithic stacked heterogeneous CFETs without the need of wafer bonding, dielectric isolation, selective epitaxial growth, and dual WFM can simplify the process for transistor 3-D stacking.