Record PMOS WSe₂ GAA Performance Using Contact Planarization, and Systematic Exploration of Manufacturable, High-Yield Contacts

Two-dimensional (2D) transition metal dichalcogenides (TMDs) hold significant promise for both front-end-of-line (FEOL) and back-end-of-line (BEOL) applications. Here, we report new approaches to contact formation in global back gate 2D PMOS transistors using a manufacturable physical vapor deposition (PVD) sputtering process. We present a systematic study of novel sputtered contacts (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{Sb} / \text{Pt}, \text{Sb}_{2} \text{Te}_{3}$</tex>, <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{Bi}_{2} \text{Te}_{3}$</tex>) to multilayer <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{WSe}_{2}$</tex> and through statistical analysis we discover trends of increasing performance with Pt thickness and post-metal anneal. Optimized conditions give <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{R}_{\mathrm{C}}$</tex> down to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$1.3 \mathrm{k} \Omega. \mu \mathrm{m}$</tex> at <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{N}(\text{inv})=1 \mathrm{e} 13 \text{cm}^{-2}$</tex> and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{I}_{\mathrm{d}, \max }=212 \mu \mathrm{A} / \mu \mathrm{m}$</tex> at <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{V}_{\mathrm{d}} =-1 \mathrm{V}$</tex>, the highest performance to date using sputtered contacts. Further, we pioneer a new approach to contact-first gate-allaround (GAA) schemes through contact planarization using chemical mechanical polishing (CMP). This first-of-kind CMP flow demonstrates significant performance gains over non-CMP contacts (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$4 \times$</tex>). CMP Ru contacts to monolayer <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{WSe}_{2}$</tex> GAA devices achieve record drive currents <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$&gt;600 \mu \mathrm{A} / \mu \mathrm{m}$</tex> and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{SS}=132 \text{mV} / \text{dec}$</tex>.