Shifter Materials and Stack Explorations for $V_{t}$ Fine-Tunable Dual Dipole Multi-$V_{t}$ Gate Stacks Compatible with Low Thermal Budget CFET

We report ALD processes, shifter stack and materials for dual dipole multi-<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{V}_{\mathrm{t}}$</tex> gate stacks having a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{V}_{\mathrm{t}}$</tex> fine tunability and compatibility with a low thermal budget RMG. EOT penalty of dipole-first stack is mitigated by the choice of ALD oxidant, q-time control and the use of a less hygroscopic shifter material. Based on the observed impact of silicate formation on La dipole magnitude and reported dipole models, fine tunable <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{n} / \mathrm{p}$</tex>-type dipole gate stacks are demonstrated via (a) buffer <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{HfO}_{\mathrm{x}}$</tex> and (b) <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{HfO}_{2}$</tex> and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{ZrO}_{2}$</tex> high- <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$k$</tex> shifters.