Impact of Al-based Dipole Formation on Gate Stack Integrity and Reliability

Combining experimental methods and multi-scale modeling we untangled the mechanism underlying the dipole formation and captured their impact on reliability through Carrier Injection (CI) model for HKMG under negative stress voltages. Simulations unveil the existence of a trade-off between dipole-induced VFB shift and device reliability metrics (leakage, breakdown). We show that: i) Al diffusion scavenges interface layer (IL) inducing <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{Vo}^{+}$</tex> defects that increase gate leakage current; ii) IL scavenging increases with Al content; iii) stress-induced defects at HK play a major role in triggering breakdown. Finally, we show that <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$4 \mathrm{A}$</tex> is the optimal Al dipole layer thickness which doesn't impact stack's integrity and device's reliability.