Reduction of random telegraph noise in High-к / metal-gate stacks for 22 nm generation FETs

This work demonstrates, for the first time, the reduction of random telegraph noise (RTN) in high-κ/metal gate (HK/MG) stacks incorporated in 22 nm generation FETs. Many thousands of such FETs have been fabricated, measured, and analyzed using a statistical technique to separate RTN as a major noise component from 1/f noise as a minor component. Based on a statistical comparison of these FETs, we find that high temperature forming gas annealing can suppress RTN threshold voltage variation (ΔV_th). In addition, properly annealed HK FETs have smaller RTN ΔV_th than SiON FETs, due mostly to fewer traps and partly to thinner inversion thickness in HK/MG. Based on these results, we project that random dopant fluctuations will have a greater impact on SRAM yield than RTN until at least the 15 nm generation, for doped channel FETs.