pFET V _t control with HfO ₂/TiN/poly-Si gate stack using a lateral oxygenation process

Abstract

In this contribution, it is demonstrated that the threshold voltage, V t, of a pFET can be modulated with lateral oxygenation of the Hf0 2/TiN/poly-Si gate stack from the S/D sidewall after spacer removal. This process can be applied to MIPS (Metal-inserted polySi) gate stacks after high-T S/D activation without any additional interfacial layer (IL) growth. Using lateral oxygenation, the pFET V t can be lowered by ∼450 mV yielding a pFET with a V t near band edge (within 250 my). The shifted V t is found to be stable during MOL/BEOL processing and the lateral oxygenation process does not degrade NBTI. Since V t control is achieved with lateral oxygen diffusion, a channel length, L, dependence of V t is observed. The L-dependence can be reduced by process optimization.