pFET Vt control with HfO2/TiN/poly-Si gate stack using a lateral oxygenation process

In this contribution, it is demonstrated that the threshold voltage, V
_t
, of a pFET can be modulated with lateral oxygenation of the HfO
₂
/TiN/poly-Si gate stack from the S/D sidewall after spacer removal. This process can be applied to MIPS (Metal-inserted poly-Si) gate stacks after high-T S/D activation without any additional interfacial layer (IL) growth. Using lateral oxygenation, the pFET V
_t
can be lowerd by ~450 mV yielding a pFET with a V
_t
near band edge (within 250 mV). The shifter 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.