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 HfO₂/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.