Performance enhancement of Poly-Si/TiN/SiON based pMOSFETs by addition of an aluminum oxide (AlO) capping layer

We investigate the influence of aluminum oxide (AlO) capping on SiON on the threshold voltage and Ion of Poly-Si/TiN gated pMOSFETs. The AlO capping resulted in threshold voltage (VT) reduction and improvement in drive current (Ion) for Poly-Si/TiN/ gated pFETS. The AlO capping on SiON also improved the interface quality making the gate stack more thermally stable. The leakage and reliability characteristics for the Poly-Si/AlO/SiON stacks are evaluated and compared with the uncapped Poly-Si/TiN/SiON reference. The AlO capping resulted in two orders of magnitude decrease in leakage at the same capacitance equivalent thickness (CET) compared to the un-capped Poly-Si/TiN/SiON reference. The AlO capping also resulted in improvement lifetime compared to the un-capped Poly-Si/TiN/SiON reference.