Gate oxide integrity (GOI) of MOS transistors with W/TiN stacked gate

With W/TiN stack gate deposited at high temperature, excellent TDDB characteristics of gate oxide are obtained on MOS capacitors. In case of negative gate bias where thin oxide reliability becomes critical, TiN gate provides much longer time to breakdown than that of n+poly gate due to larger barrier height and less F-N tunneling current. In spite of skipping conventional reoxidation process, breakdown field larger than 10MV/cm could be obtained in MOS transistors by undercutting TiN with H₂SO₄ boiling. With double spacer and undercutting scheme, the short channel effect of NMOS and PMOS transistors could be suppressed up to L_gateapprox.0.3 μm.