Low-contact resistance poly-metal gate electrode using TiN/thin TiSi2/poly-Si structure

A low-contact resistance poly-metal gate system consisting of TiN/thin TiSi2/poly-Si is described. A poly-metal gate is one of the candidates for the next generation of metal-oxide-semiconductor field effect transistor (MOSFET) gate structures. The characteristics between the barrier metal and the poly-Si are important in achieving a high-performance poly-metal gate structure. In this study, the inserting of a thin TiSi2 layer between the TiN and the poly-Si produced a low-contact resistance between the TiN and the poly-Si, which was an acceptable improvement. The thinner the inserted TiSi2, the lower the contact resistance. In n- and p-channel MOSFETs with a TiN/TiSi2 (5 nm)/poly-Si gate structure having a gate oxide thickness of 4 nm, the lateral diffusion of the gate dopant was suppressed. This occurred because the inserted TiSi2 was thin enough to prevent the gate dopants from moving through the TiSi2.