Low-resistivity poly-metal gate electrode durable for high-temperature processing

A new low-resistivity poly-metal gate structure, W/WSiN/poly-Si, is proposed, A uniform ultrathin (<1 nm) WSiN barrier layer was formed by annealing a W(100 nm)WNx(5 nm)/poly-Si structure. The W/WSiN/poly-Si structure was found to be thermally stable even after annealing at 800 degrees C. The sheet resistivity of the W(100 nm)/WNx(5 nm)/poly-Si(100 nm) structure is as low as 1.5 Omega/square and independent of line-width from 0.52 mu m to 0.12 mu m. The sheet resistivity of this layer structure is 40% lower than that of the W(100 nm)/TiN(5 nm)/poly-Si structure [2]. In addition, an equivalent circuit simulation showed that the measured contact resistivity of W and poly-Si in the W/WSiN/poly-Si system did not affect the gate RC delay time. Finally, a process integration of the poly-metal gate electrode is discussed. A SiN capped poly-metal structure was demonstrated.