Highly-reliable, low-resistivity bcc-Ta gate MOS technology using low-damage Xe-plasma sputtering and Si-encapsulated silicidation process

We present for the first time highly reliable metal-gate MOS technology with low-resistivity bcc-Ta. Low sheet resistance of 1.7 /spl Omega//sq. has been obtained by precisely controlling the ion bombardment conditions during Ta sputtering process, and by employing Si-encapsulation technique to suppress oxidation or hydrogen-accumulation in Ta thin film. By comparing Ta-gate and poly-Si gate MOS devices, it is confirmed that Ta-gate structure does not induce significant degradation in the gate-oxide reliability by using low-damage Xe-plasma sputtering and the Si encapsulation technique. It is also demonstrated that carrier mobility/velocity in the inversion layer of Ta gate SOI MOSFET is slightly higher than that of poly-Si gate SOI MOSFET because of higher thermal-conductivity of the metal gate.