Band-Edge Work Function Obtained by Plasma Doping TiN Metal Gate for nMOS Device Application
This paper proposed, for the first time, that the band-edge effective work functions (EWFs) are achieved by employing PH3 plasma doping (PLAD) TiN metal gate for nMOS device application under replacement metal gate and high dielectric constant (k) dielectric/metal gate last nMOS device. The effects of PLAD energy, dose, gas mixture, and postdoping cleaning procedure on the EWF, EOT, and properties of TiN/HfO2/ILSiO2 gate-stack are investigated; the corresponding possible mechanisms are discussed. Suitable low threshold voltages of nMOSFETs are obtained, while shrinking the EOT. It reduces the corner effect on trench gate doping uniformity, which is induced by shadowing effect in the beam-line implantation technology, to a minimum. It has the potential for the further aggressively scaled 3-D CMOS device and beyond application.