Work function and thermal stability of Ti1-xAlxNy for dual metal gate electrodes

Work function and thermal stability of reactive sputtered Ti1-xAlxNy films were investigated for a metal gate electrode using a metal-oxide-semiconductor (MOS) structure. It is found that the work function (Phi(M)) values of Ti1-xAlxNy are ranged from 4.36 to 5.13 eV with a nitrogen partial flow rate (f(N2)). The Phi(M) values of Ti1-xAlxNy films, 4.36 eV for nMOS (n-Ti1-xAlxNy) and 5.10-5.13 eV for pMOS (p-Ti1-xAlxNy), may be applicable to dual metal gate electrodes. Excellent thermal stability up to 1000 degreesC was obtained on SiO2 as observed by the negligible change of capacitance equivalent thickness and Al 2p core level spectra for p-Ti1-xAlxNy (ysimilar to1.0,f(N2)=50%), whereas a limited stability was attained in case of n-Ti1-xAlxNy (f(N2)less than or equal to40%). The p-Ti1-xAlxNy can be a good candidate for pMOS device feasibility because of good thermal stability, while the n-Ti1-xAlxNy may be applicable for nMOS gate electrode in low thermal devices using damascene gate process. (C) 2002 American Institute of Physics.