Determination of Work Functions in the $\hbox {Ta}_{1 - x}\hbox {Al}_{x}\hbox {N}_{y}/\hbox {HfO}_{2}$ Advanced Gate Stack Using Combinatorial Methodology

Combinatorial methodology enables the generation of comprehensive and consistent data sets, compared with the ldquoone-composition-at-a-timerdquo approach. We demonstrate, for the first time, the combinatorial methodology applied to the work function (Phi_m) extraction for Ta_1-xAl_xN_y alloys as metal gates on HfO₂, for complementary metal-oxide-semiconductor applications, by automated measurement of over 2000 capacitor devices. Scanning X-ray microdiffraction indicates that a solid solution exists for the Ta_1-xAl_xN_y libraries for 0.05 les x les 0.50. The equivalent oxide thickness maps offer a snapshot of gate stack thermal stability, which show that Ta_1-xAl_xN_y alloys are stable up to 950^degC . The Phi_m of the Ta_1-xAl_xN_y libraries can be tuned as a function of gate metal composition over a wide (0.05 les x les 0.50) composition range, as well as by annealing. We suggest that Ta_0.9Al_0.1N_1.24 gate metal electrodes may be useful for p-channel metal-oxide-semiconductor applications.