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 “one-composition-at-a-time” approach. We demonstrate, for the first time, the combinatorial methodology applied to the work function $(\Phi_{m})$ extraction for $\hbox{Ta}_{1 - x}\hbox{Al}_{x}\hbox{N}_{y}$ alloys as metal gates on $\hbox{HfO}_{2}$, 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 $ \hbox{Ta}_{1 - x}\hbox{Al}_{x}\hbox{N}_{y}$ libraries for $ \hbox{0.05} \leq x \leq \hbox{0.50}$. The equivalent oxide thickness maps offer a snapshot of gate stack thermal stability, which show that $\hbox{Ta}_{1 - x}\hbox{Al}_{x} \hbox{N}_{y}$ alloys are stable up to 950 $^{\circ}\hbox{C}$ . The $\Phi_{m}$ of the $\hbox{Ta}_{1 - x}\hbox{Al}_{x}\hbox{N}_{y}$ libraries can be tuned as a function of gate metal composition over a wide $(\hbox{0.05} \leq x \leq \hbox{0.50})$ composition range, as well as by annealing. We suggest that $\hbox{Ta}_{0.9} \hbox{Al}_{0.1}\hbox{N}_{1.24}$ gate metal electrodes may be useful for p-channel metal–oxide–semiconductor applica