Combinatorial methodology for the exploration of metal gate electrodes on HfO₂ for the advanced gate stack

Combinatorial methodology offers an efficient platform to accelerate the exploration of new materials. We demonstrate the effectiveness of this technique on the study of new metal gates for the advanced gate stack. We report two examples, Ni-Ti-Pt ternary composition spreads, and Tai_.xAl _xN_y binary composition spreads, using a combinatorial sputtering tool. For the Ni-Ti-Pt library, wavelength dispersive spectroscopy (WDS), and scanning x-ray microdiffraction spectroscopy were used to determine compositions, and structures, respectively. Scanning Kelvin probe microscopy (SKPM) was used to measure work functions (Φ_m) directly. Our results show Φ_m variation is consistent with the variation for the corresponding bulk values. For the Tai_.xAl_xN _y metal gate electrodes, the extracted equivalent oxide thickness (EOT) map suggests thermal stability of the stack, and flat-band voltage shift (△V_fb) varied systematically as per our expectation.