Atomic layer-deposited platinum in high-<i>k</i>/metal gate stacks

Abstract

Nanoscale platinum films are deposited by atomic layer deposition using trimethyl-methylcyclopentadienyl-platinum and oxygen as precursors on the high-k dielectrics ZrO2 and Al2O3, respectively, and on SiO2, issuing deposition temperature and precursor ratios. The ALD-grown platinum films are polycrystalline and show a preferential (1 1 1) orientation. The films are homogeneous with a root mean square roughness of 0.6–0.7 nm and reveal a low resistivity of 13.2 µΩ cm. The effective work functions are 4.76 eV for ZrO2, 5.22 eV for Al2O3 and 5.52 eV for SiO2. It is remarkable that the deposition temperature of the platinum metal gate influences the final equivalent oxide thickness. Comparing both, PVD and ALD platinum films, a decreased leakage current density is observed for the ALD films depending on ALD process conditions, along with an increase in the equivalent oxide thickness.