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

Nanoscale platinum films are deposited by atomic layer deposition using trimethyl-methylcyclopentadienyl-platinum and oxygen as precursors on the high- k dielectrics ZrO 2 and Al 2 O 3 , respectively, and on SiO 2 , 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 ZrO 2 , 5.22 eV for Al 2 O 3 and 5.52 eV for SiO 2 . 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.