Abstract
We demonstrate that the metallic capping layer has a strong impact on the effective work function (EWF) of the metal gate. Specifically, the EWF of atomic-layer-deposited (ALD)-TaN could be increased from 4.5 to 4.8 eV with chemical-vapor-deposited-TiN capping, which is sufficient amount of work function modification for silicon on insulator based devices. A strong interdiffusion of Ti atoms into the ALD-TaN film is observed and correlated well with the changes in the EWF change. Ti capping experiments confirm that the Ti interdiffusion can actually modify the EWF of Ti/ALD-TaN stack. (c) 2006 American Institute of Physics.