Lam Research Corporation
Method to recess cobalt for gate metal application

Abstract:

After forming a material stack including a gate dielectric, a work function metal and a cobalt gate electrode in a gate cavity formed by removing a sacrificial gate structure, the cobalt gate electrode is recessed by oxidizing the cobalt gate electrode to provide a cobalt oxide layer on a surface of the cobalt gate electrodes and removing the cobalt oxide layer from the surface of the cobalt gate electrodes by a chemical wet etch. The oxidation and oxide removal steps can be repeated until the cobalt gate electrode is recessed to any desired thickness. The work function metal can be recessed after the recessing of the cobalt gate electrode is completed or during the recessing of the cobalt gate electrode.