Methods of Forming a Dielectric Cap Layer on a Metal Gate Structure

Disclosed herein are various methods of forming metal-containing insulating material regions on a metal layer of a gate structure of a semiconductor device. In one example, the method includes forming a gate structure of a transistor, the gate structure comprising at least a first metal layer, and forming a first metal-containing insulating material region in the first metal layer by performing a gas cluster ion beam process using to implant gas molecules into the first metal layer.