A metal gate structure and method of making the same provides a tracer layer over a first metal or metal compound layer. When etching a metal gate, formed of tungsten, for example, with a first etchant chemistry optimized for etching tungsten, detection of the tracer layer through optical emission spectroscopy, for example, indicates the imminent clearing of the tungsten. A second etchant chemistry is then employed that is selective to the first metal or metal compound layer, such as TiN, overlying the gate dielectric. This provides a controlled etching of the TiN and thereby prevents degradation of the underlying gate dielectric material.