A metal gate structure and method of forming the same employs an etch stop layer between a first metal layer, made of TiN, for example, and the metal gate formed of tungsten. The etch stop layer prevents overetching of the TiN during the etching of the tungsten in the formation of the metal gate. The prevention of the overetching of the TiN protects the gate oxide from undesirable degradation. The provision of aluminum or tantalum in the etch stop layer allows a thin etch stop layer to be used that provides adequate etch stopping capability and does not undesirably affect the work function of the TiN.