Semiconductor device and fabrication method thereof

A method comprising:

• providing a substrate having a gate electrode disposed over a semiconductor substrate;
• forming a metal-semiconductor compound film on the gate electrode;
• and
• introducing at least one of an oxygen-containing gas, a nitrogen-containing gas, or a carbon-containing gas to the metal-semiconductor compound film to form a cover layer over the metal-semiconductor compound film.

A method for fabricating semiconductor device, comprising:

• receiving a substrate having a semiconductor structure formed thereon;
• forming a metal layer over the substrate and the semiconductor structure;
• thermally treating the metal layer to form a metal-semiconductor compound film on the semiconductor structure including a first metal;
• removing an unreacted portion of the metal layer;
• after removing the unreacted portion, forming a cover layer of a dielectric of the first metal over the metal-semiconductor compound film;
• performing a wet clean on a surface of the cover layer;
• and
• forming an overlying layer on the cleaned surface of the cover layer.