US Patent 10062784 Self-aligned gate hard mask and method forming same

A method includes forming a metal gate in a first inter-layer dielectric, performing a treatment on the metal gate and the first inter-layer dielectric, selectively growing a hard mask on the metal gate without growing the hard mask from the first inter-layer dielectric, depositing a second inter-layer dielectric over the hard mask and the first inter-layer dielectric, planarizing the second inter-layer dielectric and the hard mask, and forming a gate contact plug penetrating through the hard mask to electrically couple to the metal gate.