Patent ID: 7776696

Claim:
A method of making a semiconductor structure having at least two gates of different thickness, comprising: forming a first gate layer having a first thickness over a substrate; patterning a first hard mask over a portion of the first gate layer to define a first gate underneath the first hard mask having a first gate thickness; forming a second gate layer having a second thickness over the first gate layer and the first hard mask; patterning a second hard mask over a portion of the second gate layer to define a second gate underneath the second hard mask having a second gate thickness; forming a third gate layer having a third thickness over the second gate layer and the second hard mask; patterning a third hard mask over a portion of the third gate layer to define a third gate underneath the third hard mask having a third gate thickness; removing portions of the first gate layer, the second gate layer, and the third gate layer that are not under the first hard mask, the second hard mask, and the third hard mask; and removing the first hard mask, the second hard mask and the third hard mask to provide three gates of different thicknesses.