The present invention facilitates semiconductor fabrication by providing
methods of fabrication that selectively form high-k dielectric layers
within NMOS regions. A first oxide layer is formed in core and I/O
regions of a semiconductor device (506). The first oxide layer is removed
(508) from the core region of the device. A high-k dielectric layer is
formed (510) over the core and I/O regions. Then, the high-k dielectric
layer is removed (512) from PMOS regions of the core and I/O regions. A
second oxide layer is formed (516) within NMOS regions of the core and
I/O regions and a nitridation process is performed (518) that nitrides
the second oxide layer and the high-k dielectric layer.