Field effect transistor structures include a channel region formed in a recessed
portion of a substrate. The recessed channel portion permits the use of relatively
thicker source/drain regions thereby providing lower source/drain extension resistivity
while maintaining the physical separation needed to overcome various short channel
effects. The surface of the recessed channel portion may be of a rectangular, polygonal,
or curvilinear shape. In a further aspect of the present invention, transistors
are manufactured by a process in which a damascene layer is patterned, the channel
region is recessed by etch that is self-aligned to the patterned damascene layer,
and the gate electrode is formed by depositing a material over the channel region
and patterned damascene layer, polishing off the excess gate electrode material
and removing the damascene layer.