By forming MOSFETs on a substrate having pre-existing ridges of
semiconductor material (i.e., a “corrugated substrate”), the resolution limitations associated with conventional
semiconductor manufacturing processes can be overcome, and high-performance, low-power transistors can be reliably and repeatably produced. Forming a corrugated substrate prior to actual device formation allows the ridges on the corrugated substrate to be created using high precision techniques that are not ordinarily suitable for device production. MOSFETs that subsequently incorporate the high-precision ridges into their channel regions will typically exhibit much more precise and less variable performance than similar MOSFETs formed using optical
lithography-based techniques that cannot provide the same degree of patterning accuracy. A multi step epitaxial process can be used to extend the ridges with different
dopant types, high mobility
semiconductor, and or advanced multi-layer strutures. For
CMOS integrated circuits a capping layer is formed over the a first region. Epitaxial
layers are formed in a second region. Then the capping layer is removed from the first region and a capping layer is formed over the second region. Epitaxial
layers can than be formed in the first region.