Strained nanowire CMOS device and method of forming

A semiconductor device comprising:

• a substrate;
• first source/drain regions and a first channel region interposed between the first source/drain regions, the first source/drain regions and the first channel region comprising alternating layers of first epitaxial layers and second epitaxial layers, the second epitaxial layers in the first channel region having a greater width than the first epitaxial layers in the first channel region in a direction perpendicular to current flow through the first channel region in a plan view;
• second source/drain regions and a second channel region interposed between the second source/drain regions, the second source/drain regions and the second channel region comprising alternating layers of the first epitaxial layers and the second epitaxial layers, the second epitaxial layers in the second channel region having a greater width than the first epitaxial layers in the second channel region in a direction perpendicular to current flow through the second channel region in the plan view;
• and
• a first gate structure extending over the first epitaxial layers and the second epitaxial layers in the first channel region, the first gate structure not extending completely between a bottommost layer of the second epitaxial layers of the first channel region and the substrate;
• and
• a second gate structure extending over the first epitaxial layers and the second epitaxial layers in the second channel region, the second gate structure extending completely between a bottommost second epitaxial layer and the substrate.

A semiconductor device comprising:

• a substrate;
• first source/drain regions and a first channel region interposed between the first source/drain regions over the substrate, the first source/drain regions and the first channel region comprising alternating layers of first epitaxial layers and second epitaxial layers, the first epitaxial layers and the second epitaxial layers extending continuously between the first source/drain regions;
• second source/drain regions and a second channel region interposed between the second source/drain regions over the substrate, the second source/drain regions and the second channel region comprising alternating layers of the first epitaxial layers and the second epitaxial layers, wherein a bottommost layer of the first epitaxial layers of the first channel region is lower than a bottommost layer of the first epitaxial layers of the second channel region;
• a first gate structure extending over the first channel region;
• and
• a second gate structure extending over the second channel region, wherein the second gate structure extends completely around the second channel region.