Vertical structure for semiconductor device

A device, comprising:

• a substrate;
• a field effect transistor (finFET) on the substrate, the finFET having a first channel length;
• and
• a gate-all-around FET (GAAFET) on the substrate, the GAAFET having a second channel length different from the first channel length, wherein the GAAFET and the finFET are arranged as neighboring transistors.

A device, comprising:

• a fin field effect transistor (finFET) on a substrate, wherein the finFET comprises:
• a fin on the substrate;
• first source/drain regions extending from the fin;
• a first gate structure wrapped around a portion of the fin;
• and
• a plurality of side-by-side channels under the first gate structure and disposed between the first source/drain regions;
• and
• a gate-all-around transistor (GAAFET) on the substrate, wherein the GAAFET comprises:
• a nano-sheet stack on the substrate;
• second source/drain regions extending from the nano-sheet stack;
• a second gate structure wrapped around a portion of the nano-sheet stack;
• and
• a plurality of vertically-stacked channels under the second gate structure and disposed between the second source/drain regions.