Neighboring gate-all-around integrated circuit structures having disjoined epitaxial source or drain regions

A method of fabricating an integrated circuit structure, the method comprising:

• forming a first vertical arrangement of nanowires and a second vertical arrangement of nanowires above a substrate, the nanowires of the second vertical arrangement of nanowires having a horizontal width greater than a horizontal width of the nanowires of the first vertical arrangement of nanowires;
• forming first epitaxial source or drain structures at ends of the first vertical arrangement of nanowires, and forming second epitaxial source or drain structures at ends of the second vertical arrangement of nanowires, ones of the second epitaxial source or drain structures and corresponding ones of the first epitaxial source or drain structures having a merged region there between;
• removing the merged region to disjoin the ones of the second epitaxial source or drain structures and the corresponding ones of the first epitaxial source or drain structures;
• and
• forming an intervening dielectric structure between the ones of the second epitaxial source or drain structures and the corresponding ones of the first epitaxial source or drain structures.

An integrated circuit structure, comprising:

• a first fin having a longest dimension along a first direction;
• a first nanowire over the first fin;
• a second fin having a longest dimension along the first direction;
• a second nanowire over the second fin, wherein the second nanowire is wider than the nanowire;
• a first gate structure over the first nanowire and the first fin, the first gate structure having a longest dimension along a second direction, the second direction orthogonal to the first direction;
• a second gate structure over the second nanowire and over the second fin, the second gate structure having a longest dimension along the second direction, the second gate structure continuous with the first gate structure along the second direction;
• first epitaxial source or drain structures at ends of the first nanowire;
• second epitaxial source or drain structures at ends of the second nanowire;
• and
• an intervening dielectric structure between neighboring ones of the first epitaxial source or drain structures and of the second epitaxial source or drain structures.