Semiconductor device with fin structures

A semiconductor device structure, comprising:

• a semiconductor substrate;
• a first fin structure, a second fin structure, and a third fin structure over the semiconductor substrate;
• spacer elements over sidewalls of the third fin structure;
• a merged epitaxial structure on the first fin structure and the second fin structure;
• and
• an isolated epitaxial structure on the third fin structure, wherein the merged epitaxial structure is closer to the semiconductor substrate than the isolated epitaxial structure.

A semiconductor device structure, comprising:

• a semiconductor substrate;
• a first fin structure and a second fin structure over the semiconductor substrate, wherein a top surface of the first fin structure is closer to the semiconductor substrate than a top surface of the second fin structure;
• a first epitaxial structure on the first fin structure;
• and
• a second epitaxial structure on the third fin structure, wherein the first epitaxial structure is wider than the second epitaxial structure.