Structure and formation method of semiconductor device with fin structures

A method for forming a semiconductor device structure, comprising:

• forming a first fin structure, a second fin structure, and a third fin structure over a semiconductor substrate;
• forming spacer elements over sidewalls of the third fin structure;
• recessing the third fin structure;
• recessing the first fin structure and the second fin structure such that top surfaces of the first fin structure and the second fin structure are lower than a top surface of the third fin structure;
• and
• after the first fin structure, the second fin structure, and the third fin structure are recessed, epitaxially growing a semiconductor material over the first fin structure, the second fin structure, and the third fin structure such that a merged semiconductor element is formed on the first fin structure and the second fin structure, and an isolated semiconductor element is formed on the third fin structure.

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;
• first spacer elements over sidewalls of the first fin structure and sidewalls of the second fin structure;
• second spacer elements over sidewalls of the third fin structure, wherein each of the second spacer elements is taller than each of the first spacer elements;
• a merged semiconductor element on the first fin structure and the second fin structure;
• and
• an isolated semiconductor element on the third fin structure.