A structure and a method of a semiconductor device structure are provided. The method includes forming a first fin structure, a second fin structure, and a third fin structure over a semiconductor substrate. The method includes forming first spacer elements over sidewalls of the first fin structure and the second fin structure and partially removing the first fin structure and the second fin structure. The method includes forming second spacer elements over sidewalls of the third fin structure and partially removing the third fin structure. The second spacer element is taller than the first spacer element. The method includes 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.