In accordance with some embodiments of the present disclosure, a fin-FET device includes a substrate, a stack structure, a source and drain region, a sidewall insulator and a metal connector. The stack structure including a gate stack is disposed on the substrate. The source and drain region is disposed beside the stack structure. The sidewall insulator is disposed on the source and drain region. The sidewall insulator includes a bottom portion and an upper portion. An interface is formed between the bottom portion and the upper portion and the bottom portion is located between the upper portion and the source and drain region. The metal connector stacks on the source and drain region and the sidewall insulator is located between the metal connector and the stack structure.