A fin-type field effect transistor comprising a substrate, a plurality of insulators, at least one gate stack and strained material portions is described. The substrate has a plurality of fins thereon and the fin comprises a stop layer embedded therein. The plurality of insulators is disposed on the substrate and between the plurality of fins. The at least one gate stack is disposed over the plurality of fins and on the plurality of insulators. The strained material portions are disposed on two opposite sides of the at least one gate stack.