Fin-type field effect transistor structure and manufacturing method thereof

A fin-type field effect transistor, comprising:

• a substrate having fins and trenches between the fins;
• insulators disposed within the trenches of the substrate;
• at least one gate stack, disposed across and over channel portions of the fins and disposed on the insulators, wherein the at least one gate stack comprises a gate dielectric layer;
• an oxide layer, disposed on the channel portions, wherein the oxide layer is further sandwiched between the gate dielectric layer and the channel portions, and sandwiched between the gate dielectric layer and the insulators;
• and
• epitaxy material portions, disposed over flank portions of the fins and at two opposite sides of the at least one gate stack, wherein the epitaxy material portions wrap around the flank portions of the fins and have narrow profiles, and the flank portions and the channel portions of the fins are protruded from the insulators and the flank portions and the channel portions of the fins have substantially a same height from top surfaces of the insulators.

A fin-type field effect transistor, comprising:

• a substrate having fins and insulators located between the fins, wherein the fins comprise channel portions and flank portions beside the channel portions;
• at least one gate stack, disposed over the substrate, the insulators and the channel portions of the fins, wherein the at least one gate stack comprises a gate dielectric layer;
• an oxide layer, disposed on the channel portions, wherein the oxide layer is further sandwiched between the gate dielectric layer and the channel portions, and sandwiched between the gate dielectric layer and the insulators;
• and
• epitaxy material portions, disposed over the flank portions of the fins and at two opposite sides of the at least one gate stack, wherein the epitaxy material portions disposed at the two opposite sides of the at least one gate stack are separate from each other, and the epitaxy material portions comprise over-layers of random orientations.