A trench isolation structure and method of forming the trench isolation structure are disclosed. The method includes forming a shallow trench isolation (STI) structure having an overhang and forming a gate stack. The method further includes forming source and drain recesses adjacent to the STI structure and the gate stack. The source and drain recesses are separated from the STI structure by substrate material. The method further includes forming epitaxial source and drain regions associated with the gate stack by filling the source and drain recesses with stressor material.