The present disclosure describes a metal-oxide-semiconductor field-effect transistor (MOSFET) device. The MOSFET device includes a first-type substrate, a deep-second-type well in the first-type substrate, a first-type well over the deep-second-type well, and a second-type well over the deep-second-type well. The second-type well and the deep-second-type well form an enclosed space that includes the first-type well. The MOSFET also includes an embedded semiconductor region (ESR) in a vicinity of the enclosed space. The ESR includes a dopant concentration lower than at least one of a dopant concentration of the first-type well, a dopant concentration of the second-type well, and a dopant concentration of the deep-second-type well.