The gate 47 is formed on the top surface 41a within the device region 43a, wherein part of the first high voltage well 42 is located below and in contact with the gate 47 in the vertical direction. The gate 47 at least includes: a dielectric layer 471, a conductive layer 472, and a spacer layer 473. The dielectric layer 471 is formed on the top surface 41a and in contact with the top surface 41a, and is in contact with the first high voltage well 42 in the vertical direction. The conductive layer 472 is formed on the dielectric layer 471 and in contact with the dielectric layer 471, to serve as an electrical contact of the gate 47. The spacer layer 473 is formed outside of two sidewalls of the conductive layer 472, to serve as an electrical insulation layer of the gate 47.