The invention relates to the technical field of MOS semiconductors, and discloses an ultra-
low leakage current VDMOS switch element and a manufacturing method thereof, the ultra-
low leakage current VDMOS switch element comprises a
metal drain
electrode, a
metal source
electrode, a
semiconductor epitaxial layer and a grid
electrode, the
semiconductor epitaxial layer comprises an N substrate layer, an N drift layer, a P + layer, a P well layer and an N well layer, and a connecting layer is arranged between the
metal source electrode and the N well layer. According to the invention, TiSi, CoSi or highly-doped
polycrystalline silicon is adopted as the material of the connecting layer between the metal source electrode and the N well layer, so that the interface
contact resistance is obviously reduced, and the materials have excellent
conductivity and low interface potential barrier characteristics, so that efficient
ohmic contact can be realized, scattering and
energy loss of carriers at the interface are reduced, and the performance of the device is improved. According to the design,
Joule heat accumulation caused by poor contact is directly inhibited, so that leakage current is effectively reduced, and meanwhile, the conduction efficiency and the
thermal stability of the device are improved.