The invention provides a
semiconductor device and a manufacturing method thereof. The
semiconductor device comprises a first-class high-
voltage nLDMOS device, a first-class high-
voltage pLDMOS device,a second-class high-
voltage nLDMOS device, a second-class high-voltage pLDMOS device, a low-voltage NMOS device, a low-voltage PMOS device and a low-voltage NPN device which are integrated on the same
chip. The first p-type field reduction layer is located on the surface, so that the
conductive channel moves downwards, the
hot carrier effect is reduced, and the reliability of the device is improved. The n-type heavily doped layer, the p-type field reduction layer, the n-type deep trap, the p-type trap and the p-type substrate form a multiple RESURF structure, the specific on-resistance of thehigh-voltage device is reduced, and the manufacturing cost of the
chip is reduced. Compared with a traditional structure without an n-type heavily doped layer, the n-type heavily doped layer has smaller on-resistance under the condition of the same
chip area, the on-resistance and the
dynamic resistance of the device can be reduced through the n-type heavily doped layer, and the nLDMOS device further has the advantages of being high in
input impedance, low in
output impedance and the like.