High voltage device and manufacturing method thereof

The present invention provides a high voltage device and a manufacturing method thereof. The high voltage device includes: a semiconductor layer, a well region, a bulk region, a gate, a source, and a drain. The bulk region has a second conductivity type. The bulk region is formed in the semiconductor layer and contacts the well region in a channel direction. The gate is formed on the semiconductor layer. A portion of the bulk region is located vertically below and in contact with the gate, so as to provide an inversion region of the high voltage device during a conductive operation of the high voltage device. The source is located in the bulk region, and the drain is located in the well region and away from the bulk region. A portion of the well region is located between and separates the bulk region and the drain. A first concentration peak region of an impurity doping profile of the bulk region is located vertically below and in contact with the source. A concentration of a second conductivity type impurity