A method for manufacturing a semiconductor device, and a semiconductor device. The method includes: providing a semiconductor substrate of a first conductivity type, forming a deep well of a second conductivity type in the semiconductor substrate, forming a channel region of the first conductivity type, a first well region of the first conductivity type, and a drift region of the second conductivity type in the deep well, the first well region and the channel region being spaced by a portion of the deep well, the drift region being located between the channel region and the first well region, forming an ion implantation region of the first conductivity type in the deep well, the ion implantation region being located under the drift region, and forming a source region of the second conductivity type and a drain region of the second conductivity type in the deep well.