Ldmos transistor

An LDMOS transistor, comprising:

• a semiconductor substrate with a first doping type and a surface;
• a plurality of first trenches formed in the surface of the semiconductor substrate;
• a drift region with an increased conductive path of the LDMOS transistor in per unit area and a second doping type formed on the surface of the semiconductor substrate between adjacent first trenches and the semiconductor substrate exposed by side and bottom surfaces of the plurality of first trenches;
• a first shallow trench isolation (STI) structure formed in each of the plurality of the first trenches;
• a body region with a doping type opposite to the second doping type formed in semiconductor substrate at one side of the drift region;
• a gate structure formed over portions of the body region, the drift region and the first STI structure most close to the body region;
• a source region formed in the body region at one side of the gate structure;
• and
• a drain region formed in the drift region at one side of the first shallow trench isolation structure most far away from the body region.