Abstract: A semiconductor device comprises a drift region (100), a body region (110), a first doped region (111) and a second doped region (112)); a first trench penetrates the first doped region (111), the body region (110) extends into the drift region (100); an extension region (150) having an opposite conductivity type to the drift region (100) and surrounding the bottom wall of the first trench; where the first trench is filled with a first conductive structure (141) and a second conductive structure (142); a dielectric layer (130) formed between the second conductive structure (142) and the inner wall of the first trench, as well as between the first conductive structure (141) and the inner wall of the first trench; a second trench penetrating the first doped region (111) and the body region (110), and a dielectric layer (130) located between the third conductive structure (143) and the second trench (122).

Abstract: A preparation method for semiconductor device, comprising: forming a body region (110) in the drift region (100), forming a first doped region (111) and a second doped region (112) in the body region (110); forming a first trench (171) penetrating the first doped region (111) and the body region (110) and extending to the drift region (100); forming an extension region (150) with a conductivity type opposite to that of the drift region (100) and surrounding the bottom wall of the first trench (171); filling the first trench (171) with a dielectric layer (130) formed on the sidewall of the trench, a first conductive structure (141) located at the bottom of the trench and a second conductive structure (142) located at the top of the trench; forming a second trench (172) penetrating the body region (110) and extending into the drift region (100); filling the second trench (172) with a third conductive structure (143) and a dielectric layer (130) formed on the inner wall of the trench.