Semiconductor device and preparation method thereof

The invention discloses a semiconductor device and a preparation method thereof. The semiconductor device comprises a substrate, an epitaxial structure, a gate structure, a dielectric layer and an ohmic contact structure, the epitaxial structure is arranged on the substrate, and the gate structure is arranged on one surface, far away from the substrate, of the epitaxial structure; the dielectric layer covers the gate structure; an open hole is formed in the dielectric layer, and the epitaxial structure is exposed by the open hole; the ohmic contact structure is arranged in the open hole and extends along the inner wall of the open hole. The semiconductor device provided by the invention has relatively high breakdown voltage. 本发明公开了一种半导体器件及其制备方法。所述半导体器件包括：衬底、外延结构、栅极结构、介质层及欧姆接触结构；所述外延结构设置于所述衬底上，所述栅极结构设置于所述外延结构远离所述衬底的一面；所述介质层覆盖所述栅极结构；所述介质层形成有开孔，所述开孔暴露所述外延结构；所述欧姆接触结构设置于所述开孔内且沿所述开孔的内壁延伸。本发明的半导体器件具有较高的击穿电压。