High-voltage transistor and manufacturing method thereof

The invention discloses a high-voltage transistor and a manufacturing method thereof. The high-voltage transistor comprises a substrate with a recessed region. Doped regions are disposed on two sidesof the recessed region in the substrate. Shallow trench isolation structures are disposed in the doped regions of the substrate and are located in a surrounding region of the recessed region, whereina portion of a bottom of each of the shallow trench isolation structures in the recessed region has a protruding portion protruding to the substrate. A gate insulating layer is disposed on the substrate and is at a central region other than the shallow trench isolation structures in the recessed region, and the gate insulating layer has a protruding portion. A gate structure is disposed on the gate insulating layer and is on the shallow trench isolation structures in the recessed region, and the protruding portion of the gate insulating layer is covered. 本发明公开一种高电压晶体管及其制造方法，该高电压晶体管包括基板，基板具有凹陷区域。掺杂区域设置在所述基板中位于所述凹陷区域的两侧。