Super junction deep groove device and manufacturing method thereof

The invention provides a super junction deep trench device and a manufacturing method thereof. The method comprises the following steps: forming a first doping type epitaxial layer on a substrate; forming a mask layer on the epitaxial layer, wherein the mask layer comprises a first oxide layer, a nitride layer and a second oxide layer which are stacked from bottom to top; forming a groove extending downwards into the epitaxial layer from the upper surface of the mask layer; the second oxide layer is removed, the first oxide layers on the two sides of the groove are removed at the same time, and a top sharp corner appears at an opening of the groove; and the top sharp corner is chamfered, so that the groove opening is in transition connection with the first oxide layer. The top sharp corner at the opening of the groove is chamfered, so that a sharp corner damage area at the top end of the groove can be removed, an electric leakage channel is avoided, and the reliability of the device is improved; moreover, the