Manufacturing method of high-density trench type MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor)

The invention discloses a manufacturing method of a high-density trench type MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor), and belongs to the field of semiconductor power devices. The method comprises the following steps of: firstly realizing well region injection before a groove, adopting an epitaxial silicon-silicon oxide-silicon nitride structure for etching a hard masking layer of the groove, and keeping a film layer structure until polycrystal etching; performing SPACER etching treatment on the second silicon oxide layer and the first silicon nitride layer in the hard mask layer after polycrystal etching, and forming SPACER side walls on two sides of the polycrystal; and after the medium hole is corroded, a silicon nitride hard masking layer is formed in a hole opening region, so that self-aligned corrosion of the silicon hole is realized, and the silicon hole is always located at the central position between the grooves. According to the invention, by optimizing the process steps and the p