the present invention relates to the field of manufacturing technologies of semiconductor power devices , and more particularly to a method for manufacturing a split - gate power device . in the method for manufacturing a split - gate power device according to the present invention , lateral etching is added to form lateral recesses of a control gate groove below a first insulating film in a process of forming the control gate groove by etching , and therefore , after a first conductive film is deposited , the first conductive film can be directly etched by using the first insulating film as a mask to form control gates . the technical process of the present invention is simplified , reliable and easy to control , and can greatly improve the yield of the split - gate power device . the present invention is particularly suitable for the manufacture of 25v - 200v semiconductor power devices .