METHOD FOR MANUFACTURING SEMICONDUCTOR DEVICE HAVING FIELD PLATE STRUCTURE WITH GRADUALLY VARYING THICKNESS IN TRENCH

摘要

Disclosed is a method for manufacturing a semiconductor device having a field plate structure with gradually varying thickness in a trench, the method comprising: step A, forming a trench in a surface of a wafer; step B, filling the trench with silicon oxide by means of deposition; step C, removing a portion of the surface of the silicon oxide in the trench by means of etching; step D, forming a silicon oxide corner structure at a corner at the top of the trench by means of thermal oxidation; step E, depositing a nitrogen-containing compound on the surface of the wafer; step F, carrying out dry etching on the nitrogen-containing compound to form, on a surface of the silicon oxide corner structure, nitrogen-containing compound sidewall residues extending to the inside of the trench; step G, taking the nitrogen-containing compound sidewall residues as a mask, and removing a portion of the surface of the silicon oxide in the trench by means of etching; successively repeating step E to step G until the silicon oxide in the trench is etched to be of the thickness required for bottom silicon oxide; step H, removing the nitrogen-containing compound in the trench; and step I, filling the trench with polycrystalline silicon.