Patent ID: 11127840

Abstract:
Disclosed is a method for manufacturing an isolation structure for LDMOS, the method comprising: forming a first groove on the surface of a wafer; filling the first groove with silicon oxide; removing part of the surface of the silicon oxide within the first groove by means of etching; forming a silicon oxide corner structure at the corner of the top of the first groove by means of thermal oxidation; depositing a nitrogen-containing compound on the surface of the wafer to cover the surface of the silicon oxide within the first groove and the surface of the silicon oxide corner structure; dry-etching the nitrogen-containing compound to remove the nitrogen-containing compound from the surface of the silicon oxide within the first groove, and thereby forming a nitrogen-containing compound side wall residue; with the nitrogen-containing compound side wall residue as a mask, continuing to etch downwards to form a second groove; forming a silicon oxide layer on the side wall and the bottom of the second groove; removing the nitrogen-containing compound side wall residue; and filling the first groove and the second groove with silicon oxide.