METHOD FOR FORMING SHALLOW TRENCH ISOLATION LAYER OF SEMICONDUCTOR DEVICE TO PREVENT DISHING USING REVERSE ETCH-BACK PROCESSING

摘要

PURPOSE: A method for forming an STI(Shallow Trench Isolation) layer of a semiconductor device is provided to prevent dishing by performing reverse etch-back processing before and after CMP(Chemical Mechanical Polishing). CONSTITUTION: A nitride pattern(202) is formed on an active region of a substrate(200). A trench(204) is formed in the substrate by using the nitride pattern as a mask. A gap-fill oxide layer is filled in the trench. First reverse etch-back processing is performed to a high-density region of the nitride pattern. The gap-fill oxide layer is polished by CMP to reduce the step between high-density and low-density regions of the nitride pattern. Second reverse etch-back processing is performed to the high-density region of the nitride pattern. By removing the nitride pattern, a shallow trench isolation layer(206d) is formed.