COLLAR ISOLATION FABRICATION METHOD FOR FORMING TRENCH MEMORY CELL DEVICE BY USING AMORPHOUS SILICON AND SILICON GERMANIUM AS WELL AS SELECTIVE ETCHING PROCESS IN DEFINING COLLAR ISOLATION REGION

摘要

PURPOSE: A collar formation method using a selective SiGe/amorphous Si etch is provided to reduce the manufacturing cost by forming efficiently a collar isolation region for a trench storage memory cell structure. CONSTITUTION: A structure including at least one trench having an upper region and a lower region is formed in a surface of a semiconductor substrate(50). Amorphous Si(68) is formed on a node dielectric(66). Each trench is filled with SiGe(70). Parts of the amorphous Si and SiGe are recessed below an upper surface of the semiconductor substrate. The amorphous Si selective to SiGe is etched to form a collar isolation region on each sidewall. A recessed collar dielectric material is formed in the collar isolation region.