Analysis of etched silicon surfaces for trench isolation techniques

A trench etching and filling technique for the isolation of a power IC was investigated. This technique consists of a deep trench formation (8.5 mu m) with positive etching using HBr/SiF4 with 45 % in He-O-2 chemistries follo wed by filling and global planarization with a chemical mechanical polishin g technique. This novel trench etching technique provides better surface qu ality of 3.1 Angstrom roughness, as measured with atomic force microscopy ( AFM). The filling and the global planarization results in a lower leakage c urrent less than InA at a supplying voltage of 400 V.