Shallow trench isolation with conductive hard mask for in-line moat/trench width electrical measurements

摘要

A method for forming STI that allows for in-situ moat/trench width electrical measurement is disclosed herein. A conductive layer (18) is used in the hard mask (20) for trench etch. After the hard mask (20) is formed and the trench (12) is etched, the resistance of the conductive layer (18) is measured over a predefined length. Since the length is known, the average width of the hard mask (20)/moat (11) can be determined. Once the width of the moat (11) is known, the width of the trench (12) can easily be determined by subtracting the width of the moat (12) from the pitch, which is a known factor.