Photolithography process using multiple anti-reflective coatings

摘要

A method for fabricating an integrated circuit using a photo-lithographic process includes the steps of placing at least two anti-reflective coating layers between a reflective surface and another material. The indices of refraction, absorptions, and thicknesses of the at least two anti-reflective coating layers are chosen such that the amplitudes and phase differences of radiation reflected from the anti-reflective coating layers, as well as any other reflective surfaces below the anti-reflective coating layers, mutually cancel when combined. The invention may be practiced using more than two layers of anti-reflective coating. Multiple layers of anti-reflective coating may be used below an inter-level dielectric, in which case they may serve the additional purpose of functioning as an etch-stop.