AN ALGORITHM FOR PAD TRANSLATION IN FACE-UP CMP

摘要

Non-uniform polishing is a primary concern in copper chemical-mechanical polishing (Cu CMP), for it leads to overpolishing, and therefore Cu dishing and dielectric erosion. In conventional face-down CMP, the wafer is always in contact with the pad. Thus, due to non-uniform material removal rates at the wafer-scale, overpolishing occurs in some regions of the wafer as the entire wafer is completely polished. Recently, a face-up CMP architecture was proposed to improve wafer-scale polishing uniformity by translating the pad away from the region of the wafer that has been polished. This paper presents a numerical framework for the translation velocity of the pad in face-up CMP. Additionally, polishing experiments have been conducted on blanket Cu wafers on a face-up tool to validate the numerical model. The experimental results agree fairly well with the model.