Fine-pitch device lithography using a sacrificial hardmask

摘要

A method is described for forming a metal pattern in a low-dielectric constant substrate. A hardmask is prepared which includes a low-k lower hardmask layer and a top hardmask layer. The top hardmask layer is a sacrificial layer with a thickness of about 200 Å, preferably formed of a refractory nitride, and which serves as a stopping layer in a subsequent CMP metal removal process. The patterning is performed using resist layers. Oxidation damage to the lower hardmask layer is avoided by forming a protective layer in the hardmask, or by using a non-oxidizing resist strip process.