Poison-free and low ULK damage integration scheme for damascene interconnects

摘要

A method of forming a dual damascene structure is disclosed. A lower dielectric hardmask layer and an upper dielectric hardmask layer are deposited on an ultra low-k film. A first via is formed in the upper hardmask layer. Next, a first trench is formed using a tri-layer resist scheme. Finally, a full via and a full trench are formed simultaneously. An optional etch-stop layer can be used in the ultra low-k layer to control trench depth.