Alternative ULK integration approach using a sacrificial layer in a standard dual damascene flow

In this work an approach to integrate spin-on deposited ULK in an existing 28 nm BEOL flow is presented. Additionally, this alternative ULK integration avoids any damage by plasma etching, wet cleaning and barrier/seed deposition by employing an alternative integration scheme. This is done by using a sacrificial material and filling the new material in already manufactured dual damascene structures. Critical process steps like the removal of the sacrificial material, filling of the ULK and final planarization are investigated and promising results are presented as a first feasibility study.