A Study of Inter-Via CD and PEB Amount Correlation in Dual Damascene Process

Abstract

Nowadays, dual damascene process is widely used in ULSI circuit metal or top metal loop manufacturing. In this process, plug etch back process is a key approach to protect via profile during trench etch. It is believed that more etch back amount will leads to larger CD while less one leads to smaller CD. However, in our experiment, an opposite phenomenon take place. With longer Plug etch-back time (PEB+), CD shrink ~10%. Base on TEM image and plasma morphology analysis, a possible formation mechanism is proposed in this paper.