CD Bias Loading Control in Metal Hard Mask Open Process

摘要

In this work, CD (critical dimension) etching bias loading performance between dense and isolated (ISO) line was systematically investigated on Metal Hard Mask (M-HM) etch process in the scope of chemical gas, source power, pressure, bias power, and ESC temperature. Particularly, a CH4 based plasma curing upon photo resist mask was found with special capability to control the dense & ISO CD loading while keeping an on-target dense CD if it was properly applied. Furthermore, the remarkable impact of etch chemical gas on CD loading was also noticed between C12-based and HBr-based BARC open step. Besides, the stress and post-etch profile of M-HM were also found impacting CD loading performance. Based on these findings, a solution was successfully demonstrated on a case of electrical interconnection improvement between tungsten contact and copper trench.