Oxide via hole formation using magnetically enhanced reactive ion etching

Abstract

Oxide thin films were etched in a magnetically enhanced reactive ion etch system. The effects of CF4 flowrate on etch rate, profile anisotropy and microtrench depth (MD) were examined. Apart from the direct current bias, important radicals such as F or CF collected with optical emission spectroscopy correlated with the etch rate and profile anisotropy. The etch rate was dominated by [F] driven etching rather than polymer deposition. In particular, the MD was strongly dependent on the profile angles. Typical MD occurred at positive profile angles. Larger positive profile angles resulted in a deeper MD, possibly due to enhanced ion collision with the sidewall. Profile angle variations played a crucial role in the interpretation of predicted MD variations with the radio frequency power.