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 CF 4 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.