Effect of N2 Addition on Aluminum Alloy Etching by Electron Cyclotron Resonance Reactive Ion Etching and Magnetically Enhanced Reactive Ion Etching

Abstract

Aluminum alloy etching is an important process in ultra-large-scale integration (ULSI) fabrication. We investigated the effect of N2 addition to Cl2+BCl3 gas mixture on aluminum-copper alloy etching by electron cyclotron resonance reactive ion etching (ECR-RIE) and magnetically enhanced reactive ion etching (MERIE). In ECR-RIE, N2 addition was effective in suppressing residues and post-etch corrosion of aluminum alloy interconnects; on the other hand, in MERIE, N2 addition promoted the formation of residues and post-etch corrosion. This difference is probably caused by BClX+ in plasma, because it was found by mass spectral analysis that N2 addition increased the amount of BClX+ in plasma of ECR-RIE, but it decreased that in plasma of MERIE.