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

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 BCl X + in plasma, because it was found by mass spectral analysis that N2 addition increased the amount of BCl X + in plasma of ECR-RIE, but it decreased that in plasma of MERIE.