Characterisation of metal pattern density and metal stack composition on chlorine residues from the metal etch process

Abstract

The corrosion of aluminium metal from chlorine plasma etching causes major backend interconnects failure especially when the metal line-width shrinks to sub-half micron geometry. The reason for the corrosion is related to the low volatility and the insufficient removal of residual chlorine by-products which leads to the galvanic attack of the etched metal lines. In this paper, a systematic Capillary Electrophoresis analysis of the residual chlorine on wafer surfaces is presented, the experimental results and analysis show that the amount of chlorine residues on wafer surfaces is strongly dependence on the metal pattern density and the metal stack composition.