Comparison between gate oxide degradation induced by copper dual damascene and conventional aluminum processes

In this work, we compare gate oxide degradation induced by copper dual damascene and conventional aluminum interconnect processes. We demonstrate that high level damage induced in standard aluminum technology during both contact and metal process steps are strongly reduced with dual damascene technology. We also study the effect of a line width reduction on the degradation induced during line and hole etching in dual damascene processing, which shows first that more damage is created with narrower lines, and second that even in the most damaging case (zero overlap), dual damascene line and hole etching induces still less degradation than standard contact etching. Explanations for this behaviour are suggested.