Dry Etching Solutions to Contact Etch for Advanced Logic Technologies

Abstract

Dry Etching Solutions to Contact Etch for Advanced Logic Technologies Heavy polymer and byproducts from CD shrinkage will easily cause contact hole open, especially for the tapered hole profile. The sufficient over-etch without any silicon loss and too much silicide loss is also required to maintain enough process window for less junction leakage. Meanwhile, the circularity of contact hole needs to be well controlled to avoid the potential contact to poly gate bridge issue. In this work, we investigated the impact of dry etching process on contact hole profile and circularity, balanced contact hole CD shrink and contact open issue. Results demonstrate the overall contact hole profile needs to be rigorously controlled by optimizing the etch selectivity of silicon oxide over silicon nitride, the etch treatment is imperative to reduce the contact open issue. The circularity of contact hole can be well improved by tuning the etching chemistry at bottom anti-reflective coating open step and optimizing patterning film stack.