Selective Ru or Co Etch for 3nm Applications

Selective Cobalt (Co) and Ruthenium (Ru) etch chemistries are developed to provide controlled etch options with various metallization, including Al, Cu, W, Co, Ru, TiN and TaN. The pH effects on Co, Cu and W etching are reported. Diluted acids, such as 1% HF and 1% HCl, demonstrate etch rate profiles suitable for selective Co vs. W etch applications. Ru etch chemistries are alkaline oxidative based and expanded to meet 3 nm and below integration needs. Versatile applications include highly boosted Ru etch rates for thermally annealed Ru layers and TiN compatible WNx or WCN selective etching at ultra-dilutions.