Corrosion of Co in BEOL interconnects in dilute HF solution

Yuya Akanishi; Els Kesters; Quoc Toan Le; Frank Holsteyns

doi:10.4028/www.scientific.net/SSP.282.256

Paper Titles

Atomic Layer Deposition of TiN below 600 K Using N₂H₄
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Process Parameter Control for BEOL TiN Hard Mask Etch-Back
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BEOL Post-Etch Clean Robustness Improvement with Ultra-Diluted Hf for 28nm Node
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Optimization of Wet Strip for Metal Void Reduction in Trench First Metal Hard Mask Back End of Line Process
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Corrosion of Co in BEOL interconnects in dilute HF solution
p.256

Effect of Cleaning Chemistries on Cobalt: Surface Chemistries and Electrical Characterization
p.263

Optimization of Post Etch Cobalt Compatible Clean by pH and Oxidizer
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Developing Integrated Solutions and Wet Cleans to Eliminate Tungsten Contact Attack in Sub 0x nm Nodes
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Post-CMP Cleaners for Tungsten Advanced Nodes: 10nm and 7nm
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Corrosion of Co in BEOL interconnects in dilute HF solution

Abstract:

The impact of dissolved oxygen (O₂) on cobalt (Co) corrosion in dilute HF (dHF) solution was studied. It was confirmed that Co etch rate was enhanced as the amount of dissolved O₂ in the HF solution increased. The Co etch rate was also found to increase radially outward when performed on a single-wafer spin process in atmospheric air due to the uptake of O₂ during the dispense process. The galvanic corrosion of Co was investigated with two types of structures with a Co/Cu interface in different dissolved O₂ concentrations, i.e. (1) Co bump structures on Cu and (2) Cu lines with a Co/TaN liner/barrier structure. By controlling both the dissolved and the atmospheric O₂ levels, galvanic corrosion prevention at the Co/Cu interface was achieved.