Post-etch residue removal using choline chloride–malonic acid deep eutectic solvent (DES)

Eutectic mixture of choline chloride (CC) and malonic acid (MA) in a molar ratio of 1:1 has been evaluated as a potential chemical system for the removal of residues produced by CF4/O2 plasma etching of copper coated with DUV photoresist. Immersion cleaning was performed in the liquid at the eutectic composition at 40 and 70 °C. Residue removal rate was screened using scanning electron microscopy and verified using X-ray photoelectron spectroscopy and electrochemical impedance spectroscopy measurements. The results presented in this paper show that choline chloride–malonic acid eutectic is effective in removing post-etch residues and has the potential to function as a back end of line cleaning formulation.

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