Patterning of thin copper films under UV exposure in chlorine-based liquids

Abstract

Wet etching of thin copper films was achieved by using chlorine-based liquids, such as 1,2-dicholorethane or NaCl dissolved in water, under ultraviolet (UV) irradiation. The etching of the thin copper film was probed in-situ by using a spectroscopic ellipsometer, and the etch rate could be controlled by adjusting the exposure parameters. As UV is used in lithography, mask patterns can be transferred to a copper surface directly without resorting to a complex photoresist process. Easy control of the etch rate ranging from sub A/s and use of nontoxic liquids such as 1,2-dicholoroethane and NaCl solution are major advantages of this novel technique.