Etch Characteristics of Micrometer-Scale Masked Cu Thin Films Using Inductively Coupled Plasma of H₂/Ar.

Inductively coupled plasma reactive ion etching (ICPRIE) of copper thin films masked with photoresist (PR) and SiO₂ thin films was performed in H₂/Ar gas. As the H₂ concentration increased, the etch rates of copper films significantly decreased. The etch profiles show heavy redeposition on the sidewall of the etched films in low H₂ concentration but steep etch profiles without redeposition and etch by-product were obtained in high H₂ concentration. The systematic variation of the etch parameter such as ICP source power, dc-bias voltage to substrate, and process pressure was carried out to characterize the copper etching in H₂/Ar gas. Based on the etch characteristics of copper films, Langmuir prove analysis, and X-ray photoelectron spectroscopy, it was revealed the physical sputtering by ions and the formation of the volatile copper compound and the protection layer had great influence on achieving a good etch profile.