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 H-2/Ar gas. As the H-2 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 H-2 concentration but steep etch profiles without redeposition and etch by-product were obtained in high H-2 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 H-2/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.