Characteristics of Ag etching using inductively coupled Cl₂-based plasmas

In this study, Ag thin films deposited on glass were etched using inductively coupled Cl₂-based plasmas and the effects of various Cl₂-based gas mixtures on the formation of reactive by products affecting Ag etching were investigated. When Cl₂-based gas mixtures were used with Ar and O₂, due to the very flow vapor pressure of the etch products, thick etch products remaining on the substrate could be observed after the etching. However, these etch products were easily removed during the photoresist stripping by a photoresist stripper. In particular, when O₂ was added to Cl₂, higher Ag removal rates during the photoresist stripping than those by pure Cl₂ or O₂ could be obtained. These results are interpreted as the formations of more porous and reactive etch reaction products when O₂ was added to Cl₂. The Ag removal rates by Cl₂/O₂/50%N₂ estimated after the photoresist stripping were higher than those by Cl₂/O₂/50%Ar and the use of Cl₂/O₂/50%Ar results in higher Ag etch rates than those by Cl₂/50%Ar. Therefore, the physical and chemical properties of the etch products formed by the specific gas mixtures appear to be important in removing Ag for Cl₂-based plasmas.