Wet chemical spray etching of the copper film for the application to chip on film in display devices

Abstract

For achieving the fine pitch chip-on-film (COF) in display devices, wet chemical spray etching behaviors of the copper (Cu) films in the etching solutions with different cupric chloride (CuCl₂) and hydrochloric acid (HCl) contents have been investigated. It is found that the etching rates and etching factors of the Cu films are strongly dependent on the composition of etchant solution and spray pressure, resulting from the chemical dissolution reaction and the kinetic energy of droplet, respectively. As a result, using the mixture of the CuCl₂ and HCl, Cu films are defined successfully by wet chemical spray etching method, suggesting sufficient possibility for the application to fine pitch COF in the display devices.