Excimer-laser patterning of copper in LDE (laser dry etching)

Patterning of Cu bulk material and Cu foils (1 mu m in thickness) with etch rates up to 20 A.U./pulse is performed in an LDE (laser dry etching) process with excimer laser radiation (lambda = 248 nm) and CCl4 as processing gas. To determine the type and the kinetic temperature of ablated molecules and the LDE incubation periods, in-situ optical-emission-spectroscopy is performed. Ex-situ electron spectroscopies (XPS, AES, ADP) give information about the chemical state of the surface, the concentration profiles in the etched regions and the etching by products outside of the etched regions. Stylus profilometry is used to determine the geometries of etched features and the thickness of "bumps" created at the beginning of the etch process. A thermal model of LDE is used to discuss the observed etch rates and incubation times.