The etching of Al metal films on Si substrates in up to 1 Torr of Cl2gas using the 308hyphen;nm XeCl laser pulses is reported. Etch rates of up to sim;1 mgr;m per pulse were obtained which were laser fluence independent in the range 3gsim;fgr;gsim;0.25 J/cm2. The etch rates decreased, however, at high Cl2pressures and high laser repetition rate. Processes such as redeposition of the ablated material and slowing down of the ablation at increased Cl2pressures are considered as possible explanations of the observed results. By subsequently exposing the film to Cl2and then irradiating it under vacuum, we found that the main etching mechanism is reaction in the absence of light to form an aluminum chloride layer followed by the ablation of this layer with the subsequent laser pulse.
展开▼
