Patterning Amorphous Fluoropolymer Films by Reactive Ion Milling

Amorphous fluoropolymer films have low dielectric constants and high chemical resistance and, so, have potential to be used as the insulator for high speed interconnects and as protection layers. Many applications would require high resolution patterning of the fluoropolymer film. We have found that these films are easily etched by reactive ion beam etching using an O2/Ar gas mixture. High etching rates of 600 nm/min with a 0.2 mA/cm, 500 eV ion beam were obtained. This technique allows good selectivity with typical underlayers such as Si, Au, and photoresist. We have also found that a short Ar ion milling of the fluoropolymer surface allows good wettability of the film by photoresist.