High Performance of Silicon Oxide Selective Etching Using F2 Gas and Graphite Instead of Perfluorinated Compound Gases

We have demonstrated an environmentally benign SiO2 selective-etching process in a magnetron plasma using a graphite target and F2 gas instead of perfluorinated compound (PFC) gases. The top electrode of graphite was supplied with power from two different 13.56 MHz and 450 kHz RF sources. The amount of C-based species in the plasma was controlled by the 450 kHz RF source bias voltage. The F atom density was controlled in the plasma by changing the amount of F2 feed gas. High SiO2/resist selectivity and a vertical etching pattern profile were realized. Microtrenching was suppressed by the injection of high energy electrons.