Anisotropic Etching of Submicronic Resist Structures by Resonant Inductive Plasma Etching

The etching of submicronic resist structures in an oxygen plasma has been investigated in a helicon wave reactor. Systematic investigations have been conducted on the structure profile dependences on ion energy and on plasma pressure. For resist etching, the result of these investigations revealed the considerable heat transfer between the plasma species and the substrate. To obtain anisotropically etched resist structures, it was necessary to cool the wafer holder at low temperature ( -75°C) and reinforce the thermal conduction between the wafer and wafer holder. Comparison of an anisotropic process, obtained with conventional reactive ion etching (RIE), is made in terms of etch rate, sidewall passivation and surface pollution.