Reactive ion etching of ion-plated carbon films

Abstract

Accurate pattern transfer by dry etching methods requires resistant masks. Carbon is a good candidate due to its low sputtering rate, and it is widely used for high temperature superconductor patterning. This paper reports on radio frequency reactive ion etching of carbon films with diamond-like properties, deposited by ion plating at various bias voltages. Gold, polyimide and chalcogenide glass have been used as masks for deep carbon etching in oxygen, but failed to assure good selectivity. Best pattern transfer has been observed using a two-layer resist system based on photoresist and Mo or Ta. The etching is carried out on two stages: (1) metal etching in CF 4; (2) deep etching of carbon in oxygen plasma using the metal mask. A correlation has been found between film characteristics (etch rate, surface morphology, optical band gap) and the deposition bias voltage. The proposed technique is suitable for fine patterning of carbon films and production of masks with high ion etching resistance combined with good mechanical and thermal properties.