<title>Heat- and oxygen-RIE-resistant polysiloxane resist with three-dimensional structure for high-aspect-ratio microfabrication</title>

Abstract

An organosiloxane resist, 3D structure polysiloxane, had been developed for use as a high resolution bi-layer resist for high-aspect ratio microfabrication. The resist molecule is structured as a rigid 3D siloxane core surrounded by functional groups. The advantages of such a structure are lower degree of swelling, a high oxygen-reactive ion etching resistance, and a high softening temperature. A 100 nm line- and-space pattern is well-defined after electron beam exposure. The resist can be also used for UV lithography. Sub-half micron UV pattern with aspect-ratio or more than 10 can be delineated with the 3D structure siloxane/novolak bi- layer resist system after high density oxygen plasma etching. The novolak bottom layer is etched at about 1000 nm/min, and the etching selectivity ratio is more than 20. The excellent etching resistance of the 3D siloxane is due to its high silicon content and good film quality. The softening temperature of the 3D siloxane is more than 400, although ladder structure siloxane's softening temperature is 150. This suggests the 3D siloxane resist exhibits high heat resistance due to its rigid structure. Bi-layer resist systems with the 3D siloxane show high resolution with high- aspect ratio, demonstrating its great potential for application in microfabrication process of electronic devices.