PRISM: Process for resist profile improvement with surface modification

Abstract

The positive electron beam resist NPR is a composite of a novolac resin and a polymeric dissolution inhibitor. In this resist a surface modified layer is produced on the resist when development is interrupted. The dissolution rate of this layer at low dose is very low. A new process called prism (Process for Resist profile Improvement with Surface Modification) utilizing this layer is proposed. By repetitive development interruption, a steep and accurate resist profile is obtained with sidewall protection. This paper describes an investigation into the effects of development interruption on NPR. The surface modified layer produced by the interruption is investigated with gas analysis and x‐ray photoelectron spectroscopy. It is found that the dissolution inhibitor poly(2‐methylpentene‐1‐sulfone) accumulates at the resist surface. prism can be applied to other resists consisting of aqueous alkaline soluble base resins and polymeric dissolution inhibitors. Improvement of the resist pattern profile is observe...