Exposure parameters in proton beam writing for KMPR and EPO Core negative tone photoresists

Abstract

In spite of its recent establishment, proton beam writing (PBW) has already demonstrated to be a highly competitive lithographic technique. PBW is a fast direct-write technique capable of producing high-aspect-ratio micro- and nano-structures in resist material. Typical applications can be found in nanoimprinting, biomedical research, photonics, and optics, among other fields. The progress of PBW is linked to the successful introduction of new resist materials. In this paper, KMPR and EPO Core, negative tone photoresists are tested on their compatibility with PBW. KMPR resist has similar chemical and process properties compared to SU-8. Employing UV lithography on KMPR resist, details of 30 μm have been obtained in Ni, indicating a possible advantage compared to SU-8 for optical lithography [1]. In this study, the sensitivity to MeV proton exposure and sub-micron feature sizes are presented in KMPR. PBW has been also combined with Ni electroplating in order to determine the suitability of KMPR and EPO Core resist to fabricate 3D metallic moulds and stamps.