Exposure parameters for MeV proton beam writing on SU-8

Summary, in English

Proton beam writing was performed on a lithographic resist to determine the main parameters required to achieve the minimum feature size, maximum pattern lateral density and maximum aspect ratio. A 2.5 MeV proton beam focused to sizes between 1.5 and 2.5 mu m was used to expose SU-8 negative resist. The number of protons per pixel was varied in the exposure of SU-8 with thicknesses between 5 and 95 pm. Patterns consisting of single pixels, single-pixel lines and multi-pixel areas with different densities were fabricated. The smallest structures achieved were posts 1.5 pin in diameter with 4:1 structure-space ratio in 15 pm thick resist and the highest aspect ratio structures of 20:1 in 40 pm resist were produced. It was found that the minimum feature size depended only on the beam size, and +/- 10% post size accuracy could be achieved within 40-70% variation of the number of protons. MeV proton beam allows a direct fabrication of complex shapes without a mask in single-step irradiation and. in addition, no proximity correction is needed. We present examples of MeV proton beam written single and multi-pixel microstructures with easily reproducible high aspect ratios and densities. (c) 2006 Elsevier B.V. All rights reserved.

• Author: Vaida Auzelyte; Mikael Elfman; Per Kristiansson; Christer Nilsson; Jan Pallon; Natalia Arteaga; Marie Wegdén
• Department/s: Nuclear physics
• Publishing year: 2006
• Language: English
• Pages: 2015-2020
• Publication/Series: Microelectronic Engineering
• Volume: 83
• Issue: 10
• Links: http://dx.doi.org/10.1016/j.mee.2006.04.001
• Document type: Journal article
• Publisher: Elsevier
• Topic: Subatomic Physics
• Keywords: lithography; microfabrication; exposure latitude; proton beam writing; pattern density; aspect ratio
• Status: Published
• Research group: Nuclear Microprobe
• ISBN/ISSN/Other: ISSN: 1873-5568