Electron-beam lithography for micro- and nano-optical applications

Abstract

Direct-write electron-beam lithography has proven to be a powerful technique for fabricating a variety of micro and nano-optical devices. Binary E-beam lithography is the workhorse technique for fabricating optical devices that require complicated precision nano-scale features. We describe a bi-layer resist system and virtual-mark height measurement for improving the reliability of fabricating binary patterns. Analog E-beam lithography is a newer technique that has found significant application in the fabrication of diffractive optical elements. We describe our techniques for fabricating analog surface-relief profiles in E-beam resist, including a technique for overcoming the problem of resist heating. We also describe a multiple field size exposure scheme for suppression of diffraction orders produced field-stitch errors in blazed diffraction gratings on non-flat substrates.