Resist profile enhancement in near field holographic printing using bottom anti-reflection coatings

Abstract

Holographic lithography and near-field holography (NFH) used to print gratings in the manufacture of DFB lasers are limited in the quality of the resist profiles due to the effects of vertical standing waves occurring within the photoresist layer. We report on various attempts to produce improved grating profiles in photoresist which can thereby directly serve as dry etch masks for transferring gratings into semiconductors. Trials include both thin dielectric layers as well as bottom antireflection coatings (BARC's) to mitigate interference effects. We show that among these, a bilayer BARC/photoresist method is both practical and can greatly improve resist profiles.