Fabrication of tapered graded-refractive-index micropillars using ion-implanted-photoresist as an etch mask

Abstract

Thermally reflowed photoresist is used as an etch mask in inductively coupled plasma reactive ion etching of dielectric graded-refractive-index (GRIN) coatings. The coatings have varying compositions of TiO2 and SiO2 and are used to fabricate GRIN micropillars with tapered sidewalls. The effects of ion implantation on the dry-etch-resistance of photoresist are investigated for Si, N, and Ar ion implantation. Compared with the unimplanted photoresist, the implanted photoresists show enhanced dry-etch-resistance under fluorine chemistry (CHF3 and O2). The etch rate of the Si-implanted photoresist is 72% lower than that of the unimplanted photoresist. The measured depth of modification of the photoresist is in good agreement with the trend predicted by ion-implantation-simulation software. Using Si-implanted photoresist as an etch mask, five-layer GRIN micropillars with tapered sidewalls are fabricated.