This paper reports a batch-fabrication technique based on micromachining of silicon molds to create, after replication, arrays of microlenses characterized by high fill factors. The technique for single microlens generation (compatible with various types of replication or integration so that microlenses made of plastics or glass can be generated) was reported previously and showed its potential in terms of range of shapes and cost. However, subtleties of chemical etching makes more difficult the generation of high fill factor matrices when microlenses size overcomes several tenth of microns. Thus, in this paper, we describe the analysis of the chemical etching process and the corresponding adaptation of the mask design to achieve 100% fill factors arrays of microlenses. The process to fabricate arrays of microlens, with hexagonal footprints and element sizing from 30 to 270 microns and having NA from 0.2 to 0.4, is described. The hexagonal footprint shape of the elements in the arrays leads to 100% geometrical fill factor of fabricated structures. Isotropic etching used for the molds fabrication preserves the spherical profile of the resulting microlenses.

Date Published: 8 May 2012
PDF: 7 pages
Proc. SPIE 8428, Micro-Optics 2012, 84281G (8 May 2012); doi: 10.1117/12.921875

Published in SPIE Proceedings Vol. 8428:
Micro-Optics 2012
Hugo Thienpont; Jürgen Mohr; Hans Zappe; Hirochika Nakajima, Editor(s)