Fabrication of microlens arrays by reactive ion milling

Haluk O. Sankur; Randolph L. Hall; M. Edward Motamedi; William J. Gunning III; William E. Tennant

doi:10.1117/12.234628

8 March 1996 Fabrication of microlens arrays by reactive ion milling

Haluk O. Sankur, Randolph L. Hall, M. Edward Motamedi, William J. Gunning III, William E. Tennant

Proceedings Volume 2687, Miniaturized Systems with Micro-Optics and Micromechanics; (1996) https://doi.org/10.1117/12.234628
Event: Photonics West '96, 1996, San Jose, CA, United States

Abstract

Fabrication of refractive microlens arrays on several infrared (IR) transmissive materials was studied. The fabrication process consists of forming photoresist microlenses by thermal reflow of photoresist islands, and transferring this pattern into the IR substrate by ion milling. Microlens arrays having a wide range of F-numbers (F/0.3 - F/12) and sizes were fabricated using a modified ion milling process, where background oxygen and ion energy were used to control the photoresist and substrate erosion rates, respectively. This approach enabled a large range of milling selectivity (e.g. 0.6 - 12 for CdTe) and hence accurate control of lens sag heights. This is important since photoresist microlenses can be successfully fabricated only within a limited range of F-numbers. The etch selectivity also enabled fabrication of nonspherical shapes, starting from spherical photoresist preforms, by judicious control of sputter selectivity during the milling process. Microlens arrays were fabricated in several IR materials, including CdTe, ZnS, Ge, Si, GaAs, InP, GaP and Al₂O₃. Among these materials GaP and ZnS are also attractive visible and near IR wavelength microlens materials, where their high refractive index results in much lower sag heights than quartz lenses of comparable F-number.

Citation Download Citation

Haluk O. Sankur, Randolph L. Hall, M. Edward Motamedi, William J. Gunning III, and William E. Tennant "Fabrication of microlens arrays by reactive ion milling", Proc. SPIE 2687, Miniaturized Systems with Micro-Optics and Micromechanics, (8 March 1996); https://doi.org/10.1117/12.234628

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