Dense arrays of millimeter-sized glass lenses fabricated at wafer-level

Abstract

This paper presents the study of a fabrication technique of lenses arrays based on the reflow of glass inside cylindrical silicon cavities. Lenses whose sizes are out of the microfabrication standards are considered. In particular, the case of high fill factor arrays is discussed in detail since the proximity between lenses generates undesired effects. These effects, not experienced when lenses are sufficiently separated so that they can be considered as single items, are corrected by properly designing the silicon cavities. Complete topographic as well as optical characterizations are reported. The compatibility of materials with Micro-Opto-Electromechanical Systems (MOEMS) integration processes makes this technology attractive for the miniaturization of inspection systems, especially those devoted to imaging.

Technological Platform for Vertical Multi-Wafer Integration of Microscanners and Micro-Optical Components

“…This technique, completed by the polishing of the top side of glass wafer and releasing of silicon, is used to fabricate the plano-convex microlenses that are described in Ref. [17]. If the bonding is performed at the atmospheric pressure, it produces a piston effect that deforms the surface of the glass towards the top of the cavity and generates a conical cavity, which is used to fabricate the micro-axicons [18] that are necessary for the generation of Bessel beams.…”

Fast ultra-deep silicon cavities: Toward isotropically etched spherical silicon molds using an ICP-DRIE

“…A variety of mask materials and etching conditions were investigated to obtain a large spherical cavity (2.5 mm in radius) with good circularity and smoothness. Early works focused on microlenses, which were specifically developed for different MOEMS applications 16,20,41 . Previous reports on isotropic dry etching technology have been documented 17,19 showing that the anisotropic plasma can be optimized, when the mask opening and the process parameter are matched, to produce a sphere shape (Fig.6).…”

Array-type miniature interferometer as the core optical microsystem of an optical coherence tomography device for tissue inspection

“…Nevertheless, silicon frames are kept and thinned down to form well-controlled and auto-aligned spacers between the lenses. 9 It is then used for the doublet generation where multi-wafer anodic bonding is applied. 10 The latter ensures a high level of alignment both laterally and axially since no additional material is required.…”