<title>Wafer scale integration of micro-optic and optoelectronic elements by polymer UV reaction molding</title>

Abstract

A replication technique allowing for the wafer scale integration ofmicrooptical elements is presented and illustrated by various examples. The technique is based on polymer UV reaction moulding using a modified contact mask aligner where mask and wafer are replaced by the replication tool and an arbitrary substrate (on top ofwhich the microstructures are to be replicated), respectively. The technology takes advantage ofthe high precision and adjustment accuracy of photolithography equipment. The replication masters are nickel shims, etched Silicon wafers or uv-transparent fused silica tools. The latter ones allow for replication on opaque substrates. Additionally, polymer elements with unique properties can be obtained by the combination ofreplication and resist technology using partially transparent replication tools. Wafer scale hybrid integration of micro-optical subsystems is accomplished by replication of polymer elements like lenses, lens arrays, micro prisms etc. onto semiconductor wafers containing detectors or VCSELs, or, by combining micro-optical elements on both sides of a glass wafer. The use ofthin layers ofuv cured (crosslinked) polymers on inorganic substrates results in good thermal and mechanical stability compared to all-polymer devices.

Design and fabrication technologies for ultraviolet replicated micro-optics

“…Any distortion in the front or backside replication leads to an immediate failure in the alignment accuracy. 5,7 Such lateral distortion effects are also well studied in the field of microcontact printing. 12 Micro-optical components are typically assembled into optoelectronic systems.…”

Replication Techniques for Digital Optics

“…Ultraviolet embossing requires one side of the mold structure to be UV-transparent [9]. Ultraviolet embossing requires one side of the mold structure to be UV-transparent [9].…”

Replication of micro optical components by UV-molding process

“…3,4 Among the researchers who have pioneered developing UV-replication process, we particularly mention the work of Tanigami et al, Dannberg et al, and Rudschuck et al. [3][4][5][6] Tanigami et al 3 used UV-molding to fabricate micro-fresnel lens on a glass substrate. The fabricated micro-fresnel lens had high temperature stability, low wavefront aberration, and diffraction-limited focusing characteristics.…”

“…The fabricated micro-fresnel lens had high temperature stability, low wavefront aberration, and diffraction-limited focusing characteristics. Dannberg et al 4,5 integrated wafer scale hybrid micro-optical subsystems such as vertical cavity surface emitting lasers (VCSELs) using UV photo lithography. It is important to maximize the replication quality of UV-molded parts, because one can obtain the replicated micro-optical components with desired properties.…”

“…Among various polymer micro-replication processes, UV-molding is regarded as the most suitable process for producing micro-optical components or integrating optical components on the micro-electronic modules, because the process is operated at room temperature with relatively low applied pressure. [1][2][3][4][5][6][7][8][9][10] Furthermore, UV-molding process provides the components with low thermal expansion, enhanced stability and low birefringence, and can be applied to replicate optical components with very small features. 3,4 Among the researchers who have pioneered developing UV-replication process, we particularly mention the work of Tanigami et al, Dannberg et al, and Rudschuck et al.…”