HIGH VOLUME MANUFACTURING SOLUTION FOR WAFER LEVEL LENS MOLDING AND STACKING
Authors: Kien Mun Lau, Michael Kast, Gerald Kreindl, Markus Wimplinger, Dominik Treiblmayr, Robert Breyer and Thorsten Matthias Company: EV Group Date Published: 10/11/2010
IWLPC (Wafer-Level Packaging)
Abstract: This paper reviews the state of the art in wafer level optics (WLO) manufacturing, in the area of wafer level lens molding and stacking. The benefits and motives of migrating towards the advent of wafer level manufacturing will be established. We will introduce the wafer level camera (WLC) and discuss the current trend in wafer level lens molding pertaining to CMOS image sensor. A process flow geared towards high volume manufacturing of wafer level lens will be presented, together with details on each process step, including large area master fabrication using a step and repeat UV-NIL (ultra-violet nanomprint lithography) system, the working stamp material and its fabrication. This is followed by the lens imprinting process, lens material, alignment and stacking performed using a dedicated micromolding aligner system. To conclude, the quality of the imprinted wafer level lens and lens stacking will be evaluated according to the lens-to-lens and wafer-to-wafer alignment accuracy, quantitative optical/surface measurements and lens shape fidelity.