Fabrication of low cost wafer-level micro-lens arrays with spacers using glass molds by combining a Chemical Foaming Process (CFP) and a Hot Forming Process (HFP)

This paper reports an innovative molding process for the fabrication of low cost wafer-level micro-lens array with spacers of optical applications. The concave mold for the micro-lens includes two parts: the upper glass mold and the under silicon mold. The upper glass mold was prepared by combining the Hot Forming Process (HFP) and the Chemical Foaming Process (CFP). The under silicon mold was prepared by etching. Specially designed concave structures were prepared on both parts. An anti-adhesion layer was formed on the surface of the concave mold. UV-light curable glue, the lens material, was injected into the concave mold and cured. Results show that wafer-level micro-lens arrays with spacers were successfully fabricated after de-molding the reusable mold. Samples of 6×6 micro-lens arrays with spacers, in diameter of 800μm and pitch of 2600μm, were prepared. Fabrication imperfection and design of micro-lens array was discussed.