Thursday, December 31, 2009

SUSS Discusses Wafer-Level Camera Manufacturing

December 2009 issue of German "Optik & Photonik" journal features Suss article on wafer-level camera manufacturing. According to the company, an estimated 80 million WLC modules have been delivered in 2009. The article goes in great lengths talking about background history behind the new micro-optics ideas, with natural emphasis on Suss contribution to the history.

The article also covers microlens imprint lithography (SMILE), where a liquid polymer is dispensed on the wafer and the lenses are imprinted by using a transparent stamp or mold and UV-light for curing. Master lens arrays consisting of aspherical microlenses with profile deviation below 50nm (rms) and surface roughness below 2nm (rms) were demonstrated on full 8" wafer scale by Suss MicroOptics. Recently Kaleido Technology, Denmark, presented a first 8" diamond milled lens master in brass, providing spherical, aspherical and free-form lenses with better than 2um lateral position accuracy.

The wafer-scale master wafers are then transferred into a soft stamp, usually made of Polydimethylsiloxane (PDMS) by casting. The PDMS layer serves as a stamp imprinting the shape on the microlens material. This material is not named by the article, other than saying that it's often kept in secret by the companies and now can be sourced from DELO, Germany and Asahi Kasei, Japan.

Another article from Fraunhofer Institute for Applied Optics and Precision Engineering talks about milling to produce wafer level optics, either directly or as a master for replication.

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