Semiconductor maker OmniVision Technologies Inc. has developed a radically different image sensor that can squeeze many more pixels on a tiny chip, providing a significant improvement in camera-phone picture quality, it said today.

The new design employs a technique called "backside illumination," or BSI, that allows small pixels to absorb as much light as large pixels do in conventional image sensors. That means OmniVision can squeeze eight megapixels into the same space as current technology allows for three megapixels. In the future it will be able to make pixels even smaller.

The BSI sensors work better in low light than current ones and are an important consideration since most camera phones don't have flashes and are often used in dimly lit interior spaces. The sensors also can be placed closer to the camera lens, letting manufacturers install cameras in thinner phones than is currently possible.

One challenge with the new sensor technology was figuring out how to make the semiconductor layer thin enough to absorb light without having large numbers of defective chips, said Michael Hepp, product marketing manager. OmniVision engineers received help from Taiwan Semiconductor Manufacturing Co. (TSMC), the foundry that makes its sensors.

"Although backside illumination concepts have been studied for over 20 years, up until now nobody has been able to successfully develop the process for commercial, high volume CMOS sensor manufacturing," said Dr. Ken Chen, Senior Director, Mainstream Technology Marketing, TSMC. "Combining OmniVision's imaging expertise with TSMC's experience in process development, we have delivered a truly advanced technology that defines the future of digital imaging."

OmniVision became the leading supplier of image sensors for the world's handset makers last year. It expects eight-megapixel sensors will start appearing in high-end phones in 2009.

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