Pixcurve image sensor: microelectronics free from planar sensors

In February Leti presented a functional prototype of an 11 mm x 7 mm CMOS image sensor whose unique feature is that it is curved. The innovation could lead to a spectacular reduction in the size and complexity of lenses. It also opens the door to a whole new breed of microelectronics where the flat format will no longer be the norm.

The Pixcurve sensor was made from a commercially-available image sensor that was thinned from 725 microns to less than 100 microns. The thinned sensor is flexible enough to be curved, with a curve radius of 65 millimeters. The curved sensor fits perfectly into a conventional package for planar sensors.

Standard processes combined with unique know-how

The curved sensor is fabricated using standard CMOS dicing, thinning, and packaging processes. However, orchestrating the processes required substantial R&D that led to seven patents.

So, why make a curved sensor? Mainly because camera lenses are also curved. A curved sensor combined with curved lenses minimizes the need for optical correction. At the Photonics West trade show held in the US earlier this year, Leti demonstrated that the same image quality could be obtained with a 24-mm lens for a curved sensor as with a 60-mm lens for a planar sensor.

For 30 years, the level of precision and complexity of fabrication processes has meant that flat sensors were the only option. Pixcurve has changed all that with an innovation that will challenge the “flat” world of microelectronics and better meet the needs of the equipment that uses the sensors.

Contact: alexis.rochas@cea.fr

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