OmniVision
Technologies, Inc. (Nasdaq: OVTI), the world’s largest supplier of CMOS image
sensors, today launched its OmniBSITM architecture, a novel sensor design that
adopts a radically different approach to traditional CMOS image sensor
technology. Using backside illumination (BSI), OmniBSI enables OmniVision to
continue offering improved image quality while extending its pixel roadmap
down to 0.9 micron pixels, which is the key to continued miniaturization of
digital imaging technology. OmniVision developed OmniBSI architecture with the
support of its long-time foundry and process technology partner, Taiwan
Semiconductor Manufacturing Corporation (TSMC).
BSI methodology involves turning the CameraChip(TM) sensor upside down so
that it collects light through what was previously the backside of the sensor,
the silicon substrate. This approach differs from conventional front side
illumination (FSI) image sensors, where the amount of light reaching the
photo-sensitive area is limited, in part, by the multiple metal and dielectric
layers required to enable the sensor to convert photons into electrons. The
FSI approach can block or deflect light from reaching the pixel, ultimately
reducing the fill factor and causing additional problems, such as cross talk,
between pixels. BSI reverses the arrangement of layers so that the metal and
dielectric layers reside below the sensor array, providing the most direct
path for light to travel into the pixel. This novel approach optimizes light
absorption, enabling OmniVision to build a 1.4 micron BSI pixel that surpasses
all the performance metrics of 1.4 micron, and even most 1.75 micron, FSI
pixels.
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