OmniVision enhances near-infrared image sensing
The technology – dubbed Nyxel – appears to extend up to about 1-micron wavelength and to be intended as an augmentation to visible light for use in low-light and no-light conditions.
Nyxel uses thick silicon to increase photon absorption and offer higher quantum efficiency and increased signal compared with thinner silicon. The Nyxel pixel uses an optical scattering layer to lengthen the optical path and deep trench isolation to minimize cross-talk between pixels.
OmniVision claims the result is improved image quality, long-distance image capture and reduced light requirements compared with other NIR sensors. The quantum efficiency of Nyxel is three times higher at 850nm wavelength and five times higher at a wavelength of 940nm when compared with OmniVision’s previous NIR capable sensors. This makes Nyxel technology suitable for surveillance, machine-vision, and automotive applications.
Thick silicon pixels is the conventional way to improve NIR image sensor sensitivity but also results in cross-talk and reduced modulation transfer function. Attempts to overcome this with deep-trench isolation can lead to defects that appear in the dark areas of the image.
“We have worked to overcome these challenges in an exclusive engagement with our foundry partner, leveraging technologies in its 300mm wafer fab,” said Lindsay Grant, vice president of process engineering at OmniVision, in a statement.
Next: Made in China?
It is thought that OmniVision, which became a China-controlled private company in 2015, is using Wuhan Xinxin Semiconductor Manufacturing Corp. (XMC) as its foundry. XMC started out as an attempt by the Wuhan regional authority to get into semiconductor manufacturing and it put the management of the fab out to SMIC who characterized it as a foundry. It however spent much of its time doing volume NOR flash and image sensor fabrication. Earlier this year XMC was reported to have broken ground on a wafer fab designed for the production of 3D NAND flash memory.
OmniVision did not indicate how quickly it would produce image sensors using Nyxel technology or at what resolution. “Initial results are very promising, and have generated a great deal of interest with our OEM customers,” said Grant in the same statement.
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