More about Omnivision Nyxel Technology

EEJournal, ElectronicDesign publish more explanations about how Omnivision Nyxel IR technology works:

"The Nyxel technology adds three pieces to the puzzle. The first is increasing the thickness of the silicon, which allows the photons to travel further in the pixel cell and enables more electron to photon conversion hence a brighter image. The second is essentially putting each cell into its own deep trench with barriers between cells to avoid photon travel to the neighboring pixels and prevent crosstalk. The other is to add a layer on the surface that absorbs [scatters] the maximum amount of light. This combination provides a longer path, allowing the sensor to detect more photons and improve the overall performance of the system."

There is also a Chinese-language article on EDNChina site adding some numbers to the story:

"Now that we have a 50% market share in the security market, security products last year accounted for about 20-25% of the company's total revenues, its growth rate is much higher than the phone," OmniVision VP of China Chen Jiawang said.

"We increased the silicon layer from 4 microns to 6 microns, absorbing more photons, converting to more electrical signals and improving imaging efficiency," explained Chen Jiawang.

The technology has been successfully deployed on 12-inch wafers, while 8-inch wafers are said to be unusable.

Update: Vision Systems Design article quotes Boyd Fowler, Omnivision CTO, explaining the technology details:

"One significant change was doubling the epitaxial layer thickness from about 3 to 6 microns.

When the electrons are generated in the substrate, they need to be collected. This DTI makes sure these electrons can't easily move from the pixel where they are generated to an adjacent pixel, which is critical for effective isolation and enables higher sensitivity, without compromising spatial resolution.

Perhaps most important to the new process is careful management of wafer surface texture to scatter the light as it enters the pixel. By scattering the light, the photons must travel a significantly longer path length.

In this case, the straight path length has been extended from about 3 or 4 microns maximum in our legacy design, to a scattered path of up to 10 or 20 microns with the Nyxel technology.

In the past people have tried to develop better NIR technology, but it was almost always a tradeoff between higher sensitivity and spatial resolution. This technology enables us to give the customer both at the same time.

OmniVision is currently sampling this experimental 2MP Nyxel technology-based product to demonstrate the proof of concept, and has also launched a 5MP product in the security market in October of this year. For 2018, the company has a slew of various resolution Nyxel-based products on the roadmap for the security market throughout Q1 and Q2, and very quickly after that will be looking at products for the machine vision market, AR/VR, automotive and medical applications."

Update #2: BDTI too publishes an article on Nyxel principles, based on a talk with Lindsay Grant, Omnivision VP of Process Engineering.