Omnivision claims pixel technology breakthrough for image sensors

Omnivision has claimed a pixel technology breakthrough with the development of the smallest 0.56-µm pixel without compromising quantum efficiency (QE) and quad phase detection (QPD) autofocus performance, while delivering low power consumption. The ultra-small pixel technology targets image sensor requirements for higher resolution in multi-camera mobile devices.

“This ultra-small pixel technology will address the increasing demand for high-resolution and small pixel pitch image sensors for multi-camera mobile devices. It means the same optical size will be able to accommodate more pixels hence higher resolution,” said Lindsay Grant, Omnivision’s senior vice president of process engineering.

Omnivision will also be looking at other market applications in the future, he said.

With the development of a pixel size smaller than the wavelength of red light, Grant said Omnivision “has validated that pixel shrink is no longer limited by the wavelength of light.” At the same time QPD and QE performance is comparable to the performance of the company’s 0.61-µm pixel in the visible light range.

The 0.56-µm pixel design is attributed to a CMOS image sensor (CIS)-dedicated 28-nm process node and 22-nm logic process node at TSMC, with a new pixel transistor layout and 2×4 shared pixel architecture. The pixel is based on Omnivision’s PureCelPlus-S stacking technology, and deep photodiode technology, which embeds the photodiode deeper into the silicon.

Block diagram and cross-section of the 0.56-µm pixel design (Source: Omnivision)

“With the latest PureCelPlus-S and deep photodiode technologies, we are able to integrate all required components in 3D, which enable our continuous effort on pixel shrink,” said Grant.

As a result, the development of the small pixel has allowed for higher resolutions in the same optical format, and enables the image sensor to have more ISP functions, lower power consumption, and faster read out speed. “The detailed numbers of those all depend on the resolution of the sensors that utilize this pixel design,” Grant said.

The first 0.56-µm pixel die will be implemented in 200-megapixel image sensors for smartphones in the second quarter of 2022, with samples targeted for the third quarter. Smartphones with the new pixel die are expected to be available in early 2023.