Archives for April 2022

Image Sensors World        Go to the original article...

After the Harvest Imaging forums during the last 7 years, an eighth one will be organized on June 23 & 24, 2022 in Delft, the Netherlands. The basic intention of the Harvest Imaging forum is to have a scientific and technical in-depth discussion on one particular topic that is of great importance and value to digital imaging. Due to well-known reasons, the 2022 version of the forum will be organized in a hybrid form :

You can attend in-person and can benefit in an utmost way of the live interaction with the speakers and audience,

There will be also a live broadcast of the forum, still interactions with the speakers through a chat box will be made possible,

Finally the forum also can be watched on-line at a later date.

The 2022 Harvest Imaging forum will deal with two subjects in the field of solid-state imaging and two speakers. Both speakers are world-level experts in their own fields.

"Dark current, dim points and bright spots : coming to the dark side of image sensors"

Dr. Daniel McGrath (GOODiX, USA)

Abstract:

Charge-generating defects are an intersection of physics, material properties, manufacturing processes and image science. In this time when pixels are reduced in dimensions comparable to the wavelength of light and noise performance is approaching photon counting, processes that produce erroneous signals in the dark have come to limit image sensor performance. The reduction of dark current over the last decades has been a success story, but has got the industry to a point where it is not clear the path for further improvement.

The aim of this forum is to provide an feet-on-the-ground exploration of the nature of dark current and of bright defects in image sensors. The start will be a discussion of the nature of both with their individual challenges and a timeline to put the development that has got the technology to its present state. It will discuss the challenge and opportunity provided by extreme sensitivity of the pixel, a curse and a blessing for understanding. It will traverse the physics and material issues related in spontaneous charge generation in semiconductors. It will take time to ponder gettering, passivation and radiation effects. It will try to provide a path through the tangle of manufacturing's mysteries and challenges. The goal is to climb to the present precipice, there to consider options that can take the technology to the next advance.

Bio:

Dan McGrath has worked for 40 years specializing in the device physics of silicon-based pixels, CCD and CIS, and in the integration of image-sensor process enhancements in the manufacturing flow. He chose his first job because it offered that “studying defects in image sensors means doing physics” and has kept this passion front-and-center in his work. After obtaining his doctorate from The Johns Hopkins University, he pursued this work at Texas Instruments, Polaroid, Atmel, Eastman Kodak, Aptina and BAE Systems. He has worked with manufacturing facilities in France, Italy, Taiwan, and the USA. In 2019 he joined GOODiX Technology, a supplier to the cell phone and IoT market. He has held organizational positions in the Semiconductor Interface Specialists Conference, the International Solid State Circuits Conference, The International Electron Device Conference and the International Image Sensor Workshop. He has made presentations on dark current at ESSDERC, Electronic Imaging and the International Image Sensor Workshop. His publications include the first megapixel CCD and the basis for dark current spectroscopy (DCS).

"Random Telegraph Signal and Radiation Induced Defects in CMOS Image Sensors"

Dr. Vincent Goiffon (ISAE-SUPAERO, Fr)

Abstract:

CMOS Image Sensors (CIS) are by far the main solid-state image sensor technology in 2021. Each and every year, this technology comes closer to the ideal visible imaging device with near 100% peak quantum efficiency, sub electron readout noise and ultra-low dark current (< 1 e-/s) at room temperature. In such near-perfect pixel arrays, the appearance of a single defect can seriously jeopardize the pixel function. Oxide/silicon interface and silicon bulk defects can remain after manufacturing or can be introduced by aging or after exposure to particle radiation. This later source of performance degradation limits the use of commercial “unhardened” solid-state sensors in a wide range of key applications such as medical imaging, space exploration, nuclear power plant safety, electron microscopy, particle physics and nuclear fusion instrumentation.

The aim of this forum is to explore the influence of semiconductor defects on CIS performances through the magnifying glass of radiation damage. In a first part, a review of radiation effects on CIS will be provided alongside the main mitigation techniques (so-called radiation hardening by design or RHBD techniques). The trade-off between radiation-hardening and performance will be discussed on chosen applications. This first part has a double objective: 1) to provide image sensors professionals the background to anticipate and improve the radiation hardness of their sensors in radiation environment, and 2) to give a different perspective on parasitic physical mechanisms that can be observed in as-fabricated sensors such as hot pixels and charge transfer inefficiency.

The second part will focus on Random Telegraph Signals (RTS) in image sensors, a defect related phenomenon of growing importance in advanced technologies. The fundamental differences between the two main RTS in imagers – MOSFET channel RTS, also called RTN, and Dark Current RTS (DC-RTS) – will be presented. Similarly to the first part, radiation damage will be used to clarify the mysterious origin of DC-RTS. The discussion will conclude with an opening towards the RTS mechanisms similarities between CIS and other image sensor technologies (e.g. SPAD and infrared detectors) and integrated circuits (DRAM).

Bio:

Vincent Goiffon received his Ph.D. in EE from the University of Toulouse in 2008. The same year he joined the ISAE-SUPAERO Image Sensor Research group as Associate Professor and he has been a Full Professor of Electronics at the Institute since 2018.

He has contributed to advance the understanding of radiation effects on solid-state image sensors, notably by identifying original degradation mechanisms in pinned photodiode pixels and by clarifying the role of interface and bulk defects in the mysterious dark current random telegraph signal phenomenon.

Besides his contributions to various space R&D projects, Vincent has been leading the development of radiation hardened CMOS image sensors (CIS) and cameras for nuclear fusion experiments (e.g. ITER and CEA Laser MegaJoule) and nuclear power plant safety. Vincent recently became the head of the Image Sensor Group of ISAE-SUPAERO.

Vincent Goiffon is the author of one book chapter and more than 90 scientific publications, including more than 10 conference awards at IEEE NSREC, RADECS and IISW.

He has been an associate editor of the IEEE Transactions on Nuclear Science since 2017 and has served the community as reviewer and session chair.

Register here: https://www.harvestimaging.com/forum_introduction_2021_new.php

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