Ahead of his participation at Image Sensors Europe 2018, we spoke to Albert Theuwissen, Founder of Harvest Imaging on his perspectives of the biggest industry game changers for image sensors, the future market for VR and insights about his hybrid imagers presentation.
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Your presentation looks into hybrid imagers and why they are having a hard time beating monolithic CMOS image sensors, why do you think this is, could you give us a brief insight into what your presentation will cover?
There are several reasons why I think (= am convinced) that monolithic CMOS imagers are superior to hybrid imagers :
- The hybrid imagers are always based on 3T structures, while monolithic can make use of the 4T imagers. This results in a lower noise for the latter,
- The dark current, dark current non-uniformities and isolated hot-pixel count is always better for monolithic silicon,
- Monolithic silicon has improved quite a lot w.r.t. their response to near-IR light, such that they show even better (QE) performance in the near-IR than most of the hybrid imagers,
- Monolithic silicon has a better signal-to-noise ratio than the hybrid imagers.
These statements are valid within the wavelength range of monolithic silicon (visible spectrum up to 1.1 um). Outside this wavelength range, the story can be completely different.
What would you say are the 3 biggest game changers that will soon hit the image sensors industry and how can we prepare for it?
1) The increase of stacked imager technology - more companies are following this trend outside of just image-sensor companies, for example companies that (will) have signal-processing chips available that can be stacked to imagers. On the other hand, the stacking technology is quickly moving to the stacking on pixel level. This will result in ultra-fast devices with a huge amount of parallel processing capabilities on the (stacked) chip.
2) The use of near-IR information will not only add more features to the cameras, but also introduce new applications, e.g. face recognition in mobile phones, measurement of distances, etc.
3) Imagers are no longer mainly used for making beautiful images, but more and more applications are being created to use image sensors for totally other functions. Examples are the time-of-flight applications, the auto focus pixels, use in autonomous driving cars, etc.
Where do you foresee the market for VR in the next 5 years is headed?
My thoughts are image sensors will become faster with a better signal-to-noise ratio, etc. Their performance will increase and that means that their application field will expand again, mainly towards harsh environments. Whether it is VR or another application they will all benefit by higher sensor performance. In the case of semiconductors : more applications fields will lead to higher volumes, higher volumes will lead to lower prices, lower prices will lead to more application fields, … (the circle is closed).
What can the attendees look to gain by hearing your presentation at the conference?
Technically : I will explain on a technical basis the performance difference between monolithic CMOS devices and hybrid image sensors. But next to that, I will show the audience the great promises made by several companies that announced to replace silicon imagers (CCDs or CMOS) by a hybrid solution all failed (if they were applied in that part of the spectrum to which silicon is sensitive to). So let that be lesson for the future if again new announcements (like the ones we had in the past) are being made.
What are you most looking forward to at the Image Sensors Europe conference?
For me the networking is the greatest benefit.