Canon Patent Applications: More stacked sensor patents

Canon has released a couple of stacked sensor patent applications this week dealing with various issues surrounding the manufacturing or use of stacked sensors.
In US Patent Application 2018-0233523, they discuss sealing to form a moisture proof barrier thus protecting the internal elements from water,etc.  This is another highly detailed sensor patent, with methods of manufacturing included, indicating that Canon is quite a ways into this research.
According to an aspect of the present invention, a solid-state imaging apparatus includes a plurality of pixels each of which includes a photoelectric conversion unit and a readout circuit configured to process a signal generated by the photoelectric conversion unit or configured to read the signal, and a peripheral circuit configured to read signals from the plurality of pixels. The plurality of photoelectric conversion units is disposed in a first member, and at least a part of...

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Mar 25, 2011
I'm sure this has been said before, but what does a stacked sensor do?
On a single layer sensor, the solid state transistors and traces must be placed between and around the photo diodes. This reduces the space available for gathering light.

A 2nd method is to place the circuitry on the rear of the sensor wafer, thats referred to as BSI or back side illumination. It brings lots of problems and is difficult.
So, the circuitry can be placed on a separate wafer which is stacked with the sensor wafer and has connections to the photodiodes. This allows for more complex circuitry, and a large ground plane. That large ground plane allows for much faster frame rates because they are greatly limited by the grounding path and noise generated from the switching. A whole new set of issues and expense comes into play with stacked sensors, but they solve problems, so expect everyone to use them once they can make them work.
Right now, Sony makes stacked sensors and pretty much has the field to themselves. It was not easy for them to do it, so its a potential benefit.
We do not know when or if Canon will be able to produce them, they usually are implemented for small sensors first. Canon has been using Sony 1 inch sensors that are BSI, and might like to make their own stacked sensors.
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Jul 28, 2015
It offers a lot of opportunities for processing the data with one processing unit for each pixel. So for example if you have one memory unit for each pixel it opens the door for global shutter where every pixel captures data at exactly the same time and this removes the problem of the rolling shutter. The challenge is is then transferring the data at the same time (massive processor power) or each pixel has its own little memory unit that transfers the data over a period of time.
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1,000 frames per second sounds more in their industrial/medical equipment use. However some super high burst amounts might be showing up in retail cameras before long.

The encouraging news for all of this is the fact that they are throwing out so many patents for manufacturing techniques. Canon has always been patent happy, but when you see patents for manufacturing processes it means they are working out the kinks for mass production usually. It doesn't mean any one method is being used because it's patented, but it does mean that what the type of chip the patents pertain to is something actively being pursued and most likely produced.
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Jun 27, 2013
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Beside the Sigma use of the Foveon sensor, has there been any commercially (successful or otherwise) implementation of the stack sensor?

Sigma's Foveon is a stacked RGB standard CMOS. Standard as in it functions the same way a Bayer CFA does in terms of pixel-level signal amplification and on-sensor ADC. This patent pertains to a secondary substrate layer for faster processing like the Sony EXMOR.
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