Canon Patent Application: Stacked Sensor Method of Manufacturing

Over the years we're discovered probably most of these stacked sensor patent applications (special shoutout to Northlight images who also does the hard work reading through these patents), and while I have to admit I never thought Canon would do the incredible leap from front-side illuminated sensors to stacked sensors, here we are with the EOS R3.

Just some general thoughts because this came up in a conversation not so long ago.  Sensor (and well, and manufacturing) is an ever-evolving process involving everyone that works in Canon's fabrication and assembly plants. Nothing remains static.  Processes that were developed in 2003 at the start of the digital age and Canon's own sensor development are continually being looked at to be improved.  This brings us to "method of manufacturing" patent applications, which seek to find ways to improve either the yields, sensor performance, or reduce costs.

Back to this patent application, there are two areas of stacked sensors that you'll find Sony, Samsung, Canon, and others patent heavily and that's how either power or information get from one layer to the next. It's extremely complicated and each company is looking for the edge.  Canon actually bought out IP in 2020 for this very reason.

This patent application deals with the "pads" which move the information between the various substrates.  These have to be created with an insane amount of fine tolerances as the substrates are put together. As you can imagine, if the surface is uneven, then some pads may not connect, or connect well enough and cause inaccuracies.  Discovering methods of manufacturing that make this simpler and with a greater degree of accuracy helps reduce the cost of a stacked sensor, and improves their performance.

This patent application according to Canon will allow them to;

According to the present invention, it is possible to provide a solid-state image sensor with high reliability in the connection between a pad and a circuit. Further, according to the present invention, the connection between the pad and the circuit can be easily formed.

I'll let you all read the patent - this darn Covid headache only gets worse with patent applications ;)

Japan Patent Application 2022-000897