Canon Patent Application: Backside Illuminated Sensor

Canon has been continually researching new methods of manufacturing different sensors, while we may not hear all the buzzwords, the 90D/M6 Mark II sensor shows steady improvement in Canon's sensor manufacturing.

This patent deals specifically with backside illuminated sensors, and more specifically some methods of manufacturing.  Canon in this patent is worried that during the etching process that the photo diodes and circuits along the edge of the sensor may be damaged.  Their proposal is to arrange a charged film on top, thus reducing damage which ultimately assists in lowering the sensor dark current.

In patentspeak;

Photodiode for accumulating electrons and a plurality arranged pixel region, the solid-state imaging device is known which has a semiconductor substrate including a peripheral circuit region. As an example of this solid-state imaging device, there is a so-called back-illuminated solid-state imaging device in which a semiconductor substrate having a PD is provided between a microlens array and a wiring layer. As a technique applicable to this solid-state imaging device, there is a technique in which a hole storage layer is formed on the light receiving surface of the PD by providing a negative fixed charge film on the light receiving surface side of the PD (for example, Patent Document 1). In the solid-state imaging device of Patent Document 1, by providing a negative fixed charge film, the charge resulting from the interface state between the PD and the film provided on the light receiving surface of the PD is reduced to a dark current. .
In FIG. 7 of Patent Document 1, a positive fixed charge film is provided in the peripheral circuit region, and a negative fixed charge film is provided on the upper surface of the positive fixed charge film and the light receiving surface of the PD. Malfunctions are reduced.

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  One object of the present invention is to provide a solid-state imaging device and the malfunction of the transistor damage prevented from entering into the PD by etching at the time of manufacturing is suppressed.

Japan Patent Application 2019-212737