Photodiode array and image sensor
A photodiode array includes a plurality of elemental devices arrayed on a substrate. Each of the plurality of elemental devices includes an upper electrode, a lower electrode, a photoelectric conversion region between the upper electrode and the lower electrode, a lower conductive part located lower than the lower electrode; and an insulating layer between the lower electrode and the lower conductive part. The lower conductive part at least partially overlaps the lower electrode with the insulating layer interposed therebetween when viewed planarly.
1 . A photodiode array comprising a plurality of elemental devices arrayed on a substrate, each of the plurality of elemental devices including:
an upper electrode;
a lower electrode;
a photoelectric conversion region between the upper electrode and the lower electrode;
a lower conductive part located lower than the lower electrode;
a first insulating layer between the lower electrode and the lower conductive part;
a switch transistor configured to switch whether to electrically connect the elemental device to a signal line;
a bias electrode;
a first contact region overlapping a part of the switch transistor when viewed planarly and electrically connecting the bias electrode, wherein a part of the lower conductive part covers at least a part of a channel of the switch transistor when viewed planarly; and
a second contact region configured to electrically connect the bias electrode and the upper electrode,
wherein the switch transistor includes a source electrode and a drain electrode that are located lower than the lower electrode, and a gate electrode located lower than the source electrode and the drain electrode,
wherein each of the plurality of elemental devices includes a second insulating layer between the lower conductive part and the source and drain electrodes,
wherein the lower conductive part at least partially overlaps the lower electrode with the first insulating layer interposed therebetween when viewed planarly, and
wherein the lower conductive part is electrically insulated from the lower electrode, the source electrode, and the drain electrode.
2 . The photodiode array according to claim 1 ,
wherein the plurality of elemental devices are laid out in a matrix, and
wherein the lower conductive part is connected with other lower conductive parts horizontally and vertically adjacent to the lower conductive part.
3 . The photodiode array according to claim 1 ,
wherein each of the plurality of elemental devices further includes a switch transistor configured to switch whether to electrically connect the elemental device to a signal line, and
wherein source/drain electrodes of the switch transistor and the lower conductive part are located on a same insulating layer and made of same material.
4 . The photodiode array according to claim 1 , wherein a part of the photoelectric conversion region covers at least a part of the channel when viewed planarly.
5 . The photodiode array according to claim 1 , wherein the lower conductive part has an opening in a region opposed to the lower electrode when viewed planarly.
6 . The photodiode array according to claim 1 , wherein a part of the lower conductive part covers at least a part of a gate line configured to transmit a signal to the gate electrode when viewed planarly.
7 . The photodiode array according to claim 6 , wherein a part of the photoelectric conversion region covers at least a part of the gate line when viewed planarly.
8 . An image sensor comprising:
the photodiode array according to claim 1 ; and
a circuit configured to drive and control the photodiode array.