Photoelectric conversion device having isolation portions, and imaging system and moving body having photoelectric conversion device
A photoelectric conversion device has an isolation structure. First and second isolation portions are provided between first and second photoelectric conversion elements. The first isolation portion extends from a first plane of a semiconductor layer to a position corresponding to at least a quarter of a length from the first plane to a second plane of the semiconductor layer. The second isolation portion extends from the second plane of the semiconductor layer to a position corresponding to at least a quarter of the length from the first plane to the second plane.
1. A photoelectric conversion device comprising:
a semiconductor layer including a first plane and a second plane placed opposite to the first plane and including first, second, and third photoelectric conversion elements, wherein the second photoelectric conversion element is positioned between the first and third photoelectric conversion elements;
a first isolation portion that is disposed in the semiconductor layer, includes an insulator, and extends from the first plane to a position corresponding to at least a quarter of a length from the first plane to the second plane; and
a second isolation portion that is disposed in the semiconductor layer, includes an insulator, and extends from the second plane to a position corresponding to at least a quarter of the length from the first plane to the second plane,
wherein the first and second isolation portions are disposed between the first and second photoelectric conversion elements, and
wherein a single microlens is disposed corresponding to the second and third photoelectric conversion elements.
2. The photoelectric conversion device according to claim 1 ,
wherein the first isolation portion is provided by a part of the semiconductor layer being removed from the first plane, and
wherein the second isolation portion is provided by a part of the semiconductor layer being removed from the second plane.
3. The photoelectric conversion device according to claim 1 , wherein a width of the second isolation portion on the second plane is narrower than a width of the first isolation portion on the first plane.
4. The photoelectric conversion device according to claim 1 , wherein a length of the second isolation portion from the second plane is shorter than a length of the first isolation portion from the first plane.
5. The photoelectric conversion device according to claim 1 , wherein the first and second isolation portions are in contact with each other.
6. The photoelectric conversion device according to claim 1 , wherein between the first and second isolation portions, a first semiconductor region as a potential barrier against electric charges generated in the first and second photoelectric conversion elements is disposed.
7. The photoelectric conversion device according to claim 1 , wherein the first isolation portion includes a third isolation portion including a shallow trench isolation (STI) structure on the first plane.
8. The photoelectric conversion device according to claim 1 , wherein the first isolation portion includes at least polysilicon, and the second isolation portion includes at least hafnium oxide.
9. The photoelectric conversion device according to claim 1 , wherein the first isolation portion includes at least silicon nitride, and the second isolation portion includes at least hafnium oxide.
10. The photoelectric conversion device according to claim 1 , wherein the second isolation portion includes aluminum oxide.
11. The photoelectric conversion device according to claim 1 , wherein in a planar view, a center position of the first isolation portion and a center position of the second isolation portion are different from each other.
12. The photoelectric conversion device according to claim 1 , wherein between the second and third photoelectric conversion elements, a second semiconductor region as a potential barrier against electric charges generated in the second and third photoelectric conversion elements is provided.
13. The photoelectric conversion device according to claim 12 , wherein the first isolation portion is provided so that the first isolation portion extends to a position closer to the second plane than the second semiconductor region.
14. The photoelectric conversion device according to claim 1 , further comprising a fourth isolation portion that is disposed, in the semiconductor layer, between the second and third photoelectric conversion elements and extends at least from the second plane toward the first plane.
15. The photoelectric conversion device according to claim 14 , wherein the second isolation portion is provided so that the second isolation portion extends to a position closer to the first plane than the fourth isolation portion.
16. The photoelectric conversion device according to claim 14 , wherein a width of the fourth isolation portion on the second plane is narrower than a width of the second isolation portion on the second plane.
17. The photoelectric conversion device according to claim 1 , wherein in a case where the length from the first plane to the second plane is equal to or less than 3 μm, a width of the first isolation portion on the first plane is equal to or less than 150 nm, and a width of the second isolation portion on the second plane is equal to or less than 150 nm or less.
18. An imaging system comprising:
the photoelectric conversion device according to claim 1 ; and
a signal processing unit configured to process a signal output from the photoelectric conversion device.
19. A moving body comprising:
the photoelectric conversion device according to claim 1 ;
a distance information acquisition unit configured to acquire, from a parallax image based on a signal from the photoelectric conversion device, distance information regarding a distance from a target object; and
a control unit configured to control the moving body based on the distance information.