Photoelectric conversion device and scanner

1. A photoelectric conversion device comprising:

a semiconductor substrate on which a plurality of pixels are arrayed; and

an insulating member which is transparent and configured to cover the semiconductor substrate,

wherein, in each of the plurality of pixels, the semiconductor substrate forms a plurality of concave portions which are arranged on a face in contact with the insulating member,

each of the plurality of concave portions includes side faces and a bottom face,

in each of the plurality of pixels, a lower face of the insulating member includes a plurality of first lower faces in contact with the bottom faces of respective concave portions and a plurality of second lower faces in contact with respective faces of the semiconductor substrate each positioned between two adjacent concave portions,

in each of the plurality of pixels, an upper face of the insulating member includes a plurality of first upper faces and a plurality of second upper faces,

in each of the plurality of first upper faces, at least one of the first lower faces and at least one of the second lower faces are arranged under the first upper face so as to be overlapped by the first upper face,

in each of the plurality of second upper faces, at least one of the first lower faces and at least one of the second lower faces are arranged under the second upper face so as to be overlapped by the second upper face, and

at least three of first through fourth distances are different from each other:

the first distance from the first lower face to the first upper face above the first lower face,

the second distance from the first lower face to the second upper face above the first lower face,

the third distance from the second lower face to the first upper face above the second lower face, and

the fourth distance from the second lower face to the second upper face above the second lower face.

2. The device according to claim 1 , wherein, in a planar view,

each of the first upper faces overlaps both the first lower face and the second lower face, and/or

each of the second upper faces overlaps both the first lower face and the second lower face.

3. The device according to claim 1 , wherein, in a planar view,

the first lower faces and the second lower faces are alternately arranged at a first interval, and

the first upper faces and the second upper faces are alternately arranged at a second interval larger than the first interval.

4. The device according to claim 3 , wherein, in the planar view,

the first lower faces and the second lower faces are alternately arranged in a first direction, and

the first upper faces and the second upper faces are alternately arranged in a second direction that crosses the first direction.

5. The device according to claim 3 , wherein, in the planar view,

the first lower faces and the second lower faces are alternately arranged in a first direction, and

the first upper faces and the second upper faces are alternately arranged in the first direction.

6. The device according to claim 1 , wherein the semiconductor substrate is a silicon substrate,

the insulating member is formed by stacking a plurality of insulating layers, and

the plurality of insulating layers are each made of a material whose refractive index is not less than 1.4.

7. The device according to claim 1 , wherein the insulating member is formed by stacking the plurality of insulating layers, and

D 2=λ/(4× n 2)× k ODD ±λ/8

is satisfied where D 2 is each step between the first upper face and the second upper face, n2 is a refractive index of an uppermost layer of the plurality of insulating layers, λ is a wavelength of 630 nm, and k ODD is an arbitrary odd number.

8. The device according to claim 1 , wherein

D 2=λ/(4× n 2)× k ODD ±λ/8

is satisfied where D 2 is each step between the first upper face and the second upper face, n2 is a refractive index of the insulating member, X is a wavelength of 630 nm, and k ODD is an arbitrary odd number.

9. The device according to claim 1 , wherein the upper face of the insulating member is exposed to air.

10. The device according to claim 1 , wherein the insulating member is a first insulating member,

the photoelectric conversion device further comprises a second insulating member arranged on the first insulating member so as to cover the plurality of first upper faces and the plurality of second upper faces, and

a refractive index of the second insulating member is smaller than a refractive index of the first insulating member.

11. The device according to claim 1 , wherein the side faces of each concave portion are inclined faces, and

W 1×0.8≤ W 2≤ W 1×1.2, and

W 1×0.8≤ W 3≤ W 1×1.2,

are satisfied where W 1 is a width of the first lower face in a planar view, W 2 is a width of the second lower face, and W 3 is a width of the inclined face.

12. The device according to claim 1 , wherein the semiconductor substrate includes, in each pixel, a first region of a first conductivity type and a second region of a second conductivity type arranged deeper than the first region so as to surround the first region,

the first region is connected to a wiring portion configured to output a signal based on charges generated by photoelectric conversion, and

in a planar view, the first upper faces and the second upper faces are arranged so that the steps of the first upper faces and the second upper faces will not overlap the first region.

13. A scanner comprising:

a photoelectric conversion device defined in claim 1 , and a processor configured to process a signal from the photoelectric conversion device.

14. The scanner according to claim 13 , wherein the photoelectric conversion device is one of a plurality of photoelectric conversion devices arranged in a predetermined direction, and

the processor generates image data by processing the signal from each of the plurality of photoelectric conversion devices.

15. The device according to claim 1 , wherein, in each of the plurality of pixels, a first one of the plurality of first upper faces, a first one of the plurality of second upper faces, a second one of the plurality of first upper faces and a second one of the plurality of second upper faces are arranged in successive order.