Solid-state imaging device and manufacturing method of solid-state imaging device
According to one embodiment, there is provided a solid-state imaging device including a first photoelectric conversion layer and a color filter. The color filter includes a multi-layer interference filter and a guided mode resonant grating. The guided mode resonant grating includes a plurality of diffraction gratings and a plurality of inter-grating regions. The plurality of diffraction gratings are formed of a material having a first index of refraction and periodically arrayed at least one-dimensionally. The plurality of inter-grating regions are arranged between at least the plurality of diffraction gratings. Each of the plurality of inter-grating regions includes an insulating film region and an air gap region. The insulating film region is formed of a material having a second index of refraction lower than the first index of refraction.
1. A solid-state imaging device comprising:
a first photoelectric conversion layer; and
a color filter arranged above the first photoelectric conversion layer; wherein
the color filter includes,
a multi-layer interference filter in which a first layer and a second layer having different index of refraction from each other are alternately stacked, and
a guided mode resonant grating arranged above or below the multi-layer interference filter;
the guided mode resonant grating includes,
a plurality of diffraction gratings formed of a material having a first index of refraction and periodically arrayed at least one-dimensionally, and
a plurality of inter-grating regions arranged between at least the plurality of diffraction gratings; and
each of the plurality of inter-grating regions includes,
an insulating film region formed of a material having a second index of refraction lower than the first index of refraction, and
an air gap region.
2. The solid-state imaging device according to claim 1 , wherein
a proportion of a volume of the air gap region occupying a volume of the inter-grating region is greater than or equal to 50%.
3. The solid-state imaging device according to claim 2 , wherein
the proportion of the volume of the air gap region occupying the volume of the inter-grating region is greater than or equal to 50% and smaller than or equal to 90%.
4. The solid-state imaging device according to claim 1 , further comprising:
a second photoelectric conversion layer; and
a second color filter arranged above the second photoelectric conversion layer, and being different from the first color filter; wherein
the second color filter includes,
a second multi-layer interference filter in which a first layer and a second layer having different index of refraction from each other are alternately stacked, and
a second guided mode resonant grating arranged above or below the second multi-layer interference filter;
the second guided mode resonant grating includes,
a plurality of second diffraction gratings formed of the material having the first index of refraction and periodically arrayed at least one-dimensionally, and
a plurality of second inter-grating regions arranged between the plurality of second diffraction gratings;
the plurality of second inter-grating regions each includes,
a second insulating film region formed of a material having the second index of refraction lower than the first index of refraction, and
a second air gap region; and
a proportion of a volume of the second air gap region occupying a volume of the second inter-grating region is different from the proportion of the volume of the air gap region occupying the volume of the inter-grating region.
5. The solid-state imaging device according to claim 4 , wherein
a transparent wavelength region of the second color filter is on a long wavelength side than a transparent wavelength region of the first color filter; and
the proportion of the volume of the second air gap region occupying the volume of the second inter-grating region is smaller than the proportion of the volume of the air gap region occupying the volume of the inter-grating region.
6. The solid-state imaging device according to claim 4 , wherein
a transparent wavelength region of the second color filter is on a short wavelength side than a transparent wavelength region of the first color filter; and
the proportion of the volume of the second air gap region occupying the volume of the second inter-grating region is greater than the proportion of the volume of the air gap region occupying the volume of the inter-grating region.
7. The solid-state imaging device according to claim 1 , wherein
the air gap region has a substantially triangular shape in cross-sectional view.
8. The solid-state imaging device according to claim 7 , wherein
the insulating film region covers a side portion and a bottom portion of the air gap region.
9. The solid-state imaging device according to claim 7 , wherein
an upper end of the inter-grating region is higher than an upper surface of the diffraction grating; and
an upper end of the air gap region is higher than the upper surface of the diffraction grating.
10. The solid-state imaging device according to claim 1 , wherein
the insulating film region has a width in a direction along a surface of a semiconductor substrate gradually widening towards an upper end of the inter-grating region.
11. The solid-state imaging device according to claim 10 , wherein
the insulating film region has an even film thickness along a bottom portion of the air gap region.
12. The solid-state imaging device according to claim 1 , wherein
the air gap region has a width in a direction along a surface of a semiconductor substrate gradually narrowing towards an upper end of the inter-grating region.
13. The solid-state imaging device according to claim 1 , wherein
the plurality of diffraction gratings include a plurality of line patterns; and
the plurality of inter-grating regions include a plurality of space patterns.
14. The solid-state imaging device according to claim 13 , wherein
the insulating film region is arranged on a side wall of the line pattern, and has a substantially fin shape; and
the air gap region is arranged between the two substantially fin shapes.
15. The solid-state imaging device according to claim 1 , wherein
the plurality of inter-grating regions include a plurality of hole patterns; and
the plurality of diffraction gratings include a plurality of inter-hole pattern regions.
16. The solid-state imaging device according to claim 15 , wherein
the insulating film region is arranged on an inner side surface of the hole pattern, and has a substantially cylindrical shape; and
the air gap region is arranged on an inner side of the substantially cylindrical shape.
17. The solid-state imaging device according to claim 1 , wherein
the plurality of diffraction gratings include a plurality of columnar patterns; and
the plurality of inter-grating regions include a plurality of inter-columnar pattern regions.
18. The solid-state imaging device according to claim 17 , wherein
the insulating film region is arranged on a side surface of the columnar pattern, and has a substantially cylindrical shape; and
the air gap region is arranged on an inner side of the substantially cylindrical shape.