Solid state imaging element and electronic device
The present disclosure relates to a solid state imaging element and an electronic device that make it possible to improve sensitivity to light on a long wavelength side. A solid state imaging element according to a first aspect of the present disclosure has a solid state imaging element in which a large number of pixels are arranged vertically and horizontally, the solid state imaging element includes a periodic concave-convex pattern on a light receiving surface and an opposite surface to the light receiving surface of a light absorbing layer as a light detecting element. The present disclosure can be applied to, for example, a CMOS and the like installed in a sensor that needs a high sensitivity to light belonging to a region on the long wavelength side, such as light in the infrared region.
1. A light detecting device, comprising:
a first isolation structure disposed in a silicon layer;
a second isolation structure disposed in the silicon layer;
a light detecting element disposed in the silicon layer between the first isolation structure and the second isolation structure in a cross-sectional view;
a first concave portion and a second concave portions included in a first surface of the silicon layer, wherein the first and second concave portions are disposed between the first isolation structure and the second isolation structure in the cross-sectional view, wherein the first concave portion is adjacent to the second concave portion in the cross-sectional view;
a third concave portion and a fourth concave portions included in a second surface of the silicon layer in the cross-sectional view; and
a first insulating film comprised of an oxide or a nitride and disposed in the first and second concave portions,
wherein the second surface is opposite the first surface,
wherein the third concave portion is adjacent to the fourth concave portion in the cross-sectional view,
wherein a shape of the first concave portion is different from a shape of the third concave portion in the cross-sectional view, and
wherein a first distance between a center of the first concave portion and a center of the second concave portion is different from a second distance between a center of the third concave portion and a center of the fourth concave portion in the cross-sectional view.
2. The light detecting device according to claim 1 , further comprising a reflecting mirror structure on the second surface of the silicon layer.
3. The light detecting device according to claim 1 , further comprising:
a second insulating film disposed in the first and second concave portions between the silicon layer and the first insulating film, wherein the light detecting element detects infrared (IR) light.
4. The light detecting device according to claim 1 , wherein a crystal plane of the first surface and the second surface is (100), and wherein a crystal plane of a wall surface of the first and second concave portions is (111).
5. The light detecting device according to claim 1 , wherein the first distance and the second distance are 1 μm or less.
6. The light detecting device according to claim 1 , wherein the silicon layer is made of single crystal silicon, and wherein the first insulating film contacts the silicon layer.
7. The light detecting device according to claim 1 , wherein the first and second isolation structures are made of a material of a first refractive index lower than a second refractive index of the light detecting element.
8. The light detecting device according to claim 1 , wherein the first and second isolation structures comprise metal reflecting walls, and wherein the first insulating film comprises a flat surface that is opposite to a surface of the first insulating film that is disposed in the first and second concave portions.
9. The light detecting device according to claim 2 , wherein the reflecting mirror structure is disposed from a first region corresponding to a first trench to a second region corresponding to a second trench, wherein the first trench includes the first isolation structure, and wherein the second trench includes the second isolation structure.
10. The light detecting device according to claim 1 , wherein the first and second concave portions have an inverted triangular shape, and wherein the third and fourth concave portions have a quadrangular shape.
11. A light detecting device, comprising:
a first isolation structure disposed in a silicon layer;
a second isolation structure disposed in the silicon layer;
a light detecting element disposed in the silicon layer between the first isolation structure and the second isolation structure in a cross-sectional view;
a first concave portion and a second concave portions included in a first surface of the silicon layer, wherein the first and second concave portions are disposed between the first isolation structure and the second isolation structure in the cross-sectional view, wherein the first concave portion is adjacent to the second concave portion in the cross-sectional view; and
a third concave portion and a fourth concave portions included in a second surface of the silicon layer in the cross-sectional view,
wherein the second surface is opposite the first surface,
wherein the third concave portion is adjacent to the fourth concave portion in the cross-sectional view,
wherein a shape of the first concave portion is different from a shape of the third concave portion in the cross-sectional view,
wherein a first distance between a center of the first concave portion and a center of the second concave portion is different from a second distance between a center of the third concave portion and a center of the fourth concave portion in the cross-sectional view,
wherein the first and second concave portions have an inverted triangular shape, and
wherein the third and fourth concave portions have a quadrangular shape.
12. The light detecting device according to claim 11 , wherein the inverted triangular shape has a base surface and a tip surface that are substantially parallel to the first surface.
13. An electronic device, comprising:
a signal processor; and
a light detecting device, comprising:
a first isolation structure disposed in a silicon layer;
a second isolation structure disposed in the silicon layer;
a light detecting element disposed in the silicon layer between the first isolation structure and the second isolation structure in a cross-sectional view;
a first concave portion and a second concave portions included in a first surface of the silicon layer, wherein the first and second concave portions are disposed between the first isolation structure and the second isolation structure in the cross-sectional view, wherein the first concave portion is adjacent to the second concave portion in the cross-sectional view;
a third concave portion and a fourth concave portions included in a second surface of the silicon layer in the cross-sectional view; and
a first insulating film comprised of an oxide or a nitride and disposed in the first and second concave portions,
wherein the second surface is opposite the first surface,
wherein the third concave portion is adjacent to the fourth concave portion in the cross-sectional view,
wherein a shape of the first concave portion is different from a shape of the third concave portion in the cross-sectional view, and
wherein a first distance between a center of the first concave portion and a center the second concave portion is different from a second distance a center between the third concave portion and a center the fourth concave portion in the cross-sectional view.
14. The electronic device according to claim 13 , further comprising a reflecting mirror structure on the second surface of the silicon layer.
15. The electronic device according to claim 14 , wherein the reflecting mirror structure is disposed from a first region corresponding to a first trench to a second region corresponding to a second trench, wherein the first trench includes the first isolation structure, and wherein the second trench includes the second isolation structure.
16. The electronic device according to claim 13 , wherein the light detecting element detects infrared (IR) light.
17. The electronic device according to claim 13 , wherein the first and second concave portions have an inverted triangular shape.
18. The electronic device according to claim 17 , wherein the third and fourth concave portions have a quadrangular shape.
19. The electronic device according to claim 13 , wherein a crystal plane of the first surface and the second surface is (100), and wherein a crystal plane of a wall surface of the first and second concave portions is (111).
20. The electronic device according to claim 13 , wherein the silicon layer is made of single crystal silicon, and wherein the first and second concave portions are etched surfaces of the silicon layer.