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 light detecting element disposed in a silicon layer;
a first concave-convex pattern on a first surface on the silicon layer, the first surface being a light receiving surface of the silicon layer;
an isolation structure adjacent to the light detecting element and disposed in the silicon layer;
a metal film disposed in the isolation structure; and
an interconnection layer disposed below the silicon layer, the interconnection layer including a reflecting mirror structure, wherein at least a portion of the reflecting mirror structure extends under the isolation structure, wherein the first concave-convex pattern comprises inverted triangular shapes in a cross-sectional view, and wherein a depth of at least one of the inverted triangular shapes in the first concave-convex pattern is less than a width of a widest section of the at least one of the inverted triangular shapes.
2. The light detecting device according to claim 1 , further comprising;
a hafnium oxide film disposed over the first surface of the silicon layer.
3. The light detecting device according to claim 1 , further comprising;
an aluminum oxide film disposed over the first surface of the silicon layer.
4. The light detecting device according to claim 1 , wherein the first concave-convex pattern comprises inverted pyramid shapes in a plan view.
5. The light detecting device according to claim 1 , further comprising;
a silicon oxide film disposed between the metal film and the silicon layer.
6. The light detecting device according to claim 1 , wherein the reflecting mirror structure includes Al, Cu, or Ag.
7. The light detecting device according to claim 1 , wherein the interconnection layer includes a silicon oxide layer, wherein the silicon oxide layer is disposed between silicon layer and the reflecting mirror structure, and wherein the silicon oxide layer extends under the isolation structure.
8. The light detecting device according to claim 1 , wherein the interconnection layer includes a silicon nitride layer, wherein the silicon nitride layer is disposed between silicon layer and the reflecting mirror structure.
9. The light detecting device according to claim 1 , wherein the light detecting element detects infra-red (IR) light.
10. The light detecting device according to claim 1 , further comprising:
a second concave-convex pattern on a second surface of the silicon layer that is opposite the first surface.
11. The light detecting device according to claim 10 , wherein a period of the first concave-convex pattern on the first surface and a period of the second concave-convex pattern on the second surface vary based on a wavelength of light that is to be sensed by the light detecting element.
12. The light detecting device according to claim 10 , wherein the first concave-convex pattern and the second periodic concave-convex pattern are one of one-dimensional or two-dimensional.
13. The light detecting device according to claim 1 , wherein a first crystal plane of the first surface is (100), and wherein a second crystal plane of a wall surface of the first concave-convex pattern is (111).
14. The light detecting device according to claim 1 , wherein a period of the first concave-convex pattern is 1 μm or less.
15. The light detecting device according to claim 1 , wherein the silicon layer is made of single crystal silicon.
16. The light detecting device according to claim 1 , further comprising:
a second concave-convex pattern on a second surface of the silicon layer that is opposite the first surface, wherein, in the cross-sectional view, a width of a part of the first concave-convex pattern is different from a width of a part of the second concave-convex pattern.
17. The light detecting device according to claim 1 , wherein the width of the widest section of the at least one of the inverted triangular shapes is less than or equal to a period of the first concave-convex pattern.
18. The light detecting device according to claim 4 , wherein the inverted pyramid shape has a base surface and a tip surface that are parallel to the first surface.
19. An electronic device, comprising:
a light detecting element disposed in a silicon layer;
a first concave-convex pattern on a first surface on the silicon layer, the first surface being a light receiving surface of the silicon layer;
an isolation structure adjacent to the light detecting element and disposed in the silicon layer;
a metal film disposed in the isolation structure; and
an interconnection layer disposed below the silicon layer, the interconnection layer including a reflecting mirror structure, wherein at least a portion of the reflecting mirror structure extends under the isolation structure, wherein the first concave-convex pattern comprises inverted triangular shapes in a cross-sectional view, and wherein a depth of at least one of the inverted triangular shapes in the first concave-convex pattern is less than a width of a widest section of the at least one of the inverted triangular shapes.