Solid-state imaging device and method for making the same, and imaging apparatus
View Patent ↗A solid-state imaging device includes a light receiving unit formed in a semiconductor base and configured to perform photoelectric conversion; an insulating layer disposed on the semiconductor base; a film constituting a cladding of a waveguide together with the insulating layer and being formed in an outer part of an interior of a hole by coating, the hole being formed in the insulating layer above the light receiving unit; a core of the waveguide, the core being composed of a material having a higher refractive index than a material for the insulating layer and a material for the film formed by coating, the core being formed in an inner part of the interior of the hole; and an inner lens integrated with the waveguide, the inner lens having a lens surface formed at the bottom of the hole at the interface between the film formed by coating and the core.
1. A solid-state imaging device comprising:
a light receiving unit formed in a semiconductor base and configured to perform photoelectric conversion;
an insulating layer disposed on the semiconductor base, the insulating layer having an opening above the light receiving unit;
a film coating side walls and a flat bottom surface of the opening, the film having a thickness in a range of 1 nm to 100 nm to provide the film with a curved surface, the curved surface being a concave surface facing an interior of the opening resulting from a surface tension characteristic of the film;
a core of a waveguide, the core being composed of a material having a refractive index higher than that of a material for the insulating layer and that of a material for the film, the core being on the film and filling the opening; and
an inner lens integrated with the waveguide, the inner lens having a lens surface that comprises the curved surface
wherein,
the insulating layer and the film constitute a cladding of the waveguide.
2. The solid-state imaging device according to claim 1 , wherein the material for the film is siloxane.
3. The imaging apparatus of claim 1 , wherein the insulating layer and the film constitute a cladding of the waveguide.
4. A method for making a solid-state imaging device, comprising the steps of:
forming an insulating layer on a semiconductor base in which a light receiving unit configured to perform photoelectric conversion is formed;
forming an opening in the insulating layer above the light receiving unit;
coating sidewalls and a flat bottom surface of the opening with a film, the film having a thickness in a range of 1 nm to 100 nm to provide the film with a curved surface, the curved surface being a concave surface facing an interior of the opening resulting from a surface tension characteristic of the film;
forming a layer composed of a material for a core of a waveguide, the material having a refractive index higher than that of a material for the insulating layer and that of a material for the film, the layer being on the film and filling the opening; and
removing the material for the core from regions other than the interior of the hole,
wherein,
the insulating layer and the film constitute a cladding of the waveguide.
5. The method according to claim 4 , wherein the width of the hole is within the range of 0.1 μm to 2 μm.
6. The method according to claim 4 , wherein the core is formed by a coating technique.
7. The method according to claim 4 , wherein the material for the film is siloxane.
8. An imaging apparatus comprising:
a light-focusing optical unit configured to focus incident light;
a solid-state imaging device including
a light receiving unit formed in a semiconductor base and configured to perform photoelectric conversion,
an insulating layer disposed on the semiconductor base, the insulating layer having an opening above the light receiving unit,
a film coating side walls and a flat bottom surface of the opening, the film having a thickness in a range of 1 nm to 100 nm to provide the film with a curved surface, the curved surface being a concave surface facing an interior of the opening resulting from a surface tension characteristic of the film;
a core of a waveguide, the core being composed of a material having a refractive index higher than that of a material for the insulating layer and that of a material for the film, the core being on the film and filling the opening, and
an inner lens integrated with the waveguide, the inner lens having a lens surface that comprises the curved surface; and
a signal processor unit configured to process a signal obtained by photoelectric conversion by the solid-state imaging device.