Solid-state imaging element and solid-state imaging device
View Patent ↗A solid-state imaging element or the like capable of limiting an abrupt refractive index distribution and collecting incident light at high efficiency is provided. The solid-state imaging element (size: 5.6 μm square) has a distributed index lens, a G color filter, Al wiring, a signal transmitting unit, a planarizing layer, a light receiving element (Si photodiode) and a Si substrate. A concentric structure of the distributed index lens is formed of SiO 2 (n=1.43). This structure is a two-stage structure having film thicknesses of 1.2 and 0.8 μm. The distributed index lens is constructed by cutting concentric circular recesses into SiO 2 and has a planar region about the center. A medium surrounding the lens is air (n=1).
1. A solid-state imaging device, comprising:
a plurality of unit pixels arranged in a two-dimensional array, each of the unit pixels comprising a light collecting element and a light receiving element,
wherein each of the light collecting elements comprises:
a plurality of zone regions of light transmitting films positioned in a concentric structure, which are divided by a line width substantially equal to or shorter than a wavelength of incident light; and
a planar region positioned at a center of the concentric structure and having a diameter which is substantially equal to or larger than the wavelength of the incident light,
wherein said planar region in said light collecting element has a constant refractive index produced by a light transmitting film which is uniformly formed, and
each of said zone regions has an effective refractive index distribution produced by a light transmitting film which is partially formed.
2. The solid-state imaging device according to claim 1 ,
wherein phase modulation caused by a refractive index distribution in said zone regions is divided by a product of 2π and a natural number except zero.
3. The solid-state imaging device according to claim 1 ,
wherein a boundary corresponding to 2π of phase modulation caused by a refractive index distribution in said zone regions abuts on a single side or a plurality of sides of a pixel.
4. The solid-state imaging device according to claim 1 ,
wherein a boundary corresponding to 2π of phase modulation caused by a refractive index distribution in said zone regions contains a pixel region.
5. The solid-state imaging device according to claim 1 ,
wherein a position of a center of the concentric structure in said light collecting element differs from a position of a center of said solid-state imaging device.
6. The solid-state imaging device according to claim 1 ,
wherein a multilayer film structure having an optical antireflection effect produced by a difference in refractive index is formed on said planar region of said light transmitting film.
7. The solid-state imaging device according to claim 1 ,
wherein the structure of said light collecting device is a multilayer film structure having an optical antireflection effect produced by a difference in refractive index.
8. The solid-state imaging device according to claim 1 ,
wherein the structure of said light collecting element is a dielectric multilayer film structure having a color separating function.
9. The solid-state imaging device according to claim 1 ,
wherein said planar regions are formed with a transmitting film containing a refractive material, and
said unit pixels which are positioned at a center of said solid-state imaging device are formed so that a center axis of each light receiving element and a center axis of the corresponding light collecting element coincide with each other, and said unit pixels which are positioned on a periphery of said solid-state imaging device are formed so that a center of each light collecting element is closer to a center of said solid-state imaging device than the corresponding light receiving element.
10. The solid-state imaging device according to claim 1 ,
wherein said planar region of said light transmitting film in each light collecting element positioned on the periphery of said solid-state imaging device is smaller than said planar region of said light transmitting film in each light collecting element positioned at the center of said solid-state imaging device, and the number of said zone regions in said light collecting elements positioned on the periphery of said solid-state imaging device is larger than the number of said zone regions in said light collecting elements positioned at the center of said solid-state imaging device.
11. The solid-state imaging device according to claim 1 , wherein a refractive index of said light collecting element is highest at the center of said light collecting element.