Photonic crystal-based lens elements for use in an image sensor
View Patent ↗The invention, in various exemplary embodiments, incorporates a photonic crystal lens element into an image sensor. The photonic crystal lens element comprises a substrate and a plurality of pillars forming a photonic crystal structure over the substrate. The pillars are spaced apart from each other. Each pillar has a height and a horizontal cross sectional shape. A material with a different dielectric constant than the pillars is provided within the spacing between the pillars. The photonic crystal element can be a lens configured to focus electromagnetic radiation onto an underlying pixel cell.
1. A processor system comprising:
(i) a processor; and
(ii) an image sensor coupled to the processor, the image sensor comprising:
a substrate,
an array of pixel cells at a surface of the substrate, each pixel cell comprising a photo-conversion device, and
at least one photonic crystal lens element over at least one of the pixel cells configured to focus light onto at least one photo-conversion device, the photonic crystal lens element comprising a plurality of pillars being spaced apart from each other, and a material within the spacing between the pillars, the material having a dielectric constant that is lower than a dielectric constant of the pillars.
2. The processor system of claim 1 , wherein the image sensor is a CMOS image sensor.
3. The processor system of claim 1 , wherein the image sensor is a charge coupled device image sensor.
4. The processor system of claim 1 , wherein the photonic crystal lens element has a negative index of refraction.
5. The processor system of claim 1 , wherein a shape of the photonic crystal lens element is approximately the same shape as the photo-conversion device and the photonic crystal lens element is approximately aligned with the photo-conversion device.
6. The processor system of claim 1 , further comprising a micro-lens over at least a portion of the pixel cells.
7. The processor system of claim 6 , wherein the photonic crystal lens element is provided over at least one micro-lens.
8. The processor system of claim 1 , wherein the array comprises an interlayer dielectric region and the photonic crystal lens element is on a same horizontal plane as the interlayer dielectric region.
9. The processor system of claim 1 , wherein the photonic crystal lens element is within a pixel cell.
10. The processor system of claim 1 , wherein the at least one photonic crystal lens element is a photonic crystal layer comprising at least one lens region configured to focus light onto the photo-conversion device and at least one light blocking region configured to block at least a portion of light from reaching the substrate.
11. The processor system of claim 10 , wherein the at least one lens region has a different photonic crystal structure than a photonic crystal structure of the at least one light blocking region.
12. The processor system of claim 10 , wherein a shape of the lens region is approximately the same shape as the photo-conversion device and the lens region is aligned with the photo-conversion device.
13. The processor system of claim 1 , further comprising a least two photonic crystal lens elements over at least one of the pixel cells.
14. The processor system of claim 1 , further comprising a photonic crystal filter over the substrate for selectively permitting electromagnetic wavelengths to reach at least one photo-conversion device.
15. The processor system of claim 1 , wherein the processor system is a camera system.
16. A camera system comprising:
(i) a camera system processor; and
(ii) an image sensor coupled to the camera system processor, the image sensor comprising:
a substrate,
an array of pixel cells at a surface of a substrate, each pixel cell comprising a photo-conversion device, and
at least one lens element having a photonic crystal structure over at least one of the photo-conversion devices for focusing light onto the at least one photo-conversion device, the photonic crystal structure comprising a plurality of pillars being spaced apart from each other, and a material within the spacing between the pillars, the material having a dielectric constant that is lower than a dielectric constant of the pillars.
17. The camera system of claim 16 , wherein the photonic crystal lens element comprises a plurality of pillars spaced apart from each other, a material within the spacing between the pillars has a dielectric constant that is lower than a dielectric constant of the pillars.
18. A camera system comprising:
(i) a camera system processor; and
(ii) an image sensor coupled to the camera system processor, the image sensor comprising:
a substrate,
an array of pixel cells at a surface of a substrate, each pixel cell comprising a photo-conversion device, and
at least one lens element over at least one of the photo-conversion devices, the lens element comprising a photonic crystal structure configured such that the lens element has a negative index of refraction, a top surface and a bottom surface, the top and bottom surfaces being approximately parallel with respect to each other, the lens element further comprising a plurality of pillars being spaced apart from each other, and a material within the spacing between the pillars, the material having a dielectric constant that is lower than a dielectric constant of the pillars.