CMOS image sensors with per-pixel micro-lens arrays
An image sensor includes an array of CMOS pixels and a plurality of micro-lens arrays. Each micro-lens array of the plurality of micro-lens arrays includes a plurality of horizontally adjacent micro-lenses. Each micro-lens array of the plurality of micro-lens arrays is situated above a respective CMOS pixel in the array of CMOS pixels.
1. An integrated-circuit image sensor, comprising:
pixels disposed in rows and columns; and
micro-lens arrays disposed in rows and columns, each of the micro-lens arrays having a plurality of micro-lenses situated laterally to one another on a planar surface above a respective one of the pixels, wherein micro-lenses within at least one of the micro-lens arrays include at least one symmetrically-shaped micro-lens and at least one asymmetrically-shaped micro-lens, wherein the at least one symmetrically-shaped micro-lens covers a first area on the planar surface and has a peak height along an axis normal to and centered within the first area, and wherein the at least one asymmetrically-shaped micro-lens covers a second area on the planar surface and has a peak height along an axis normal to and off-centered within the second area.
2. The integrated-circuit image sensor of claim 1 wherein sizes of the micro-lenses within at least one other of the micro-lens arrays are non-uniform.
3. The integrated-circuit image sensor of claim 1 wherein the at least one asymmetrically-shaped micro-lens is smaller than the at least one symmetrically-shaped micro-lens.
4. The integrated-circuit image sensor of claim 1 wherein the at least one of the micro-lens arrays include micro-lenses having a pitch size of 0.5 μm or more.
5. The integrated-circuit image sensor of claim 1 wherein the at least one of the micro-lens arrays comprises:
a first plurality of edge micro-lenses disposed at a periphery of the at least one micro-lens arrays that are symmetrically-shaped; and
one or more interior micro-lenses surrounded by the edge micro-lenses that are asymmetrically-shaped.
6. The integrated-circuit image sensor of claim 5 wherein the edge micro-lenses have a first shape and the one or more interior micro-lenses have a second shape different from the first shape, and the second shape comprises at least one of a circular shape, an oblong shape, a hexagonal shape or an octagonal shape.
7. The integrated-circuit image sensor of claim 5 wherein the at least one of the micro-lens arrays is a 4×4 micro-lens array.
8. The integrated-circuit image sensor of claim 5 wherein the at least one of the micro-lens arrays comprises:
symmetrically-shaped edge micro-lenses that are within a specified number of pixel rows or columns from one or more edges of the micro-lens array; and
asymmetrically-shaped interior micro-lenses that are more than the specified number of pixel rows or columns from the one or more edges.
9. The integrated-circuit image sensor of claim 5 wherein the edge micro-lenses have off-centered peak heights that are off-centered in a direction away from the one or more interior micro-lenses.
10. The integrated-circuit image sensor of claim 1 wherein the pixels comprise metal-oxide-semiconductor (MOS) pixels.
11. The integrated-circuit image sensor of claim 1 wherein the planar surface comprises the surface of one or more material layers disposed over the pixels.
12. The integrated-circuit image sensor of claim 11 wherein the one or more material layers comprise a passivation layer disposed over the pixels and beneath any others of the material layers.
13. The integrated-circuit image sensor of claim 11 wherein the one or more material layers include a color filtering layer comprising a plurality of color filters, each of the color filters disposed between a respective one of the micro-lens arrays and a respective one of the pixels.
14. The integrated-circuit image sensor of claim 13 wherein the plurality of color filters comprise red, green and blue color filters disposed in a Bayer pattern.
15. The integrated-circuit image sensor of claim 11 wherein the one or more material layers include a color filtering layer comprising a plurality of color filter arrays, each of the color filter arrays disposed between a respective one of the micro-lens arrays and a respective one of the pixels and having a plurality of laterally-adjacent color filters.
16. An integrated-circuit image sensor, comprising:
pixels disposed in rows and columns; and
micro-lens arrays disposed in rows and columns, each of the micro-lens arrays having a plurality of micro-lenses situated laterally to one another on a planar surface above a respective one of the pixels, wherein micro-lenses within at least one of the micro-lens arrays include at least one symmetrically-shaped micro-lens and at least one asymmetrically-shaped micro-lens, wherein the at least one symmetrically-shaped micro-lens is rotationally symmetrical about a line normal to the planar surface, and wherein the at least one asymmetrically-shaped micro-lens lacks rotational symmetry about any line normal to the planar surface.