Micro-lenses for CMOS imagers
View Patent ↗A micro-lens and a method for forming the micro-lens is provided. A micro-lens includes a substrate an lens material located within the substrate, the substrate having a recessed area serving as a mold for the lens material. The recessed can be shaped such that the lens material corrects for optical aberrations. The micro-lens can be part of a micro-lens array. The recessed area can serve as a mold for lens material for the micro-lens array and can be shaped such that the micro-lens array includes arcuate, non-spherical, or non-symmetrical micro-lenses.
1. A micro-lens array for use in an imager, comprising:
a semiconductor substrate positioned over an array of pixel cells, the semiconductor substrate having a bottom surface facing towards the pixel cells and an upper surface opposite the bottom surface;
an opening in the semiconductor substrate recessed below the upper surface of the substrate, the opening serving as a mold for a plurality of micro-lenses; and
lens material located within the opening mold of the semiconductor substrate, wherein the lens material forms the plurality of micro-lenses, each of the micro-lenses having a respective focal point, wherein the focal point of at least one of the plurality of micro-lenses differs from the focal point of at least one other of the plurality of micro-lenses.
2. The micro-lens array of claim 1 , wherein the opening has at least one arcuate portion.
3. The micro-lens array of claim 1 , wherein the opening mold is shaped such that the lens material corrects for optical aberrations.
4. The micro-lens array of claim 1 , wherein the semiconductor substrate comprises silicon dioxide.
5. The micro-lens array of claim 4 , wherein the differing focal points of the plurality of micro-lenses focus light to different depths in the semiconductor substrate.
6. The micro-lens array of claim 1 , wherein the lens material exhibits a refractive index greater than that of the semiconductor substrate.
7. The micro-lens array of claim 1 , wherein the lens material exhibits a refractive index less than the semiconductor substrate.
8. The micro-lens array of claim 1 , further comprising a plurality of openings in the semiconductor substrate forming a plurality of molds, wherein each opening mold contains lens material that forms a respective plurality of micro-lenses, each of the micro-lenses having a respective focal point, wherein the focal point of at least one of the plurality of micro-lenses differs from the focal point of at least one other of the plurality of micro-lenses in the same opening.
9. The micro-lens array of claim 1 , wherein the focal point of at least one of the plurality of micro-lenses differs from the focal point of at least one other of the plurality of micro-lenses such that the focal points of the plurality of micro-lenses change gradually across the micro-lens array.
10. The micro-lens array of claim 1 , wherein each micro-lens is respectively associated with a photosensor of one of the array of pixel cells.
11. The micro-lens array of claim 1 , wherein at least one of the plurality of micro-lenses has a different shape than another one of the plurality of micro-lenses.
12. The micro-lens array of claim 1 , wherein at least one of the plurality of micro-lenses has a different size than another one of the plurality of micro-lenses.
13. The micro-lens array of claim 1 , wherein at least one of the plurality of micro-lenses has a different profile than another one of the plurality of micro-lenses.
14. A micro-lens array, comprising:
a semiconductor substrate positioned over an array of pixel cells, the substrate having a bottom surface facing towards the pixel cells and an upper surface opposite the bottom surface, and the substrate being formed of silicon dioxide;
an opening in the substrate recessed below the upper surface of the semiconductor substrate, the opening serving as a mold for a plurality of micro-lenses; and
lens material located within the opening of the semiconductor substrate, wherein the opening mold is shaped such that the lens material corrects for optical aberrations, and wherein the lens material forms the plurality of micro-lenses, each of the micro-lenses having a respective focal point, wherein the focal point of at least one of the plurality of micro-lenses differs from the focal point of at least one other of the plurality of micro-lenses.
15. The micro-lens array of claim 14 , wherein the opening mold is structured such that the focal point of each micro-lens of the array is associated with a color of light.
16. The micro-lens array of claim 14 , wherein the lens material exhibits a refractive index greater than that of the semiconductor substrate.
17. The micro-lens array of claim 14 , wherein the lens material exhibits a refractive index less than that of the semiconductor substrate.
18. The micro-lens array of claim 14 , wherein each micro-lens is respectively associated with a photosensor of one of the array of pixel cells.
19. The micro-lens array of claim 14 , further comprising a plurality of openings in the semiconductor substrate forming a plurality of molds, wherein each opening mold contains lens material that forms a respective plurality of micro-lenses, each of the micro-lenses having a respective focal point, wherein the focal point of at least one of the plurality of micro-lenses differs from the focal point of at least one other of the plurality of micro-lenses in the same opening.
20. The micro-lens array of claim 14 , wherein the focal point of at least one of the plurality of micro-lenses differs from the focal point of at least one other of the plurality of micro-lenses such that the focal points of the plurality of micro-lenses change gradually across the micro-lens array.