Image sensor with phase difference detection pixel
An image sensor includes a pixel array having a plurality of pixels arranged therein. At least any one of the plurality of pixels include: a photoelectric conversion unit including first and second photoelectric conversion elements; a first sub-lens formed over the first photoelectric conversion element, and having a vertex out of a central axis of the first photoelectric conversion element; a second sub-lens formed over the second photoelectric conversion element, and having a vertex out of a central axis of the second photoelectric conversion element; and a microlens formed over the photoelectric conversion element so as to overlap the first and second sub-lenses. The first sub-lens is symmetrical with the second sub-lens, based on a boundary surface between the first and second photoelectric conversion elements.
1. An image sensor comprising a pixel array having a plurality of pixels arranged therein,
wherein at least any one of the plurality of pixels comprises:
a photoelectric conversion unit comprising first and second photoelectric conversion elements;
a first sub-lens formed over the first photoelectric conversion element, and having a first vertex misaligned from a first central vertical axis of the first photoelectric conversion element;
a second sub-lens formed over the second photoelectric conversion element, and having a second vertex misaligned from a second central vertical axis of the second photoelectric conversion element; and
a microlens formed over the photoelectric conversion element to overlap the first and second sub-lenses,
wherein the first sub-lens is symmetrical with the second sub-lens, relative to a boundary surface between the first and second photoelectric conversion elements.
2. The image sensor of claim 1 , further comprising a color filter layer formed over the photoelectric conversion element to cover the first and second sub-lenses,
wherein the microlens is formed over the color filter layer.
3. The image sensor of claim 1 , wherein the first and second vertexes of the first and second sub-lenses are closer to a third central vertical axis of the microlens than edges of the microlens.
4. The image sensor of claim 1 , wherein each of cross-sections of the first and second sub-lenses, taken in a vertical direction, has an asymmetric convex lens shape.
5. The image sensor of claim 4 , wherein each of cross-sections of the first and second sub-lenses has a bar shape in a plan view.
6. The image sensor of claim 4 , wherein each of the first and second sub-lenses has a hemispherical shape in a longitudinal cross-sectional view.
7. The image sensor of claim 1 , wherein the first vertex of the first sub-lens is located between a third central vertical axis of the microlens and the first central vertical axis of the first photoelectric conversion element, and
the second vertex of the second sub-lens is located between a third central vertical axis of the microlens and the second central vertical axis of the second photoelectric conversion element.
8. The image sensor of claim 1 ,
wherein the first and second vertexes of the first and second sub-lenses located in a center of the pixel array, are closer to a third central vertical axis of the microlens than the first and second central vertical axes of the first and second photoelectric conversion elements, respectively, and
the first and second vertexes of the first and second sub-lenses located at an edge of the pixel array are closer to the first and second central vertical axes of the first and second photoelectric conversion elements, respectively, than the third central vertical axis of the microlens.
9. The image sensor of claim 1 , wherein a bottom area of the first sub-lens and a bottom area of the second sub-lens are equal to or larger than a light receiving area of the first photoelectric conversion element and a light receiving area of the second photoelectric conversion element, respectively.
10. An image sensor comprising a pixel array having a plurality of pixels arranged therein,
wherein at least any one of the plurality of pixels comprises:
a photoelectric conversion unit comprising first and second photoelectric conversion elements;
a first sub-lens formed over the first photoelectric conversion element, and having a first vertex misaligned from a first central vertical axis of the first photoelectric conversion element;
a second sub-lens formed over the second photoelectric conversion element, and having a second vertex misaligned from a second central vertical axis of the second photoelectric conversion element;
an isolation pattern formed over the photoelectric conversion unit, and surrounding the first and second sub-lenses; and
a microlens formed over the photoelectric conversion element to overlap the first and second sub-lenses,
wherein the first sub-lens is symmetrical with the second sub-lens, relative to the boundary surface between the first and second photoelectric conversion elements.
11. The image sensor of claim 10 , further comprising a color filter layer formed over the photoelectric conversion element to cover the first and second sub-lenses and including the isolation pattern formed therein,
wherein the microlens is formed over the color filter layer.
12. The image sensor of claim 11 , wherein the isolation pattern comprises a material having a smaller refractive index than the color filter layer.
13. The image sensor of claim 10 , wherein the first and second vertexes of the first and second sub-lenses are closer to a third central vertical axis of the microlens than edges of the microlens.
14. The image sensor of claim 10 , wherein each of cross-sections of the first and second sub-lenses, taken in a vertical direction, has an asymmetric convex lens shape.
15. The image sensor of claim 14 , wherein each of cross-sections of the first and second sub-lenses has a bar shape in a plan view.
16. The image sensor of claim 14 , wherein each of cross-sections of the first and second sub-lenses has a hemispherical shape in a longitudinal cross-sectional view.
17. The image sensor of claim 10 , wherein the first vertex of the first sub-lens is located between a third central vertical axis of the microlens and the first central vertical axis of the first photoelectric conversion element, and
the second vertex of the second sub-lens is located between the third central vertical axis of the microlens and the second central vertical axis of the second photoelectric conversion element.
18. The image sensor of claim 10 ,
wherein the first and second vertexes of the first and second sub-lenses located in the center of the pixel array, are closer to a third central vertical axis of the microlens than the first and second central vertical axes of the first and second photoelectric conversion elements, respectively, and
the first and second vertexes of the first and second sub-lenses located at the edge of the pixel array are closer to the first and second central vertical axes of the first and second photoelectric conversion elements, respectively, than the third central vertical axis of the microlens.
19. The image sensor of claim 1 ,
wherein the first central vertical axis vertically crosses the first photoelectric conversion element and the first sub-lens, and
wherein the second central vertical axis vertically crosses the second photoelectric conversion element and the first sub-lens.