Lens array and manufacturing method therefor, solid-state imaging apparatus, and electronic apparatus
The present technology relates to a lens array and a manufacturing method therefor, a solid-state imaging apparatus, and an electronic apparatus that can improve the AF performance while suppressing the deterioration of image quality. A lens array includes microlenses that are formed corresponding to phase difference detection pixels that are provided to be mixed in imaging pixels. Each of the microlenses is formed such that a lens surface thereof is a substantially spherical surface, the microlens has a rectangular shape in a planar view and four corners are not substantially rounded, and a bottom surface in vicinity of an opposite-side boundary portion that includes an opposite-side center portion of a pixel boundary portion in a cross-sectional view is higher than a bottom surface in vicinity of a diagonal boundary portion that includes a diagonal boundary portion. The present technology is applicable to a lens array of a CMOS image sensor, for example.
1. A lens array, comprising:
a microlens that corresponds to a phase difference detection pixel, wherein the phase difference detection pixel is mixed with an imaging pixel,
wherein the microlens comprises:
a lens surface that is a substantially spherical surface, the microlens has a square shape in a planar view and four corners of the microlens are not substantially rounded,
a first bottom surface in vicinity of an opposite-side boundary portion that includes an opposite-side center portion of a pixel boundary portion, and a second bottom surface in vicinity of a diagonal boundary portion that includes a diagonal boundary portion,
wherein the first bottom surface in a cross-sectional view is higher than the second bottom surface,
the lens surface has a first curvature radius r 1 and a second curvature radius r 2 , the first curvature radius r 1 is a curvature radius in a cross-section of the opposite-side center portion and the second curvature radius r 2 is a curvature radius of the lens surface in a cross-section of the diagonal boundary portion,
the curvature radius of the lens surface is r=(d 2 +4t 2 )/8t, where d denotes a width of a third bottom surface of the microlens in a cross-section that extends through a top of the lens surface and t denotes a height of the top of the lens surface with the third bottom surface as a reference, and
wherein a curvature radius ratio r 1 /r 2 between the first curvature radius r 1 and the second curvature radius r 2 is a value in a range of 0.98 to 1.20.
2. The lens array according to claim 1 , further comprising at least one inorganic film is on a top surface of the lens surface, and wherein the at least one inorganic film is an antireflection film.
3. The lens array according to claim 2 , wherein a difference between the first curvature radius r 1 and the second curvature radius r 2 is based on the at least one inorganic film.
4. A manufacturing method for a lens array, the method comprising:
forming a microlens that corresponds to a phase difference detection pixel, wherein the phase difference detection pixel is mixed with an imaging pixel,
wherein the microlens is formed such that:
a lens surface of the microlens is a substantially spherical surface, the microlens has a square shape in a planar view and four corners of the microlens are not substantially rounded,
a first bottom surface of the microlens is in vicinity of an opposite-side boundary portion that includes an opposite-side center portion of a pixel boundary portion,
a second bottom surface of the microlens is in vicinity of a diagonal boundary portion that includes a diagonal boundary portion,
the first bottom surface in a cross-sectional view is higher than the second bottom surface,
the lens surface has a first curvature radius r 1 and a second curvature radius r 2 , the first curvature radius r 1 is a curvature radius in a cross-section of the opposite-side center portion and the second curvature radius r 2 is a curvature radius of the lens surface in a cross-section of the diagonal boundary portion,
the curvature radius of the lens surface is r=(d 2 +4t 2 )/8t, where d denotes a width of a third bottom surface of the microlens in a cross-section extending through a top of the lens surface and t denotes a height of the top of the lens surface with the third bottom surface as a reference, and
a curvature radius ratio r 1 /r 2 between the first curvature radius r 1 and the second curvature radius r 2 is a value in a range of 0.98 to 1.20.
5. A solid-state imaging apparatus, comprising:
a lens array that includes a plurality of microlenses, each microlens of the plurality of microlenses corresponds to a phase difference detection pixel, wherein the phase difference detection pixel is mixed with an imaging pixel,
wherein a microlens of the plurality of microlenses comprises:
a lens surface that is a substantially spherical surface, the microlens has a square shape in a planar view and four corners of the microlens are not substantially rounded,
a first bottom surface in vicinity of an opposite-side boundary portion that includes an opposite-side center portion of a pixel boundary portion, and
a second bottom surface in vicinity of a diagonal boundary portion that includes a diagonal boundary portion,
wherein the first bottom surface in a cross-sectional view is higher than the second bottom surface,
the lens surface has a first curvature radius r 1 and a second curvature radius r 2 , the first curvature radius r 1 is a curvature radius in a cross-section of the opposite-side center portion and the second curvature radius r 2 is a curvature radius of the lens surface in a cross-section of the diagonal boundary portion,
the curvature radius of the lens surface is r=(d 2 +4t 2 )/8t, where d denotes a width of a third bottom surface of the microlens in a cross-section that extends through a top of the lens surface and t denotes a height of the top of the lens surface with the third bottom surface as a reference, and
wherein a curvature radius ratio r 1 /r 2 between the first curvature radius r 1 and the second curvature radius r 2 is a value in a range of 0.98 to 1.20.
6. An electronic apparatus, comprising:
a solid-state imaging apparatus that includes:
a lens array, wherein the lens array includes a plurality of microlenses, and each microlens of the plurality of microlenses corresponds to a phase difference detection pixel, and wherein the phase difference detection pixel is mixed with an imaging pixel,
wherein a microlens of the plurality of microlenses comprises:
a lens surface that is a substantially spherical surface, the microlens has a square shape in a planar view and four corners of the microlens are not substantially rounded,
a first bottom surface in vicinity of an opposite-side boundary portion that includes an opposite-side center portion of a pixel boundary portion, and
a second bottom surface in vicinity of a diagonal boundary portion that includes a diagonal boundary portion,
wherein the first bottom surface in a cross-sectional view is higher than the second bottom surface,
the lens surface has a first curvature radius r 1 and a second curvature radius r 2 , the first curvature radius r 1 is a curvature radius in a cross-section of the opposite-side center portion and the second curvature radius r 2 is a curvature radius of the lens surface in a cross-section of the diagonal boundary portion,
the curvature radius of the lens surface is r=(d 2 +4t 2 )/8t, where d denotes a width of a third bottom surface of the microlens in a cross-section that extends through a top of the lens surface and t denotes a height of the top of the lens surface with the third bottom surface as a reference, and
wherein a curvature radius ratio r 1 /r 2 between the first curvature radius r 1 and the second curvature radius r 2 is in a range of 0.98 to 1.20.