Image sensor including nano-photonic microlens array and electronic apparatus including the image sensor
An image sensor includes a sensor substrate including a plurality of pixels for sensing incident light, and a nano-photonic microlens array arranged to face a light incident surface of the sensor substrate, and including a plurality of nano-photonic microlenses for condensing incident light. Each of the plurality of pixels includes a plurality of photosensitive cells that are two-dimensionally arranged in a first direction and a second direction perpendicular to the first direction and are configured to independently sense the incident light, and an isolation for electrically isolating the plurality of photosensitive cells, each of the nano-photonic microlenses includes a plurality of nano-structures that are arranged such that the light transmitting each of the nano-photonic microlenses has a convex phase profile, and the plurality of nano-structures are arranged in the form of a two-dimensional array in a diagonal direction between the first direction and the second direction.
1 . An image sensor comprising:
a sensor substrate comprising a plurality of pixels configured to sense incident light; and
a nano-photonic microlens array arranged to face a light incident surface of the sensor substrate, the nano-photonic microlens array comprising a plurality of nano-photonic microlenses configured to condense the incident light,
wherein each pixel of the plurality of pixels comprises:
a plurality of photosensitive cells that are two-dimensionally arranged in a first direction and a second direction perpendicular to the first direction and are configured to independently sense the incident light, and
a first isolation structure extending in the first direction and a second isolation structure extending in the second direction, the first isolation structure and the second isolation structure configured to electrically isolate the plurality of photosensitive cells from each other,
wherein each nano-photonic microlens of the plurality of nano-photonic microlenses comprises a plurality of nano-structures that are configured to output light having a convex phase profile,
wherein the plurality of nano-structures are arranged in a two-dimensional array in a first diagonal direction between the first direction and the second direction and in a second diagonal direction crossing the first diagonal direction, and
wherein a first interval between two nano-structures that are adjacent to each other in the first direction or the second direction, among the plurality of nano-structures, is greater than or equal to a second interval between two nano-structures that are adjacent to each other in the first diagonal direction or the second diagonal direction, among the plurality of nano-structures.
2 . The image sensor of claim 1 , wherein a first arrangement period of the plurality of nano-structures arranged in the first direction or the second direction is greater than or equal to a second arrangement period of the plurality of nano-structures arranged in the first diagonal direction or the second diagonal direction.
3 . The image sensor of claim 1 , wherein each nano-structure of the plurality of nano-structures arranged in each nano-photonic microlens of the plurality of nano-photonic microlenses has a width or a diameter such that a phase of the light after passing through a center portion of each nano-photonic microlens is largest and is reduced away from the center portion of each nano-photonic microlens.
4 . The image sensor of claim 3 , wherein a nano-structure arranged at the center portion of each nano-photonic microlens faces, in a vertical direction, a cross point between the first isolation structure extending in the first direction and the second isolation structure extending in the second direction.
5 . The image sensor of claim 3 , wherein a nano-structure that is closest to the nano-structure arranged at the center portion of each nano-photonic microlens is arranged so as not to face the first and the second isolation structures in a vertical direction.
6 . The image sensor of claim 3 , wherein, from among the plurality of nano-structures arranged in each nano-photonic microlens, nano-structures having same widths or same diameters are arranged in the form of a rectangle inclined in the first diagonal direction or the second diagonal direction and surround other nano-structures.
7 . The image sensor of claim 3 , wherein the light after passing through each nano-photonic microlens has a phase profile formed as a rectangle inclined in the first diagonal direction or the second diagonal direction.
8 . The image sensor of claim 3 , wherein a minimum value of the phase of the light after passing through each nano-photonic microlens, on a cross-section passing through the center portion of each nano-photonic microlens in the first direction, is greater than a minimum value of the phase of light after passing through each nano-photonic microlens on a cross-section passing an edge of each nano-photonic microlens in the first direction.
9 . The image sensor of claim 1 , wherein the plurality of nano-photonic microlenses correspond to the plurality of pixels in a one-to-one correspondence, and each nano-photonic microlens of the plurality of nano-photonic microlenses is arranged to condense incident light to one pixel from among the plurality of pixels corresponding to the respective nano-photonic microlenses.
10 . The image sensor of claim 9 , wherein, in each pixel of the plurality of pixels, the plurality of photosensitive cells are arranged in a 2×2 array, each nano-photonic microlens of the plurality of nano-photonic microlenses is arranged to face the plurality of photosensitive cells arranged in the 2×2 array, and a focusing spot formed by each of the plurality of nano-photonic microlenses is located at a center of the 2×2 array.
11 . The image sensor of claim 1 , wherein each pixel of the plurality of pixels includes four sub-pixels arranged in a 2×2 array, and the plurality of photosensitive cells are arranged in a 2×2 array in each sub-pixel of the four sub-pixels.
12 . The image sensor of claim 11 , wherein the plurality of nano-photonic microlenses correspond to the four sub-pixels in a one-to-one correspondence, each nano-photonic microlens of the plurality of nano-photonic microlenses is arranged to face the plurality of photosensitive cells that are arranged in the 2×2 array so as to condense incident light to a corresponding sub-pixel from among the four sub-pixels, and a focusing spot formed by each nano-photonic microlens of the plurality of nano-photonic microlenses is located at a center of the 2×2 array including the plurality of photosensitive cells.
13 . The image sensor of claim 1 , further comprising a color filter layer between the sensor substrate and the nano-photonic microlens array.
14 . The image sensor of claim 13 , wherein the color filter layer comprises a plurality of color filters that respectively transmit light of different wavelength bands of the incident light, and each color filter of the plurality of color filters comprises one of an organic color filter, an inorganic color filter, or an organic/inorganic hybrid color filter.
15 . The image sensor of claim 1 , further comprising an anti-reflection layer on a light incident surface of the nano-photonic microlens array.
16 . The image sensor of claim 1 , wherein each of the plurality of nano-photonic microlenses further comprises a dielectric layer filled in a space among the plurality of nano-structures, and
wherein a refractive index of the plurality of nano-structures is greater than a refractive index of the dielectric layer.
17 . The image sensor of claim 1 , wherein each nano-structure of the plurality of nano-structures has a circular column shape, a polygonal column shape, a cylindrical shape, or a polygonal container shape.
18 . The image sensor of claim 1 , wherein each nano-structure of the plurality of nano-structures comprises a first nano-structure and a second nano-structure provided on the first nano-structure.
19 . An electronic apparatus comprising:
a lens assembly configured to form an optical image of a subject;
an image sensor configured to convert the optical image formed by the lens assembly into an electrical signal; and
a processor configured to process a signal generated by the image sensor,
wherein the image sensor comprises:
a sensor substrate comprising a plurality of pixels configured to sense incident light; and
a nano-photonic microlens array arranged to face a light incident surface of the sensor substrate, the nano-photonic microlens array comprising a plurality of nano-photonic microlenses configured to condense the incident light,
wherein each of the plurality of pixels comprises:
a plurality of photosensitive cells that are two-dimensionally arranged in a first direction and a second direction perpendicular to the first direction and are configured to independently sense the incident light, and
a first isolation structure extending in the first direction and a second isolation structure extending in the second direction, the first isolation structure and the second isolation structure configured to electrically isolate the plurality of photosensitive cells from each other,
wherein each nano-photonic microlens of the plurality of nano-photonic microlenses comprises a plurality of nano-structures that are configured to output light having a convex phase profile,
wherein the plurality of nano-structures are arranged in a two-dimensional array in a first diagonal direction between the first direction and the second direction and in a second diagonal direction crossing the first diagonal direction, and
wherein a first interval between two nano-structures that are adjacent to each other in the first direction or the second direction, among the plurality of nano-structures, is greater than or equal to a second interval between two nano-structures that are adjacent to each other in the first diagonal direction or the second diagonal direction, among the plurality of nano-structures.