Backside illumination image sensor and image-capturing device

1. A backside illumination image sensor that includes a semiconductor substrate with a plurality of pairs of photoelectric conversion elements formed thereat and a read circuit formed on a side where a front surface of the semiconductor substrate is present, and captures an image by outputting, via the read circuit, electrical signals generated as incident light having passed through an image forming optical system and having reached a side where a back surface of the semiconductor substrate is present, is received at a plurality of pairs of light receiving areas, each pair of light receiving areas being formed in each pair of the plurality of pairs of photoelectric conversion elements, comprising:

an on-chip lens formed at a position set apart from the each pair of light receiving areas by a predetermined distance;

a first separating area that is constituted with a type of semiconductor and that separates unit pixel areas from each other, each of the unit pixel areas including the each pair of the plurality of pairs of photoelectric conversion elements; and

a second separating area that is constituted with the type of semiconductor and that forms a boundary between the each pair of photoelectric conversion elements; wherein:

the each pair of light receiving areas and an exit pupil plane at which an exit pupil of the image forming optical system is present achieve a conjugate relation to each other with regard to the on-chip lens.

2. A backside illumination image sensor that includes a semiconductor substrate with a plurality of pairs of photoelectric conversion elements formed thereat and a read circuit formed on a side where a front surface of the semiconductor substrate is present, and captures an image by outputting, via the read circuit, electrical signals generated as incident light having passed through an image forming optical system and having reached a side where a back surface of the semiconductor substrate is present, is received at a plurality of pairs of light receiving areas, each pair of light receiving areas being formed in each pair of the plurality of pairs of photoelectric conversion elements, comprising:

an on-chip lens formed at a position set apart from the each pair of light receiving areas by a predetermined distance, wherein:

the each pair of light receiving areas and an exit pupil plane at which an exit pupil of the image forming optical system is present achieve a conjugate relation to each other with regard to the on-chip lens; and

a radius of curvature R of the on-chip lens, a distance D from an apex of the on-chip lens to the each pair of light receiving areas and an average refractive index n of a medium present between the on-chip lens and the each pair of light receiving areas achieve a relationship expressed as: D=R·n/(n−1).

3. A backside illumination image sensor according to claim 2 , wherein:

the plurality of pairs of photoelectric conversion elements are disposed in a two-dimensional grid array; and

a pitch P of the two-dimensional grid array, a smallest F number F0 of the exit pupil of the image forming optical system and the distance D achieve a relationship expressed as: F0·P·n>D>P·n/(2·(n−1)).

4. A backside illumination image sensor according to claim 3 , wherein:

the radius of curvature over a periphery of the on-chip lens is greater than the radius of curvature at a central area of the on-chip lens.

5. A backside illumination image sensor according to claim 2 , further comprising:

a light shielding member that prevents entry of passing light, which is part of the incident light that passes through the on-chip lens, into a pair of photoelectric conversion elements corresponding to an adjacent on-chip lens adjacent to the on-chip lens, among the plurality of pairs of photoelectric conversion elements, wherein:

the light shielding member is disposed between the on-chip lens and the each pair of light receiving areas,

the light shielding member includes a first color filter disposed near the on-chip lens and a second color filter assuming a color matching the color of the first color filter, which is disposed near the each pair of light receiving areas; and

a color of the light shielding member is different from a color of a light shielding member disposed in conjunction with the adjacent on-chip lens adjacent to the on-chip lens.

6. A backside illumination image sensor that includes a semiconductor substrate with a plurality of pairs of photoelectric conversion elements formed thereat and a read circuit formed on a side where a front surface of the semiconductor substrate is present, and captures an image by outputting, via the read circuit, electrical signals generated as incident light having passed through an image forming optical system and having reached a side where a back surface of the semiconductor substrate is present, is received at a plurality of pairs of light receiving areas, each pair of light receiving areas being formed in each pair of the plurality of pairs of photoelectric conversion elements, comprising:

an on-chip lens formed at a position set apart from the each pair of light receiving areas by a predetermined distance; and

a barrier member that is disposed parallel to an optical axis of the on-chip lens and that prevents entry of passing light, which is part of the incident light that passes through the on-chip lens, into a pair of photoelectric conversion elements corresponding to an adjacent on-chip lens adjacent to the on-chip lens, among the plurality of pairs of photoelectric conversion elements, wherein:

the each pair of light receiving areas and an exit pupil plane at which an exit pupil of the image forming optical system is present achieve a conjugate relation to each other with regard to the on-chip lens

the barrier member is disposed between the on-chip lens and the each pair of light receiving areas; and

an anti-reflection film is formed at a surface of the barrier member so as to prevent reflection of the passing light.

7. A backside illumination image sensor, comprising:

a plurality of pairs of photoelectric conversion elements each including a pair of light receiving areas that receive incident light having entered a back surface of a semiconductor substrate through an image forming optical system, a read circuit being formed on a front surface of the semiconductor substrate;

an on-chip lens formed at a position set apart from the pair of light receiving areas;

a first separating area that is constituted with a type of semiconductor and that separates unit pixel areas from each other, each of the unit pixel areas including each pair of photoelectric conversion elements; and

a second separating area that is constituted with the type of semiconductor and that forms a boundary between the each pair of photoelectric conversion elements, wherein:

the pair of light receiving areas and an exit pupil of the image forming optical system achieve a conjugate relation to each other with regard to the on-chip lens.

8. A backside illumination image sensor, comprising:

a plurality of pairs of photoelectric conversion elements each including a pair of light receiving areas that receive incident light having entered a back surface of a semiconductor substrate through an image forming optical system, a read circuit being formed on a front surface of the semiconductor substrate;

an on-chip lens formed at a position set apart from the pair of light receiving areas by a predetermined distance, wherein:

the pair of light receiving areas and an exit pupil of the image forming optical system achieve a conjugate relation to each other with regard to the on-chip lens; and

a radius of curvature R of the on-chip lens, a distance D from an apex of the on-chip lens to the pair of light receiving areas and an average refractive index n of a medium present between the on-chip lens and the pair of light receiving areas achieve a a relationship expressed as: D=R·n/(n−1).

9. A backside illumination sensor, comprising:

a plurality of pairs of photoelectric conversion elements each including a pair of light receiving areas that receive incident light having entered a back surface of a semiconductor substrate through an image forming optical system, a read circuit being formed on a front surface of the semiconductor substrate;

an on-chip lens formed at a position set apart from the pair of light receiving areas; and

a barrier member that is disposed parallel to an optical axis of the on-chip lens and that prevents entry of passing light, which is part of the incident light that passes through the on-chip lens, into a pair of photoelectric conversion elements corresponding to an adjacent on-chip lens adjacent to the on-chip lens, among the plurality of pairs of photoelectric conversion elements, wherein:

the pair of light receiving areas and an exit pupil of the image forming optical system achieve a conjugate relation to each other with regard to the on-chip lens

the barrier member is disposed between the on-chip lens and the pair of light receiving areas; and

an anti-reflection film is formed at a surface of the barrier member so as to prevent reflection of the passing light.