Semiconductor photosensor

Abstract

According to the present invention, there is provided a semiconductor photosensor having: a first photo detector and a second photo detector formed in a surface portion of a semiconductor substrate;a first resin layer formed on a light-receiving region of the first photo detector, and including a first spectral sensitivity characteristic;a second resin layer formed on a light-receiving region of the second photo detector, and including a second spectral sensitivity characteristic; andan operation circuit which performs a predetermined operation between a first output from the first photo detector and a second output from the second photo detector, and outputs a result of the operation,wherein the first spectral sensitivity characteristic is a characteristic which removes a wavelength component in a short-wavelength region, and the second spectral sensitivity characteristic is a characteristic which removes a wavelength component in an infrared region.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a circuit diagram showing the arrangement of a semiconductor photosensor according to the first embodiment of the present invention;

FIG. 2A is a sectional view showing the longitudinal sectional structure of photodiode portions in the semiconductor photosensor according to the first embodiment; FIG. 2B is a sectional view showing a modification of FIG. 2A;

FIG. 3A is a graph showing an example of the transmittance characteristic of a short-wavelength cut filter in the semiconductor photosensor according to the first embodiment; FIG. 3B is a graph showing an example of the transmittance characteristic of an infrared transmitting filter in the semiconductor photosensor according to the first embodiment; FIG. 3C is a graph showing an example of the characteristic of a photodiode usable in the semiconductor photosensor according to the first embodiment when no filter is used; FIG. 3D is a graph showing an example of the characteristic obtained in a photodiode portion 1 using only a short-wavelength cut filter in the semiconductor photosensor according to the first embodiment; FIG. 3E is a graph showing an example of the characteristic obtained in a photodiode portion 2 using a short-wavelength cut filter and an infrared transmitting filter 11 in the semiconductor photosensor according to the first embodiment; FIG. 3F is a graph showing an example of the characteristic finally obtained by using the photodiode portions 1 and 2 in the semiconductor photosensor according to the first embodiment;

FIG. 4A is a plan view showing an example of a chip layout pattern in the semiconductor photosensor according to the first embodiment; FIG. 4B is a plan view showing another example of the chip layout pattern in the semiconductor photosensor according to the first embodiment;

FIG. 5 is a circuit diagram showing the arrangement of a semiconductor photosensor according to a reference example;

FIG. 6 is a graph showing an example of the spectral sensitivity characteristic of the semiconductor photosensor according to the reference example;

FIG. 7 is a graph showing the light emission spectra of various light sources;

FIG. 8 is a circuit diagram showing the arrangement of a semiconductor photosensor according to the second embodiment of the present invention;

FIG. 9 is a circuit diagram showing the arrangement of a semiconductor photosensor according to the third embodiment of the present invention;

FIG. 10A is a sectional view showing the longitudinal sectional structure of photodiode portions in a semiconductor photosensor according to the fourth embodiment of the present invention; FIG. 10B is a sectional view showing a modification of FIG. 10A; and

FIG. 11 is a sectional view showing the longitudinal sectional structure of photodiode portions in a semiconductor photosensor according to the fifth embodiment of the present invention.

Claims

1. A semiconductor photosensor comprising: a first photo detector and a second photo detector formed in a surface portion of a semiconductor substrate;a first resin layer formed on a light-receiving region of the first photo detector, and including a first spectral sensitivity characteristic;a second resin layer formed on a light-receiving region of the second photo detector, and including a second spectral sensitivity characteristic; andan operation circuit which performs a predetermined operation between a first output from the first photo detector and a second output from the second photo detector, and outputs a result of the operation,wherein the first spectral sensitivity characteristic is a characteristic which removes a wavelength component in a short-wavelength region, and the second spectral sensitivity characteristic is a characteristic which removes a wavelength component in an infrared region.

2. A photosensor according to claim 1, wherein a wavelength at a half width of the first spectral sensitivity characteristic when a transmittance is 50% is 400 to 600 nm.

3. A photosensor according to claim 1, wherein a wavelength at a half width of the second spectral sensitivity characteristic when a transmittance is 50% is 550 to 700 nm.

4. A photosensor according to claim 2, wherein a wavelength at a half width of the second spectral sensitivity characteristic when a transmittance is 50% is 550 to 700 nm.

5. A photosensor according to claim 1, wherein the operation circuit subtracts a first photocurrent output from the first photo detector from a second photocurrent-output from the second photo detector.

6. A photosensor according to claim 1, further comprising a first amplifier which amplifies the first output from the first photo detector and outputs the amplified output, and a second amplifier which amplifies the second output from the second photo detector and outputs the amplified output, wherein the operation circuit performs the predetermined operation between the first output amplified by the first amplifier and the second output amplified by the second amplifier, and outputs a result of the operation.

7. A photosensor according to claim 1, wherein the first photo detector and the second photo detector are arranged adjacent to each other.

8. A photosensor according to claim 1, wherein each of the first photo detector and the second photo detector comprises a plurality of elements, and the plurality of elements of the first photo detectors and the plurality of elements of the second photo detectors are alternately arranged adjacent to each other.

9. A photosensor according to claim 1, further comprising: a comparative voltage generator which generates a comparative voltage related to illuminance; anda comparator which compares the comparative voltage with the result of the predetermined operation output from the operation circuit, and outputs a result of the comparison.

10. A semiconductor photosensor comprising: a first photo detector and a second photo detector formed in a surface portion of a semiconductor substrate;a first resin layer formed on a light-receiving region of the first photo detector, and including a first spectral sensitivity characteristic;a second resin layer formed on a light-receiving region of the second photo detector, and including the first spectral sensitivity characteristic;a third resin layer formed on the light-receiving region of the second photo detector such that the second resin layer and the third resin layer are stacked, and including a second spectral sensitivity characteristic; andan operation circuit which performs a predetermined operation between a first output from the first light-receiving element and a second output from the second light-receiving element, and outputs a result of the operation,wherein the first spectral sensitivity characteristic is a characteristic which removes a wavelength component in a short-wavelength region, and the second spectral sensitivity characteristic is a characteristic which removes a wavelength component in an infrared region.

11. A photosensor according to claim 10, wherein the first resin layer is integrated with the second resin layer.

12. A photosensor according to claim 10, wherein the third resin layer is stacked on a surface of the second resin layer on the light-receiving region of the second photo detector.

13. A photosensor according to claim 10, wherein a wavelength at a half width of the first spectral sensitivity characteristic when a transmittance is 50% is 400 to 600 nm.

14. A photosensor according to claim 10, wherein a wavelength at a half width of the second spectral sensitivity characteristic when a transmittance is 50% is 550 to 700 nm.

15. A photosensor according to claim 13, wherein a wavelength at a half width of the second spectral sensitivity characteristic when a transmittance is 50% is 550 to 700 nm.

16. A photosensor according to claim 10, wherein the operation circuit subtracts a first photocurrent output from the first photo detector from a second photocurrent output from the second photo detector.

17. A photosensor according to claim 10, further comprising a first amplifier which amplifies the first output from the first photo detector and outputs the amplified output, and a second amplifier which amplifies the second output from the second photo detector and outputs the amplified output, wherein the operation circuit performs the predetermined operation between the first output amplified by the first amplifier and the second output amplified by the second amplifier, and outputs a result of the operation.

18. A photosensor according to claim 10, wherein the first photo detector and the second photo detector are arranged adjacent to each other.

19. A photosensor according to claim 10, wherein each of the first photo detector and the second photo detector comprises a plurality of elements, and the plurality of elements of the first photo detectors and the plurality of elements of the second photo detectors are alternately arranged adjacent to each other.

20. A photosensor according to claim 10, further comprising: a comparative voltage generator which generates a comparative voltage related to illuminance; anda comparator which compares the comparative voltage with the result of the predetermined operation output from the operation circuit, and outputs a result of the comparison.