Photodetectors useful as ambient light sensors and methods for use in manufacturing the same
Photodetectors, methods for use in manufacturing photodetectors, and systems including photodetectors, are described herein. In an embodiment, a photodetector includes a plurality of photodiode regions, at least some of which are covered by an optical filter. A plurality of metal layers are located between the photodiode regions and the optical filter. The metal layers include an uppermost metal layer that is closest to the optical filter and a lowermost metal layer that is closest to the photodiode regions. One or more inter-level dielectric layers separate the metal layers from one another. Each of the metal layers includes one or more metal portions and one or more dielectric portions. The uppermost metal layer is devoid of any metal portions underlying the optical filter.
1. A photodetector, comprising:
a plurality of photodiode regions;
an optical filter covering one or more of the photodiode regions;
a plurality of metal layers located between the photodiode regions and the optical filter, wherein the plurality of metal layers include an uppermost metal layer that is closest to the optical filter and a lowermost metal layer that is closest to the photodiode regions; and
one or more inter-level dielectric layers that separate the metal layers from one another;
wherein each of the metal layers includes one or more metal portions and one or more dielectric portions; and
wherein the uppermost metal layer is devoid of any metal portions underlying the optical filter.
2. The photodetector of claim 1 , wherein one or more of the photodiode regions are not covered by the optical filter.
3. The photodetector of claim 1 , wherein a portion of the uppermost metal layer, which is devoid of any metal portions underlying the optical filter, consists of a dielectric portion of the uppermost metal layer.
4. The photodetector of claim 1 , wherein a distance between a periphery of the optical filter and a closest metal portion of the uppermost metal layer is at least 20 microns.
5. The photodetector of claim 1 , wherein:
the plurality of photodiode regions include one or more first photodiode regions that are covered by the optical filter, and one more second photodiode regions that are covered by a light blocking material; and
the light blocking material comprises one or more metal portions of one or more of the metal layers other than the uppermost metal layer.
6. The photodetector of claim 5 , wherein the one or more second photodiode regions that are covered by the light blocking material are also covered by the optical filter.
7. The photodetector of claim 5 , wherein the light blocking material comprises one or more metal portions of the lowermost metal layer.
8. The photodetector of claim 5 , wherein:
the plurality of metal layers, located between the photodiode regions and the optical filter, comprise at least four metal layers;
the light blocking material comprises one or more metal portions of the at least one of the two metal layers that are closest to the photodiode regions; and
the two metal layers, that are closest to the optical filter, are each devoid of any metal portions underlying the optical filter.
9. The photodetector of claim 1 , wherein an outer periphery of the optical filter includes obtuse angles and is devoid any angles that are equal to or less than 90 degrees.
10. The photodetector of claim 1 , wherein the optical filter comprises a dielectric reflective optical coating filter configured to reject infrared (IR) light.
11. The photodetector of claim 1 , wherein:
the plurality of photodiode regions include one or more first photodiode regions that are covered by the optical filter, one more second photodiode regions that are covered by a light blocking material, and one or more third photodiode regions that are not covered by the optical filter and are not covered by the light blocking material; and
the light blocking material comprises one or more metal portions of one or more of the metal layers other than the uppermost metal layer.
12. A method for use in manufacturing a photodetector that includes an optical filter that shapes a spectral response of the photodetector, comprising:
(a) forming a plurality of metal layers over a plurality of photodiode regions,
wherein the plurality of metal layers include a lowermost metal layer that is closest to the photodiode regions and an uppermost metal layer that is farthest from the photodiode regions, and
wherein each of the metal layers includes one or more metal portions and one or more dielectric portions; and
(b) forming an optical filter over at least a portion of the uppermost metal layer such that the optical filter, after it if formed, covers one or more of the photodiode regions;
wherein step (a) is performed such that the uppermost metal layer is devoid of any metal portions that will underlie the optical filter after the optical filter is formed at step (b).
13. The method of claim 12 , wherein step (a) comprises forming the plurality of metal layers such that one or more of the metal portions of one or more of the metal layers, other than the uppermost metal layer, block light from reaching one or more of the photodiode regions.
14. The method of claim 12 , wherein step (b) comprises forming the optical filter such that an outer periphery of the optical filter includes obtuse angles and is devoid any angles that are equal to or less than 90 degrees.
15. The method of claim 12 , wherein the forming the optical filter at step (b) comprises depositing a dielectric reflective optical coating filter that is configured to reject infrared (IR) light and then patterning the dielectric reflective optical coating filter.
16. The method of claim 12 , wherein the forming the optical filter at step (b) comprises depositing a dielectric reflective optical coating using an evaporative deposition process and then patterning the dielectric reflective optical coating filter.
17. A system, comprising:
a photodetector configured to produce a current indicative of ambient visible light; and
a subsystem that is adjusted in dependence on the current produced by the photodetector;
wherein the photodetector includes
a plurality of photodiode regions;
an optical filter covering one or more of the photodiode regions;
a plurality of metal layers located between the photodiode regions and the optical filter, wherein the plurality of metal layers include an uppermost metal layer that is closest to the optical filter and a lowermost metal layer that is closest to the photodiode regions; and
one or more inter-level dielectric layers that separate the metal layers from one another;
wherein each of the metal layers includes one or more metal portions and one or more dielectric portions; and
wherein the uppermost metal layer is devoid of any metal portions underlying the optical filter.
18. The system of claim 17 , further comprising:
at least one of a processor or comparator configured to compare the current indicative of ambient visible light, or a voltage produced therefrom, to one or more threshold, to determine whether to enable, disable or adjust a brightness of the subsystem.
19. The system of claim 17 , wherein:
the plurality of photodiode regions of the photodetector include one or more first photodiode regions that are covered by the optical filter, and one more second photodiode regions that are covered by a light blocking material; and
the light blocking material of the photodetector comprises metal portions of one or more of the metal layers other than the uppermost metal layer.
20. The system of claim 17 , wherein an outer periphery of the optical filter of the photodetector include obtuse angles and is devoid any angles that are equal to or less than 90 degrees.