Light sensor having IR cut interference filter with color filter integrated on-chip
Techniques are described to furnish a light sensor that includes a patterned IR cut interference filter integrated with a patterned color pass filter. In one or more implementations, the light sensor includes a substrate having a surface. An IR cut interference filter configured to block infrared light is formed over the surface of the substrate. The light sensor also includes one or more color pass filters placed above or below the IR cut interference filter. The color pass filters are configured to filter visible light to pass light in a limited spectrum of wavelengths to the one or more photodetectors. In an implementation, a buffer layer is formed over the surface and configured to encapsulate the plurality of color pass filters to facilitate formation of the IR cut interference filter. In another implementation, the buffer layer is formed over the IR cut interference filter to function as a quasi-sacrificial buffer layer to facilitate formation of the color pass filters.
1. A light sensor comprising:
a substrate having a surface;
one or more photodetectors formed in the substrate and configured to detect light and to provide a signal in response thereto;
one or more color pass filters disposed over the surface and configured to filter visible light to pass light in a limited spectrum of wavelengths to the one or more photodetectors;
a buffer layer disposed over the surface such that the buffer layer at least substantially encloses the one or more color pass filters; and
an IR cut interference filter disposed over the buffer layer and configured to filter infrared light to at least substantially block infrared light from reaching the plurality of photodetectors,
wherein at least one of the one or more photodetectors comprises a clear photodetector, the clear photodetector configured to receive light unfiltered by the one or more color pass filters to detect an ambient light environment.
2. The light sensor as recited in claim 1 , wherein the buffer layer comprises a polymer.
3. The light sensor as recited in claim 1 , wherein the IR cut interference filter is a patternable IR cut interference filter.
4. The light sensor as recited in claim 1 , further comprising an adhesion layer disposed between the surface and the one or more color pass filters.
5. The light sensor as recited in claim 1 , further comprising:
an insulation layer disposed over the surface such that the insulation layer substantially encloses the one or more color pass filters, the buffer layer, and the IR cut interference filter.
6. The light sensor as recited in claim 1 , further comprising a dark mirror edge formed about a periphery of the IR cut interference filter and an edge of the buffer layer, the dark mirror edge configured to at least substantially eliminate impingement of light that does not pass through the IR cut interference filter and at least substantially block light from passing through the edge of the buffer layer.
7. A light sensor comprising:
a substrate having a surface;
one or more photodetectors formed in the substrate, the one or more photodetectors configured to detect light and provide a signal in response thereto;
an IR cut interference filter formed over the surface and configured to filter infrared light to at least substantially block infrared light from reaching the one or more photodetectors;
one or more color pass filters formed proximate to the IR cut interference filter and configured to filter visible light to pass light in a limited spectrum of wavelengths to the one or more photodetectors;
an adhesion layer formed over the surface for holding the one or more color pass filters in position; and
a buffer layer formed over the surface of the substrate to facilitate formation of at least one of the IR cut interference or the color pass filter.
8. The light sensor as recited in claim 7 , further comprising a dark mirror edge formed about a periphery of the IR cut interference filter and an edge of the buffer layer, the dark mirror edge configured to at least substantially eliminate impingement of light that does not pass through the IR cut interference filter and at least substantially blocks light from passing through the edge of the buffer layer.
9. The light sensor as recited in claim 7 , wherein the one or more color pass filters is formed on the adhesion layer, the buffer layer is formed over the surface such that the buffer layer substantially encloses the one or more color pass filters, and the IR cut interference filter is formed at least partially over the buffer layer.
10. The light sensor as recited in claim 7 , wherein the one or more photodetectors comprises a clear photodetector, the clear photodetector configured to receive light unfiltered by a color pass filter to detect an ambient light environment.
11. The light sensor as recited in claim 7 , wherein the one or more photodetectors comprise at least one of photodiodes or phototransistors.
12. The light sensor as recited in claim 7 , wherein the IR cut interference filter is a patternable IR cut interference filter.
13. A process comprising:
forming one or more photodetectors in a substrate, the one or more photodetectors configured to detect light and to provide a signal in response thereto;
forming one or more color pass filters over a surface of a substrate, the one or more color pass filters configured to filter visible light to pass light in a limited spectrum of wavelengths to the one or more photodetectors;
forming a buffer layer proximate to the surface;
forming an IR cut interference filter over the surface, the IR cut interference filter configured to configured to at least substantially block infrared light from reaching the surface; and
forming an adhesion layer over the surface, the adhesion layer configured to hold the one or more color pass filters in position; and
wherein the one or more color pass filters are formed on the adhesion layer.
14. The process as recited in claim 13 , further comprising:
forming the adhesion layer over the surface of the substrate;
forming the one or more color pass filters on the adhesion layer;
forming the buffer layer over the surface of the substrate such that the buffer layer substantially encloses the one or more color pass filters to protect and insulate the one or more color pass filters; and
forming the IR cut interference filter over a surface of the buffer layer,
wherein the IR cut interference filter is at least substantially coextensive with the one or more color pass filters.
15. The process as recited in claim 13 , further comprising:
forming the IR cut interference filter over the surface of the substrate;
forming the buffer layer over the IR cut interference filter;
planarizing at least a portion of the buffer layer;
forming the adhesion layer on a surface of the IR cut interference filter; and
forming the one or more color pass filters on the adhesion layer.
16. The process as recited in claim 13 , wherein the buffer layer comprises a Benzocyclobutene (BCB) polymer.
17. The process as recited in claim 13 , further comprising forming a dark mirror edge about the IR cut interference filter and the buffer layer, the dark mirror edge configured to at least substantially eliminate impingement of light that does not pass through the IR cut interference filter onto the one or more photodetectors.
18. The process as recited in claim 13 , wherein the one or more photodetectors, the one or more color pass filters, the buffer layer, and the IR cut interference filter are formed at wafer level, and wherein the wafer is thereafter diced into one or more dies, at least one of the dies being packaged individually to form a light sensor.
19. The process as recited in claim 13 , wherein the one or more photodetectors, the one or more color pass filters, the buffer layer, and the IR cut interference filter are formed at wafer level, and wherein the wafer is further processed using wafer level packaging (WLP) and diced to form one or more light sensors.
20. A light sensor comprising:
a substrate having a surface;
one or more photodetectors formed in the substrate and configured to detect light and to provide a signal in response thereto;
one or more color pass filters disposed over the surface and configured to filter visible light to pass light in a limited spectrum of wavelengths to the one or more photodetectors;
a buffer layer disposed over the surface such that the buffer layer at least substantially encloses the one or more color pass filters;
an adhesion layer disposed between the surface and the one or more color pass filters; and
an IR cut interference filter disposed over the buffer layer and configured to filter infrared light to at least substantially block infrared light from reaching the plurality of photodetectors.
21. The light sensor as recited in claim 20 , wherein the buffer layer comprises a polymer.
22. The light sensor as recited in claim 20 , wherein at least one of the one or more photodetectors comprises a clear photodetector, the clear photodetector configured to receive light unfiltered by the one or more color pass filters to detect an ambient light environment.
23. The light sensor as recited in claim 20 , wherein the IR cut interference filter is a patternable IR cut interference filter.
24. The light sensor as recited in claim 20 , further comprising:
an insulation layer disposed over the surface such that the insulation layer substantially encloses the one or more color pass filters, the buffer layer, and the IR cut interference filter.
25. The light sensor as recited in claim 20 , further comprising a dark mirror edge formed about a periphery of the IR cut interference filter and an edge of the buffer layer, the dark mirror edge configured to at least substantially eliminate impingement of light that does not pass through the IR cut interference filter and at least substantially block light from passing through the edge of the buffer layer.
26. A light sensor comprising:
a substrate having a surface;
one or more photodetectors formed in the substrate and configured to detect light and to provide a signal in response thereto;
one or more color pass filters disposed over the surface and configured to filter visible light to pass light in a limited spectrum of wavelengths to the one or more photodetectors;
a buffer layer disposed over the surface such that the buffer layer at least substantially encloses the one or more color pass filters;
an IR cut interference filter disposed over the buffer layer and configured to filter infrared light to at least substantially block infrared light from reaching the plurality of photodetectors; and
a dark mirror edge formed about a periphery of the IR cut interference filter and an edge of the buffer layer, the dark mirror edge configured to at least substantially eliminate impingement of light that does not pass through the IR cut interference filter and at least substantially block light from passing through the edge of the buffer layer.
27. The light sensor as recited in claim 26 , wherein the buffer layer comprises a polymer.
28. The light sensor as recited in claim 26 , wherein at least one of the one or more photodetectors comprises a clear photodetector, the clear photodetector configured to receive light unfiltered by the one or more color pass filters to detect an ambient light environment.
29. The light sensor as recited in claim 26 , wherein the IR cut interference filter is a patternable IR cut interference filter.
30. The light sensor as recited in claim 26 , further comprising an adhesion layer disposed between the surface and the one or more color pass filters.
31. The light sensor as recited in claim 26 , further comprising:
an insulation layer disposed over the surface such that the insulation layer substantially encloses the one or more color pass filters, the buffer layer, and the IR cut interference filter.
32. A light sensor comprising:
a substrate having a surface;
one or more photodetectors formed in the substrate, the one or more photodetectors configured to detect light and provide a signal in response thereto;
an IR cut interference filter formed over the surface and configured to filter infrared light to at least substantially block infrared light from reaching the one or more photodetectors;
one or more color pass filters formed proximate to the IR cut interference filter and configured to filter visible light to pass light in a limited spectrum of wavelengths to the one or more photodetectors;
a buffer layer formed over the surface of the substrate to facilitate formation of at least one of the IR cut interference or the color pass filter; and
a dark mirror edge formed about a periphery of the IR cut interference filter and an edge of the buffer layer, the dark mirror edge configured to at least substantially eliminate impingement of light that does not pass through the IR cut interference filter and at least substantially blocks light from passing through the edge of the buffer layer.
33. The light sensor as recited in claim 32 , further comprising an adhesion layer formed over the surface for holding the one or more color pass filters in position.
34. The light sensor as recited in claim 33 , wherein the one or more color pass filters is formed on the adhesion layer, the buffer layer is formed over the surface such that the buffer layer substantially encloses the one or more color pass filters, and the IR cut interference filter is formed at least partially over the buffer layer.
35. The light sensor as recited in claim 32 , wherein the one or more photodetectors comprises a clear photodetector, the clear photodetector configured to receive light unfiltered by a color pass filter to detect an ambient light environment.
36. The light sensor as recited in claim 32 , wherein the one or more photodetectors comprise at least one of photodiodes or phototransistors.
37. The light sensor as recited in claim 32 , wherein the IR cut interference filter is a patternable IR cut interference filter.
38. A light sensor comprising:
a substrate having a surface;
one or more photodetectors formed in the substrate, the one or more photodetectors configured to detect light and provide a signal in response thereto;
an IR cut interference filter formed over the surface and configured to filter infrared light to at least substantially block infrared light from reaching the one or more photodetectors;
one or more color pass filters formed proximate to the IR cut interference filter and configured to filter visible light to pass light in a limited spectrum of wavelengths to the one or more photodetectors; and
a buffer layer formed over the surface of the substrate to facilitate formation of at least one of the IR cut interference or the color pass filter,
wherein the one or more photodetectors comprises a clear photodetector, the clear photodetector configured to receive light unfiltered by a color pass filter to detect an ambient light environment.
39. The light sensor as recited in claim 38 , further comprising a dark mirror edge formed about a periphery of the IR cut interference filter and an edge of the buffer layer, the dark mirror edge configured to at least substantially eliminate impingement of light that does not pass through the IR cut interference filter and at least substantially blocks light from passing through the edge of the buffer layer.
40. The light sensor as recited in claim 38 , further comprising an adhesion layer formed over the surface for holding the one or more color pass filters in position.
41. The light sensor as recited in claim 40 , wherein the one or more color pass filters is formed on the adhesion layer, the buffer layer is formed over the surface such that the buffer layer substantially encloses the one or more color pass filters, and the IR cut interference filter is formed at least partially over the buffer layer.
42. The light sensor as recited in claim 38 , wherein the one or more photodetectors comprise at least one of photodiodes or phototransistors.
43. The light sensor as recited in claim 38 , wherein the IR cut interference filter is a patternable IR cut interference filter.