Light filtering image sensor

• US 20050258351A1
• Filed: 05/21/2004
• Published: 11/24/2005
• Est. Priority Date: 05/21/2004
• Status: Active Grant

• Current Assignee: Aptina Imaging Corporation (ON Semiconductor Corporation)
• Original Assignee: Aptina Imaging Corporation (ON Semiconductor Corporation)
• Inventors: Ma, Guolin
• Granted Patent: US 7,608,811 B2
• Time in Patent Office: Days
• US Class Current: 250/239
• CPC Class Codes: H01L 27/14625 Optical elements or arrangements associated with the device
• CPC Class Codes: H01L 27/14627 Microlenses
• CPC Class Codes: H01L 27/14643 Photodiode arrays; MOS imagers

Abstract

A method and apparatus for directing light to a light sensor and filtering out an infrared component from the directed light. In one embodiment, the apparatus includes an array of light sensors disposed on a substrate, wherein the light sensors are operable to convert light intensity into a voltage signal. The apparatus further includes a cover plate disposed over the light sensors such that the cover plate creates a cavity over the array of sensors. The apparatus further includes filter material disposed between the cover plate and the light sensors in the cavity formed between the light sensors and the cover plate. The filter material is operable to filter the light passing through the cover plate. In particular, in one embodiment, light having wavelengths in the infrared range may be filtered out.

Claims

1. An apparatus, comprising:

a light sensor disposed on a substrate, the light sensor operable to convert light intensity into a voltage signal;

a cover plate disposed over the light sensor, the cover plate operable to pass light; and

a filter material disposed between the cover plate and the light sensor, the filter material operable to filter a portion of the light passing through the cover plate.

2. The apparatus of claim 1 wherein the filter material comprises a polymer.

3. The apparatus of claim 1 wherein the filter material comprises an absorptive dye.

4. The apparatus of claim 1 wherein the portion of light filtered by the filter material comprises infrared light.

5. The apparatus of claim 1 wherein the portion of light filtered by the filter material comprises near infrared light.

6. The apparatus of claim 1, further comprising a microlens coupled to the substrate and operable to focus the filtered light onto the light sensor.

7. The apparatus of claim 1 wherein the cover plate comprises transparent glass.

8. The apparatus of claim 1 wherein the light sensor is a photodiode.

9. The apparatus of claim 8, further comprising a three-transistor active-pixel sensor electrically coupled to the photodiode and operable to facilitate the conversion of light to a voltage signal.

10. A method, comprising:

directing light having an infrared component toward a light sensor, the light directed through a cavity adjacent to the light sensor, the cavity filled with a filter material; and

filtering at least a portion of the light when the light passes through the cavity.

11. The method of claim 10, further comprising measuring the intensity of the filtered light at the light sensor.

12. The method of claim 11, further comprising translating the measured intensity of the light into an electrical signal indicative of the measured intensity.

13. The method of claim 12, further comprising storing a digital value in a memory, the digital value proportional to the electrical signal, the digital value indicative of the measured intensity.

14. The method of claim 10 wherein the filter material comprises a polymer having absorptive dye and operable to filter an infrared component from the light.

15. The method of claim 10 wherein the filtering further comprises passing a portion of the light not in an infrared range.

16. A system, comprising:

a CMOS array having;

a plurality of light sensors disposed on a substrate, each light sensor operable to convert light intensity into a voltage signal;

a cover plate disposed over the plurality of light sensor, the cover plant operable to pass light; and

a filter material disposed between the cover plate and each of the plurality of light sensors, the filter material operable to filter a portion of the light passing through the cover plate;

a control circuit coupled to the CMOS array and operable to sense each of the voltage signals individually and to store each of the sensed voltage signals in a memory; and

a processor coupled to the control circuit and operable to control the control circuit.

17. The system of claim 16 wherein the filter material comprises a polymer having absorptive dye and operable to filter an infrared component from the light.

18. A method of manufacture, comprising

fabricating a plurality of active-pixel sensors on a substrate, each active pixel sensor having a light sensor operable to convert light intensity into a voltage signal;

disposing a cover plate over the substrate such that a cavity is formed between the light sensor of each active-pixel sensor and the cover plate;

filling each formed cavity with a filter material operable to filter a component of light that passes though the filter material.

19. The method of claim 18 wherein the filter material comprises a polymer having absorptive dye and operable to filter an infrared component from the light.

20. The method of claim 18, wherein the filling further comprises injecting the polymer into each cavity.