Method and device for optoelectronic sensors with ir blocking filter

Abstract

Semiconductor structures for optoelectronic sensors with an infrared (IR) blocking filter and methods for using such sensors with post-detection compensation for IR content that passes through the IR blocking filter are provided herein.

1 . A method comprising:
 receiving, by a semiconductor device having first and second optoelectronic sensors formed therein, light having an infrared (IR) light component and a visible light component;   filtering a portion of the IR light component from the received light using an IR blocking filter to exclude the filtered portion of the IR light from detection by the first and second optoelectronic sensors;   filtering a portion of the visible light component using a first visible light filter to exclude a first set of visible light wavelengths from detection by the first optoelectronic sensor, wherein the first set of visible light wavelengths is not filtered for the second optoelectronic sensor;   generating first and second sensor responses by the first and second optoelectronic sensors, respectively, wherein the first and second sensor responses represent the received light detected by the first and second optoelectronic sensors after filtering the IR light portion and the first set of visible light wavelengths; and   performing at least one calculation based on the first and second sensor responses to compensate for IR light remaining after filtering the IR light portion.   
     
     
         2 . The method of  claim 1  further comprising filtering a second set of visible light wavelengths from the received visible light using a second visible light filter to exclude the second set of visible light wavelengths from detection by both the first and second optoelectronic sensors. 
     
     
         3 . The method of  claim 2  wherein the compensating includes determining a difference between the first and second sensor responses. 
     
     
         4 . The method of  claim 1  further comprising filtering a second set of visible light wavelengths from the received visible light using a second visible light filter to exclude the second set of visible light wavelengths from detection by one of the first and second optoelectronic sensors, wherein the first set of visible light wavelengths is not filtered for the other of the first and second optoelectronic sensors. 
     
     
         5 . The method of  claim 1  further comprising generating a third sensor response by a third sensor of the semiconductor device, wherein the third response represents the IR light component without filtering by the IR blocking filter. 
     
     
         6 . The method of  claim 5  further comprising filtering a portion of the visible light using a second visible light filter to exclude a second set of visible light wavelengths from detection by the third optoelectronic sensor. 
     
     
         7 . The method of  claim 1  wherein excluding the first set of visible light wavelengths includes blocking all visible light from an upper surface of the first optoelectronic sensor facing the first visible light filter. 
     
     
         8 . The method of  claim 7  wherein the compensating is based on the first sensor response representing only a first detectable set of wavelengths of the IR light received by the first optoelectronic sensor due to wavelength dependent absorption of the IR light, and on the second sensor response representing a second detectable set of wavelengths that is larger than the first detectable set of wavelengths and includes the first detectable set of wavelengths, and wherein the first detectable set of wavelengths is biased to longer wavelengths than the remainder of the second detectable set of wavelengths. 
     
     
         9 . A method comprising:
 providing a first IR blocking filter configured to block a first portion of IR light and to let a second portion of the IR light pass through, wherein the first IR blocking filter is positioned over first and second optoelectronic sensors to block the first portion of IR light from reaching the first and second optoelectronic sensors;   providing a first visible light filter configured to block a first portion of visible light and to let a second portion of the visible light pass through, wherein the first visible light filter is positioned over the first optoelectronic sensor to block the first portion of visible light from reaching the first optoelectronic sensor and is not positioned over the second optoelectronic sensor;   obtaining a first response from the first optoelectronic sensor representing at least part of the second portion of the visible light and at least part of the second portion of the IR light detected by the first optoelectronic sensor;   obtaining a second response from the second optoelectronic sensor representing at least part of the first and second portions of the visible light and at least part of the second portion of the IR light detected by the second optoelectronic sensor; and   compensating for the IR light in the first and second responses to approximate a photopic response.   
     
     
         10 . The method of  claim 9  further comprising providing a second visible light filter configured to block part of the second portion of visible light and to let a third portion of the visible light pass through, wherein the second visible light filter is positioned over the first and second optoelectronic sensors. 
     
     
         11 . The method of  claim 10  wherein compensating for the IR light includes determining a difference between the first and second sensor responses. 
     
     
         12 . The method of  claim 9  wherein compensating for the IR light includes determining a ratio between the first and second responses, wherein the ratio represents a spectral response. 
     
     
         13 . The method of  claim 9  further comprising providing a second visible light filter configured to block part of the second portion of visible light and to let a third portion of the visible light pass through, wherein the second visible light filter is positioned over the second optoelectronic sensor and not the first optoelectronic sensor. 
     
     
         14 . The method of  claim 9  further comprising obtaining a third response from a third optoelectronic sensor of the semiconductor device having no IR blocking filter associated therewith. 
     
     
         15 . The method of  claim 14  further comprising providing a second visible light filter positioned over the third optoelectronic sensor and not over the first and second optoelectronic sensors, wherein the second visible light filter is configured to exclude a portion of the visible light from detection by the third optoelectronic sensor. 
     
     
         16 . A device comprising:
 a first semiconductor layer having first and second optoelectronic sensors formed therein;   a second semiconductor layer formed over the first semiconductor layer and positioned above the first and second optoelectronic sensors; and   an infrared (IR) blocking filter formed directly on the second layer and positioned above the first and second optoelectronic sensors.   
     
     
         17 . The device of  claim 16  further comprising a third optoelectronic sensor formed in the first semiconductor layer, wherein the IR blocking filter is not positioned above the third optoelectronic sensor. 
     
     
         18 . The device of  claim 17  further comprising a visible light filter formed over at least one of the first and second sensors. 
     
     
         19 . The device of  claim 18  further comprising a visible light filter formed over the third sensor. 
     
     
         20 . The device of  claim 17  further comprising a visible light filter formed over the third sensor. 
     
     
         21 . A device comprising:
 a first optoelectronic sensor configured to detect electromagnetic radiation in the visible light spectrum and the infrared (IR) spectrum and to generate a first response representing a spectral content of the detected electromagnetic radiation;   a second optoelectronic sensor configured to detect electromagnetic radiation in the visible light spectrum and the IR spectrum and to generate a second response representing a spectral content of the detected electromagnetic radiation;   an IR blocking filter integral to the device and positioned above the first and second optoelectronic sensors, wherein the IR blocking filter is configured to attenuate electromagnetic radiation in the IR spectrum; and   a visible light filter integral to the device and positioned above the first optoelectronic sensor, wherein the visible light filter is configured to attenuate electromagnetic radiation forming a first portion of the visible light spectrum.   
     
     
         22 . The device of  claim 21  further comprising a second visible light filter integral to the device and positioned above the first and second optoelectronic sensors, wherein the second visible light filter is configured to attenuate electromagnetic radiation forming a second portion of the visible light spectrum. 
     
     
         23 . The device of  claim 22  further comprising circuitry for generating a differential response by determining a difference between the first and second responses, wherein the differential response represents a photopic response. 
     
     
         24 . The device of  claim 21  further comprising a third optoelectronic sensor configured to detect electromagnetic radiation in the visible light spectrum and the IR spectrum and to generate a third response representing a spectral content of the detected electromagnetic radiation, wherein the third optoelectronic sensor is not associated with an IR blocking filter. 
     
     
         25 . The device of  claim 24  further comprising a second visible light filter positioned above the third optoelectronic sensor, wherein the second visible light filter is configured to attenuate electromagnetic radiation forming a third portion of the visible light spectrum. 
     
     
         26 . The device of  claim 25  wherein the third portion of the visible light spectrum overlaps at least one of the first and second portions of the visible light spectrum. 
     
     
         27 . The device of  claim 21  wherein the visible light filter is configured to block all visible light and wherein the device further comprises circuitry for determining a ratio between the first and second responses, wherein the ratio represents a spectral response. 
     
     
         28 . The device of  claim 27  wherein the second response represents a plurality of wavelengths, and wherein the first response represents only longer wavelengths present in the second response. 
     
     
         29 . The device of  claim 27  further comprising a third optoelectronic sensor configured to detect electromagnetic radiation in the visible light spectrum and the IR spectrum and to generate a third response representing a spectral content of the detected electromagnetic radiation, wherein the third optoelectronic sensor is not associated with an IR blocking filter. 
     
     
         30 . The device of  claim 29  further comprising a second visible light filter integral to the device and positioned above the third optoelectronic sensor, wherein the second visible light filter is configured to attenuate electromagnetic radiation forming a third portion of the visible light spectrum. 
     
     
         31 . The device of  claim 30  wherein the third portion of the visible light spectrum overlaps at least one of the first and second portions of the visible light spectrum. 
     
     
         32 . The device of  claim 21  wherein a semiconductor layer overlays the first and second optoelectronic sensors, and wherein the IR blocking filter directly overlays the semiconductor layer.