Stacked multiple photosensor structure including independent...

Details Stacked multiple photosensor structure including independent... Stacked multiple photosensor structure including independent...

1999-05-03

2002-04-16

Flynn, Nathan (Department: 2826)

Active solid-state devices (e.g., transistors, solid-state diode

Responsive to non-electrical signal

Electromagnetic or particle radiation

C257S072000, C257S448000, C257S449000

Reexamination Certificate

active

06373117

ABSTRACT:

FIELD OF INVENTION
This invention relates generally to active pixel photosensors. In particular, it relates to a stacked multiple active pixel photo sensor that includes independent electrical connections to each photosensor, allowing multiple color detection.
BACKGROUND
An array of photo pixel sensors detect the intensity of light received by the photo pixel sensors. The photo pixel sensors typically generate electronic signals that have amplitudes that are proportionate to the intensity of the light received by the photo pixel sensors. The photo pixel sensors can convert an optical image into a set of electronic signals. The electronic signals may represent intensities of colors of light received by the photo pixel sensors. The electronic signals can be conditioned and sampled to allow image processing.
Integration of the photo pixel sensors with signal processing circuitry is becoming more important because integration enables miniaturization and simplification of imaging systems. Integration of photo pixel sensors along with analog and digital signal processing circuitry allows electronic imaging systems to be low cost, compact and require low power.
Historically, photo pixel sensors have predominantly been charged coupled devices (CCDs). CCDs are relatively small and can provide a high-fill factor. However, CCDs are very difficult to integrate with digital and analog circuitry. Further, CCDs dissipate large amounts of power and suffer from image smearing problems.
An alternative to CCD sensors are active pixel sensors. Active pixel sensors can be fabricated using standard CMOS processes. Therefore, active pixel sensors can easily be integrated with digital and analog signal processing circuitry. Further, CMOS circuits dissipate small amounts of power.
FIG. 1
shows a prior art array of active pixel sensors. An array of sensors
12
are formed over a substrate
10
. An array of color filters
14
is formed over the array of sensors
12
. Light passes through the color filters
14
and is received by the array of sensors
12
. The sensors
12
typically conduct charge at a rate that is proportional to the intensity of the light received by the sensors
12
. Circuitry located on the substrate
10
provides determination of the amount of charge conducted by the sensors
12
. Therefore, the sensors
12
provide detection of the intensity of the received light.
The array of color filters
14
includes filters which pass different wavelengths of light. For example, the array of color filters
14
can include blue light, green light and red light filters. The blue light filters only passes blue light, the green light filters only passes green light and the red light filters only pass red light. Generally, each sensor of the array of sensors
12
corresponds with a single color filter of the array of color filters
14
. Color detection can be obtained by knowing which sensor corresponds with which type of color filter.
The active pixel sensor array of
FIG. 1
is inefficient because up to 70% of the photons within the received light are lost during the filtering process. That is, the color filters
14
attenuate the intensity of the light received by the array of sensors
12
. Removing the color filters
14
increases the intensity of light received by the array of sensors
12
. As a result, the color filters
14
reduce the signal to noise ratio of the electronic signals generated by the array of sensors
12
.
The active pixel sensor array of
FIG. 1
requires demosaicing. Each sensor of the array of sensors
12
detects the intensity of a particular color of light. Each sensor is physically displaced from all of the other sensors of the array of sensors
12
. Therefore, special image processing (demosaicing) is required for determination of a representation of the color intensity received by the array of sensors
12
at each particular pixel location.
It is desirable to have an array of active pixel sensors which provide efficient absorption of photons within light received by the array of active pixel sensors, and be able to detect the color of received light. It is also desirable that the array of active pixel sensors be manufacturable without an array of color filters and not require demosaicing.
SUMMARY OF THE INVENTION
The present invention is a color detection active pixel sensor which provides efficient absorption of photons of light received by the color active detection pixel sensor while providing detection of the color of the received light. The color detection is accomplished without color filters and does not require demosaicing.
A first embodiment of the invention includes a multiple-photosensor structure. The multiple-photosensor structure includes a substrate. A first photosensor is formed adjacent to the substrate. A first pixel electrode of the first photosensor is electrically connected to the substrate. A first transparent conductive layer is formed adjacent to the first photosensor. The first transparent conductive layer electrically connects a first outer electrode of the first photosensor to the substrate. A second photosensor is adjacent to the first transparent conductive layer. A second pixel electrode of the second photosensor is electrically connected to the substrate through the first transparent conductive layer. A second transparent conductive layer is adjacent to the second photosensor. The second transparent conductive layer electrically connects a second outer electrode of the second photosensor to the substrate.
A second embodiment of the invention is similar to the first embodiment. The second embodiment includes a third photosensor formed adjacent to the second transparent conductive layer. A third pixel electrode of the third photosensor is electrically connected to the substrate through the second transparent conductive layer. A third transparent conductive layer is formed adjacent to the third photosensor. The third transparent conductive layer electrically connects a third outer electrode of the third photosensor to the substrate.
A third embodiment of the invention is similar to the first embodiment. The third embodiment includes the first photosensor detecting a first range of wavelengths of light.
A fourth embodiment of the invention is similar to the first embodiment. The fourth embodiment includes the second photosensor detecting a second range of wavelengths of light.
A fifth embodiment of the invention is similar to the second embodiment. The fifth embodiment includes the third photosensor detecting a third range of wavelengths of light.
Other aspects and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.


REFERENCES:
patent: 5838054 (1998-11-01), Kwasnick et al.
patent: 6114739 (2000-09-01), Theil et al.
patent: 0 428 050 (1990-07-01), None

Affiliated with

Also associated with

Rating

Stacked multiple photosensor structure including independent... does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Stacked multiple photosensor structure including independent..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Stacked multiple photosensor structure including independent... will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2824569