Communications: electrical – Condition responsive indicating system – Specific condition
Reexamination Certificate
2001-01-09
2001-11-27
Trieu, Van (Department: 2632)
Communications: electrical
Condition responsive indicating system
Specific condition
C340S551000, C340S553000
Reexamination Certificate
active
06323768
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to energy detection systems and more particularly to energy detection systems disposed on a single crystal substrate.
As is known in the art, electromagnetic energy detection systems have a wide range of application, e.g. from cameras to missile seekers. In such systems, electromagnetic energy, e.g., visible light or infrared energy, is focused by an optical system onto one, or more, electromagnetic energy detectors. These detectors are often arranged in an array which is disposed at the focal plane of the optical system. The detector produces an indication of the detected energy by, for example, producing a corresponding electrical output signal. In one focal plane array, the detectors are semiconductor devices, such as HgCdTe or InSb, formed in different isolated regions of an upper surface of a single crystal semiconductor body. Thus, in response to light impinging upon the detector, charge is produced in the corresponding isolated region of the semiconductor body having the detector.
In one system, a read-out electronics (“ROE”), formed as an integrated circuit in a second semiconductor substrate, typically silicon, is mounted to a back surface of the first-mentioned substrate. The charge produced in the first-mentioned substrate passes to different isolated regions of the second-mentioned substrate through electrical contacts disposed therebetween. The read-out electronics provides clock signals to regulate the propagation of charge in the second-mentioned substrate to output signal processing circuitry. In order to transfer the charge produced in the first-mentioned substrate to the second substrate, a wire or other metal contacts are connected to ohmic contact diffusion regions in the semiconductor bodies to provide electrical contact. The ohmic contact regions result in the generation of generation-recombination (GR) noise. While this technique may be acceptable for some wavelengths of energy, the GR noise produced may create, in some applications, an unacceptably low signal to noise ratio (SNR) for some combinations of wavelength and substrate.
The use of a single silicon substrate for both the detectors and the read-out electronics has been suggested. However, with a silicon substrate, near infrared energy above about 8,000 Å passes readily through the substrate without generating sufficient charge for system SNR requirements. One technique has been presented in two articles, one entitled “Active-Pixel Image Sensor Integrated With Readout Circuits,” by Robert Nixon, Eric Fossum, and Sabrina Kemeny and the other entitled “CMOS Active-Pixel Image Sensor Containing Pinned Photodiodes,” by Eric R. Fossum both published in NASA Tech Briefs, October, 1996, from NASA's Jet Propulsion Laboratory in Pasadena, Calif. In the articles, the authors describe an attempt at an image sensor including readout circuits and pinned diode detectors, for visible and ultraviolet light, on one chip. According to the second-mentioned article, however, the operation of the device has not been demonstrated.
SUMMARY OF THE INVENTION
In accordance with one feature of the invention, an electromagnetic energy detection system is provided having a plurality of detectors disposed in a single crystal body. Each one of the detectors is adapted to produce charge in a doped region disposed in the body in response to electromagnetic energy impinging upon such one of the detectors. A first charge transfer device (“CTD”) is provided having a plurality of first charge transfer regions disposed in the body and includes a plurality of serially coupled charge storage cells. A plurality of second charge transfer devices is provided for transferring the charge in a corresponding one of the doped regions to a corresponding one of the charge storage cells of the first charge transfer device.
With such an arrangement, ohmic contacts between each one of the detectors and the charge storage cells of the first charge transfer device are eliminated thereby reducing GR noise and improving the SNR performance of the detection system.
In accordance with another feature of the invention, an electromagnetic energy detection system is provided having a plurality of detectors disposed in a single crystal body. Each one of the detectors is adapted to produce charge in the body in response to electromagnetic energy impinging upon such one of the detectors. Read-out electronics is disposed on the body. The read-out electronics includes a first charge transfer device having a plurality of first charge transfer regions disposed in the body and includes a plurality of serially coupled charge storage cells. A last one of the cells is coupled to an output port. A charge coupling structure is disposed on the body to couple the charge produced by the detectors to the read-out electronics, The charge coupling structure includes a plurality of second charge transfer devices, including a plurality of second charge transfer regions, disposed in the body. Each one of the plurality of second charge transfer regions is adapted to transfer charge produced in a corresponding one of the detectors to a corresponding one of the plurality of charge storage cells. With such an arrangement, an effective electromagnetic energy detection system is provided wherein energy detectors, charge coupling structure and read-out electronics are formed on a single crystal substrate.
In a preferred embodiment of the invention, a shield is provided to reduce incident electromagnetic energy from impinging upon portions of the read-out electronics and portions of the charge coupling structure.
In accordance with still another feature of the invention, a detector is provided having a single crystal body with a doped region therein. Such detector is adapted to produce charge in the doped region in response to electromagnetic energy impinging upon such detector. A second region is disposed in the body and laterally displaced from the detector. The doped region has a doping profile selected to produce an electric field therein along a direction from the doped region toward the second region.
With such a structure, charge produced in the body is efficiently transferred from the doped region to a region displaced therefrom for processing by electronic circuitry also disposed on the body.
In a preferred embodiment, the body comprises silicon and the detector comprises a light detector.
In accordance with still another feature of the invention, apparatus is provided for reducing noise, e.g., transients, in an output of a charge transfer device formed in a first region of a single crystal body. Such apparatus includes a transient suppression circuit. The circuit includes a pair of inputs; one of the inputs being coupled to the output of the charge transfer device and the other input being coupled to a second region of the body displaced from the first region. The circuit includes a differencing arrangement for subtracting signals at the pair of inputs to reduce noise components on at least one of such signals.
With such an arrangement, noise generated in the body is present at the output of the charge transfer device, along with a desired signal, and is also present in the second region of the body. Therefore, substantially the same noise is present at both of the inputs of the transient suppression circuit. The differencing arrangement combines the two signals at the two inputs to thereby cancel, or reduce, the noise present at the output of the charge transfer device thereby yielding the desired signal with a reduced noise component.
In accordance with another feature of the invention, an electromagnetic energy detection system is provided having a single crystal body. A detector is disposed in a first region the body. The detector produces charge in the body in response to electromagnetic energy impinging upon such detector. At least a portion of the produced charge passes through a second region of the body to an output port. A charge detector, disposed in the body, is coupled to the output port and
Bessendorf Simon
Kemper Richard V.
Lewis Edward T.
Sciarretta William A.
Daly, Crowley & Mofford LLP
Raytheon Company
Trieu Van
LandOfFree
Electromagnetic energy detection does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Electromagnetic energy detection, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electromagnetic energy detection will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2571038