Radiation Detector with Isolated Pixels Photosensitive Array for CT and Other Imaging Applications

• US 20090314947A1
• Filed: 05/29/2009
• Published: 12/24/2009
• Est. Priority Date: 05/30/2008
• Status: Abandoned Application

• Current Assignee: Array Optronix, Inc.
• Original Assignee: Array Optronix, Inc.
• Inventors: Goushcha, Alexander O., Flitsch, Frederick A., Denning, Perry A.
• Application Number:
  US12/475,274
• Publication Number:
  US 20090314947A1
• Time in Patent Office: Days
• US Class Current: 250/363.10
• CPC Class Codes: G01T 1/20183 Arrangements for preventing or correcting crosstalk, e.g. optical or electrical arrangements for correcting crosstalk
• CPC Class Codes: H01L 2224/16225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 27/1463 Pixel isolation structures
• CPC Class Codes: H01L 27/14634 Assemblies, i.e. Hybrid structures
• CPC Class Codes: H01L 27/14659 Direct radiation imagers structures
• CPC Class Codes: H01L 27/14663 Indirect radiation imagers, e.g. using luminescent members

Abstract

This invention describes an imaging system based on an array of semiconductor photosensitive elements with isolating structure between elements (pixels) of the array. The isolated pixels of the array may be photodiodes and they provide excellent imaging capabilities that are important for many applications. The isolated photosensitive pixels may be comprised also by photoconductors, avalanche photodiodes, photosensitive IC, or other similar solid-state devices. The fields of possible application include but are not limited to the detector modules for homeland security, medical imaging systems (CT, SPECT, and PET including), fundamental and applied research, etc.

Claims

1. A radiation detection system comprising:

a photo-sensitive device having multiple photo-sensitive elements arrayed upon a semiconductor substrate with isolation surrounding the periphery of each of said multiple elements, wherein said isolation propagates between a first, top surface and a second, back surface of the semiconductor substrate;

a plurality of scintillator elements which convert x-ray radiation into light, attached to a surface of the semiconductor substrate and aligned with the multiple elements thereupon; and

,

at least one electrical amplification element which electrically contacts said multiple elements, wherein said amplification element is affixed to a support substrate in contact with a surface of the semiconductor substrate.

2. The radiation detection system of claim 1 wherein the semiconductor substrate surface in contact with the scintillator elements is free of electrical contacts.

3. A radiation detector array comprising:

a radiation sensitive surface which converts received radiation into photons of light;

a photodiode array that comprises a semiconductor substrate of a first conductivity type having first and second surfaces, the second, back surface being free of electrical contacts in optical communication with the radiation sensitive surface, and which photodiode array generates electrical signals responsive to the photons of light generated by the radiation sensitive surface, the second surface having a layer of the first conductivity type having a greater conductivity than the semiconductor substrate;

a matrix of regions of a first conductivity type of a higher conductivity than the semiconductor substrate extending from the first surface of the semiconductor substrate to the layer of the first conductivity type having a greater conductivity than the said semiconductor substrate, wherein the entire matrix regions are semiconductor doped regions;

a plurality of regions of the second conductivity type interspersed within the matrix of regions of the first conductivity type and not extending to the layer of the first conductivity type on the second surface of the semiconductor substrate;

a plurality of contacts on the first surface for making electrical contact to the matrix of regions of the first conductivity type and the plurality of regions of the second conductivity type;

and which has its contacts arranged on a first, top surface opposite the second, back surface, and a support substrate supporting the photodiode, the support substrate configured to provide an electrical path from the contacts on the first surface of the photodiode through the support substrate.

4. A radiation detector array comprising:

a radiation sensitive surface which converts received radiation into photons of light;

a photodiode array that comprises a semiconductor substrate of a first conductivity type having first and second surfaces, the second, back surface in optical communication with the radiation sensitive surface, which generates electrical signals responsive to the photons of light generated by the radiation sensitive surface, the second surface having a layer of the first conductivity type having a greater conductivity than the said semiconductor substrate;

a first matrix of regions of a first conductivity type of a higher conductivity than the semiconductor substrate extending into the semiconductor substrate from the first surface of the said semiconductor substrate;

a second matrix of regions of a first conductivity type of a higher conductivity than the semiconductor substrate extending into the said semiconductor substrate from the second surface of the semiconductor substrate and aligned with the first matrix, the first and second matrices not extending into the said semiconductor substrate to touch each other;

a plurality of regions of the second conductivity type interspersed within the first matrix of regions of the first conductivity type on the first surface of the semiconductor substrate and not extending to the layer of the first conductivity type on the second surface of the said semiconductor substrate;

a plurality of contacts on the first surface of a semiconductor substrate for making electrical contact to the matrix of regions of the first conductivity type and the plurality of regions of the second conductivity type;

and which has its signal contacts arranged on a first, top surface opposite the second, back surface of the semiconductor substrate; and

a support substrate supporting the photodiode, the support substrate configured to provide an electrical path from the contacts on the first surface of the photodiode through the support substrate.

5. A radiation detector array comprising:

a radiation sensitive surface which converts received radiation into photons of light;

a photodiode which has a second, back surface that includes electrical contacts, useful for testing, but not electrically connected other than for testing in optical communication with the radiation sensitive surface, which generates electrical signals responsive to the photons of light generated by the radiation sensitive surface, and which has its electrically connected signal contacts arranged on a first, top surface opposite the second, back surface;

and a support substrate supporting the photodiode, the support substrate configured to provide an electrical path from the contacts on the first, top surface of the photodiode through the support substrate.

6. The radiation detector array of claim 5:

wherein the photodiode is configured into a photodiode array,

wherein the photodiode array comprises a semiconductor substrate of a first conductivity type having first and second surfaces;

the second surface having a layer of the first conductivity type having a greater conductivity than the semiconductor substrate;

a matrix of regions of a first conductivity type of a higher conductivity than the said semiconductor substrate extending from the first surface of the semiconductor substrate to the layer of the first conductivity type having a greater conductivity than the semiconductor substrate, wherein the entire matrix regions are semiconductor doped regions;

a plurality of regions of the second conductivity type interspersed within the matrix of regions of the first conductivity type and not extending to the layer of the first conductivity type on the second surface of the semiconductor substrate; and

,

a plurality of contacts on the first surface for making electrical contact to the matrix of regions of the first conductivity type and the plurality of regions of the second conductivity type;

7. A method comprising:

illuminating a radiation sensitive surface with x-rays;

converting the x-rays illuminating the radiation sensitive surface into light;

producing an electrical signal proportional to the converted light with a photodiode array wherein said photodiode array comprises a semiconductor substrate of a first conductivity type having first and second surfaces;

the second surface having a layer of the first conductivity type having a greater conductivity than the semiconductor substrate;

a matrix of regions of a first conductivity type of a higher conductivity than the semiconductor substrate extending from the first surface of the said semiconductor substrate to the layer of the first conductivity type having a greater conductivity than the semiconductor substrate, wherein the entire matrix regions are semiconductor doped regions;

a plurality of regions of the second conductivity type interspersed within the matrix of regions of the first conductivity type and not extending to the layer of the first conductivity type on the second surface of the semiconductor substrate;

a plurality of contacts on the first surface for making electrical contact to the matrix of regions of the first conductivity type and the plurality of regions of the second conductivity type; and

,

communicating the electrical signal through a support substrate to processing circuitry sheltered from the x-rays via a path orthogonal to the radiation sensitive surface.

8. A method comprising:

illuminating a radiation sensitive surface with x-rays;

converting the x-rays illuminating the radiation sensitive surface into light;

producing an electrical signal proportional to the converted light with a photodiode array wherein said photodiode array comprises a semiconductor substrate of a first conductivity type having first and second surfaces;

the second surface having a layer of the first conductivity type having a greater conductivity than the semiconductor substrate;

a first matrix of regions of a first conductivity type of a higher conductivity than the semiconductor substrate extending into the said semiconductor substrate from the first surface;

a second matrix of regions of a first conductivity type of a higher conductivity than the semiconductor substrate extending into the said semiconductor substrate from the second surface of the semiconductor substrate and aligned with the first matrix, the first and second matrices not extending into the semiconductor substrate to touch each other;

a plurality of regions of the second conductivity type interspersed within the first matrix of regions of the first conductivity type on the first surface of the semiconductor substrate and not extending to the layer of the first conductivity type on the second surface of the said semiconductor substrate;

a plurality of contacts on the first surface for making electrical contact to the matrix of regions of the first conductivity type and the plurality of regions of the second conductivity type; and

,

communicating the electrical signal through a support substrate to processing circuitry sheltered from the x-rays via a path orthogonal to the radiation sensitive surface.

9. A radiation detection system comprising:

a scintillator block for converting X-rays into light;

a photo-sensitive device having multiple photo-sensitive elements arrayed upon a semiconductor substrate with isolation surrounding the periphery of each of said multiple elements, wherein said isolation propagates between a first, top surface and a second, back surface of the semiconductor substrate;

a plurality of contacts on the first surface for making electrical contact to the plurality of photosensitive elements and to the isolation regions;

communicating the electrical signal through a first support substrate to processing circuitry sheltered from the x-rays via a path orthogonal to the radiation sensitive surface;

a processing circuitry or readout electronics formed on a chip or second support substrate attached to the first support substrate;

a switch for selecting a photodiode, from said photodiode array, from which an electrical signal is to be output;

a data acquisition chip for acquiring data output from said photodiode array selected by said switch; and

means for integrating said scintillator block, said photosensitive device, said support substrates, and said data acquisition, said switch and processing circuitry chip.

10. A radiation detection system comprising:

a scintillator block for converting X-rays into light;

a photodiode array for converting the light into electrical signals wherein said photodiode array comprises a semiconductor substrate of a first conductivity type having first and second surfaces;

the second surface having a layer of the first conductivity type having a greater conductivity than the semiconductor substrate;

a matrix of regions of a first conductivity type of a higher conductivity than the semiconductor substrate extending from the first surface of said semiconductor substrate to the layer of the first conductivity type having a greater conductivity than the semiconductor substrate, wherein the entire matrix regions are semiconductor doped regions;

a plurality of regions of the second conductivity type interspersed within the matrix of regions of the first conductivity type and not extending to the layer of the first conductivity type on the second surface of the semiconductor substrate;

a plurality of contacts on the first surface for making electrical contact to the matrix of regions of the first conductivity type and the plurality of regions of the second conductivity type;

communicating the electrical signal through a first support substrate to processing circuitry sheltered from the x-rays via a path orthogonal to the radiation sensitive surface;

a processing circuitry and readout electronics formed on a chip or second support substrate attached to the first support substrate;

a switch for selecting a photodiode, from said photodiode array, from which an electrical signal is to be output;

a data acquisition chip for acquiring data output from said photodiode array selected by said switch; and

means for integrating said scintillator block, said photodiode array, said support substrates for signal communication, and said data acquisition chip and switch.

11. An imaging system comprising:

an x-ray radiation source selectively generating a beam of x-ray radiation that traverses an examination region from a multiplicity of directions;

a radiation detector positioned opposite the examination region from the radiation source, the radiation detector comprising a photo-sensitive device having multiple photo-sensitive elements arrayed upon a semiconductor substrate with isolation surrounding the periphery of each of said multiple elements, wherein said isolation propagates between a first, top surface and a second, back surface of the substrate;

a plurality of contacts on the first surface of the semiconductor substrate for making electrical contact to the plurality of photosensitive elements and to the isolation regions;

a scintillation crystal overlaying the photodetector array for converting received x-ray radiation into light, the scintillation crystals being optically coupled to the elements of the photo-sensitive device;

a support substrate comprising a first support substrate layer disposed parallel to the photo-sensitive array and a second support substrate layer or chip disposed at any angle to and in support of the first support substrate layer; and

,

a plurality of contacts and paths below the photo-sensitive array through the substrate, the paths providing electrical connectivity between the photodetectors and signal processing circuitry.

12. An imaging system comprising:

an x-ray radiation source selectively generating a beam of x-ray radiation that traverses an examination region from a multiplicity of directions,

a radiation detector array positioned opposite the examination region from the radiation source, the radiation detector array including a plurality of photodetectors arranged in an array, the photodetector array comprising a semiconductor substrate of a first conductivity type having first and second surfaces, the second surface having a layer of the first conductivity type having a greater conductivity than the substrate, a matrix of regions of a first conductivity type of a higher conductivity than the said semiconductor substrate extending from the first surface of the semiconductor substrate to the layer of the first conductivity type having a greater conductivity than the semiconductor substrate, wherein the entire matrix regions are semiconductor doped regions, a plurality of regions of the second conductivity type interspersed within the matrix of regions of the first conductivity type and not extending to the layer of the first conductivity type on the second surface of the semiconductor substrate, and a plurality of contacts on the first surface for making electrical contact to the matrix of regions of the first conductivity type and the plurality of regions of the second conductivity type;

a scintillation crystal overlaying the photodetector array for converting received x-ray radiation into light, the scintillation crystals being optically coupled to the primary photodetectors;

a support substrate comprising a first support substrate layer disposed parallel to the photodetector array and a second support substrate layer or chip disposed at any angle to and in support of the first support substrate layer; and

,

a plurality of contacts and paths below the primary photodetector array through the substrate, the paths providing electrical connectivity between the photodetectors and signal processing circuitry.