Cross-strip semiconductor detector with cord-wood construction

• US 6,002,134 A
• Filed: 10/21/1997
• Issued: 12/14/1999
• Est. Priority Date: 10/13/1995
• Status: Expired due to Fees

• Current Assignee: Digirad Corporation
• Original Assignee: Digirad Corporation
• Inventors: Lingren, Clinton L.
• Primary Examiner(s): Westin, Edward P.
• Assistant Examiner(s): HANIG, RICHARD E
• Application Number:
  US08/955,474
• Time in Patent Office: 784 Days
• Field of Search: 250/370.01, 250/370.09, 250/370.13, 250/370.14, 257/428
• US Class Current: 250/370.01
• CPC Class Codes: G01T 1/241 Electrode arrangements, e.g. continuous or parallel strips or the like constructional or manufacturing details H01L31/00
• CPC Class Codes: G01T 1/243 Modular detectors, e.g. arrays formed from self contained units constructional or manufacturing details H01L25/00
• CPC Class Codes: H01L 27/14603 Special geometry or disposition of pixel-elements, address-lines or gate-electrodes
• CPC Class Codes: H01L 27/14659 Direct radiation imagers structures
• CPC Class Codes: H01L 27/14676 X-ray, gamma-ray or corpuscular radiation imagers measuring X-, gamma- or corpuscular radiation G01T1/00

Abstract

A cross-strip radiation detector for detecting ionizing radiation. The detector includes a semiconductor having at least two sides, a radiation side and an opposing signal collecting side. A plurality of parallel radiation-side electrode strips are formed on the radiation side of the semiconductor. Multiple of signal-collecting-side electrodes are formed on a signal collecting side of the semiconductor and are connected to form a plurality of parallel signal strips that are not parallel to the radiation-side electrode strips. For common semiconductors, anodes are used to detect the energy level of the ionizing radiation. The signals from the cathode strips are used in conjunction with the signals from the anodes to determine the location of an ionizing event. At least one additional electrode, a control electrode, may also be formed on the semiconductor to alter the electric field within the semiconductor to improve the collection efficiency of the signal electrode. A high-voltage decoupling circuit is implemented on the signal collecting side with high-voltage capacitors arranged in a cord-wood configuration to allow for all-side buttability. A thin circuit layer is formed on a lateral side of the semiconductor to transfer the signals from the radiation side to the signal collecting side. A shield electrode may also be formed on the signal collecting side and be capacitively coupled to the semiconductor to reduce the effect on the anodes of charge trapping in the semiconductor.

Claims

1. A cross-strip radiation detector, comprising:

(a) a semiconductor having a plurality of sides and of sufficient thickness to interact with ionizing radiation;

(b) at least one independent radiation-side strip electrode formed on a radiation side of the semiconductor and maintained at a first bias voltage;

(c) a plurality of signal-collecting-side electrodes formed on a signal collecting side of the semiconductor opposing the radiation side and intercoupled as at least two independent signal-collecting-side signal strips effectively forming an angle with respect to the radiation-side strip electrode, each signal-collecting-side signal strip including one or more electrically coupled signal-collecting-side electrodes and being set at a second bias voltage, wherein at least one of the first and second bias voltages is at a high voltage with respect to the ground level;

(d) a high-voltage decoupling circuit having an array of high-voltage capacitors formed over the plurality of signal-collecting-side electrodes within the perimeter of the signal collecting side, the high-voltage decoupling circuit connected to the electrodes at the high voltage to receive and decouple signals that are superimposed on the high voltage and are indicative of the ionizing radiation; and

(e) at least one electrical conductor that interconnects the radiation side and the signal collecting side to transfer a signal from the radiation side to the signal collecting side.

2. The cross-strip radiation detector of claim 1, further comprising a first circuit layer formed between the signal-collecting-side electrodes and the high-voltage decoupling circuit and second circuit layer formed over the high-voltage decoupling circuit, wherein each high-voltage capacitor of the high-voltage decoupling circuit is connected to the first circuit layer at one terminal and to the second circuit layer at the other terminal and the spacing between the first and the second circuit layers is configured to accommodate the high voltage.

3. The cross-strip radiation detector of claim 1, further comprising an electronic circuit which is configured to receive and process signals from the radiation side and the signal collecting side to measure an ionizing event, wherein the electronic circuit is operable to determine a position of the ionizing event according to signals on the radiation side and the signal collecting side electrodes.

4. The cross-strip radiation detector of claim 1, wherein the electrical conductor is a conductor within a printed circuit which is interposed between two insulating dielectric layers.

5. The cross-strip radiation detector of claim 4, wherein the printed circuit is at least in part formed on a lateral side of the semiconductor which intersects the radiation side and signal collecting side.

6. The cross-strip radiation detector of claim 1, further comprising at least one control electrode, formed on the signal collecting side of the semiconductor and electrically insulated from the signal electrodes, the control electrode having a geometry and control potential to affect the charge collection of the signal-collecting-side electrodes.

7. The cross-strip radiation detector of claim 6, wherein the control potential of the control electrode is within a range between the first bias voltage and the second bias voltage and effects a guiding force that drives charge towards the signal-collecting-side electrodes.

8. The cross-strip radiation detector of claim 6, wherein the geometry of the control electrode effects a shielding to the signal-collecting-side electrodes and substantially reduces induced charge on the signal-collecting-side electrodes caused by charge trapping in the semiconductor.

9. The cross-strip radiation detector of claim 1, further comprising a shield electrode which is a continuous conducting layer overlapping the signal-collecting-side electrodes and defining an array of openings to allow access to the signal-collecting-side electrodes, wherein the shield electrode is insulated from other electrodes and the semiconductor and is capacitively coupled to the semiconductor to reduce induced charge on the signal-collecting-side electrodes.

10. A cross-strip radiation detector, comprising:

(a) a semiconductor having a plurality of sides which include a radiation side and an opposing signal collecting side and a sufficient thickness between the radiation side and the signal collecting side to interact with ionizing radiation;

(b) at least one independent radiation-side strip electrode formed on the radiation side of the semiconductor and maintained at a first bias voltage;

(c) a plurality of independent and parallel signal-collecting-side strip signal electrodes that are formed on the signal collecting side of the semiconductor and effectively form an angle with respect to the radiation-side strip electrode, the signal-collecting-side strip signal electrodes being set at a second bias voltage, wherein at least one of the first and second bias voltages is at a high voltage with respect to the ground level;

(d) a high-voltage decoupling circuit having an array of high-voltage capacitors formed over the plurality of signal-collecting-side strip signal electrodes within the perimeter of the signal collecting side, the high-voltage decoupling circuit connected to the electrodes at the high voltage to receive and decouple signals that are superimposed on the high voltage and are indicative of the ionizing radiation; and

(e) at least one electrical conductor that interconnects the radiation side and the signal collecting side to transfer a signal from the radiation side to the signal collecting side.

11. The cross-strip radiation detector of claim 10, further comprising a first circuit layer formed between the signal-collecting-side stip signal electrodes and the high-voltage decoupling circuit and second circuit layer formed over the high-voltage decoupling circuit, wherein each high-voltage capacitor of the high-voltage decoupling circuit is connected to the first circuit layer at one terminal and to the second circuit layer at the other terminal and the spacing between the first and the second circuit layers is configured to accommodate the high voltage.

12. The cross-strip radiation detector of claim 10, wherein the electrical conductor is a conductor within a printed circuit which is interposed between two insulating dielectric layers.

13. The cross-strip radiation detector of claim 12, wherein the printed circuit is at least in part formed on a lateral side of the semiconductor which intersects the radiation side and signal collecting side.

14. The cross-strip radiation detector for claim 10, further comprising a plurality of parallel strip control electrodes, formed on the signal collecting side of the semiconductor near and interdigitated with the signal-collecting-side strip signal electrodes and electrically insulated from the signal-collecting-side strip signal electrodes, the parallel strip control electrodes operable to perform at least one of the functions of (A) directing charge clouds resulting from ionizing events in the semiconductor towards the signal-collecting-side strip signal electrodes and (B) substantially reducing the effect on the signal-collecting-side strip signal electrodes of charge trapping in the semiconductor.

15. The cross-strip radiation detector of claim 10, further comprising an electronic circuit which is configured to receive and process signals from the radiation side and the signal collecting side to measure an ionizing event, wherein the electronic circuit is operable to determine a position of the ionizing event according to signals on the radiation side and the signal collecting side electrodes.

16. A radiation imaging device, comprising a plurality of detector modules arranged relative to one another side-by-side to form a detector array, each detector module comprising:

(1) a semiconductor having a plurality of sides and of sufficient thickness to interact with ionizing radiation;

(2) at least one independent radiation-side strip electrode formed on a radiation side of the semiconductor and maintained at a first bias voltage;

(3) a plurality of signal-collecting-side electrodes formed on a signal collecting side of the semiconductor opposing the radiation side and intercoupled as at least two independent signal-collecting-side signal strips effectively forming an angle with respect to the radiation-side strip electrode, each signal-collecting-side signal strip including one or more electrically coupled signal-collecting-side electrodes and being set at a second bias voltage, wherein at least one of the first and second bias voltages is at a high voltage with respect to the ground level;

(4) a high-voltage decoupling circuit having an array of high-voltage capacitors formed over the plurality of signal-collecting-side electrodes within the perimeter of the signal collecting side, the high-voltage decoupling circuit connected to the electrodes at the high voltage to receive and decouple signals that are superimposed on the high voltage and are indicative of the ionizing radiation; and

(5) at least one electrical conductor that interconnects the radiation side and the signal collecting side to transfer a signal from the radiation side to the signal collecting side.

17. The cross-strip radiation detector of claim 16, wherein each detector module further comprises a first circuit layer formed between the signal-collecting-side electrodes and the high-voltage decoupling circuit and second circuit layer formed over the high-voltage decoupling circuit, wherein each high-voltage capacitor of the high-voltage decoupling circuit is connected to the first circuit layer at one terminal and to the second circuit layer at the other terminal and the spacing between the first and the second circuit layers is configured to accommodate the high voltage.

18. The imaging device of claim 16, further comprising a signal processor which receives and processes signals from the detector array to form an electronic image representation of the ionizing radiation.

19. The cross-strip radiation detector for claim 16, wherein each detector module further comprises a plurality of parallel strip control electrodes, formed on the signal collecting side of the semiconductor near and interdigitated with the signal-collecting-side electrodes and electrically insulated from the signal-collecting-side electrodes, the parallel strip control electrodes operable to perform at least one of the functions of (A) directing charge clouds resulting from ionizing events in the semiconductor towards the signal-collecting-side electrodes and (B) substantially reducing the effect on the signal-collecting-side electrodes of charge trapping in the semiconductor.

22. The imaging device of claim 16, further comprising a signal processor which receives and processes signals from the detector array to form an electronic image representation of the ionizing radiation.

23. The cross-strip radiation detector for claim 16, wherein each detector module further comprises a plurality of parallel strip control electrodes, formed on the signal collecting side of the semiconductor near and interdigitated with the signal-collecting-side electrodes and electrically insulated from the signal-collecting-side electrodes, the parallel strip control electrodes operable to perform at least one of the functions of (A) directing charge clouds resulting from ionizing events in the semiconductor towards the signal-collecting-side electrodes and (B) substantially reducing the effect on the signal-collecting-side electrodes of charge trapping in the semiconductor.

20. A radiation imaging device, comprising a plurality of detector modules arranged relative to one another side-by-side to form a detector array, each detector module comprising:

(1) a semiconductor having a plurality of sides which include a radiation side and an opposing signal collecting side and a sufficient thickness between the radiation side and the signal collecting side to interact with ionizing radiation;

(2) at least one independent radiation-side strip electrode formed on the radiation side of the semiconductor and maintained at a first bias voltage;

(3) a plurality of independent and parallel signal-collecting-side strip signal electrodes that are formed on the signal collecting side of the semiconductor and effectively form an angle with respect to the radiation-side strip electrode, the signal-collecting-side strip signal electrodes being set at a second bias voltage, wherein at least one of the first and second bias voltages is at a high voltage with respect to the ground level;

(4) a high-voltage decoupling circuit having an array of high-voltage capacitors formed over the plurality of signal-collecting-side strip signal electrodes within the perimeter of the signal collecting side, the high-voltage decoupling circuit connected to the electrodes at the high voltage to receive and decouple signals that are superimposed on the high voltage and are indicative of the ionizing radiation; and

(5) at least one electrical conductor that interconnects the radiation side and the signal collecting side to transfer a signal from the radiation side to the signal collecting side.

21. The cross-strip radiation detector of claim 20, wherein each detector module further comprises a first circuit layer formed between the signal-collecting-side strip signal electrodes and the high-voltage decoupling circuit and second circuit layer formed over the high-voltage decoupling circuit, wherein each high-voltage capacitor of the high-voltage decoupling circuit is connected to the first circuit layer at one terminal and to the second circuit layer at the other terminal and the spacing between the first and the second circuit layers is configured to accommodate the high voltage.