Radiation image pickup device

• US 7,541,617 B2
• Filed: 02/10/2004
• Issued: 06/02/2009
• Est. Priority Date: 02/14/2003
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Mochizuki, Chiori, Ishii, Takamasa, Watanabe, Minoru, Nomura, Keiichi, Morishita, Masakazu
• Primary Examiner(s): Mandala; Victor A
• Assistant Examiner(s): CRUZ, LESLIE PILAR
• Application Number:
  US10/538,013
• Publication Number:
  US 20060249763A1
• Time in Patent Office: 1,939 Days
• Field of Search: 250/370.01, 250/370.08, 250/370.09
• US Class Current: 257/72
• CPC Class Codes: H01L 27/14658 X-ray, gamma-ray or corpuscular radiation imagers measuring X-, gamma- or corpuscular radiation G01T1/00
• CPC Class Codes: H04N 5/32 Transforming X-rays cameras or camera modules for generating image signals from X-rays H04N23/30; circuitry of SSIS for transforming X-rays into image signals H04N25/30

Abstract

In a radiation image pickup device including: a sensor element for converting radiation into an electrical signal; and a thin film transistor connected to the sensor element, an electrode of the sensor element connected to the thin film transistor is disposed above the thin film transistor, and that the thin film transistor has a top gate type structure in which a semiconductor layer, a gate insulating layer, and a gate electrode layer are laminated in this order on a substrate, so that a channel portion of the thin film transistor is protected by a gate electrode, thereby providing stable TFT characteristics without undesirable turning ON any of the TFT elements due to the back gate effect by the fluctuation in electric potentials corresponding to outputs from the sensor electrodes, and thereby greatly improving image quality.

Claims

1. A photoelectric converter comprising a plurality of pixels each comprising a sensor element for converting incident light into an electrical signal and a plurality of thin film transistors electrically connected to the sensor element,

wherein each of the plurality of thin film transistors has a top gate type structure in which a semiconductor layer, a gate insulating layer, and a gate electrode layer are laminated successively on a substrate, and an electrode of the sensor element electronically connected to the plurality of thin film transistors is disposed above the thin film transistor, and

wherein the electrode of the sensor element covers each channel region of the plurality of thin film transistors, and each of the plurality of thin film transistors is constituted by a respective further plurality of thin film transistors which are connected in series with one another and which have gate electrodes that are connected electrically.

2. A photoelectric converter according to claim 1, wherein the plurality of thin film transistors electrically connected to the sensor element comprise:

a transferring thin film transistor for transferring an electrical signal from the sensor element, a resetting thin film transistor for resetting the sensor element, the transferring thin film transistor having the gate electrodes of its further plurality of thin film transistors connected to the same gate wiring, and the resetting thin film transistor having the gate electrodes of its further plurality of thin film transistors connected to the same gate wiring.

3. A photoelectric converter according to claim 1, wherein the plurality of thin film transistors electrically connected to the sensor element comprise:

an amplifying thin film transistor for receiving an electrical signal from the sensor element;

a transferring thin film transistor for outputting the electrical signal; and

a resetting thin film transistor for resetting the sensor element, the amplifying thin film transistor having the gate electrodes of its further plurality of thin film transistors connected to the electrode of the sensor element, the transferring thin film transistor having the gate electrodes of its further plurality of thin film transistors connected to the same gate wiring, and the resetting thin film transistor having the gate electrodes of its further plurality of thin film transistors connected to the same gate wiring.

4. A photoelectric converter according to claim 1, wherein the channel regions of the plurality of thin film transistors electrically connected to the sensor element are wider than the gate electrodes of those thin film transistors.

5. A radiation image pickup device, comprising:

the photoelectric converter as claimed in claim 1; and

a conversion unit provided on a light incidence side of the photoelectric converter for converting radiation into light.

6. A photoelectric converter according to claim 1, wherein the electrode of the sensor element covers the semiconductor layer of the plurality of thin film transistors.

7. A photoelectric converter according to claim 1, wherein two interlayer insulating layers are disposed between the electrode of the sensor element electrically connected to the plurality of thin film transistors and gate electrodes of the plurality of thin film transistors, and a single interlayer insulating layer is disposed between the electrode of the sensor element electrically connected to the plurality of thin film transistors and a wiring electrically connected to the plurality of thin film transistors.

13. A radiation image pickup system comprising:

the radiation image pickup device as claimed in claim 5;

processing means for generating an image as an object for image pickup on the basis of electrical signals obtained from the radiation image pickup device; and

display means for displaying the image generated by the processing means.

8. A radiation image pickup device comprising a plurality of pixels each comprising a sensor element for convening radiation into an electrical signal and a plurality of thin film transistors electronically connected to the sensor element,

wherein each of the plurality of thin film transistors has a top gate type structure in which a semiconductor layer, a gate insulating layer, and a gate electrode layer are laminated successively on a substrate, and an electrode of the sensor element electrically connected to the plurality of thin film transistors is disposed above the thin film transistors, and

wherein the electrode of the sensor element covers each channel region of the plurality of thin film transistors, and each of the plurality of thin film transistors is constituted by respective further plurality of thin film transistors which are connected in series with one another and which have gate electrodes that are connected electrically.

9. A radiation image pickup device according to claim 8, wherein a storage capacitor is connected to the sensor element.

10. A radiation image pickup device according to claim 8, wherein the plurality of thin film transistors electrically connected to the sensor element comprise:

a transferring thin film transistor for transferring an electrical signal from the sensor element; and

a resetting thin film transistor for resetting the sensor element, the transferring thin film transistor having the gate electrodes of its plurality of thin film transistors connected to the same gate wiring, and the resetting thin film transistor having the gate electrodes of its plurality of thin film transistors connected to the same gate wiring.

11. A radiation image pickup device according to claim 8, wherein the plurality of thin film transistors electrically connected to the sensor element comprise:

an amplifying thin film transistors transistor for receiving as its input an electrical signal from the sensor element;

a transferring thin film transistor for outputting the electrical signal; and

a resetting thin film transistor for resetting the sensor element, the amplifying thin film transistor having the gate electrodes of its plurality of thin film transistors connected to the electrode of the sensor element, the transferring thin film transistor having the gate electrodes of its plurality of thin film transistors connected to the same gate wiring, and the resetting thin film transistor having the gate electrodes of its plurality of thin film transistors connected to the same gate wiring.

12. A radiation image pickup device according to claim 8, wherein the channel regions of the plurality of thin film transistors electrically connected to the sensor element are wider than the gate electrodes of those thin film transistors.

14. A radiation image pickup system comprising:

the radiation image pickup device as claimed in claim 8;

processing means for generating an image as an object for image pickup on the basis of electrical signals obtained from the radiation image pickup device; and

display means for displaying the image generated by the processing means.