Radiation image-pickup device and radiation image-pickup display system

Patent metadata

Field	Value
Publication number	US-9536921-B2
Application number	US-201414456905-A
Country	US
Kind code	B2
Filing date	Aug 11, 2014
Priority date	Aug 20, 2013
Publication date	Jan 3, 2017
Grant date	Jan 3, 2017

Abstract

A radiation image-pickup device includes: a plurality of pixels each configured to generate signal charge based on radiation; and a field effect transistor used to read the signal charge from each of the plurality of pixels, wherein the field effect transistor includes a semiconductor layer including an active layer and a low concentration impurity layer formed to be adjacent to the active layer, and a first and a second gate electrode disposed to face each other with the active layer interposed therebetween, and one or both of the first and the second gate electrodes are provided in a region not facing the low concentration impurity layer.

First claim

What is claimed is:

1. A radiation image-pickup device comprising:
a plurality of pixels each configured to generate signal charge based on radiation; and
a field effect transistor used to read the signal charge from each of the plurality of pixels,
wherein the field effect transistor includes
a semiconductor layer including an active region and a lightly doped drain (LDD) region formed to be adjacent to the active region, and
a first and a second gate electrode disposed to face each other with the active layer interposed therebetween, and
both of the first and the second gate electrodes are provided only in a region not facing the LDD region, and the first and second gate electrodes each have a width that is equal to or less than a width of the active region.

2. The radiation image-pickup device according to claim 1 , wherein
the field effect transistor further includes a first and a second gate insulating film,
the first gate electrode, the first gate insulating film, the semiconductor layer, the second gate insulating film, and the second gate electrode are provided in order from a substrate side, and
the first gate electrode has a width smaller than a width of the second gate electrode.

3. The radiation image-pickup device according to claim 2 , wherein the second gate electrode is disposed to face the active region and has the width substantially same as the width of the active region.

4. The radiation image-pickup device according to claim 2 , wherein a thickness of the second gate insulating film is larger than a thickness of the first gate insulating film.

5. The radiation image-pickup device according to claim 1 , wherein the first and the second gate electrodes are formed in a pixel section, of the pixel section and a peripheral circuit section, the pixel section having the plurality of pixels, and the peripheral circuit section being peripheral to the pixel section.

6. The radiation image-pickup device according to claim 1 , wherein impurity concentration in the LDD layer region is higher in a pixel section having the plurality of pixels than in a peripheral circuit section peripheral to the pixel section.

7. The radiation image-pickup device according to claim 1 , wherein
the active region has two ends configured to be electrically connected to a source electrode and a drain electrode, respectively, and
the LDD region is formed to be adjacent to one or both of the two ends of the active region.

8. The radiation image-pickup device according to claim 1 , wherein the semiconductor layer includes any of amorphous silicon, polycrystal silicon, and micro-crystal silicon.

9. The radiation image-pickup device according to claim 8 , wherein the semiconductor layer includes low temperature poly-silicon.

10. The radiation image-pickup device according to claim 1 , further comprising a wavelength conversion layer provided on a light incident side of the plurality of pixels,
wherein the plurality of pixels each include a photoelectric conversion element, and
the wavelength conversion layer is configured to convert the radiation to a wavelength in a sensitivity range of the photoelectric conversion element.

11. The radiation image-pickup device according to claim 1 , wherein the plurality of pixels each include a conversion layer configured to generate the signal charge by absorbing the radiation.

12. The radiation image-pickup device according to claim 1 , wherein the radiation includes X-rays.

13. A radiation image-pickup display system comprising:
a radiation image-pickup device; and
a display configured to perform image display based on an image pickup signal obtained by the radiation image-pickup device,
wherein the radiation image-pickup device includes
a plurality of pixels each configured to generate signal charge based on radiation, and
a field effect transistor used to read the signal charge from each of the plurality of pixels, and
the field effect transistor includes
a semiconductor layer including an active region and a lightly doped drain (LDD) region formed to be adjacent to the active region, and
a first and a second gate electrode disposed to face each other with the active layer interposed therebetween, and
both of the first and the second gate electrodes are provided only in a region not facing the LDD region, and the first and second gate electrodes each have a width that is equal to or less than a width of the active region.

14. The radiation image-pickup display system according to claim 13 , wherein
the field effect transistor further includes a first and a second gate insulating film,
the first gate electrode, the first gate insulating film, the semiconductor layer, the second gate insulating film, and the second gate electrode are provided in order from a substrate side, and
the first gate electrode has a width smaller than a width of the second gate electrode.

15. The radiation image-pickup display system according to claim 13 , wherein impurity concentration in the LDD layer region is higher in a pixel section having the plurality of pixels than in a peripheral circuit section peripheral to the pixel section.

Assignees

• Sony Corp
• Sony Semiconductor Solutions Corp

Inventors

• Yamada Yasuhiro

Classifications

• H01L27/14603

  Electricity · mapped topic

• H01L27/14663 Primary

  Electricity · mapped topic

• H01L27/14601

  Electricity · mapped topic

• H01L27/14659

  Electricity · mapped topic

• H10F39/1892

  Direct radiation image sensors · CPC title