Optical sensor element, optical sensor device and image display device using optical sensor element

• US 20080303022A1
• Filed: 02/25/2008
• Published: 12/11/2008
• Est. Priority Date: 06/11/2007
• Status: Abandoned Application

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Tai, Mitsuharu, Kinoshita, Masayoshi
• Application Number:
  US12/071,704
• Publication Number:
  US 20080303022A1
• Time in Patent Office: Days
• US Class Current: 257/53
• CPC Class Codes: H01L 27/14609 Pixel-elements with integrated switching, control, storage or amplification elements scanning details of imagers (circuitry of solid-state image sensors H04N25/00); circuitry of imagers H04N25/70
• CPC Class Codes: H01L 27/14676 X-ray, gamma-ray or corpuscular radiation imagers measuring X-, gamma- or corpuscular radiation G01T1/00
• CPC Class Codes: H01L 27/14692 Thin film technologies, e.g. amorphous, poly, micro- or nanocrystalline silicon
• CPC Class Codes: H01L 31/03762 including only elements of Group IV of the Periodic Table
• CPC Class Codes: H01L 31/115 Devices sensitive to very short wavelength, e.g. X-rays, gamma-rays or corpuscular radiation
• CPC Class Codes: Y02E 10/548 Amorphous silicon PV cells

Abstract

A highly sensitive optical sensor element, and a switch element such as a sensor driver circuit are formed on the same insulating substrate by using an LTPS planar process to provide a low cost area sensor (optical sensor device) incorporating the sensor driver circuit and the like or an image display device incorporating the optical sensor element. As an optical sensor element structure, one electrode of the sensor element is manufactured with the same film of the polycrystalline silicon film that is an active layer of the switch element constituting a circuit. A photoelectric conversion unit for performing photoelectric conversion is made of an amorphous silicon or a polycrystalline silicon film of an intrinsic layer. A structure in which the amorphous silicon of the photoelectric conversion unit and the insulating layer are sandwiched between two electrodes of the sensor element is adopted.

Claims

1. An optical sensor element formed over an insulating substrate, comprising:

a first electrode;

a second electrode;

a photoelectric conversion layer composed of a semiconductor layer formed between the first electrode and the second electrode; and

an insulating film formed between the first electrode and the second electrode,

wherein the first electrode is composed of a polycrystalline silicon film.

2. The optical sensor element according to claim 1,

wherein the photoelectric conversion layer composed of an amorphous silicon film is formed on an upper part of the first electrode, the insulating layer is formed on an upper part of the photoelectric conversion layer, and the second electrode is further formed on an upper part of the insulating layer.

3. The optical sensor element according to claim 2,

wherein the first electrode has a resistivity of 2.5×

10<sup>−

4</sup> Ω

·

m or smaller, and the photoelectric conversion layer has a resistivity of 1.0×

10<sup>−

3</sup> Ω

·

m or larger.

4. The optical sensor element according to claim 2,

wherein the second electrode has a transmittance of 75% or larger with respect to light of a visible near-infrared light region of 400 nm to 1000 nm.

5. The optical sensor element according to claim 2,

wherein a region adjacent to an interface with the first electrode in the amorphous silicon film forming the photoelectric conversion layer is an impurity implanted region with higher concentration of 1×

10²⁵/m³ or higher.

6. The optical sensor element according to claim 5,

wherein an impurity element with the same kind as that of an impurity element in the impurity implanted region with higher concentration is present in the first electrode, and is at least one selected from phosphorus, arsenic, boron, and aluminum.

7. The optical sensor element according to claim 2,

wherein the insulating layer is composed of a silicon oxide layer or a silicon nitride layer.

8. The optical sensor element according to claim 1,

wherein the insulating layer is formed on an upper part of the first electrode, the photoelectric conversion layer composed of an amorphous silicon film is formed on an upper part of the insulating layer, and the second electrode is further formed on an upper part of the photoelectric conversion layer.

9. The optical sensor element according to claim 8,

wherein the first electrode has a resistivity of 2.5×

10<sup>−

4</sup> Ω

·

m or smaller, and the photoelectric conversion layer has a resistivity of 1.0×

10<sup>−

3</sup> Ω

·

m or larger.

10. The optical sensor element according to claim 8,

wherein the second electrode has a transmittance of 75% or larger with respect to light of a visible near-infrared light region of 400 nm to 1000 nm.

11. The optical sensor element according to claim 8,

wherein in the amorphous silicon film forming the photoelectric conversion layer, a region adjacent to an interface with the second electrode is an impurity implanted region with higher concentration of 1×

10²⁵/m³ or higher.

12. The optical sensor element according to claim 11,

wherein an impurity element different in kind from an impurity element in the impurity implanted region with higher concentration is present in the first electrode, and is at least one selected from phosphor, arsenic, boron, and aluminum.

13. The optical sensor element according to claim 8,

wherein the insulating layer is composed of a silicon oxide layer or a silicon nitride layer.

14. The optical sensor element according to claim 1,

wherein the first electrode;

the photoelectric conversion layer adjacent to the first electrode and composed of the same film of the polycrystalline silicon film forming the first electrode;

the insulating layer formed on an upper part of the photoelectric conversion layer; and

the second electrode formed on an upper part of the insulating layer are formed.

15. The optical sensor element according to claim 14,

wherein the first electrode has a resistivity of 2.5×

10<sup>−

4</sup> Ω

·

m or smaller, and the photoelectric conversion layer has a resistivity of 1.0×

10<sup>−

3</sup> Ω

·

m or larger.

16. The optical sensor element according to claim 14,

wherein the second electrode has a transmittance of 75% or larger with respect to light of a visible near-infrared light region of 400 nm to 1000 nm.

17. The optical sensor element according to claim 14,

wherein the insulating layer is composed of a silicon oxide layer or a silicon nitride layer.

18. An optical sensor device comprising:

an optical sensor element formed on an insulating substrate, wherein the optical sensor element includes a first electrode composed of a polycrystalline silicon film, a second electrode, a photoelectric conversion layer composed of a semiconductor layer formed between the first electrode and the second electrode, and an insulating layer formed between the first electrode and the second electrode; and

at least one of a thin-film transistor device, a diode element, and a resistor element, each of which is composed of the same film of the polycrystalline silicon film forming the first electrode of the optical sensor element and which configure an active layer

wherein an amplification circuit and a sensor driver circuit constituted by at least one of the thin-film transistor device, the diode element, and the resistor element are manufactured on the same insulating substrate together with the optical sensor element.

19. The optical sensor device according to claim 18,

wherein sets of the optical sensor or the optical sensor element and amplification circuit thereof, and a switch group are arranged in a matrix shape, and the sensor driver circuit is disposed around the matrix.

20. An image display device comprising:

An optical sensor device including;

an optical sensor element formed over an insultating film, wherein the optical sensor element includes a first electrode composed of a polycrystalline silicon film, a second electrode, a photoelectric conversion layer composed of a semiconductor layer formed between the first electrode and the second electrode, and an insulating layer formed between the first electrode and the second electrode; and

at least one of a thin-film transistor device, a diode element, and a resistor element, each of which is composed of the same film of the polycrystalline silicon film forming the first electrode of the optical sensor element and which configure an active layer,

wherein an amplification circuit and a sensor driver circuit constituted by at least one of the thin-film transistor device, the diode element, and the resistor element are manufactured on the same insulating substrate together with the optical sensor element,

wherein a pixel switch, an amplification circuit and a pixel driver circuit, each of which is constituted by at least one of the thin-film transistor device, the diode element, and the resistor element, are manufactured on the same insulating substrate.

21. The image display device according to claim 20,

wherein sets of one pixel or a plurality of pixels, the optical sensor element or the optical sensor and the amplification circuit thereof, and a switch group are arranged in a matrix shape, and the pixel driver circuit and the sensor driver circuit are disposed around the matrix.

22. The image display device according to claim 20,

wherein the pixels are arranged in a matrix shape, and the optical sensor element, the pixel driver circuit, and the sensor driver circuit are arranged at a periphery of the matrix.