Thin film transistor and method of producing the same, display device, image sensor, X-ray sensor, and X-ray digital imaging device

Patent metadata

Field	Value
Publication number	US-9324880-B2
Application number	US-201414175482-A
Country	US
Kind code	B2
Filing date	Feb 7, 2014
Priority date	Aug 12, 2011
Publication date	Apr 26, 2016
Grant date	Apr 26, 2016

Abstract

A thin film transistor includes a gate electrode; a gate insulating film which contacts the gate electrode; an oxide semiconductor layer which includes a first region represented by In(a)Ga(b)Zn(c)O(d), wherein 0<a≦37/60, 3a/7−3/14≦b≦91a/74−17/40, b>0, 0<c≦3/5, a+b+c=1, and d>0, and a second region represented by In(p)Ga(q)Zn(r)O(s), wherein q/(p+q)>0.250, p>0, q>0, r>0, and s>0, and located farther than the first region with respect to the gate electrode and which is arranged facing the gate electrode with the gate insulating film provided therebetween. A source electrode and a drain electrode are arranged so as to be apart from each other and are capable of being electrically conducted through the oxide semiconductor layer.

First claim

The invention claimed is:

1. A thin film transistor comprising:
a gate electrode;
a gate insulating film which contacts the gate electrode;
an oxide semiconductor layer which includes a first region represented by In(a) Ga(b) Zn(c) O(d), wherein 0<a≦37/60, 3a/7−3/14≦b≦91a/74−17/40, b>0, 0<c≦3/5, a+b+c=1, and d>0, and wherein a, b, and c correspond to a cation composition and d corresponds to a molar ratio of oxygen to cation composition to form oxide formed from zinc oxide, gallium oxie and zinc oxide, and a second region represented by In(p) Ga(q) Zn(r) O(s), wherein q/(p+q)>0.250, p>0, q>0, r>0, and s>0, and located farther than the first region with respect to the gate electrode, and which is arranged facing the gate electrode with the gate insulating film provided therebetween; and,
a source electrode and a drain electrode which are arranged so as to be apart from each other and are capable of being electrically conducted through the oxide semiconductor layer.

2. The thin film transistor according to claim 1 , wherein the first region is in a composition range represented by b≦17a/23-28/115, b≦−9a+28/5, b≧3a/7-3/14, and c≦3/5.

3. The thin film transistor according to claim 1 , wherein the first region is in a composition range represented by b≦17a/23−28/115, b≦−9a+28/5, and b≧3a/37.

4. The thin film transistor according to claim 1 , wherein the second region is represented by q/(p+q)≦0.875.

5. The thin film transistor according to claim 1 , wherein a film thickness of the second region is more than 10 nm and less than 70 nm.

6. The thin film transistor according to claim 1 , wherein the oxide semiconductor layer is amorphous.

7. The thin film transistor according to claim 1 , wherein the thin film transistor is a bottom gate-top contact type or a top gate-bottom contact type.

8. A display device comprising the thin film transistor according to claim 1 .

9. An image sensor comprising the thin film transistor according to claim 1 .

10. An X-ray sensor comprising the thin film transistor according to claim 1 .

11. An X-ray digital imaging device comprising the X-ray sensor according to claim 10 .

12. The X-ray digital imaging device according to claim 11 capable of imaging a moving image.

13. The thin film transistor according to claim 1 , wherein an off-current of the thin film transistor is 1×10−9A or less.

14. The thin film transistor according to claim 1 , wherein a field-effect mobility of the thin film transistor is 30 cm 2 /Vs or more.

15. The thin film transistor according to claim 5 , wherein the film thickness of the second region is 30 nm or more and less than 70 nm.

Assignees

• Fujifilm Corp

Inventors

• Ono Masashi
• Takata Masahiro
• Tanaka Atsushi
• Suzuki Masayuki

Classifications

• H10P14/3434

  being oxide semiconductor materials (Group IIB-VIA semiconductor materials H10P14/3424) · CPC title

• H10P14/3426

  Oxides · CPC title

• H10P14/3234

  being oxide semiconducting materials (Group IIB-VIA semiconductors H10P14/3224) · CPC title

• H10P14/3226

  Oxides · CPC title

• H10P14/2922

  being non-crystalline insulating materials, e.g. glass or polymers · CPC title