Display device

• US 9,411,208 B2
• Filed: 06/16/2015
• Issued: 08/09/2016
• Est. Priority Date: 12/04/2009
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei
• Primary Examiner(s): Thai, Luan C
• Application Number:
  US14/740,599
• Publication Number:
  US 20150309347A1
• Time in Patent Office: 420 Days
• Field of Search: 257/43, 257/347
• US Class Current: 1/1
• CPC Class Codes: G02F 1/1337 Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers
• CPC Class Codes: G02F 1/1368 in which the switching element is a three-electrode device G02F1/136277 takes precedence
• CPC Class Codes: H01L 27/1225 with semiconductor materials not belonging to the group IV of the periodic table, e.g. InGaZnO
• CPC Class Codes: H01L 29/78606 with supplementary region or layer in the thin film or in the insulated bulk substrate supporting it for controlling or increasing the safety of the device H01L29/78642, H01L29/78645 take precedence
• CPC Class Codes: H01L 29/78648 arranged on opposing sides of the channel
• CPC Class Codes: H01L 29/7869 having a semiconductor body comprising an oxide semiconductor material, e.g. zinc oxide, copper aluminium oxide, cadmium stannate

Abstract

One object is to provide a transistor including an oxide semiconductor film which is used for the pixel portion of a display device and has high reliability. A display device has a first gate electrode; a first gate insulating film over the first gate electrode; an oxide semiconductor film over the first gate insulating film; a source electrode and a drain electrode over the oxide semiconductor film; a second gate insulating film over the source electrode, the drain electrode and the oxide semiconductor film; a second gate electrode over the second gate insulating film; an organic resin film having flatness over the second gate insulating film; a pixel electrode over the organic resin film having flatness, wherein the concentration of hydrogen atoms contained in the oxide semiconductor film and measured by secondary ion mass spectrometry is less than 1×10¹⁶ cm⁻³.

Claims

1. A semiconductor device comprising:

an intrinsic or substantially intrinsic oxide semiconductor film that includes a channel formation region of a transistor and comprises indium, zinc and a metal other than indium and zinc;

a source electrode and a drain electrode electrically connected with the oxide semiconductor film; and

a gate electrode overlapping with the channel formation region with an insulating film therebetween,

wherein carrier density of the oxide semiconductor film is less than 1×

10¹² cm<sup>−

3</sup>,

wherein an off-state current of the transistor is 1×

10<sup>−

18</sup> A/μ

m or less, and

wherein a relation of E_c−

E_f<

E_g/2 is satisfied where E_g is a band gap of the oxide semiconductor film, E_c is an energy at a bottom of a conduction band of the oxide semiconductor film, and E_f is a Fermi energy of the oxide semiconductor film.

2. The semiconductor device according to claim 1, wherein hydrogen concentration of the oxide semiconductor film is less than 1×

10¹⁶ cm<sup>−

3</sup>.

3. The semiconductor device according to claim 1, wherein the gate electrode is provided over the oxide semiconductor film.

4. The semiconductor device according to claim 1, further comprising:

a second gate electrode overlapping with the gate electrode with the channel formation region therebetween; and

a second insulating film between the second gate electrode and the oxide semiconductor film.

5. The semiconductor device according to claim 1, wherein the metal other than indium and zinc is gallium.

6. The semiconductor device according to claim 1, wherein the channel formation region comprises a crystalline region in which c-axis is oriented in a direction substantially perpendicular to a surface of the oxide semiconductor film.

7. An electronic device including the semiconductor device according to claim 1.

8. A semiconductor device comprising:

an intrinsic or substantially intrinsic oxide semiconductor film that includes a channel formation region of a transistor and comprises indium, zinc and a metal other than indium and zinc;

a source electrode and a drain electrode electrically connected with the oxide semiconductor film; and

a gate electrode overlapping with the channel formation region with an insulating film therebetween,

wherein the channel formation region comprises a crystalline region in which c-axis is oriented in a direction substantially perpendicular to a surface of the oxide semiconductor film,

wherein carrier density of the oxide semiconductor film is less than 1×

10¹² cm<sup>−

3</sup>, and

wherein a relation of E_c−

E_f<

E_g/2 is satisfied where E_g is a band gap of the oxide semiconductor film, E_c is an energy at a bottom of a conduction band of the oxide semiconductor film, and E_f is a Fermi energy of the oxide semiconductor film.

9. The semiconductor device according to claim 8, wherein hydrogen concentration of the oxide semiconductor film is less than 1×

10¹⁶ cm<sup>−

3</sup>.

10. The semiconductor device according to claim 8, wherein the gate electrode is provided over the oxide semiconductor film.

11. The semiconductor device according to claim 8, further comprising:

a second gate electrode overlapping with the gate electrode with the channel formation region therebetween; and

a second insulating film between the second gate electrode and the oxide semiconductor film.

12. The semiconductor device according to claim 8, wherein the metal other than indium and zinc is gallium.

13. An electronic device including the semiconductor device according to claim 8.

14. A semiconductor device comprising:

an intrinsic or substantially intrinsic oxide semiconductor film that includes a channel formation region of a transistor and comprises indium, zinc and a metal other than indium and zinc;

a source electrode and a drain electrode electrically connected with the oxide semiconductor film; and

a gate electrode overlapping with the channel formation region with an insulating film therebetween,

wherein the channel formation region comprises microcrystals,

wherein carrier density of the oxide semiconductor film is less than 1×

10¹² cm<sup>−

3</sup>, and

wherein a relation of E_c−

E_f<

E_g/2 is satisfied where E_g is a band gap of the oxide semiconductor film, E_c is an energy at a bottom of a conduction band of the oxide semiconductor film, and E_f is a Fermi energy of the oxide semiconductor film.

15. The semiconductor device according to claim 14, wherein hydrogen concentration of the oxide semiconductor film is less than 1×

10¹⁶ cm<sup>−

3</sup>.

16. The semiconductor device according to claim 14, wherein the gate electrode is provided over the oxide semiconductor film.

17. The semiconductor device according to claim 14, further comprising:

a second gate electrode overlapping with the gate electrode with the channel formation region therebetween; and

a second insulating film between the second gate electrode and the oxide semiconductor film.

18. The semiconductor device according to claim 14, wherein the metal other than indium and zinc is gallium.

19. The semiconductor device according to claim 14, wherein particle size of the microcrystals is 2 nm or more and 4 nm or less.

20. An electronic device including the semiconductor device according to claim 14.