Semiconductor device

• US 9,059,047 B2
• Filed: 02/19/2014
• Issued: 06/16/2015
• Est. Priority Date: 04/09/2010
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei
• Primary Examiner(s): Harrison, Monica D
• Application Number:
  US14/183,755
• Publication Number:
  US 20140167039A1
• Time in Patent Office: 482 Days
• Field of Search: 257/43, 257/E29.273
• US Class Current: 1/1
• CPC Class Codes: H01L 21/02565 Oxide semiconducting materials not being Group 12/16 materials, e.g. ternary compounds
• CPC Class Codes: H01L 21/02631 Physical deposition at reduced pressure, e.g. MBE, sputtering, evaporation
• CPC Class Codes: H01L 21/441 Deposition of conductive or insulating materials for electrodes
• CPC Class Codes: H01L 21/46 Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/428 manufacture of electrodes thereon H01L21/44
• 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 29/24 including, apart from doping materials or other impurities, only semiconductor materials not provided for in groups H01L29/16, H01L29/18, H01L29/20, H01L29/22 including organic materials H10K99/00
• CPC Class Codes: H01L 29/42384 for thin film field effect transistors, e.g. characterised by the thickness or the shape of the insulator or the dimensions, the shape or the lay-out of the conductor
• CPC Class Codes: H01L 29/66969 of devices having semiconductor bodies not comprising group 14 or group 13/15 materials comprising selenium or tellurium in uncombined form other than as impurities in semiconductor bodies of other materials, comprising cuprous oxide or cuprous iodide H01L21/02365
• 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

An object is to provide a semiconductor device using an oxide semiconductor having stable electric characteristics and high reliability. A transistor including the oxide semiconductor film in which a top surface portion of the oxide semiconductor film is provided with a metal oxide film containing a constituent similar to that of the oxide semiconductor film and functioning as a channel protective film is provided. In addition, the oxide semiconductor film used for an active layer of the transistor is an oxide semiconductor film highly purified to be electrically i-type (intrinsic) by heat treatment in which impurities such as hydrogen, moisture, a hydroxyl group, or a hydride are removed from the oxide semiconductor and oxygen which is a major constituent of the oxide semiconductor and is reduced concurrently with a step of removing impurities is supplied.

Claims

1. A display device comprising:

a pixel electrode; and

a transistor,

wherein the transistor comprises;

a gate electrode;

a gate insulating film over the gate electrode;

an oxide semiconductor film including a channel formation region;

a metal oxide film over the oxide semiconductor film; and

a source electrode and a drain electrode over and in contact with the oxide semiconductor film and the metal oxide film,

wherein the metal oxide film overlaps the channel formation region,

wherein the oxide semiconductor film contains one or more metal elements, and

wherein the metal oxide film contains at least one of the metal elements contained in the oxide semiconductor film, and

wherein the pixel electrode is electrically connected to one of the source electrode and the drain electrode.

2. The display device according to claim 1, wherein a side edge of the oxide semiconductor film is aligned with a side edge of the metal oxide film.

3. The display device according to claim 1, wherein a side surface of the oxide semiconductor film is in contact with the metal oxide film.

4. The display device according to claim 1, wherein the source electrode and the drain electrode are in contact with the oxide semiconductor film through openings of the metal oxide film.

5. The display device according to claim 1, wherein the metal oxide film has a larger band gap than the oxide semiconductor film.

6. The display device according to claim 1,

wherein the oxide semiconductor film contains indium, gallium and zinc, and

wherein the metal oxide film contains at least gallium.

7. The display device according to claim 1, further comprising:

an insulating film over the source electrode, the drain electrode and the metal oxide film; and

an electrode over the insulating film and overlapping with the gate electrode.

8. The display device according to claim 1, wherein the source electrode and the drain electrode comprise a metal selected from aluminum, chromium, cupper, tantrum, molybdenum and tungsten.

9. An electronic appliance comprising the display device according to claim 1.

10. A display device comprising:

a pixel electrode; and

a transistor,

wherein the transistor comprises;

an oxide semiconductor film including a channel formation region;

a metal oxide film over the oxide semiconductor film;

a source electrode and a drain electrode over and in contact with the oxide semiconductor film and the metal oxide film,

a gate insulating film over the oxide semiconductor film, the metal oxide film, the source electrode and the drain electrode; and

a gate electrode over the gate insulating film,

wherein the metal oxide film overlaps the channel formation region,

wherein the oxide semiconductor film contains one or more metal elements, and

wherein the metal oxide film contains at least one of the metal elements contained in the oxide semiconductor film, and

wherein the pixel electrode is electrically connected to one of the source electrode and the drain electrode.

11. The display device according to claim 10, wherein a side edge of the oxide semiconductor film is aligned with a side edge of the metal oxide film.

12. The display device according to claim 10, wherein a side surface of the oxide semiconductor film is in contact with the metal oxide film.

13. The display device according to claim 10, wherein the metal oxide film has a larger band gap than the oxide semiconductor film.

14. The display device according to claim 10,

wherein the oxide semiconductor film contains indium, gallium and zinc, and

wherein the metal oxide film contains at least gallium.

15. The display device according to claim 10, wherein the source electrode and the drain electrode comprise a metal selected from aluminum, chromium, cupper, tantrum, molybdenum and tungsten.

16. An electronic appliance comprising the display device according to claim 10.

17. A display device comprising:

a pixel electrode; and

a transistor;

wherein the transistor comprises;

a gate electrode;

a gate insulating film over the gate electrode;

a first metal oxide film over the gate insulating film;

an oxide semiconductor film including a channel formation region over the first metal oxide film;

a second metal oxide film over the oxide semiconductor film; and

a source electrode and a drain electrode over and in contact with the oxide semiconductor film and the second metal oxide film,

wherein the channel formation region is between the first metal oxide film and the second metal oxide film,

wherein the oxide semiconductor film contains one or more metal elements, and

wherein the first metal oxide film and the second metal oxide film contain at least one of the metal elements contained in the oxide semiconductor film, and

wherein the pixel electrode is electrically connected to one of the source electrode and the drain electrode.

18. The display device according to claim 17, wherein a side edge of the oxide semiconductor film is aligned with a side edge of the second metal oxide film.

19. The display device according to claim 17, wherein a side surface of the oxide semiconductor film is in contact with the second metal oxide film.

20. The display device according to claim 17, wherein each of the first metal oxide film and the second metal oxide film has a larger band gap than the oxide semiconductor film.

21. The display device according to claim 17,

wherein the oxide semiconductor film contains indium, gallium and zinc, and

wherein the first metal oxide film and the second metal oxide film contain at least gallium.

22. The display device according to claim 17, wherein the source electrode and the drain electrode comprises a metal selected from aluminum, chromium, cupper, tantrum, molybdenum and tungsten.

23. An electronic appliance comprising the display device according to claim 17.