THIN FILM TRANSISTOR, MANUFACTURING METHOD OF SAME, AND DISPLAY DEVICE

• US 20140147948A1
• Filed: 02/03/2014
• Published: 05/29/2014
• Est. Priority Date: 03/02/2011
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Saito, Nobuyoshi, Hara, Yujiro, Yamaguchi, Hajime, Ueda, Tomomasa, Nakano, Shintaro, Miura, Kentaro
• Granted Patent: US 9,412,765 B2
• Time in Patent Office: Days
• US Class Current: 438/29
• 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 29/66969 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 29/7869 having a semiconductor body comprising an oxide semiconductor material, e.g. zinc oxide, copper aluminium oxide, cadmium stannate

Abstract

According to one embodiment, a thin film transistor includes: a substrate; a semiconductor layer; first and second insulating films; and gate, source and drain electrodes. The semiconductor layer is provided on the substrate. The semiconductor layer is made of an oxide having indium. The semiconductor layer has first and second regions and other region. The first insulating film covers a top face of the other region. The second insulating film covers at least a pair of side surfaces of the semiconductor layer. The second insulating film is formed under a condition different from that for the first insulating film. The gate electrode is provided on the first and second insulating films or below the semiconductor layer. The source and drain electrodes are provided on the first and second regions, respectively. The drain and source electrodes sandwich the pair of the side surfaces of the semiconductor layer.

Claims

1-15. -15. (canceled)

16. A manufacturing method for a thin film transistor, comprising:

forming a structure on a substrate, the structure including;

a semiconductor layer provided on the substrate, the semiconductor layer being made of an oxide including indium, the semiconductor layer having a top face, a first side face and a second side face, the first side face and the second side face being non-parallel to the top face, the second side face being apart from the first side face in a first direction, the top face having a first region, a second region, and an other region except the first region and the second region;

a gate electrode provided between the semiconductor layer and the substrate;

a gate insulating film provided between the gate electrode and the semiconductor layer;

a first insulating film covering the other region of the semiconductor layer; and

a second insulating film covering and physically contacting at least a part of the first side face and at least a part of the second side face of the semiconductor layer, the forming the structure including forming the first insulating film under a first condition of film forming with a first source gas including a first gas containing silicon and a second gas containing oxygen with a first value—

showing a ratio of a silicon quantity to an oxygen quantity and including forming the second insulating film under a second condition of film forming with a second source gas including a the first gas containing silicon and the second gas oxygen with a second value showing a ratio of a silicon quantity to an oxygen quantity, the second condition being different from the first condition of film forming;

forming a source electrode on the first region of the semiconductor layer; and

forming a drain electrode on the second region of the semiconductor layer, the drain electrode being apart from the source electrode in a second direction perpendicular to the first direction and parallel to the top face, the part of the first side face and the part of the second side face of the semiconductor layer being disposed between the source electrode and the drain electrode,

wherein the second condition of film forming includes at least one of;

the second value lower than the first value;

a flow rate of the second source gas lower than a flow rate of the first source gas; and

a film forming temperature lower than a film forming temperature in the forming the first insulating film,

the first insulating film has a part provided between the semiconductor layer and the source electrode and a part provided between the semiconductor layer and the drain electrode, and

the second insulating film has a part provided between the semiconductor layer and the source electrode and a part provided between the semiconductor layer and the drain electrode.

17. The method according to claim 16, wherein

a flow rate of the first gas in the second condition of film forming is smaller than a flow rate of the first gas in the second condition of film forming.

18. The method according to claim 16, wherein,

annealing at a highest temperature in forming process of the thin film transistor for 10 minutes or more is performed after the forming the first insulating film;

or

annealing at the highest temperature in forming process of the thin film transistor for 10 minutes or more is performed in the forming the first insulating film.

19. The method according to claim 16, wherein the forming the structure includes:

forming a film of the oxide including indium on the substrate, the film being served as the semiconductor layer,

annealing the film, and

processing the annealed film to form the semiconductor layer.

21. The method according to claim 16, wherein the first insulating film has a third side face and a fourth side face, in the forming the structure, the first side face and the second side face being formed in tapered shape and a the third side face and the fourth side face being formed in tapered shape.

22. The method according to claim 16, wherein the second insulating film is formed by a coating.

23. The method according to claim 16, wherein the first region and the second region are disposed inside the first insulating film and inside the second insulating film when projected to a plane parallel to the substrate.

20. (canceled)

24. A manufacturing method for a thin film transistor, comprising:

forming a structure on a substrate, the structure including;

a semiconductor layer provided on the substrate, the semiconductor layer being made of an oxide including indium, the semiconductor layer having a top face, a first side face and a second side face, the first side face and the second side face being non-parallel to the top face, the second side face being apart from the first side face in a first direction, the top face having a first region, a second region, and an other region except the first region and the second region;

a first insulating film covering the other region of the semiconductor layer;

a second insulating film covering and physically contacting at least a part of the first side face and at least a part of the second side face of the semiconductor layer;

a gate electrode provided on the first insulating film and the second insulating film;

the firming the structure including forming the first insulating film under a first condition of film forming with a first source gas including a first gas containing silicon and a second gas containing oxygen with a first value showing a ratio of a silicon quantity to an oxygen quantity and including forming the second insulating film under a second condition of film forming with a second source gas including a the first gas containing silicon and the second gas oxygen with a second value showing a ratio of a silicon quantity to an oxygen quantity, the second condition being different from the first condition of film forming;

forming a source electrode on the first region of the semiconductor layer; and

forming a drain electrode on the second region of the semiconductor layer, the drain electrode being apart from the source electrode in a second direction perpendicular to the first direction and parallel to the top face, the part of the first side face and the part of the second side face of the semiconductor layer being disposed between the source electrode and the drain electrode,

wherein the second condition of film forming includes at least one of;

the second value lower than the first value;

a flow rate of the second source gas lower than a flow rate of the first source gas; and

a film forming temperature lower than a film forming temperature in the forming the first insulating film,

the first insulating film has a part provided between the semiconductor layer and the gate electrode, and

the second insulating film has a part provided between the semiconductor layer and the gate electrode.

25. The method according to claim 24, wherein,

annealing at a highest temperature in forming process of the thin film transistor for 10 minutes or more is performed after the forming the first insulating film;

or

annealing at the highest temperature in forming process of the thin film transistor for 10 minutes or more is performed in the forming the first insulating film.

26. The method according to claim 25, wherein the forming the structure includes:

forming a film of the oxide including indium on the substrate, the film being served as the semiconductor layer;

annealing the film; and

processing the annealed film to form the semiconductor layer.

27. The method according to claim 24, wherein the first insulating film has a third side face and a fourth side face, in the forming the structure, the first side face and the second side face being formed in tapered shape and the third side face and the fourth side face being formed in tapered shape.

28. The method according to claim 24, wherein the second insulating film is formed by a coating.

29. The method according to claim 24, wherein the first region and the second region are disposed inside the first insulating film and inside the second insulating film when projected to a plane parallel to the substrate.

30. A manufacturing method for a display device, comprising:

forming a structure on a substrate, the structure including;

a semiconductor layer provided on the substrate, the semiconductor layer being made of an oxide including indium, the semiconductor layer having a top face, a first side face and a second side face, the first side face and the second side face being non-parallel to the top face, the second side face being apart from the first side face in a first direction, the top face having a first region, a second region, and an other region except the first region and the second region;

a gate electrode provided between the semiconductor layer and the substrate;

a gate insulating film provided between the gate electrode and the semiconductor layer;

a first insulating film covering the other region of the semiconductor layer; and

a second insulating film covering and physically contacting at least a part of the first side face and at least a part of the second side face of the semiconductor layer, the forming the structure including forming the first insulating film under a first condition of film forming with a first source gas including a first gas containing silicon and a second gas containing oxygen with a first value showing a ratio of a silicon quantity to an oxygen quantity and including forming the second insulating film under a second condition of film forming with a second source gas including a the first gas containing silicon and the second gas oxygen with a second value showing a ratio of a silicon quantity to an oxygen quantity, the second condition being different from the first condition of film forming;

forming a source electrode on the first region of the semiconductor layer;

forming a drain electrode on the second region of the semiconductor layer, the drain electrode being apart from the source electrode in a second direction perpendicular to the first direction and parallel to the top face, the part of the first side face and the part of the second side face of the semiconductor layer being disposed between the source electrode and the drain electrode; and

forming a display layer configured to cause at least one of optical emission and a change in an optical property including at least one of birefringence, optical activity, scattering property, diffraction property, and optical absorption, according to at least one of a voltage and a current supplied through the thin film transistor,

wherein the second condition of film forming includes at least one of;

the second value lower than the first value;

a flow rate of the second source gas lower than a flow rate of the first source gas; and

a film forming temperature lower than a film forming temperature in the forming the first insulating film,

the first insulating film has a part provided between the semiconductor layer and the source electrode and a part provided between the semiconductor layer and the drain electrode, and

the second insulating film has a part provided between the semiconductor layer and the source electrode and a part provided between the semiconductor layer and the drain electrode.

31. A manufacturing method for a display device, comprising:

forming a structure on a substrate, the structure including;

a semiconductor layer provided on the substrate, the semiconductor layer being made of an oxide including indium, the semiconductor layer having a top face, a first side face and a second side face, the first side face and the second side face being non-parallel to the top face, the second side face being apart from the first side face in a first direction, the top face having a first region, a second region, and an other region except the first region and the second region;

a first insulating film covering the other region of the semiconductor layer;

a second insulating film covering and physically contacting at least a part of the first side face and at least a part of the second side face of the semiconductor layer;

a gate electrode provided on the first insulating film and the second insulating film;

the firming the structure including forming the first insulating film under a first condition of film forming with a first source gas including a first gas containing silicon and a second gas containing oxygen with a first value showing a ratio of a silicon quantity to an oxygen quantity and including forming the second insulating film under a second condition of film forming with a second source gas including a the first gas containing silicon and the second gas oxygen with a second value showing a ratio of a silicon quantity to an oxygen quantity, the second condition being different from the first condition of film forming;

forming a source electrode on the first region of the semiconductor layer;

forming a drain electrode on the second region of the semiconductor layer, the drain electrode being apart from the source electrode in a second direction perpendicular to the first direction and parallel to the top face, the part of the first side face and the part of the second side face of the semiconductor layer being disposed between the source electrode and the drain electrode; and

forming a display layer configured to cause at least one of optical emission and a change in an optical property including at least one of birefringence, optical activity, scattering property, diffraction property, and optical absorption, according to at least one of a voltage and a current supplied through the thin film transistor,

wherein the second condition of film forming includes at least one of;

the second value lower than the first value;

a flow rate of the second source gas lower than a flow rate of the first source gas; and

a film forming temperature lower than a film forming temperature in the forming the first insulating film,

the first insulating film has a part provided between the semiconductor layer and the gate electrode, and

the second insulating film has a part provided between the semiconductor layer and the gate electrode.