THIN FILM TRANSISTOR AND DISPLAY DEVICE USING THE SAME

• US 20160284867A1
• Filed: 06/03/2016
• Published: 09/29/2016
• Est. Priority Date: 04/11/2013
• Status: Active Application

• Current Assignee: Japan Display Incorporated
• Original Assignee: Japan Display Incorporated
• Inventors: SUZUMURA, Isao, UEMURA, Norihiro, NODA, Takeshi, MIYAKE, Hidekazu, YAMAGUCHI, Yohei
• Granted Patent: US 10,283,644 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G02F 1/133345 Insulating layers G02F1/1335, G02F1/1337, G02F1/135, G02F1/136 take precedence
• CPC Class Codes: G02F 1/133357 Planarisation layers
• CPC Class Codes: G02F 1/133512 Light shielding layers, e.g. black matrix G02F1/136209 takes precedence
• CPC Class Codes: G02F 1/133514 Colour filters
• CPC Class Codes: G02F 1/1337 Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers
• CPC Class Codes: G02F 1/134309 characterised by their geometrical arrangement
• 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 27/1285 using control of the annealing or irradiation parameters, e.g. using different scanning direction or intensity for different transistors
• 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 29/78606 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 29/78618 characterised by the drain or the source properties, e.g. the doping structure, the composition, the sectional shape or the contact structure silicide contacts, electrodes in general H01L29/458
• CPC Class Codes: H01L 29/78633 with a light shield
• CPC Class Codes: H01L 29/7869 having a semiconductor body comprising an oxide semiconductor material, e.g. zinc oxide, copper aluminium oxide, cadmium stannate
• CPC Class Codes: H01L 29/78693 the semiconducting oxide being amorphous
• CPC Class Codes: H01L 29/78696 characterised by the structure of the channel, e.g. multichannel, transverse or longitudinal shape, length or width, doping structure, or the overlap or alignment between the channel and the gate, the source or the drain, or the contacting structure of the channel H01L29/78612 takes precedence; transistors having a drain offset region or a lightly doped drain [LDD] H01L29/78621

Abstract

In a bottom gate thin film transistor using a first oxide semiconductor layer as a channel layer, the first oxide semiconductor layer and second semiconductor layers include In and O. An (O/In) ratio of the second oxide semiconductor layers is equal to or larger than that of the first oxide semiconductor layer, and a film thickness thereof is thicker than that of the first oxide semiconductor layer.

Claims

1-15. -15. (canceled)

16. A thin film transistor using a first oxide semiconductor layer as a channel layer, the transistor comprising:

a substrate, a first oxide semiconductor layer which is formed on the substrate, a gate insulating film which is formed on the first oxide semiconductor layer, a gate electrode which is formed on the gate insulating film;

a first laminated film which includes a source electrode and a second oxide semiconductor layer formed to extend from the first oxide semiconductor layer to one upper end part of the gate insulating film in a source region; and

a second laminated film which includes a drain electrode and a second oxide semiconductor layer formed to extend from the first oxide semiconductor layer to other upper end part of the gate insulating film in a drain region, and wherein

the first and second oxide semiconductor layers include indium and oxygen, and a content ratio of oxygen to indium (O/In) of the second oxide semiconductor layer is equal to or larger than that of the first oxide semiconductor layer, and

a film thickness of the second oxide semiconductor layer is thicker than that of the first oxide semiconductor layer below the gate insulating film.

17. The thin film transistor according to claim 16, further comprising

overlapped regions of the gate electrode with the source electrode and the drain electrode, viewed vertically upward.

18. The thin film transistor according to claim 16,

wherein a region of the first oxide semiconductor layer which is covered with the gate insulating film has a thicker thickness than a region thereof which is not covered therewith.

19. The thin film transistor according to claim 16,

wherein the first laminated film has a third oxide semiconductor layer as a source contact layer between the second oxide semiconductor layer and the source electrode, and

the second laminated film has a third oxide semiconductor layer as a drain contact layer between the second oxide semiconductor layer and the drain electrode.

20. The thin film transistor according to claim 16, wherein a fourth oxide semiconductor layer is formed between the first oxide semiconductor layer and the second oxide semiconductor layer, in the source region and the drain region.

21. The thin film transistor according to claim 16,

wherein:

¹¹³In concentration in the second oxide semiconductor layer is 0.1 to 1 times that in the first oxide semiconductor layer, and

¹¹⁵In¹⁶ concentration in the second oxide semiconductor layer is 1 to 2 times that in the first oxide semiconductor layer.

22. The thin film transistor according to claim 16, wherein the first and second oxide semiconductors further include Zn or Ga.

23. The thin film transistor according to claim 16, wherein a film thickness of the channel layer is in a range from 5 nm to 50 nm.

24. The thin film transistor according to claim 16, wherein

a film thickness of the second oxide semiconductor layer in the source region and the drain region is in a range from 10 nm to 200 nm.

25. The thin film transistor according to claim 16, wherein oxygen concentration in the first and second oxide semiconductor layers is 1 to 1.5 times that in the gate insulating film.

26. A display device which includes a display unit and a driving circuit unit, the display unit comprising:

a substrate, a first oxide semiconductor layer which is formed on the substrate, a gate insulating film which is formed on the first oxide semiconductor layer, a gate electrode which is formed on the gate insulating film;

a first laminated layer which includes a source electrode and a second oxide semiconductor layer formed to extend from the first oxide semiconductor layer to one upper end part of the gate insulating film in a source region;

a second laminated layer which includes a drain electrode and a second oxide semiconductor layer formed to extend from the first oxide semiconductor layer to other upper end part of the gate insulating film in a drain region, and wherein

the first and second oxide semiconductor layers include indium and oxygen, and a content ratio of oxygen to indium (O/In) of the second oxide semiconductor layer is equal to or larger than that of the first oxide semiconductor layer, and

a film thickness of the second oxide semiconductor layer is thicker than that of the first oxide semiconductor layer below the gate insulating film.

27. The display device according to claim 26, further comprising

overlapped regions of the gate electrode with the source electrode and the drain electrode, viewed vertically upward.

28. The display device according to claim 26, wherein the display unit includes a liquid crystal layer, an alignment film, a color filter, and a black matrix layer.

29. The display device according to claim 26, wherein the display unit includes a charge transport layer and a light emission layer.

30. The display device according to claim 26, wherein the substrate has a light-shielding property.

31. The display device according to claim 26, wherein a lower film is disposed between the substrate and the first oxide semiconductor layer.