Transistor

• US 8,598,635 B2
• Filed: 10/26/2010
• Issued: 12/03/2013
• Est. Priority Date: 10/30/2009
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei
• Primary Examiner(s): Mandala, Michelle
• Application Number:
  US12/912,374
• Publication Number:
  US 20110101356A1
• Time in Patent Office: 1,134 Days
• Field of Search: 257/213, 257/E51.005, 257/E29.151, 438/149, 438/FOR.201, 438/FOR.184
• US Class Current: 257/213
• 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 29/41733 for thin film transistors with insulated gate
• CPC Class Codes: H01L 29/42392 fully surrounding the channel, e.g. gate-all-around
• 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 29/78642 Vertical transistors
• 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 29/78696 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

It is an object to provide a thin film transistor with high speed operation, in which a large amount of current can flow when the thin film transistor is on and off-state current is extremely reduced when the thin film transistor is off. The thin film transistor is a vertical thin film transistor in which a channel formation region is formed using an oxide semiconductor film in which hydrogen is contained in an oxide semiconductor at a concentration of lower than or equal to 5×10¹⁹/cm³, preferably lower than or equal to 5×10¹⁸/cm³, more preferably lower than or equal to 5×10¹⁷/cm³, hydrogen or an OH group contained in the oxide semiconductor is/are removed, and carrier concentration is lower than or equal to 5×10¹⁴/cm³, preferably lower than or equal to 5×10¹²/cm³.

Claims

1. A transistor comprising:

a first electrode over a substrate, wherein end portions of the first electrode have a tapered shape;

an oxide semiconductor film on and in contact with the first electrode, wherein end portions of the oxide semiconductor film have a tapered shape;

a second electrode on and in contact with the oxide semiconductor film, wherein end portions of the second electrode have a tapered shape;

a gate insulating film on at least side surfaces of the oxide semiconductor film; and

a third electrode having a ring shape, the third electrode adjacent to the side surfaces of the oxide semiconductor film with the gate insulating film interposed therebetween.

2. The transistor according to claim 1,

wherein the first electrode functions as one of a source electrode and a drain electrode,

wherein the second electrode functions as the other of the source electrode and the drain electrode, and

wherein the third electrode functions as a gate electrode.

3. The transistor according to claim 1, wherein carrier concentration of the oxide semiconductor film is lower than or equal to 5×

10¹⁴/cm³.

4. The transistor according to claim 1, wherein hydrogen concentration of the oxide semiconductor film is lower than or equal to 5×

10¹⁹/cm³.

5. A display device comprising the transistor according to claim 1, wherein the display device is incorporated into one selected from the group consisting of a portable game machine, a digital camera, a television set, a computer, a mobile phone and a device including electronic paper.

6. A transistor comprising:

a first electrode over a substrate;

an oxide semiconductor film on and in contact with the first electrode;

a second electrode on and in contact with the oxide semiconductor film;

a gate insulating film on at least side surfaces of the oxide semiconductor film;

a third electrode having a ring shape, the third electrode adjacent to the side surfaces of the oxide semiconductor film with the gate insulating film interposed therebetween;

an interlayer insulating film over the third electrode,

an opening in the gate insulating film and the interlayer insulating film, and

a wiring electrically connected to the second electrode via the opening.

7. The transistor according to claim 6,

wherein the first electrode functions as one of a source electrode and a drain electrode,

wherein the second electrode functions as the other of the source electrode and the drain electrode, and

wherein the third electrode functions as a gate electrode.

8. The transistor according to claim 6, wherein carrier concentration of the oxide semiconductor film is lower than or equal to 5×

10¹⁴/cm³.

9. The transistor according to claim 6, wherein hydrogen concentration of the oxide semiconductor film is lower than or equal to 5×

10¹⁹/cm³.

10. The transistor according to claim 6, wherein the interlayer insulating film comprises a material selected from the group consisting of a silicon oxide film, a silicon oxynitride film, an aluminum oxide film, an aluminum oxynitride film, a silicon nitride film, a silicon nitride oxide film, an aluminum nitride film and an aluminum nitride oxide film.

11. An display device comprising the transistor according to claim 6, wherein the display device is incorporated into one selected from the group consisting of a portable game machine, a digital camera, a television set, a computer, a mobile phone and a device including electronic paper.

12. A transistor comprising:

a first electrode over a substrate, wherein end portions of the first electrode have a tapered shape;

an island-shaped oxide semiconductor film on and in contact with the first electrode, wherein the island-shaped oxide semiconductor film includes a crystal grain, and end portions of the island-shaped oxide semiconductor film have a tapered shape;

a second electrode on and in contact with the island-shaped oxide semiconductor film, wherein end portions of the second electrode have a tapered shape;

a gate insulating film on at least side surfaces of the island-shaped oxide semiconductor film; and

a third electrode covering the side surfaces of the island-shaped oxide semiconductor film with the gate insulating film interposed therebetween.

13. The transistor according to claim 12,

wherein the first electrode functions as one of a source electrode and a drain electrode,

wherein the second electrode functions as the other of the source electrode and the drain electrode, and

wherein the third electrode functions as a gate electrode.

14. The transistor according to claim 12, wherein carrier concentration of the island-shaped oxide semiconductor film is lower than or equal to 5×

10¹⁴/cm³.

15. The transistor according to claim 12, wherein hydrogen concentration of the island-shaped oxide semiconductor film is lower than or equal to 5×

10¹⁹/cm³.

16. A display device comprising the transistor according to claim 12, wherein the display device is incorporated into one selected from the group consisting of a portable game machine, a digital camera, a television set, a computer, a mobile phone and a device including electronic paper.