Oxide semiconductor film and semiconductor device

• US 10,418,491 B2
• Filed: 12/19/2017
• Issued: 09/17/2019
• Est. Priority Date: 09/24/2009
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei, Sakakura, Masayuki, Watanabe, Ryosuke, Sakata, Junichiro, Akimoto, Kengo, Miyanaga, Akiharu, Hirohashi, Takuya, Kishida, Hideyuki
• Primary Examiner(s): Dang, Phuc T
• Application Number:
  US15/846,518
• Publication Number:
  US 20180122958A1
• Time in Patent Office: 637 Days
• CPC Class Codes: H01L 21/2636 for heating, e.g. electron beam heating
• 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 29/04 characterised by their crystalline structure, e.g. polycrystalline, cubic or particular orientation of crystalline planes characterised by physical imperfections H01L29/30
• CPC Class Codes: H01L 29/045 by their particular orientation of crystalline planes
• CPC Class Codes: H01L 29/12 characterised by the materials of which they are formed
• 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 29/41733 for thin film transistors with insulated gate
• 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 29/7869 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 highly reliable semiconductor device with good electrical characteristics and a display device including the semiconductor device as a switching element. In a transistor including an oxide semiconductor layer, a needle crystal group provided on at least one surface side of the oxide semiconductor layer grows in a c-axis direction perpendicular to the surface and includes an a-b plane parallel to the surface, and a portion except for the needle crystal group is an amorphous region or a region in which amorphousness and microcrystals are mixed. Accordingly, a highly reliable semiconductor device with good electrical characteristics can be formed.

Claims

1. A semiconductor device comprising:

a gate electrode layer;

a gate insulating layer over the gate electrode layer;

a first oxide semiconductor layer over the gate insulating layer;

a second oxide semiconductor layer over the first oxide semiconductor layer;

a source electrode and a drain electrode; and

an oxide insulating layer in contact with an upper surface of the second oxide semiconductor layer,

wherein each of the source electrode and the drain electrode are electrically connected to the first oxide semiconductor layer and the second oxide semiconductor layer,

wherein the first oxide semiconductor layer comprises first nanocrystals,

wherein the second oxide semiconductor layer comprises at least two crystals whose crystal axes are aligned, and

wherein a length of one of the two crystals in the second oxide semiconductor layer in a c-axis direction is greater than or equal to five times a length of the one of the two crystals in the second oxide semiconductor layer in a direction of an a-axis or a b-axis.

2. The semiconductor device according to claim 1,

wherein the length of each of the two crystals in the second oxide semiconductor layer in the direction of the a-axis or the b-axis is greater than or equal to 2 nm and less than or equal to 50 nm.

3. The semiconductor device according to claim 1,

wherein each of the first oxide semiconductor layer and the second oxide semiconductor layer comprises In, Ga and Zn.

4. The semiconductor device according to claim 1,

wherein the gate insulating layer is a laminate film of silicon nitride and silicon oxynitride.

5. The semiconductor device according to claim 1,

wherein the oxide insulating layer comprises silicon oxide or aluminum oxide.

6. A semiconductor device comprising:

a gate electrode layer;

a gate insulating layer over the gate electrode layer;

a first oxide semiconductor layer over the gate insulating layer;

a second oxide semiconductor layer over the first oxide semiconductor layer;

a source electrode and a drain electrode; and

an oxide insulating layer in contact with an upper surface of the second oxide semiconductor layer,

wherein each of the source electrode and the drain electrode are electrically connected to the first oxide semiconductor layer and the second oxide semiconductor layer,

wherein the first oxide semiconductor layer comprises first nanocrystals,

wherein the second oxide semiconductor layer comprises at least two crystals whose crystal axes are aligned,

wherein the two crystals in the second oxide semiconductor layer are c-axis-oriented in a direction substantially perpendicular to the upper surface of the second oxide semiconductor layer, and

wherein a length of one of the two crystals in the second oxide semiconductor layer in a c-axis direction is greater than or equal to five times a length of the one of the two crystals in the second oxide semiconductor layer in a direction of an a-axis or a b-axis.

7. The semiconductor device according to claim 6,

wherein the length of each of the two crystals in the second oxide semiconductor layer in the direction of the a-axis or the b-axis is greater than or equal to 2 nm and less than or equal to 50 nm.

8. The semiconductor device according to claim 6,

wherein each of the first oxide semiconductor layer and the second oxide semiconductor layer comprises In, Ga and Zn.

9. The semiconductor device according to claim 6,

wherein the gate insulating layer is a laminate film of silicon nitride and silicon oxynitride.

10. The semiconductor device according to claim 6,

wherein the oxide insulating layer comprises silicon oxide or aluminum oxide.