Semiconductor device and manufacturing method thereof

• US 10,658,522 B2
• Filed: 08/02/2018
• Issued: 05/19/2020
• Est. Priority Date: 07/08/2011
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei, Shinohara, Satoshi
• Primary Examiner(s): Warren, Matthew E
• Application Number:
  US16/053,188
• Publication Number:
  US 20180366588A1
• Time in Patent Office: 656 Days
• Field of Search: 257 43, 257 59, 257 72
• CPC Class Codes: H01L 29/045 by their particular orientation of crystalline planes
• 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 29/786 Thin film transistors, i.e. transistors with a channel being at least partly a thin film transistors having only the source or the drain region on an insulator layer H01L29/0653; thin film FinFETs H01L29/785
• 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

Provided are a transistor which has electrical characteristics requisite for its purpose and uses an oxide semiconductor layer and a semiconductor device including the transistor. In the bottom-gate transistor in which at least a gate electrode layer, a gate insulating film, and the semiconductor layer are stacked in this order, an oxide semiconductor stacked layer including at least two oxide semiconductor layers whose energy gaps are different from each other is used as the semiconductor layer. Oxygen and/or a dopant may be added to the oxide semiconductor stacked layer.

Claims

1. A semiconductor device comprising:

an oxide semiconductor stacked layer comprising a first oxide semiconductor layer, a second oxide semiconductor layer over the first oxide semiconductor layer, and a third oxide semiconductor layer over the second oxide semiconductor layer;

a gate electrode layer; and

a gate insulating film between the gate electrode layer and the oxide semiconductor stacked layer,

wherein the gate electrode layer and the oxide semiconductor stacked layer overlap each other,

wherein the third oxide semiconductor layer is in direct contact with a side surface of the first oxide semiconductor layer and a side surface of the second oxide semiconductor layer, and

wherein each of the first oxide semiconductor layer, the second oxide semiconductor layer and the third oxide semiconductor layer comprise indium and zinc.

2. The semiconductor device according to claim 1,

wherein each of the first oxide semiconductor layer and the third oxide semiconductor layer further comprise gallium.

3. The semiconductor device according to claim 2,

wherein a proportion of gallium with respect to indium in the third oxide semiconductor layer is greater than a proportion of gallium with respect to indium in the second oxide semiconductor layer.

4. The semiconductor device according to claim 1,

wherein the second oxide semiconductor layer further comprises Sn.

5. The semiconductor device according to claim 1, further comprising a first insulating film on and in direct contact with the third oxide semiconductor layer,

wherein the first insulating film comprises aluminum and oxygen.

6. The semiconductor device according to claim 1,

wherein an energy gap of the second oxide semiconductor layer is smaller than an energy gap of the third oxide semiconductor layer, and

wherein an energy gap of the second oxide semiconductor layer is smaller than an energy gap of the first oxide semiconductor layer.

7. The semiconductor device according to claim 1,

wherein the second oxide semiconductor layer comprises a crystal including a c-axis alignment.

8. A semiconductor device comprising:

an oxide semiconductor stacked layer comprising a first oxide semiconductor layer, a second oxide semiconductor layer over the first oxide semiconductor layer, and a third oxide semiconductor layer over the second oxide semiconductor layer;

a gate electrode layer;

a gate insulating film between the gate electrode layer and the oxide semiconductor stacked layer; and

a first insulating film on and in direct contact with the third oxide semiconductor layer,

wherein the gate electrode layer and the oxide semiconductor stacked layer overlap each other,

wherein the third oxide semiconductor layer is in direct contact with a side surface of the first oxide semiconductor layer and a side surface of the second oxide semiconductor layer, and

wherein each of the first oxide semiconductor layer, the second oxide semiconductor layer and the third oxide semiconductor layer comprise indium and zinc.

9. The semiconductor device according to claim 8,

wherein each of the first oxide semiconductor layer and the third oxide semiconductor layer further comprise gallium.

10. The semiconductor device according to claim 9,

wherein a proportion of gallium with respect to indium in the third oxide semiconductor layer is greater than a proportion of gallium with respect to indium in the second oxide semiconductor layer.

11. The semiconductor device according to claim 8,

wherein the second oxide semiconductor layer further comprises Sn.

12. The semiconductor device according to claim 8,

wherein the first insulating film comprises aluminum and oxygen.

13. The semiconductor device according to claim 8,

wherein the first insulating film comprises silicon and oxygen.