Semiconductor device and manufacturing method thereof

• US 9,202,927 B2
• Filed: 08/11/2014
• Issued: 12/01/2015
• Est. Priority Date: 11/30/2010
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei
• Primary Examiner(s): Lee, Calvin
• Application Number:
  US14/456,313
• Publication Number:
  US 20140346507A1
• Time in Patent Office: 477 Days
• Field of Search: 438/104, 438/162, 438/479, 438/519, 257/43, 257/325, 257E21135-E21153
• US Class Current: 1/1
• CPC Class Codes: H01L 29/1054 with a variation of the composition, e.g. channel with strained layer for increasing the mobility
• CPC Class Codes: H01L 29/247 Amorphous materials
• CPC Class Codes: H01L 29/4908 for thin film semiconductor, e.g. gate of TFT
• 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

An object is to provide a transistor in which the state of an interface between an oxide semiconductor layer and an insulating film (gate insulating layer) in contact with the oxide semiconductor layer is favorable; and a method for manufacturing the transistor. In order to obtain the transistor, nitrogen is added to a region of the oxide semiconductor layer in the vicinity of the interface with the gate insulating layer. Specifically, a concentration gradient of nitrogen is formed in the oxide semiconductor layer, and a region containing much nitrogen is provided at the interface with the gate insulating layer. By the addition of nitrogen, a region with high crystallinity can be formed in the region of the oxide semiconductor layer in the vicinity of the interface with the gate insulating layer, so that a stable interface state can be obtained.

Claims

1. A semiconductor device comprising:

a substrate;

a gate electrode layer over the substrate;

a gate insulating layer in contact with the gate electrode layer;

an oxide semiconductor layer in contact with the gate insulating layer; and

an insulating layer in contact with the oxide semiconductor layer,

wherein the oxide semiconductor layer has a stepwise concentration gradient of oxygen, which becomes higher at a closer region to the insulating layer.

2. The semiconductor device according to claim 1, wherein the oxide semiconductor layer is non-single-crystalline.

3. The semiconductor device according to claim 1, further comprising a source electrode layer and a drain electrode layer overlapping the oxide semiconductor layer.

4. The semiconductor device according to claim 1, wherein the insulating layer is a protective insulating layer whose thickness is greater than or equal to 50 nm.

5. The semiconductor device according to claim 1, wherein the semiconductor device is incorporated in one selected from the group consisting of a portable information terminal, a mobile phone and a television set.

6. A semiconductor device comprising:

a substrate;

a gate electrode layer over the substrate;

a gate insulating layer in contact with the gate electrode layer;

an oxide semiconductor layer in contact with the gate insulating layer; and

an insulating layer in contact with the oxide semiconductor layer,

wherein the oxide semiconductor layer has a stepwise concentration gradient of oxygen, which becomes higher at a closer region to the insulating layer, and

wherein the stepwise concentration gradient of oxygen becomes highest at an interface with the insulating layer.

7. The semiconductor device according to claim 6, wherein the oxide semiconductor layer is non-single-crystalline.

8. The semiconductor device according to claim 6, further comprising a source electrode layer and a drain electrode layer overlapping the oxide semiconductor layer.

9. The semiconductor device according to claim 6, wherein the insulating layer is a protective insulating layer whose thickness is greater than or equal to 50 nm.

10. The semiconductor device according to claim 6, wherein the semiconductor device is incorporated in one selected from the group consisting of a portable information terminal, a mobile phone and a television set.

11. A semiconductor device comprising:

a substrate;

a gate electrode layer over the substrate;

a gate insulating layer in contact with the gate electrode layer;

an oxide semiconductor layer in contact with the gate insulating layer; and

an insulating layer in contact with the oxide semiconductor layer,

wherein the oxide semiconductor layer has a stepwise concentration gradient of oxygen, which becomes higher at a closer region to the insulating layer, and

wherein the oxide semiconductor layer has a stepwise concentration gradient of nitrogen, which becomes highest at an interface with the gate insulating layer.

12. The semiconductor device according to claim 11, wherein the oxide semiconductor layer is non-single-crystalline.

13. The semiconductor device according to claim 11, further comprising a source electrode layer and a drain electrode layer overlapping the oxide semiconductor layer.

14. The semiconductor device according to claim 11, wherein the insulating layer is a protective insulating layer whose thickness is greater than or equal to 50 nm.

15. The semiconductor device according to claim 11, wherein the semiconductor device is incorporated in one selected from the group consisting of a portable information terminal, a mobile phone and a television set.

16. A semiconductor device comprising:

a substrate;

a gate electrode layer over the substrate;

a gate insulating layer in contact with the gate electrode layer;

an oxide semiconductor layer in contact with the gate insulating layer; and

an insulating layer in contact with the oxide semiconductor layer,

wherein the oxide semiconductor layer has a stepwise concentration gradient of oxygen, which becomes higher at a closer region to the insulating layer,

wherein the oxide semiconductor layer has a stepwise concentration gradient of nitrogen, which becomes highest at an interface with the gate insulating layer, and

wherein the stepwise concentration gradient of oxygen becomes highest at an interface with the insulating layer.

17. The semiconductor device according to claim 16, wherein the oxide semiconductor layer is non-single-crystalline.

18. The semiconductor device according to claim 16, further comprising a source electrode layer and a drain electrode layer overlapping the oxide semiconductor layer.

19. The semiconductor device according to claim 16, wherein the insulating layer is a protective insulating layer whose thickness is greater than or equal to 50 nm.

20. The semiconductor device according to claim 16, wherein the semiconductor device is incorporated in one selected from the group consisting of a portable information terminal, a mobile phone and a television set.