Semiconductor device

• US 9,330,909 B2
• Filed: 10/15/2013
• Issued: 05/03/2016
• Est. Priority Date: 10/17/2012
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei, Suzawa, Hideomi, Sasagawa, Shinya, Tanaka, Tetsuhiro
• Primary Examiner(s): Abdelaziez, Yasser A
• Assistant Examiner(s): Lu, Farun
• Application Number:
  US14/054,082
• Publication Number:
  US 20140103338A1
• Time in Patent Office: 931 Days
• Field of Search: 257/9, 257/11, 257/12, 257/16, 257/27, 257/43, 257/57, 257/153, 257/282, 257/346, 257/382, 257/383, 257/384, 257/E29.151, 257/E21.621, 257/E21.635, 438/145, 438/147, 438/151, 438/153, 438/154, 349/139, 349/142
• US Class Current: 1/1
• CPC Class Codes: H01L 21/02554 Oxides
• CPC Class Codes: H01L 21/02565 Oxide semiconducting materials not being Group 12/16 materials, e.g. ternary compounds
• CPC Class Codes: H01L 21/02581 Transition metal or rare earth elements
• CPC Class Codes: H01L 21/02617 Deposition types
• CPC Class Codes: H01L 21/02631 Physical deposition at reduced pressure, e.g. MBE, sputtering, evaporation
• CPC Class Codes: H01L 21/32139 using masks
• 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 29/26 including, apart from doping materials or other impurities, elements provided for in two or more of the groups H01L29/16, H01L29/18, H01L29/20, H01L29/22, H01L29/24 , e.g. alloys
• CPC Class Codes: H01L 29/42384 for thin film field effect transistors, e.g. characterised by the thickness or the shape of the insulator or the dimensions, the shape or the lay-out of the conductor
• CPC Class Codes: H01L 29/4908 for thin film semiconductor, e.g. gate of TFT
• CPC Class Codes: H01L 29/78 with field effect produced by an insulated gate H01L29/7725, H01L29/775, H01L29/778 take precedence
• 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 29/7869 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

Abstract

A semiconductor device in which an increase in oxygen vacancies in an oxide semiconductor layer can be suppressed is provided. A semiconductor device with favorable electrical characteristics is provided. A highly reliable semiconductor device is provided. A semiconductor device includes an oxide semiconductor layer in a channel formation region, and by the use of an oxide insulating film below and in contact with the oxide semiconductor layer and a gate insulating film over and in contact with the oxide semiconductor layer, oxygen of the oxide insulating film or the gate insulating film is supplied to the oxide semiconductor layer. Further, a conductive nitride is used for a metal film of a source electrode layer and a drain electrode layer, whereby diffusion of oxygen to the metal film is suppressed.

Claims

1. A semiconductor device comprising:

an oxide insulating film;

an oxide semiconductor layer over the oxide insulating film;

a first source electrode layer and a first drain electrode layer on and in contact with the oxide semiconductor layer;

a second source electrode layer and a second drain electrode layer covering the first source electrode layer and the first drain electrode layer, respectively, and being in direct contact with the oxide semiconductor layer;

a gate insulating film over the oxide insulating film, the oxide semiconductor layer, the second source electrode layer, and the second drain electrode layer;

a gate electrode layer over the gate insulating film and overlapping with the oxide semiconductor layer; and

a protective insulating film over the gate insulating film and the gate electrode layer,

wherein the gate insulating film is partly in contact with the oxide insulating film in a region exterior to the second source electrode layer and the second drain electrode layer.

2. The semiconductor device according to claim 1, wherein the first source electrode layer and the first drain electrode layer comprise at least a material selected from Al, Cr, Cu, Ta, Ti, Mo, and W.

3. The semiconductor device according to claim 1, wherein end portions of the first source electrode layer and the first drain electrode layer have a step.

4. The semiconductor device according to claim 1, wherein the second source electrode layer and the second drain electrode layer comprise at least a material selected from tantalum nitride, titanium nitride, and ruthenium.

5. The semiconductor device according to claim 1, wherein the protective insulating film comprises silicon nitride.

6. The semiconductor device according to claim 1, wherein the oxide semiconductor layer contains a crystal, and wherein a c-axis of the crystal is parallel to a normal vector of a surface of the oxide semiconductor layer.

7. The semiconductor device according to claim 1, wherein the second source electrode layer extends beyond side edges of the first source electrode layer, and the second drain electrode layer extends beyond side edges of the first drain electrode layer.

8. The semiconductor device according to claim 1, wherein the second source electrode layer is in contact with the first source electrode layer, and the second drain electrode layer is in contact with the first drain electrode layer.

9. An electronic device comprising the semiconductor device according to claim 1.

10. The semiconductor device according to claim 1, wherein the oxide insulating film is in direct contact with the oxide semiconductor layer.

11. A semiconductor device comprising:

an oxide insulating film;

an oxide semiconductor layer over the oxide insulating film;

a first source electrode layer and a first drain electrode layer on and in contact with the oxide semiconductor layer;

a second source electrode layer and a second drain electrode layer in contact with the first source electrode layer and the first drain electrode layer, respectively, and in direct contact with the oxide semiconductor layer;

a gate insulating film over the oxide insulating film, the oxide semiconductor layer, the first source electrode layer, the first drain electrode layer, the second source electrode layer, and the second drain electrode layer;

a gate electrode layer over the gate insulating film and overlapping with the oxide semiconductor layer; and

a protective insulating film over the gate insulating film and the gate electrode layer,

wherein the gate insulating film is partly in contact with the oxide insulating film in a region exterior to the first source electrode layer and the first drain electrode layer.

12. The semiconductor device according to claim 11, wherein the first source electrode layer and the first drain electrode layer comprise at least a material selected from Al, Cr, Cu, Ta, Ti, Mo, and W.

13. The semiconductor device according to claim 11, wherein end portions of the first source electrode layer and the first drain electrode layer have a step.

14. The semiconductor device according to claim 11, wherein the second source electrode layer and the second drain electrode layer comprise at least a material selected from tantalum nitride, titanium nitride, and ruthenium.

15. The semiconductor device according to claim 11, wherein the protective insulating film comprises silicon nitride.

16. The semiconductor device according to claim 11,

wherein the oxide semiconductor layer contains a crystal, and

wherein a c-axis of the crystal is parallel to a normal vector of a surface of the oxide semiconductor layer.

17. An electronic device comprising the semiconductor device according to claim 11.

18. A semiconductor device comprising:

an oxide insulating film;

an oxide semiconductor layer over the oxide insulating film;

a first source electrode layer and a first drain electrode layer on and in contact with the oxide semiconductor layer;

a second source electrode layer and a second drain electrode layer covering the first source electrode layer and the first drain electrode layer, respectively, and being in direct contact with the oxide semiconductor layer;

a gate insulating film over the oxide insulating film, the oxide semiconductor layer, the second source electrode layer, and the second drain electrode layer;

a gate electrode layer over the gate insulating film and overlapping with the oxide semiconductor layer; and

a protective insulating film over the gate insulating film and the gate electrode layer,

wherein the gate insulating film is partly in contact with the oxide insulating film in a region exterior to the second source electrode layer and the second drain electrode layer, and

wherein the second source electrode layer and the second drain electrode layer are in contact with the oxide insulating film.