SEMICONDUCTOR DEVICE AND METHOD FOR MANUFACTURING THE SAME

• US 20100117073A1
• Filed: 11/04/2009
• Published: 05/13/2010
• Est. Priority Date: 11/07/2008
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: KOEZUKA, Junichi, YAMAZAKI, Shunpei, IMOTO, Yuki, SAKATA, Junichiro, MARUYAMA, Tetsunori, ASANO, Yuji
• Granted Patent: US 8,338,827 B2
• Time in Patent Office: Days
• US Class Current: 257/43
• CPC Class Codes: C04B 2235/3284 Zinc oxides, zincates, cadmium oxides, cadmiates, mercury oxides, mercurates or oxide forming salts thereof
• CPC Class Codes: C04B 2235/3286 Gallium oxides, gallates, indium oxides, indates, thallium oxides, thallates or oxide forming salts thereof, e.g. zinc gallate
• CPC Class Codes: C04B 35/58 based on borides, nitrides, i.e. nitrides, oxynitrides, carbonitrides or oxycarbonitrides or silicides containing free binder metal C22C29/00
• 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 29/66742 Thin film unipolar transistors
• 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 29/78618 characterised by the drain or the source properties, e.g. the doping structure, the composition, the sectional shape or the contact structure silicide contacts, electrodes in general H01L29/458
• CPC Class Codes: H01L 29/7869 having a semiconductor body comprising an oxide semiconductor material, e.g. zinc oxide, copper aluminium oxide, cadmium stannate

Abstract

In a thin film transistor which uses an oxide semiconductor, buffer layers containing indium, gallium, zinc, oxygen, and nitrogen are provided between the oxide semiconductor layer and the source and drain electrode layers.

Claims

1. A thin film transistor comprising:

a gate electrode;

a gate insulating film which covers the gate electrode;

an oxide semiconductor layer which overlaps with the gate electrode with the gate insulating film interposed therebetween;

a first electrode and a second electrode over the oxide semiconductor layer, an end portion of the first electrode and an end portion of the second electrode overlapping with the gate electrode;

a first buffer layer which is in contact with the oxide semiconductor layer and the first electrode and interposed between the oxide semiconductor layer and the first electrode; and

a second buffer layer which is in contact with the oxide semiconductor layer and the second electrode and interposed between the oxide semiconductor layer and the second electrode,

wherein the first buffer layer and the second buffer layer include indium, gallium, zinc, oxygen, and nitrogen.

2. The thin film transistor according to claim 1, wherein an proportion (N/O) of nitrogen (N) to oxygen (O) included in the buffer layers is greater than or equal to 5 at. % and less than or equal to 80 at. %.

3. The thin film transistor according to claim 1, wherein the oxide semiconductor layer contains indium, gallium, and zinc.

4. A thin film transistor comprising:

a gate electrode;

a gate insulating film which covers the gate electrode;

a first electrode and a second electrode, an end portion of the first electrode and an end portion of the second electrode overlapping with the gate electrode with the gate insulating film interposed therebetween;

a first buffer layer over the first electrode;

a second buffer layer over the second electrode; and

an oxide semiconductor layer which overlaps with the end portion of the first electrode and the end portion of the second electrode,

wherein the oxide semiconductor layer is in contact with side surfaces of the first electrode and the second electrode and top surfaces and side surfaces of the first buffer layer and the second buffer layer; and

wherein the first buffer layer and the second buffer layer contain indium, gallium, zinc, oxygen, and nitrogen.

5. The thin film transistor according to claim 4, wherein a proportion (N/O) of nitrogen (N) to oxygen (O) included in the buffer layers is greater than or equal to 5 at. % and less than or equal to 80 at. %.

6. The thin film transistor according to claim 4, wherein the oxide semiconductor layer contains indium, gallium, and zinc.

7. A method for manufacturing a semiconductor device comprising:

forming a gate electrode over a substrate;

forming a gate insulating film over the gate electrode;

forming an oxide semiconductor layer over the gate insulating film, which contains indium, gallium, and zinc and overlaps with the gate electrode;

forming buffer layers over the oxide semiconductor layer; and

forming a first electrode and a second electrode over the buffer layers,

wherein the buffer layers are formed in such a manner that a target which includes, as its component, an oxide containing indium, gallium, and zinc is sputtered in an atmosphere including a nitrogen gas.

8. A method for manufacturing a semiconductor device comprising:

forming a gate electrode over a substrate;

forming a gate insulating film over the gate electrode;

forming a first electrode and a second electrode over the gate insulating film, whose end portions overlap with the gate electrode;

forming buffer layers over the first electrode and the second electrode; and

forming an oxide semiconductor layer containing indium, gallium, and zinc over the buffer layers,

wherein the buffer layers are formed in such a manner that a target which includes, as its component, an oxide containing indium, gallium, and zinc is sputtered in an atmosphere including a nitrogen gas.

9. A semiconductor device comprising a thin film transistor, the thin film transistor comprising:

a gate electrode;

a gate insulating film which covers the gate electrode;

an oxide semiconductor layer which overlaps with the gate electrode with the gate insulating film interposed therebetween;

a first electrode and a second electrode over the oxide semiconductor layer, an end portion of the first electrode and an end portion of the second electrode overlapping with the gate electrode;

a first buffer layer which is in contact with the oxide semiconductor layer and the first electrode and interposed between the oxide semiconductor layer and the first electrode; and

a second buffer layer which is in contact with the oxide semiconductor layer and the second electrode and interposed between the oxide semiconductor layer and the second electrode,

wherein the first buffer layer and the second buffer layer include indium, gallium, zinc, oxygen, and nitrogen.

10. The semiconductor device according to claim 9, wherein an proportion (N/O) of nitrogen (N) to oxygen (O) included in the buffer layers is greater than or equal to 5 at. % and less than or equal to 80 at. %.

11. The semiconductor device according to claim 9, wherein the oxide semiconductor layer contains indium, gallium, and zinc.

12. A semiconductor device comprising a thin film transistor, the thin film transistor comprising:

a gate electrode;

a gate insulating film which covers the gate electrode;

a first electrode and a second electrode, an end portion of the first electrode and an end portion of the second electrode overlapping with the gate electrode with the gate insulating film interposed therebetween;

a first buffer layer over the first electrode;

a second buffer layer over the second electrode; and

an oxide semiconductor layer which overlaps with the end portion of the first electrode and the end portion of the second electrode,

wherein the oxide semiconductor layer is in contact with side surfaces of the first electrode and the second electrode and top surfaces and side surfaces of the first buffer layer and the second buffer layer; and

wherein the first buffer layer and the second buffer layer contain indium, gallium, zinc, oxygen, and nitrogen.

13. The semiconductor device according to claim 12, wherein a proportion (N/O) of nitrogen (N) to oxygen (O) included in the buffer layers is greater than or equal to 5 at. % and less than or equal to 80 at. %.

14. The semiconductor device according to claim 12, wherein the oxide semiconductor layer contains indium, gallium, and zinc.