SEMICONDUCTOR DEVICE AND METHOD FOR MANUFACTURING THE SAME

• US 20110068388A1
• Filed: 09/23/2010
• Published: 03/24/2011
• 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, SUZUKI, Kunihiko, TSUJI, Takahiro
• Granted Patent: US 9,029,191 B2
• Time in Patent Office: Days
• US Class Current: 257/329
• 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 21/02595 polycrystalline
• CPC Class Codes: H01L 21/02667 Crystallisation or recrystallisation of non-monocrystalline semiconductor materials, e.g. regrowth
• CPC Class Codes: H01L 22/14 for electrical parameters, e.g. resistance, deep-levels, CV, diffusions by electrical means
• 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 29/66742 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 29/78606 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

Abstract

An object is to provide a high reliability thin film transistor using an oxide semiconductor layer which has stable electric characteristics. In the thin film transistor in which an oxide semiconductor layer is used, the amount of change in threshold voltage of the thin film transistor before and after a BT test is made to be 2 V or less, preferably 1.5 V or less, more preferably 1 V or less, whereby the semiconductor device which has high reliability and stable electric characteristics can be manufactured. In particular, in a display device which is one embodiment of the semiconductor device, a malfunction such as display unevenness due to change in threshold voltage can be reduced.

Claims

1. A semiconductor device comprising:

a gate electrode layer over a substrate having an insulating surface;

a gate insulating layer over the gate electrode layer;

an oxide semiconductor layer over the gate insulating layer;

a source and drain electrode layers over the oxide semiconductor layer; and

a protective insulating layer in contact with part of the oxide semiconductor layer, over the gate insulating layer, the oxide semiconductor layer, and the source and drain electrode layers,

wherein an amount of change in threshold voltage according to a BT test on the semiconductor device is less than or equal to 2 V.

2. The semiconductor device according to claim 1, wherein a thickness of the oxide semiconductor layer is less than or equal to 50 nm.

3. The semiconductor device according to claim 1, wherein the amount of change in threshold voltage according to the BT test is less than or equal to 1.5 V.

4. The semiconductor device according to claim 1, wherein the amount of change in threshold voltage according to the BT test is less than or equal to 1.0 V.

5. A semiconductor device comprising:

a thin film transistor over a substrate having an insulating surface, the thin film transistor comprising;

a gate electrode layer;

an oxide semiconductor layer; and

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

wherein an amount of change in threshold voltage according to a BT test on the thin film transistor is less than or equal to 2 V.

6. The semiconductor device according to claim 5, wherein a thickness of the oxide semiconductor layer is less than or equal to 50 nm.

7. The semiconductor device according to claim 5, wherein the amount of change in threshold voltage according to the BT test is less than or equal to 1.5 V.

8. The semiconductor device according to claim 5, wherein the amount of change in threshold voltage according to the BT test is less than or equal to 1.0 V.

9. A method for manufacturing a semiconductor layer, comprising the steps of:

forming a gate electrode layer over a substrate having an insulating surface;

forming a gate insulating layer over the gate electrode layer;

forming an oxide semiconductor layer over the gate insulating layer;

performing a first heat treatment after the oxide semiconductor layer is formed;

forming a source and drain electrode layers over the oxide semiconductor layer after performing the first heat treatment;

forming a protective insulating layer in contact with part of the oxide semiconductor layer, over the gate insulating layer, the oxide semiconductor layer, and the source and drain electrode layers; and

performing a second heat treatment after the protective insulating layer is formed,

wherein an amount of change in threshold voltage according to a BT test is less than or equal to 2 V.

10. The method for manufacturing a semiconductor device, according to claim 9, wherein the amount of change in threshold voltage according to the BT test is less than or equal to 1.5 V.

11. The method for manufacturing a semiconductor device, according to claim 9, wherein the amount of change in threshold voltage according to the BT test is less than or equal to 1.0 V.

12. The method for manufacturing a semiconductor device, according to claim 9, wherein the first heat treatment is performed under a condition that the highest temperature in the treatment is higher than or equal to 350°

C. and lower than or equal to 750°

C.

13. The method for manufacturing a semiconductor device, according to claim 9, wherein the first heat treatment is performed in a nitrogen atmosphere or a rare gas atmosphere.

14. The method for manufacturing a semiconductor device, according to claim 9, wherein the second heat treatment is performed at a temperature higher than or equal to 100°

C. and lower than or equal to the maximum temperature in the first heat treatment.

15. The method for manufacturing a semiconductor device, according to claim 9, wherein the second heat treatment is performed in an air atmosphere, an oxygen atmosphere, a nitrogen atmosphere, or a rare gas atmosphere.

16. A method for manufacturing a semiconductor layer, comprising the steps of:

forming a gate electrode layer over a substrate having an insulating surface;

forming a gate insulating layer over the gate electrode layer;

forming an oxide semiconductor layer over the gate insulating layer; and

performing a heat treatment after the oxide semiconductor layer is formed;

wherein an amount of change in threshold voltage according to a BT test is less than or equal to 2 V.

17. The method for manufacturing a semiconductor device, according to claim 16, wherein the amount of change in threshold voltage according to the BT test is less than or equal to 1.5 V.

18. The method for manufacturing a semiconductor device, according to claim 16, wherein the amount of change in threshold voltage according to the BT test is less than or equal to 1.0 V.

19. The method for manufacturing a semiconductor device, according to claim 16, wherein the heat treatment is performed under a condition that the highest temperature in the treatment is higher than or equal to 350°

C. and lower than or equal to 750°

C.

20. The method for manufacturing a semiconductor device, according to claim 16, wherein the heat treatment is performed in a nitrogen atmosphere or a rare gas atmosphere.