Semiconductor device

• US 9,576,795 B2
• Filed: 08/06/2015
• Issued: 02/21/2017
• Est. Priority Date: 06/30/2009
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Sasaki, Toshinari, Sakata, Junichiro, Ohara, Hiroki, Yamazaki, Shunpei
• Primary Examiner(s): BACHNER, ROBERT G
• Application Number:
  US14/819,664
• Publication Number:
  US 20150340477A1
• Time in Patent Office: 565 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: H01L 21/02565 Oxide semiconducting materials not being Group 12/16 materials, e.g. ternary compounds
• CPC Class Codes: H01L 21/02664 Aftertreatments planarisation in general H01L21/304
• CPC Class Codes: H01L 21/383 using diffusion into or out of a solid from or into a gaseous phase
• CPC Class Codes: H01L 21/46 Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/428 manufacture of electrodes thereon H01L21/44
• CPC Class Codes: H01L 21/477 Thermal treatment for modifying the properties of semiconductor bodies, e.g. annealing, sintering H01L21/38 - H01L21/449 and H01L21/461 - H01L21/475 take precedence
• 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 29/66969 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 29/78693 the semiconducting oxide being amorphous

Abstract

An object is to manufacture a highly reliable semiconductor device including a thin film transistor with stable electric characteristics. In a method for manufacturing a semiconductor device including a thin film transistor in which an oxide semiconductor film is used for a semiconductor layer including a channel formation region, heat treatment (for dehydration or dehydrogenation) is performed to improve the purity of the oxide semiconductor film and reduce impurities including moisture or the like. After that, slow cooling is performed under an oxygen atmosphere. Besides impurities including moisture or the like exiting in the oxide semiconductor film, heat treatment causes reduction of impurities including moisture or the like exiting in a gate insulating layer and those in interfaces between the oxide semiconductor film and films which are provided over and below the oxide semiconductor and in contact therewith.

Claims

1. A semiconductor device comprising:

a gate electrode;

a gate insulating layer over the gate electrode;

an oxide semiconductor layer over the gate insulating layer;

a source electrode and a drain electrode electrically connected to the oxide semiconductor layer, and

an oxide insulating layer over and in contact with a region of the oxide semiconductor layer,

wherein the gate electrode and the region of the oxide semiconductor layer overlap with each other with the gate insulating layer interposed therebetween, and

wherein carrier density of the region of the oxide semiconductor layer is lower than or equal to 1×

10¹⁴/cm³.

2. The semiconductor device according to claim 1,

wherein the region of the oxide semiconductor layer comprises an intrinsic oxide semiconductor.

3. The semiconductor device according to claim 1,

wherein the region of the oxide semiconductor layer is thinner than the other region of the oxide semiconductor layer.

4. The semiconductor device according to claim 1,

wherein hydrogen concentration of the oxide semiconductor layer is less than or equal to 1×

10²⁰ cm<sup>−

3</sup>.

5. The semiconductor device according to claim 1,

wherein the region of the oxide semiconductor layer comprises an oxide semiconductor which is oxygen-excess type.

6. The semiconductor device according to claim 1,

wherein the oxide insulating layer is a layer which blocks moisture, hydrogen ion and OH⁻

.

7. The semiconductor device according to claim 1,

wherein a peak of a desorption constituent, which is derived from moisture, is not shown in a spectrum of the oxide semiconductor layer which is shown with thermal desorption spectroscopy in a temperature range of greater than or equal to 200°

C.

8. A semiconductor device comprising:

an oxide semiconductor layer;

a source electrode and a drain electrode electrically connected to the oxide semiconductor layer;

an oxide insulating layer over and in contact with a region of the oxide semiconductor layer; and

an electrode over the oxide insulating layer,

wherein the electrode overlaps the region of the oxide semiconductor layer, and

wherein carrier density of the region of the oxide semiconductor layer is lower than or equal to 1×

10¹⁴/cm³.

9. The semiconductor device according to claim 8, further comprising:

a gate electrode; and

a gate insulating layer,

wherein the oxide semiconductor layer is over the gate insulating layer, and

wherein the gate electrode and the electrode overlap with each other with the region of the oxide semiconductor layer interposed therebetween.

10. The semiconductor device according to claim 8,

wherein the region of the oxide semiconductor layer comprises an intrinsic oxide semiconductor.

11. The semiconductor device according to claim 8,

wherein the region of the oxide semiconductor layer is thinner than the other region of the oxide semiconductor layer.

12. The semiconductor device according to claim 8,

wherein hydrogen concentration of the oxide semiconductor layer is less than or equal to 1×

10²⁰ cm<sup>−

3</sup>.

13. The semiconductor device according to claim 8,

wherein the region of the oxide semiconductor layer comprises an oxide semiconductor which is oxygen-excess type.

14. The semiconductor device according to claim 8,

wherein the oxide insulating layer is a layer which blocks moisture, hydrogen ion and OH⁻

.

15. The semiconductor device according to claim 8,

wherein a peak of a desorption constituent, which is derived from moisture, is not shown in a spectrum of the oxide semiconductor layer which is shown with thermal desorption spectroscopy in a temperature range of greater than or equal to 200°

C.

16. A semiconductor device comprising:

a gate electrode;

a gate insulating layer over the gate electrode;

a first oxide semiconductor layer over the gate insulating layer;

a second oxide semiconductor layer over the first oxide semiconductor layer;

an electrode electrically connected to the second oxide semiconductor layer; and

an oxide insulating layer over the first oxide semiconductor layer, the second oxide semiconductor layer and the electrode,

wherein the first oxide semiconductor layer comprises a channel formation region,

wherein the oxide insulating layer overlaps the channel formation region,

wherein thickness of the second oxide semiconductor layer is smaller than thickness of the first oxide semiconductor layer, and

wherein conductivity of the second oxide semiconductor layer is higher than conductivity of the first oxide semiconductor layer.

17. The semiconductor device according to claim 16,

wherein the oxide insulating layer is a silicon oxide layer.

18. The semiconductor device according to claim 16,

wherein the channel formation region comprises an intrinsic oxide semiconductor.

19. The semiconductor device according to claim 16,

wherein hydrogen concentration of the first oxide semiconductor layer is less than or equal to 1×

10²⁰ cm<sup>−

3</sup>.