Semiconductor device

• US 9,087,908 B2
• Filed: 04/17/2014
• Issued: 07/21/2015
• Est. Priority Date: 10/14/2011
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Tsubuku, Masashi, Nonaka, Yusuke, Shimazu, Takashi, Yamazaki, Shunpei, Honda, Tatsuya
• Primary Examiner(s): HOANG, QUOC DINH
• Application Number:
  US14/255,124
• Publication Number:
  US 20140225109A1
• Time in Patent Office: 460 Days
• Field of Search: 257/43, 257/59, 257/72, 257/291
• US Class Current: 1/1
• 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 29/42384 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 29/7869 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

The concentration of impurity elements included in an oxide semiconductor film in the vicinity of a gate insulating film is reduced. Further, crystallinity of the oxide semiconductor film in the vicinity of the gate insulating film is improved. A semiconductor device includes an oxide semiconductor film over a substrate, a source electrode and a drain electrode over the oxide semiconductor film, a gate insulating film which includes an oxide containing silicon and is formed over the oxide semiconductor film, and a gate electrode over the gate insulating film. The oxide semiconductor film includes a region in which the concentration of silicon is lower than or equal to 1.0 at. %, and at least the region includes a crystal portion.

Claims

1. A semiconductor device comprising:

an oxide semiconductor film over a substrate;

a source electrode and a drain electrode over the oxide semiconductor film;

a gate insulating film over the oxide semiconductor film, wherein the gate insulating film comprises an oxide containing silicon; and

a gate electrode over the gate insulating film,

wherein the oxide semiconductor film comprises;

a first region in which a concentration of silicon is lower than or equal to 1.0 at. %; and

a pair of second regions, each of the pair of second regions comprising a dopant,

wherein the first region is located at an interface between the oxide semiconductor film and the gate insulating film and in contact with the gate insulating film, and

wherein the first region comprises a crystal portion.

2. The semiconductor device according to claim 1, wherein an end portion of the oxide semiconductor film is tapered at an angle of 20°

to 50°

.

3. The semiconductor device according to claim 1, further comprising a base insulating film between the substrate and the oxide semiconductor film,

wherein in the crystal portion, a c-axis is aligned in a direction perpendicular to an interface between the base insulating film and the oxide semiconductor film.

4. The semiconductor device according to claim 1, wherein the concentration of silicon in the first region is lower than or equal to 0.1 at. %.

5. The semiconductor device according to claim 1, further comprising an interlayer insulating film over the gate insulating film and the gate electrode.

6. The semiconductor device according to claim 1, wherein a concentration of carbon in the first region is lower than or equal to 1.0×

10²⁰ atoms/cm³.

7. The semiconductor device according to claim 1, wherein the first region has a thickness less than or equal to 5 nm.

8. The semiconductor device according to claim 1, wherein the dopant comprises one or more elements selected from the group consisting of phosphorus, arsenic, antimony, boron, aluminum, nitrogen, argon, helium, neon, indium, fluorine, chlorine, titanium, and zinc.

9. The semiconductor device according to claim 1, wherein a concentration of dopant in each of the pair of second regions is higher than or equal to 5×

10¹⁸ atoms/cm³ and lower than or equal to 1×

10²² atoms/cm³.

10. The semiconductor device according to claim 1, wherein the pair of second regions and the gate electrode do not overlap each other.

11. A semiconductor device comprising:

an oxide semiconductor film over a substrate;

a source electrode and a drain electrode over the oxide semiconductor film;

a gate insulating film over the oxide semiconductor film, wherein the gate insulating film comprises an oxide containing silicon; and

a gate electrode over the gate insulating film,

wherein the oxide semiconductor film comprises;

a first region in which a concentration of silicon is lower than or equal to 1.0 at. %; and

a pair of second regions, each of the pair of second regions comprising a dopant,

wherein the first region is located at an interface between the oxide semiconductor film and the gate insulating film and in contact with the gate insulating film,

wherein the first region comprises a crystal portion, and

wherein the dopant comprises argon.

12. The semiconductor device according to claim 11, wherein an end portion of the oxide semiconductor film is tapered at an angle of 20°

to 50°

.

13. The semiconductor device according to claim 11, further comprising a base insulating film between the substrate and the oxide semiconductor film,

wherein in the crystal portion, a c-axis is aligned in a direction perpendicular to an interface between the base insulating film and the oxide semiconductor film.

14. The semiconductor device according to claim 11, wherein the concentration of silicon in the first region is lower than or equal to 0.1 at. %.

15. The semiconductor device according to claim 11, further comprising an interlayer insulating film over the gate insulating film and the gate electrode.

16. The semiconductor device according to claim 11, wherein a concentration of carbon in the first region is lower than or equal to 1.0×

10²⁰ atoms/cm³.

17. The semiconductor device according to claim 11, wherein the first region has a thickness less than or equal to 5 nm.

18. The semiconductor device according to claim 11, wherein the dopant comprises one or more elements selected from the group consisting of phosphorus, arsenic, antimony, boron, aluminum, nitrogen, argon, helium, neon, indium, fluorine, chlorine, titanium, and zinc.

19. The semiconductor device according to claim 11, wherein a concentration of dopant in each of the pair of second regions is higher than or equal to 5×

10¹⁸ atoms/cm³ and lower than or equal to 1×

10²² atoms/cm³.

20. The semiconductor device according to claim 11, wherein the pair of second regions and the gate electrode do not overlap each other.