Semiconductor device

• US 8,698,214 B2
• Filed: 10/18/2012
• Issued: 04/15/2014
• Est. Priority Date: 10/27/2011
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Honda, Tatsuya, Tsubuku, Masashi, Nonaka, Yusuke, Shimazu, Takashi
• Primary Examiner(s): Rizkallah, Kimberly
• Assistant Examiner(s): Karimy, Timor
• Application Number:
  US13/654,864
• Publication Number:
  US 20130105865A1
• Time in Patent Office: 544 Days
• Field of Search: 257/255, 257/E29.296
• US Class Current: 257/255
• 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
• CPC Class Codes: H01L 29/78696 characterised by the structure of the channel, e.g. multichannel, transverse or longitudinal shape, length or width, doping structure, or the overlap or alignment between the channel and the gate, the source or the drain, or the contacting structure of the channel H01L29/78612 takes precedence; transistors having a drain offset region or a lightly doped drain [LDD] H01L29/78621

Abstract

A semiconductor device includes a base insulating film including silicon, an oxide semiconductor film over the base insulating film, a gate insulating film over the oxide semiconductor film, a gate electrode which is in contact with the gate insulating film and overlaps with at least the oxide semiconductor film, and a source electrode and a drain electrode electrically connected to the oxide semiconductor film. The oxide semiconductor film includes a region in which a concentration of silicon distributed from the interface with the base insulating film toward an inside of the oxide semiconductor film is lower than or equal to 1.0 at. %. A crystal portion is included at least in the region.

Claims

1. A semiconductor device comprising:

an insulating film including silicon;

an oxide semiconductor layer over the insulating film;

a gate insulating film over the oxide semiconductor layer;

a gate electrode over the gate insulating film;

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

a drain electrode electrically connected to the oxide semiconductor layer,

wherein the oxide semiconductor layer comprises;

a first region in contact with the insulating film; and

a second region over the first region,

wherein a concentration of silicon distributed in the first region is lower than or equal to 1.0 at. %, and

wherein the first region includes a first crystal portion.

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

3. The semiconductor device according to claim 1, wherein the insulating film further includes oxygen.

4. The semiconductor device according to claim 1, wherein at least part of silicon in the insulating film is bonded to oxygen.

5. The semiconductor device according to claim 1, wherein the oxide semiconductor layer comprises a second crystal portion in the second region.

6. The semiconductor device according to claim 5, wherein a c-axis in at least one of the first crystal portion and the second crystal portion is aligned in a direction substantially parallel to a normal vector of a surface of the insulating film.

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

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

10²⁰ atoms/cm³.

9. A semiconductor device comprising:

a base insulating film including silicon;

an oxide semiconductor film over the base insulating film;

a gate insulating film over the oxide semiconductor film;

a gate electrode overlapping with the oxide semiconductor film; and

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

wherein the oxide semiconductor film comprises a first region in which a concentration of silicon distributed from an interface with the base insulating film toward an inside of the oxide semiconductor film is lower than or equal to 1.0 at. %, and

wherein at least the first region comprises a first crystal portion.

10. The semiconductor device according to claim 9, wherein the first region is formed to be in contact with the interface with the base insulating film and have a thickness less than or equal to 5 nm.

11. The semiconductor device according to claim 9, wherein the base insulating film further includes oxygen.

12. The semiconductor device according to claim 9, wherein at least part of silicon in the base insulating film is bonded to oxygen.

13. The semiconductor device according to claim 9, wherein the oxide semiconductor film comprises a second crystal portion in a second region.

14. The semiconductor device according to claim 13, wherein a c-axis in at least one of the first crystal portion and the second crystal portion is aligned in a direction substantially parallel to a normal vector of a surface of the base insulating film.

15. The semiconductor device according to claim 9, wherein a silicon concentration of the first region is lower than or equal to 0.1 at. %.

16. The semiconductor device according to claim 9, wherein a carbon concentration of the first region is lower than or equal to 1.0×

10²⁰ atoms/cm³.