Semiconductor device

• US 8,860,023 B2
• Filed: 04/25/2013
• Issued: 10/14/2014
• Est. Priority Date: 05/01/2012
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Tsubuku, Masashi, Nonaka, Yusuke, Ishihara, Noritaka, Oota, Masashi, Kishida, Hideyuki
• Primary Examiner(s): Nguyen, Dao H
• Application Number:
  US13/870,399
• Publication Number:
  US 20130292675A1
• Time in Patent Office: 537 Days
• Field of Search: 257/43, 257/57, 257/288, 257/E21.409, 257/E21.473, 257/E29.255, 257/E29.296, 438/104, 438/301
• US Class Current: 257/43
• CPC Class Codes: H01L 21/02565 Oxide semiconducting materials not being Group 12/16 materials, e.g. ternary compounds
• 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 29/045 by their particular orientation of crystalline planes
• CPC Class Codes: H01L 29/4908 for thin film semiconductor, e.g. gate of TFT
• 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 29/786 Thin film transistors, i.e. transistors with a channel being at least partly a thin film transistors having only the source or the drain region on an insulator layer H01L29/0653; thin film FinFETs H01L29/785
• CPC Class Codes: H01L 29/78603 characterised by the insulating substrate or support H01L29/78657 takes precedence
• 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
• 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

Reducing hydrogen concentration in a channel formation region of an oxide semiconductor is important in stabilizing threshold voltage of a transistor including an oxide semiconductor and improving reliability. Hence, hydrogen is attracted from the oxide semiconductor and trapped in a region of an insulating film which overlaps with a source region and a drain region of the oxide semiconductor. Impurities such as argon, nitrogen, carbon, phosphorus, or boron are added to the region of the insulating film which overlaps with the source region and the drain region of the oxide semiconductor, thereby generating a defect. Hydrogen in the oxide semiconductor is attracted to the defect in the insulating film. The defect in the insulating film is stabilized by the presence of hydrogen.

Claims

1. A semiconductor device comprising:

an insulating film;

an oxide semiconductor film in contact with the insulating film and including a channel formation region provided between a source region and a drain region; and

a gate electrode overlapping with the oxide semiconductor film with a gate insulating film provided therebetween,

wherein, in at least one of the insulating film and the gate insulating film, a region overlapping with at least the source region and the drain region contains a higher proportion of hydrogen than a region overlapping with the channel formation region.

2. The semiconductor device according to claim 1,

wherein, in at least one of the insulating film and the gate insulating film, the region overlapping with at least the source region and the drain region contains a higher proportion of impurity than the region overlapping with the channel formation region.

3. The semiconductor device according to claim 2,

wherein the impurity is at least one kind selected from nitrogen (N), argon (Ar), carbon (C), phosphorus (P), and boron (B).

4. The semiconductor device according to claim 2,

wherein, in at least one of the insulating film and the gate insulating film, an impurity concentration in the region overlapping with at least the source region and the drain region is higher than or equal to 10¹⁴ atoms/cm³ and lower than or equal to 10²² atoms/cm³.

5. The semiconductor device according to claim 2,

wherein the source region and the drain region contain the impurity.

6. The semiconductor device according to claim 1,

wherein a hydrogen concentration in the channel formation region of the oxide semiconductor film is lower than or equal to 5×

10¹⁸ atoms/cm³.

7. The semiconductor device according to claim 1,

wherein crystallinity of the source region and the drain region of the oxide semiconductor film is lower than crystallinity of the channel formation region.

8. A semiconductor device comprising:

an insulating film;

an oxide semiconductor film in contact with the insulating film and including a channel formation region provided between a source region and a drain region;

a source electrode electrically connected to the source region, and a drain electrode electrically connected to the drain region;

a gate insulating film over the oxide semiconductor film, the source electrode and the drain electrode; and

a gate electrode overlapping with the oxide semiconductor film with the gate insulating film provided therebetween,

wherein, in at least one of the insulating film and the gate insulating film, a region overlapping with at least the source region and the drain region contains a higher proportion of hydrogen than a region overlapping with the channel formation region.

9. The semiconductor device according to claim 8,

wherein, in at least one of the insulating film and the gate insulating film, the region overlapping with at least the source region and the drain region contains a higher proportion of impurity than the region overlapping with the channel formation region.

10. The semiconductor device according to claim 9,

wherein the impurity is at least one kind selected from nitrogen (N), argon (Ar), carbon (C), phosphorus (P), and boron (B).

11. The semiconductor device according to claim 9,

wherein, in at least one of the insulating film and the gate insulating film, an impurity concentration in the region overlapping with at least the source region and the drain region is higher than or equal to 10¹⁴ atoms/cm³ and lower than or equal to 10²² atoms/cm³.

12. The semiconductor device according to claim 9,

wherein the source region and the drain region contain the impurity.

13. The semiconductor device according to claim 8,

wherein a hydrogen concentration in the channel formation region of the oxide semiconductor film is lower than or equal to 5×

10¹⁸ atoms/cm³.

14. The semiconductor device according to claim 8,

wherein crystallinity of the source region and the drain region of the oxide semiconductor film is lower than crystallinity of the channel formation region.

15. The semiconductor device according to claim 8,

wherein the source electrode and the drain electrode are provided between the insulating film and the oxide semiconductor film.

16. The semiconductor device according to claim 8,

wherein the source electrode and the drain electrode are provided between the oxide semiconductor film and the gate insulating film.

17. The semiconductor device according to claim 8, further comprising a conductive layer,

wherein the insulating film is provided between the conductive layer and the oxide semiconductor film.