Oxide semiconductor stacked film and semiconductor device

• US 8,890,159 B2
• Filed: 07/29/2013
• Issued: 11/18/2014
• Est. Priority Date: 08/03/2012
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei, Tsubuku, Masashi, Oota, Masashi, Ishihara, Noritaka, Inoue, Koki, Watanabe, Ryosuke
• Primary Examiner(s): Pham, Hoai V
• Application Number:
  US13/953,428
• Publication Number:
  US 20140034946A1
• Time in Patent Office: 477 Days
• Field of Search: 257/43, 257/59, 257/60, 257/72, 257/E29.095, 257/E29.117, 257/E29.273
• US Class Current: 257/59
• CPC Class Codes: H01L 22/14 for electrical parameters, e.g. resistance, deep-levels, CV, diffusions by electrical means
• CPC Class Codes: H01L 29/1054 with a variation of the composition, e.g. channel with strained layer for increasing the mobility
• CPC Class Codes: H01L 29/247 Amorphous materials
• CPC Class Codes: H01L 29/42356 Disposition, e.g. buried gate electrode H01L29/42324 and H01L29/4234 take precedence
• 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 29/78606 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 29/78693 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
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

An oxide semiconductor stacked film which does not easily cause a variation in electrical characteristics of a transistor and has high stability is provided. Further, a transistor which includes the oxide semiconductor stacked film in its channel formation region and has stable electrical characteristics is provided. An oxide semiconductor stacked film includes a first oxide semiconductor layer, a second oxide semiconductor layer, and a third oxide semiconductor layer which are sequentially stacked and each of which contains indium, gallium, and zinc. The content percentage of indium in the second oxide semiconductor layer is higher than that in the first oxide semiconductor layer and the third oxide semiconductor layer, and the absorption coefficient of the oxide semiconductor stacked film, which is measured by the CPM, is lower than or equal to 3×10⁻³/cm in an energy range of 1.5 eV to 2.3 eV.

Claims

1. An oxide semiconductor stacked film comprising a first oxide semiconductor layer, a second oxide semiconductor layer, and a third oxide semiconductor layer which are sequentially stacked and each of which includes indium, gallium, and zinc,

wherein the content percentage of indium in the second oxide semiconductor layer is higher than the content percentage of indium in the first oxide semiconductor layer and the content percentage of indium in the third oxide semiconductor layer, and

wherein an absorption coefficient of the oxide semiconductor stacked film, which is measured by a CPM, is lower than or equal to 3×

10<sup>−

3</sup>/cm in an energy range of 1.5 eV to 2.3 eV.

2. The oxide semiconductor stacked film according to claim 1, wherein the second oxide semiconductor layer includes a crystal part whose c-axis is substantially perpendicular to a surface of the oxide semiconductor stacked film.

3. The oxide semiconductor stacked film according to claim 1, wherein in the second oxide semiconductor layer, the content percentage of indium is higher than the content percentage of gallium.

4. The oxide semiconductor stacked film according to claim 1, wherein the second oxide semiconductor layer has a stacked-layer structure.

5. The oxide semiconductor stacked film according to claim 1, wherein the conductivity of the second oxide semiconductor layer is higher than the conductivity of the first oxide semiconductor layer and the conductivity of the third oxide semiconductor layer.

6. A semiconductor device comprising:

a first gate electrode layer;

a first insulating film over the first gate electrode layer;

an oxide semiconductor stacked film overlapping with the first gate electrode layer with the first insulating film interposed therebetween; and

a pair of electrode layers in contact with the oxide semiconductor stacked film,

wherein the oxide semiconductor stacked film includes a first oxide semiconductor layer, a second oxide semiconductor layer, and a third oxide semiconductor layer which are sequentially stacked and each of which contains indium, gallium, and zinc,

wherein the content percentage of indium in the second oxide semiconductor layer is higher than the content percentage of indium in the first oxide semiconductor layer and the content percentage of indium in the third oxide semiconductor layer, and

wherein an absorption coefficient of a channel formation region in the oxide semiconductor stacked film, which is measured by the CPM, is lower than or equal to 3×

10<sup>−

3</sup>/cm in an energy range of 1.5 eV to 2.3 eV.

7. The semiconductor device according to claim 6, wherein the second oxide semiconductor layer includes a crystal part whose c-axis is substantially perpendicular to a surface of the oxide semiconductor stacked film.

8. The semiconductor device according to claim 6, wherein in the second oxide semiconductor layer, the content percentage of indium is higher than the content percentage of gallium.

9. The semiconductor device according to claim 6, wherein the second oxide semiconductor layer has a stacked-layer structure.

10. The semiconductor device according to claim 6, wherein the conductivity of the second oxide semiconductor layer is higher than the conductivity of the first oxide semiconductor layer and the conductivity of the third oxide semiconductor layer.

11. The semiconductor device according to claim 6 further comprising an oxide insulating film over the pair of electrode layers and the oxide semiconductor stacked film.

12. The semiconductor device according to claim 6 further comprising:

a second insulating film over the pair of electrode layers and the oxide semiconductor stacked film, and

a second gate electrode layer overlapping with the oxide semiconductor stacked film with the second insulating film interposed therebetween.

13. A semiconductor device comprising:

an oxide semiconductor stacked film;

a pair of electrode layers in contact with the oxide semiconductor stacked film;

a gate insulating film over the oxide semiconductor stacked film; and

a gate electrode layer overlapping with the oxide semiconductor stacked film with the gate insulating film interposed therebetween,

wherein the oxide semiconductor stacked film includes a first oxide semiconductor layer, a second oxide semiconductor layer, and a third oxide semiconductor layer which are sequentially stacked and each of which contains indium, gallium, and zinc,

wherein the content percentage of indium in the second oxide semiconductor layer is higher than the content percentage of indium in the first oxide semiconductor layer and the content percentage of indium in the third oxide semiconductor layer, and

wherein an absorption coefficient of a channel formation region in the oxide semiconductor stacked film, which is measured by the CPM, is lower than or equal to 3×

10<sup>−

3</sup>/cm in an energy range of 1.5 eV to 2.3 eV.

14. The semiconductor device according to claim 13, wherein the second oxide semiconductor layer includes a crystal part whose c-axis is substantially perpendicular to a surface of the oxide semiconductor stacked film.

15. The semiconductor device according to claim 13, wherein in the second oxide semiconductor layer, the content percentage of indium is higher than the content percentage of gallium.

16. The semiconductor device according to claim 13, wherein the second oxide semiconductor layer has a stacked-layer structure.

17. The semiconductor device according to claim 13, wherein the conductivity of the second oxide semiconductor layer is higher than the conductivity of the first oxide semiconductor layer and the conductivity of the third oxide semiconductor layer.

18. The semiconductor device according to claim 13 further comprising an oxide insulating film over the pair of electrode layers and the oxide semiconductor stacked film.