Oxide semiconductor, thin film transistor, and display device

• US 10,141,343 B2
• Filed: 04/06/2017
• Issued: 11/27/2018
• Est. Priority Date: 10/24/2008
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Ito, Shunichi, Sasaki, Toshinari, Hosoba, Miyuki, Sakata, Junichiro
• Primary Examiner(s): McCall Shepard, Sonya D
• Application Number:
  US15/480,560
• Publication Number:
  US 20170213855A1
• Time in Patent Office: 600 Days
• CPC Class Codes: G09G 3/20 for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
• 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 27/1248 with a particular composition or shape of the interlayer dielectric specially adapted to the circuit arrangement
• CPC Class Codes: H01L 27/1259 Multistep manufacturing methods
• CPC Class Codes: H01L 29/247 Amorphous materials
• CPC Class Codes: H01L 29/45 Ohmic electrodes
• 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 29/78618 characterised by the drain or the source properties, e.g. the doping structure, the composition, the sectional shape or the contact structure silicide contacts, electrodes in general H01L29/458
• 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

An object is to control composition and a defect of an oxide semiconductor, another object is to increase a field effect mobility of a thin film transistor and to obtain a sufficient on-off ratio with a reduced off current. A solution is to employ an oxide semiconductor whose composition is represented by InMO₃(ZnO)_m, where M is one or a plurality of elements selected from Ga, Fe, Ni, Mn, Co, and Al, and m is preferably a non-integer number of greater than 0 and less than 1. The concentration of Zn is lower than the concentrations of In and M. The oxide semiconductor has an amorphous structure. Oxide and nitride layers can be provided to prevent pollution and degradation of the oxide semiconductor.

Claims

1. A semiconductor device comprising:

a first conductive layer;

a second conductive layer;

a first insulating layer over the first conductive layer and the second conductive layer;

an oxide semiconductor layer over the first insulating layer;

a third conductive layer electrically connected to the oxide semiconductor layer;

a fourth conductive layer electrically connected to the oxide semiconductor layer; and

a fifth conductive layer over the first insulating layer,

wherein the first conductive layer includes a region functioning as a gate electrode of a transistor,

wherein the second conductive layer includes a region functioning as a first electrode of a capacitor,

wherein the oxide semiconductor layer includes a region functioning as a channel formation region of the transistor,

wherein the third conductive layer includes a region functioning as one of a source electrode and a drain electrode of the transistor,

wherein the fourth conductive layer includes a region functioning as the other one of the source electrode and the drain electrode of the transistor,

wherein the fourth conductive layer is electrically connected to the second conductive layer,

wherein the fifth conductive layer includes a region functioning as a second electrode of the capacitor,

wherein the oxide semiconductor layer includes In, Ga, and Zn, and

wherein a concentration of Zn is lower than a concentration of In or a concentration of Ga.

2. The semiconductor device according to claim 1,

wherein the oxide semiconductor layer includes a nanocrystal.

3. The semiconductor device according to claim 1, the semiconductor device further comprising a sixth conductive layer over the oxide semiconductor layer, the third conductive layer, the fourth conductive layer, and the fifth conductive layer,

wherein the sixth conductive layer includes a region functioning as a pixel electrode, and

wherein the sixth conductive layer includes a region overlapping with both of the region of the second conductive layer functioning as the first electrode of the capacitor and the region of the fifth conductive layer functioning as the second electrode of the capacitor.

4. The semiconductor device according to claim 1, the semiconductor device further comprising a second insulating layer over the oxide semiconductor layer, the third conductive layer, the fourth conductive layer, and the fifth conductive layer,

wherein the first insulating layer contains oxygen, and

wherein the second insulating layer contains oxygen.

5. The semiconductor device according to claim 1, the semiconductor device further comprising a second insulating layer over the oxide semiconductor layer, the third conductive layer, the fourth conductive layer, and the fifth conductive layer, and a third insulating layer over the second insulating layer,

wherein the first insulating layer contains oxygen,

wherein the second insulating layer contains oxygen, and

wherein the third insulating layer contains nitrogen.

6. A display device comprising:

a pixel portion including the semiconductor device according to claim 1; and

an input terminal,

wherein the input terminal includes an eighth conductive layer on a same layer as the first conductive layer and a transparent conductive layer, and

wherein the eighth conductive layer is electrically connected to the transparent conductive layer.

7. A display device comprising:

a pixel portion including the semiconductor device according to claim 1; and

an input terminal,

wherein the input terminal includes an eighth conductive layer over the first conductive layer and a transparent conductive layer, and

wherein the eighth conductive layer is electrically connected to the transparent conductive layer.

8. A semiconductor device comprising:

a first conductive layer;

a second conductive layer;

a first insulating layer over the first conductive layer and the second conductive layer;

a first oxide semiconductor layer over the first insulating layer;

a second oxide semiconductor layer over the first insulating layer;

a third conductive layer electrically connected to the first oxide semiconductor layer;

a fourth conductive layer electrically connected to the first oxide semiconductor layer;

a fifth conductive layer electrically connected to the second oxide semiconductor layer; and

a sixth conductive layer electrically connected to the second oxide semiconductor layer,

wherein the first conductive layer includes a region functioning as a gate electrode of a first transistor,

wherein the second conductive layer includes a region functioning as a gate electrode of a second transistor,

wherein the first oxide semiconductor layer includes a region functioning as a channel formation region of the first transistor,

wherein the second oxide semiconductor layer includes a region functioning as a channel formation region of the second transistor,

wherein the region functioning as the channel formation region of the second transistor in the second oxide semiconductor layer includes a first region extending to a channel width direction of the second transistor and a second region extending to the channel width direction of the second transistor,

wherein a longer side direction of the first region is substantially parallel to a longer side direction of the second region,

wherein the third conductive layer includes a region functioning as one of a source electrode and a drain electrode of the first transistor,

wherein the fourth conductive layer includes a region functioning as the other one of the source electrode and the drain electrode of the first transistor,

wherein the fourth conductive layer is electrically connected to the second conductive layer,

wherein the fifth conductive layer includes a region functioning as one of a source electrode and a drain electrode of the second transistor,

wherein the sixth conductive layer includes a region functioning as the other one of the source electrode and the drain electrode of the second transistor,

wherein each of the first oxide semiconductor layer and the second oxide semiconductor layer include In, Ga, and Zn, and

wherein a concentration of Zn is lower than a concentration of In or a concentration of Ga.

9. The semiconductor device according to claim 8, further comprising a second insulating layer over the first oxide semiconductor layer, the second oxide semiconductor layer, the third conductive layer, the fourth conductive layer, the fifth conductive layer, and the sixth conductive layer,

wherein the first insulating layer contains oxygen, and

wherein the second insulating layer contains oxygen.

10. The semiconductor device according to claim 8, further comprising a second insulating layer over the first oxide semiconductor layer, the second oxide semiconductor layer, the third conductive layer, the fourth conductive layer, the fifth conductive layer, and the sixth conductive layer, and a third insulating layer over the second insulating layer,

wherein the first insulating layer contains oxygen,

wherein the second insulating layer contains oxygen, and

wherein the third insulating layer contains nitrogen.

11. A display device comprising:

a pixel portion including the semiconductor device according to claim 8; and

an input terminal,

wherein the input terminal includes an eighth conductive layer on a same layer as the first conductive layer and a transparent conductive layer, and

wherein the eighth conductive layer is electrically connected to the transparent conductive layer.

12. A display device comprising:

a pixel portion including the semiconductor device according to claim 8; and

an input terminal,

wherein the input terminal includes an eighth conductive layer over the first conductive layer and a transparent conductive layer, and

wherein the eighth conductive layer is electrically connected to the transparent conductive layer.

13. A semiconductor device comprising:

a first conductive layer;

a second conductive layer;

a first insulating layer over the first conductive layer and the second conductive layer;

a first oxide semiconductor layer over the first insulating layer;

a second oxide semiconductor layer over the first insulating layer;

a third conductive layer electrically connected to the first oxide semiconductor layer;

a fourth conductive layer electrically connected to the first oxide semiconductor layer;

a fifth conductive layer electrically connected to the second oxide semiconductor layer;

a sixth conductive layer electrically connected to the second oxide semiconductor layer;

a second insulating layer over the first oxide semiconductor layer, the second oxide semiconductor layer, the third conductive layer, the fourth conductive layer, the fifth conductive layer, and the sixth conductive layer; and

a seventh conductive layer over the second insulating layer,

wherein the first conductive layer includes a region functioning as a gate electrode of a first transistor,

wherein the second conductive layer includes a region functioning as a gate electrode of a second transistor,

wherein the first oxide semiconductor layer includes a region functioning as a channel formation region of the first transistor,

wherein the second oxide semiconductor layer includes a region functioning as a channel formation region of the second transistor,

wherein the region functioning as the channel formation region of the second transistor of the second oxide semiconductor layer includes a first region extending to a channel width direction of the second transistor and a second region extending to the channel width direction of the second transistor,

wherein a longer side direction of the first region is substantially parallel to a longer side direction of the second region,

wherein the third conductive layer includes a region functioning as one of a source electrode and a drain electrode of the first transistor,

wherein the fourth conductive layer includes a region functioning as the other one of the source electrode and the drain electrode of the first transistor,

wherein the fourth conductive layer is electrically connected to the second conductive layer,

wherein the fifth conductive layer includes a region functioning as one of a source electrode and a drain electrode of the second transistor,

wherein the sixth conductive layer includes a region functioning as the other one of the source electrode and the drain electrode of the second transistor,

wherein the seventh conductive layer has a function as a pixel electrode,

wherein the seventh conductive layer is electrically connected to the sixth conductive layer,

wherein each of the first oxide semiconductor layer and the second oxide semiconductor layer include In, Ga, and Zn, and

wherein a concentration of Zn is lower than a concentration of In or a concentration of Ga.

14. The semiconductor device according to claim 13,

wherein the first insulating layer contains oxygen, and

wherein the second insulating layer contains oxygen.

15. The semiconductor device according to claim 13, further comprising a third insulating layer over the second insulating layer,

wherein the first insulating layer contains oxygen,

wherein the second insulating layer contains oxygen, and

wherein the third insulating layer contains nitrogen.

16. The semiconductor device according to claim 13,

wherein the seventh conductive layer does not overlap with the first conductive layer.

17. The semiconductor device according to claim 13,

wherein the seventh conductive layer does not overlap with the fifth conductive layer.

18. The semiconductor device according to claim 13,

wherein each of the first oxide semiconductor layer and the second oxide semiconductor layer includes a nanocrystal.

19. A display device comprising:

a pixel portion including the semiconductor device according to claim 13; and

an input terminal,

wherein the input terminal includes an eighth conductive layer on a same layer as the first conductive layer and a transparent conductive layer, and

wherein the eighth conductive layer is electrically connected to the transparent conductive layer.

20. A display device comprising:

a pixel portion including the semiconductor device according to claim 13; and

an input terminal,

wherein the input terminal includes an eighth conductive layer over the first conductive layer and a transparent conductive layer, and

wherein the eighth conductive layer is electrically connected to the transparent conductive layer.