Transistors in display device

• US 9,640,670 B2
• Filed: 06/02/2016
• Issued: 05/02/2017
• Est. Priority Date: 09/04/2009
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei, Sasaki, Toshinari, Sakata, Junichiro, Tsubuku, Masashi
• Primary Examiner(s): Pham, Thanh V
• Application Number:
  US15/171,292
• Publication Number:
  US 20160284865A1
• Time in Patent Office: 334 Days
• CPC Class Codes: H01L 27/1214 comprising a plurality of TFTs formed on a non-semiconducting substrate, e.g. driving circuits for AMLCDs
• 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 27/1255 integrated with passive devices, e.g. auxiliary capacitors
• CPC Class Codes: H01L 29/24 including, apart from doping materials or other impurities, only semiconductor materials not provided for in groups H01L29/16, H01L29/18, H01L29/20, H01L29/22 including organic materials H10K99/00
• CPC Class Codes: H01L 29/42356 Disposition, e.g. buried gate electrode H01L29/42324 and H01L29/4234 take precedence
• CPC Class Codes: H01L 29/45 Ohmic electrodes
• CPC Class Codes: H01L 29/458 for thin film silicon, e.g. source or drain electrode
• CPC Class Codes: H01L 29/4908 for thin film semiconductor, e.g. gate of TFT
• 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 29/78618 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: H10K 59/1213 the pixel elements being TFTs
• CPC Class Codes: H10K 59/1216 the pixel elements being capacitors
• CPC Class Codes: H10K 59/123 Connection of the pixel electrodes to the thin film transistors [TFT]

Abstract

It is an object to manufacture a highly reliable display device using a thin film transistor having favorable electric characteristics and high reliability as a switching element. In a bottom gate thin film transistor including an amorphous oxide semiconductor, an oxide conductive layer having a crystal region is formed between an oxide semiconductor layer which has been dehydrated or dehydrogenated by heat treatment and each of a source electrode layer and a drain electrode layer which are formed using a metal material. Accordingly, contact resistance between the oxide semiconductor layer and each of the source electrode layer and the drain electrode layer can be reduced; thus, a thin film transistor having favorable electric characteristics and a highly reliable display device using the thin film transistor can be provided.

Claims

1. A display device comprising:

a first transistor comprising;

a first gate electrode;

a first insulating layer over the first gate electrode;

a first oxide semiconductor layer over the first insulating layer;

a second insulating layer over the first oxide semiconductor layer; and

a first source electrode and a first drain electrode over the second insulating layer;

a second transistor comprising;

a second gate electrode, wherein the second gate electrode and the first gate electrode of the first transistor are provided on a same surface;

the first insulating layer over the second gate electrode;

a second oxide semiconductor layer over the first insulating layer;

the second insulating layer over the second oxide semiconductor layer; and

a second source electrode and a second drain electrode over the second insulating layer;

a third insulating layer over the first source electrode, the first drain electrode, the second source electrode, and the second drain electrode;

a first electrode over the third insulating layer and electrically connected to the first source electrode or the first drain electrode;

an electroluminescent layer on and in contact with the first electrode; and

a conductive layer over the third insulating layer and comprising a region overlapping the second gate electrode,

wherein the second insulating layer comprises;

a first region covering a periphery of the first oxide semiconductor layer;

a second region in contact with an upper surface of the first oxide semiconductor layer;

a third region covering a periphery of the second oxide semiconductor layer; and

a fourth region in contact with an upper surface of the second oxide semiconductor layer,

wherein the first source electrode or the first drain electrode is electrically connected to the first oxide semiconductor layer between the first region and the second region of the second insulating layer, and

wherein the second source electrode or the second drain electrode is electrically connected to the second oxide semiconductor layer between the third region and the fourth region of the second insulating layer.

2. The display device according to claim 1, wherein the first oxide semiconductor layer and the second oxide semiconductor layer comprises indium.

3. The display device according to claim 1, wherein the first oxide semiconductor layer and the second oxide semiconductor layer comprises indium, gallium, and zinc.

4. The display device according to claim 1,

wherein the first transistor is provided in a pixel portion, and

wherein the second transistor is provided in a driver circuit portion.

5. The display device according to claim 1, wherein the first oxide semiconductor layer and the second oxide semiconductor layer comprises an amorphous oxide semiconductor.

6. The display device according to claim 1, comprising an oxide conductive layer between the first oxide semiconductor layer and each of the first source electrode and the first drain electrode.

7. The display device according to claim 1, comprising an oxide conductive layer between the second oxide semiconductor layer and each of the second source electrode and the second drain electrode.

8. The display device according to claim 1, comprising a protective insulating layer over the third insulating layer.

9. The display device according to claim 8, wherein the protective insulating layer comprises nitrogen.

10. A display device comprising:

a first transistor comprising;

a first gate electrode;

a first insulating layer over the first gate electrode;

a first oxide semiconductor layer over the first insulating layer;

a second insulating layer over the first oxide semiconductor layer; and

a first source electrode and a first drain electrode over the second insulating layer;

a second transistor comprising;

a second gate electrode, wherein the second gate electrode and the first gate electrode of the first transistor are provided on a same surface;

the first insulating layer over the second gate electrode;

a second oxide semiconductor layer over the first insulating layer;

the second insulating layer over the second oxide semiconductor layer; and

a second source electrode and a second drain electrode over the second insulating layer;

a capacitor comprising;

a first conductive film;

a second conductive film; and

the first insulating layer between the first conductive film and the second conductive film, wherein the first conductive film and the first gate electrode of the first transistor are provided on the same surface;

a third insulating layer over the first source electrode, the first drain electrode, the second source electrode, the second drain electrode, and the second conductive film;

a first electrode over the third insulating layer and electrically connected to the first source electrode or the first drain electrode;

an electroluminescent layer on and in contact with the first electrode; and

a conductive layer over the third insulating layer and comprising a region overlapping the second gate electrode,

wherein the second insulating layer comprises;

a first region covering a periphery of the first oxide semiconductor layer;

a second region in contact with an upper surface of the first oxide semiconductor layer;

a third region covering a periphery of the second oxide semiconductor layer; and

a fourth region in contact with an upper surface of the second oxide semiconductor layer,

wherein the first source electrode or the first drain electrode is electrically connected to the first oxide semiconductor layer between the first region and the second region of the second insulating layer,

wherein the second source electrode or the second drain electrode is electrically connected to the second oxide semiconductor layer between the third region and the fourth region of the second insulating layer, and

wherein the first electrode comprises a region overlapping the capacitor.

11. The display device according to claim 10, wherein the first oxide semiconductor layer and the second oxide semiconductor layer comprises indium.

12. The display device according to claim 10, wherein the first oxide semiconductor layer and the second oxide semiconductor layer comprises indium, gallium, and zinc.

13. The display device according to claim 10,

wherein the first transistor is provided in a pixel portion, and

wherein the second transistor is provided in a driver circuit portion.

14. The display device according to claim 10, wherein the first oxide semiconductor layer and the second oxide semiconductor layer comprises an amorphous oxide semiconductor.

15. The display device according to claim 10, comprising an oxide conductive layer between the first oxide semiconductor layer and each of the first source electrode and the first drain electrode.

16. The display device according to claim 10, comprising an oxide conductive layer between the second oxide semiconductor layer and each of the second source electrode and the second drain electrode.

17. The display device according to claim 10, comprising a protective insulating layer over the third insulating layer.

18. The display device according to claim 17, wherein the protective insulating layer comprises nitrogen.