Indium oxide-based thin film transistors and circuits

• US 20050275038A1
• Filed: 06/14/2004
• Published: 12/15/2005
• Est. Priority Date: 06/14/2004
• Status: Active Grant

• Current Assignee: Chunong Qiu, Cindy Xing Qiu, Ishiang Shih, Yi-Chi Shih
• Original Assignee: Chunong Qiu, Cindy Xing Qiu, Ishiang Shih, Yi-Chi Shih
• Inventors: Shih, Yi-Chi, Qiu, Chunong, Shih, Ishiang, Qiu, Cindy Xing
• Granted Patent: US 7,211,825 B2
• Time in Patent Office: Days
• US Class Current: 257/382
• CPC Class Codes: H01L 29/78633 with a light shield
• CPC Class Codes: H01L 29/78645 with multiple gate
• CPC Class Codes: H01L 29/78648 arranged on opposing sides of the channel
• CPC Class Codes: H01L 29/7869 having a semiconductor body comprising an oxide semiconductor material, e.g. zinc oxide, copper aluminium oxide, cadmium stannate

Abstract

In electronic displays or imaging units, the control of pixels is achieved by an array of transistors. These transistors are in a thin film form and arranged in a two-dimensional configuration to form switching circuits, driving circuits or even read-out circuits. In this invention, thin film transistors and circuits with indium oxide-based channel layers are provided. These thin film transistors and circuits may be fabricated at low temperatures on various substrates and with high charge carrier mobilities. In addition to conventional rigid substrates, the present thin film transistors and circuits are particularly suited for the fabrication on flexible and transparent substrates for electronic display and imaging applications. Methods for the fabrication of the thin film transistors with indium oxide-based channels are provided.

Claims

1. An indium oxide-based thin film transistor for forming a switching array or a circuit comprising:

a first substrate;

a first conductive gate layer;

a first gate insulating layer overlapping at least a portion of said conductive gate layer;

a source electrode overlapping a first portion of said first gate insulating layer; and

a drain electrode overlapping a second portion of said first gate insulating layer.

an indium oxide-based channel layer overlapping a portion of said first gate insulating layer, overlapping at least a portion of said source electrode and at least a portion of said drain electrode.

2. An indium oxide-based thin film transistor for forming a switching array or a circuit as defined in claim 1, wherein said first substrate is selected from a group comprising:

glass substrates, silica substrates, plastic sheets, metallic sheets with a dielectric coating, ceramic substrates and semiconductor substrates.

3. An indium oxide-based thin film transistor for forming a switching array or a circuit as defined in claim 1, wherein material of said indium oxide-based channel layer is selected from a group comprising:

indium oxide, indium tin oxide, indium zinc oxide and indium gallium oxide and their alloys.

4. An indium oxide-based thin film transistor for forming a switching array or a circuit as defined in claim 1 further comprising at least a first interlayer dielectric layer, said first interlayer dielectric layer overlaps at least a portion of said indium oxide-based channel layer, a portion of said source electrode and a portion of said drain electrode for electrical isolation and passivation.

5. An indium oxide-based thin film transistor for forming a switching array or a circuit as defined in claim 1, further comprising a thin substrate dielectric layer, said thin substrate dielectric layer being introduced between said indium oxide-based channel layer and said first substrate, to minimize elemental inter-diffusion between said indium oxide-based channel layer and said first substrate.

6. An indium oxide-based thin film transistor for forming a switching array or a circuit as defined in claim 1, further comprising a first light shield layer deposited below said indium oxide-based channel layer and a second light shield layer deposited above said indium oxide-based channel layer, said first light shield and second light shield being selected from a group of materials:

Al, Cu, Ni, Ti, Ta, W, Cr, Mo, alloys and combinations, said first light shield and second light shield are substantially non-transmissive to ultra-violet light and visible light and are deposited to minimize generations of electron hole pairs due to illumination of said indium oxide-based channel layer.

7. An indium oxide-based thin film transistor for forming a switching array or a circuit as defined in claim 1, further comprising a first contact layer between said source electrode and a first output electrode to minimize contact resistance of said first output electrode, and a second contact layer between said drain electrode and a second output electrode to minimize contact resistance of said second output electrode.

8. An indium oxide-based thin film transistor for forming a switching array or a circuit as defined in claim 1, further comprising a second gate insulating layer and a second conductive gate layer to facilitate modulation of electrical conduction of said indium oxide-based channel layer.

9. An indium oxide-based thin film transistor for forming a switching array or a circuit as defined in claim 1, further comprising a second substrate have a top electrode, said second substrate being installed between said first substrate to enclose and protect said switching array or said circuit and light emitting elements or light switching elements.

10. An indium oxide-based thin film transistor for forming a switching array or a circuit as defined in claim 1, wherein said first conductive gate layer overlaps at least a portion of said first gate insulating layer, a portion of said source electrode and a portion of said drain electrode, said first gate insulating layer overlaps at least a portion of said indium oxide-based channel layer, forming a top-gate thin film transistor structure having an indium oxide-based channel layer.

11. An indium oxide-based thin film transistor for forming a switching array or a circuit as defined in claim 1, wherein said indium oxide-based channel layer is deposited on said first gate insulating layer, said first gate insulating layer overlaps at least a portion of said first conductive gate layer, a portion of said source electrode and a portion of said drain electrode, forming a bottom-gate thin film transistor structure having an indium oxide-based channel layer.

12. An indium oxide-based thin film transistor for forming a switching array or a circuit as defined in claim 1, further comprising a pixel electrode, said pixel electrode forming a part of a light switching or receiving element and being connected electrically to said drain electrode and is selected from a material group comprising:

indium tin oxide, indium oxide, zinc oxide and their alloys.

13. An indium oxide-based thin film transistor for forming a switching array or a circuit as defined in claim 1, further comprising a data line and a gate line, said data line being connected electrically to drain electrodes of a plurality of said indium oxide-based thin film transistors whereas said gate line being connected electrically to gate electrodes of said indium oxide-based thin film transistors for control and addressing of light switching and receiving elements connected to said drain electrodes.

14. A method of fabricating a thin film transistor with indium oxide-based channel layer for a switching array or a circuit, comprising the steps of:

forming a first gate electrode on a first substrate;

forming a first gate insulating layer on said first gate electrode and said first substrate;

forming a first source electrode and a second drain electrode and a gate line on portions of said first gate insulating layer;

forming an indium oxide-based semiconductor and patterning said indium oxide-based semiconductor into a channel layer;

depositing and patterning a first interlayer dielectric layer; and

depositing and patterning at least a first output electrode source data line and a second output electrode gate line.

15. A method of fabricating a thin film transistor for a switching array or a circuit as defined in claim 14, wherein said first substrate is selected from a group comprising:

glass substrates, silica substrates, plastic sheets, metallic sheets with a dielectric coating, ceramic substrates and semiconductor substrates

16. A method of fabricating a thin film transistor for a switching array or a circuit as defined in claim 14, wherein material of said indium oxide-based semiconductor for said channel layer is selected from a group comprising:

indium oxide, indium tin oxide, indium zinc oxide, indium gallium oxide and their mixtures.

17. A method of fabricating a thin film transistor for a switching array or a circuit as defined in claim 14, further comprising a step of forming a pixel electrode, said pixel electrode being connected electrically to said drain electrode of said thin film transistor, for supplying or receiving an electrical signal and is selected from a material group comprising:

indium tin oxide, indium oxide, zinc oxide, indium gallium oxide and their alloys.

18. A method of fabricating a thin film transistor for a switching array or a circuit as defined in claim 14, further comprising a step of forming a first light shield and a thin substrate insulating layer on said substrate, said first light shield being selected to be substantially non-transmissive to ultra-violet light and visible light to minimize the generation of electrons and holes due to illumination of said indium oxide-based semiconductor for ultra-violet, visible and infrared applications and further selected to be non-transmissive to X-ray for X-ray applications.

19. A method of fabricating a thin film transistor for a switching array or a circuit as defined in claim 14, further comprising a step of forming a second light shield on said first interlayer dielectric, said second light shield being selected to be non-transmissive to ultra-violet light and visible light to minimize the generation of electrons and holes due to illumination of said indium oxide-based semiconductor for ultra-violet, visible and infrared applications and further selected to be substantially non-transmissive to X-ray for X-ray applications.

20. A method of fabricating a thin film transistor for a switching array or a circuit as defined in claim 14, further comprising a step of forming a thin substrate dielectric layer on said substrate for passivation in order to minimize elemental inter-diffusion between said substrate and said indium oxide-based semiconductor.

21. A method of fabricating a thin film transistor for a switching array or a circuit as defined in claim 14, further comprising a step of heating said first substrate during the deposition of said indium oxide-based semiconductor to improve crystallinity and charge carrier mobilities.

22. A method of fabricating a thin film transistor for a switching array or a circuit as defined in claim 14, further comprising a step of heating said first substrate after the formation of said indium oxide-based semiconductor to improve crystallinity and charge carrier mobilities, said heating being performed in an atmosphere containing oxygen.

23. A method of fabricating a thin film transistor for a switching array or a circuit as defined in claim 14, wherein resistivity of said indium oxide-based semiconductor being controlled by regulating the deposition rate, substrate temperature and partial pressure of oxygen in chamber atmosphere.

24. A method of fabricating a thin film transistor with indium oxide-based channel layer for a switching array or a circuit, comprising the steps of:

forming a source electrode and a drain electrode and a gate line on a first substrate;

forming an indium oxide-based semiconductor and patterning said indium oxide-based semiconductor into a channel layer, said indium oxide-based semiconductor overlaps a portion of said source electrode and a potion of said drain electrode;

forming a first gate insulating layer on said indium oxide-based semiconductor;

forming a first gate electrode on said first gate insulating layer;

depositing and patterning a first interlayer dielectric layer; and

depositing and patterning at least a first output electrode source data line and at least a second output electrode gate line.

25. A method of fabricating a thin film transistor for a switching array or a circuit as defined in claim 24, wherein said first substrate is selected from a group comprising:

glass substrates, plastic sheets, metallic sheets with a dielectric coating, ceramic substrates and semiconductor substrates

26. A method of fabricating a thin film transistor for a switching array or a circuit as defined in claim 24, wherein material of said indium oxide-based semiconductor for said channel layer is selected from a group comprising:

indium oxide, indium tin oxide, indium zinc oxide, indium gallium oxide and their mixtures.

27. A method of fabricating a thin film transistor for a switching array or a circuit as defined in claim 24, further comprising a step of forming a pixel electrode, said pixel electrode being connected electrically to said drain electrode, for supplying or receiving an electrical signal and is selected from a material group comprising:

indium tin oxide, indium oxide, zinc oxide, indium gallium oxide and their alloys.

28. A method of fabricating a thin film transistor for a switching array or a circuit as defined in claim 24, further comprising a step of forming a first light shield and a thin substrate insulating layer on said first substrate to minimize generation of electrons and holes due to illumination of said indium oxide-based semiconductor for ultra-violet, visible and infrared applications and further selected to be substantially non-transmissive to X-ray for X-ray applications.

29. A method of fabricating a thin film transistor for a switching array or a circuit as defined in claim 24, further comprising a step of forming a second light shield on said first interlayer dielectric to minimize generation of electrons and holes due to illumination of said indium oxide-based semiconductor for ultra-violet, visible and infrared applications and further selected to be substantially non-transmissive to X-ray for X-ray applications.

30. A method of fabricating a thin film transistor for a switching array or a circuit as defined in claim 24, further comprising a step of forming a thin substrate dielectric layer on said first substrate for passivation in order to minimize elemental inter-diffusion between said first substrate and said indium oxide-based semiconductor.

31. A method of fabricating a thin film transistor for a switching array or a circuit as defined in claim 24, further comprising a step of heating said first substrate during the deposition of said indium oxide-based semiconductor to improve crystallinity and charge carrier mobilities.

32. A method of fabricating a thin film transistor for a switching array or a circuit as defined in claim 24, further comprising a step of heating said first substrate after forming of said indium oxide-based semiconductor to improve crystallinity and charge carrier mobilities, said heating being performed in an atmosphere containing oxygen.

33. A method of fabricating a thin film transistor for a switching array or a circuit as defined in claim 24, wherein resistivity of said indium oxide-based semiconductor being controlled by regulating the deposition rate, substrate temperature and partial pressure of oxygen in chamber atmosphere.