Semiconductor thin film, method for manufacturing the same, thin film transistor, and active-matrix-driven display panel

• US 7,998,372 B2
• Filed: 11/16/2006
• Issued: 08/16/2011
• Est. Priority Date: 11/18/2005
• Status: Active Grant

• Current Assignee: Idemitsu Kosan Company Limited
• Original Assignee: Idemitsu Kosan Company Limited
• Inventors: Tanaka, Nobuo, Inoue, Kazuyoshi, Yano, Koki
• Primary Examiner(s): MC GINTY, DOUGLAS J
• Application Number:
  US12/094,228
• Publication Number:
  US 20100163860A1
• Time in Patent Office: 1,734 Days
• Field of Search: 252/519.51, 252/520.1, 252/519.1, 252/519.33, 257/43, 257/57, 257/59, 257/E29.08, 257/E21.459, 438/104, 977/773
• US Class Current: 252/519.51
• 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: Y10S 977/773 Nanoparticle, i.e. structure having three dimensions of 100 nm or less

Abstract

Disclosed is a semiconductor thin film which can be formed at a relatively low temperature even on a flexible resin substrate. Since the semiconductor thin film is stable to visible light and has high device characteristics such as transistor characteristics, in the case where the semiconductor thin film is used as a switching device for driving a display, even when overlapped with a pixel part, the luminance of a display panel does not deteriorate. Specifically, a transparent semiconductor thin film 40 is produced by forming an amorphous film containing zinc oxide and indium oxide and then oxidizing the film so that the resulting film has a carrier density of 10⁺¹⁷ cm⁻³ or less, a Hall mobility of 2 cm²/V·sec or higher, and an energy band gap of 2.4 EV or more.

Claims

1. A semiconductor thin film comprising:

an amorphous film containing zinc oxide, and indium oxide, said amorphous film having a carrier density of 10⁺¹⁷ cm<sup>−

3</sup> or less, a Hall mobility of 2 cm²/V·

sec or higher, and an energy band gap of 2.4 eV or more, and wherein the atom ratio between zinc [Zn] and indium [In] in said amorphous film, expressed as Zn/(Zn+In), is 0.51 to 0.80.

2. The semiconductor thin film according to claim 1, wherein said semiconductor thin film is a non-degenerate semiconductor thin film having a work function of 3.5 to 6.5 eV.

3. The semiconductor thin film according to claim 1, wherein a maximum value of a radial distribution function (RDF) obtained by X-ray scatter measurement in an atomic distance of 0.3 to 0.36 nm is A, and a maximum value of the RDF in an atomic distance of 0.36 to 0.42 nm is B, and wherein the ratio of relation A/B is >

0.8.

4. The semiconductor thin film according to claim 1, wherein the transmittance of wavelength of 550 nm of said semiconductor thin film is 75% or higher.

5. The transparent oxide semiconductor thin film according to claim 2, wherein the work function is 3.8 to 6.2 eV.

6. The semiconductor thin film according to claim 1, wherein nanocrystals are dispersed in said amorphous film.

7. The semiconductor thin film according to claim 1, wherein said amorphous film further contains a third metallic element [M], wherein atom ratio [M/(M+In)] between said third metallic element [M] and indium [In] is 0 to 0.5.

8. The semiconductor thin film according to claim 1, wherein said amorphous film further contains a third metallic element [M], wherein atom ratio [M/(M+In)] between said third metallic element [M] and indium [In] is 0 to 0.3.

9. The transparent oxide semiconductor thin film according to claim 3, wherein the ratio A/B is >

0.9.

10. A method for manufacturing a semiconductor thin film according to claim 1, said method comprising:

forming said amorphous film containing zinc oxide and indium oxide under a partial pressure of water H₂O in an atmospheric gas of 10<sup>−

3</sup> Pa or less.

11. The method for manufacturing a semiconductor thin film according to claim 10, further comprising oxidizing said amorphous film physically formed at a substrate temperature of 200°

C. or less.

12. A thin film transistor comprising the semiconductor thin film according to claim 1.

13. The thin film transistor according to claim 12, wherein the semiconductor thin film is provided on a resin substrate.

14. An active-matrix-driven display panel comprising the thin film transistor according to claim 12.

15. The transparent oxide semiconductor thin film according to claim 1, wherein the carrier density is 10⁺¹⁶ cm⁻

3 or less, the Hall mobility is 5 cm²/Vs or higher, and the energy band gap is 2.6 eV or larger.

16. The transparent oxide semiconductor thin film according to claim 1, wherein the specific resistance is 10⁻

1 to 10⁺⁸ Ω

cm.

17. The transparent oxide semiconductor thin film according to claim 1, wherein the atom ratio [Zn/(Zn+In)] is 0.55 to 0.80.

18. The semiconductor thin film according to claim 1, wherein the transmittance of wavelength of 550 nm of said semiconductor thin film is 80% or higher.