Semiconductor thin film and method for manufacturing same, and thin film transistor

• US 7,906,777 B2
• Filed: 11/16/2006
• Issued: 03/15/2011
• 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): Monbleau; Davienne
• Assistant Examiner(s): Reames; Matthew
• Application Number:
  US12/093,827
• Publication Number:
  US 20090267064A1
• Time in Patent Office: 1,580 Days
• Field of Search: 438/658, 257/43, 257/E29.289
• US Class Current: 257/43
• CPC Class Codes: C01G 19/00 Compounds of tin
• CPC Class Codes: C01P 2006/40 Electric properties
• 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

The present invention provides a semiconductor thin film which can be manufactured at a relatively low temperature even on a flexible resin substrate. As a semiconductor thin film having a low carrier concentration, a high Hall mobility and a large energy band gap, an amorphous film containing zinc oxide and tin oxide is formed to obtain 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. Then, the amorphous film is oxidized to form a transparent semiconductor thin film 40.

Claims

1. A semiconductor thin film made by an amorphous film containing zinc oxide and tin oxide and whose specific resistance is 10 Ω

cm to 10⁷ Ω

cm, wherein the film is a non-degenerate semiconductor thin 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.

2. The semiconductor thin film according to claim 1, wherein atom ratio between zinc [Zn] and tin [Sn] in the amorphous film is expressed as Zn/(Zn+Sn)=0.40 to 0.95.

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

4. The semiconductor thin film according to claim 1, wherein work function is 3.5 to 6.5 eV.

5. A method of manufacturing a semiconductor thin film according to claim 1, comprising:

forming an amorphous film containing zinc oxide and tin oxide by a physical film forming method; and

performing a post process in which temperature in a film surface in the presence of oxygen becomes a temperature equal to or higher than a substrate temperature at the time of the film formation.

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

7. The semiconductor thin film according to claim 1, wherein work function is 4.5 to 5.5 eV.

8. The semiconductor thin film according to claim 1, wherein the film is a non-degenerate semiconductor thin film having a carrier density of 10⁺¹⁴ cm⁻

3 or less.

9. The semiconductor thin film according to claim 1, wherein the film is a non-degenerate semiconductor thin film having a Hall mobility of 14 cm²/Vs or higher.

10. The semiconductor thin film according to claim 1, wherein the film is a non-degenerate semiconductor thin film having an energy band gap of 3.2 eV or larger.

11. The semiconductor thin film according to claim 1, wherein atom ratio between zinc [Zn] and tin [Sn] in the amorphous film is expressed as Zn/(Zn+Sn)=0.7 to 0.9.

12. The semiconductor thin film according to claim 1, wherein transmittance of wavelength of 550 nm is 85% or higher.

13. The semiconductor thin film according to claim 1, wherein the film is a non-degenerate semiconductor thin film having a carrier density of 10⁺¹⁷ to 10⁺¹⁴ cm⁻

3, a Hall mobility of 2 to 14 cm²/V·

sec, and an energy band gap of 2.4 to 3.2 eV.

14. The semiconductor thin film according to claim 13, wherein atom ratio between zinc [Zn] and tin [Sn] in the amorphous film is expressed as Zn/(Zn+Sn)=0.40 to 0.95.

15. The semiconductor thin film according to claim 13, wherein transmittance of wavelength of 550 nm is 75% or higher.

16. The semiconductor thin film according to claim 13, wherein work function is 3.5 to 6.5 eV.

17. The semiconductor thin film according to claim 13, wherein atom ratio between zinc [Zn] and tin [Sn] in the amorphous film is expressed as Zn/(Zn+Sn)=0.7 to 0.9.

18. The semiconductor thin film according to claim 13, wherein transmittance of wavelength of 550 nm is 85% or higher.

19. A thin film transistor comprising the semiconductor thin film according to claim 13.

20. A method of manufacturing a semiconductor thin film according to claim 13, comprising:

forming an amorphous film containing zinc oxide and tin oxide by a physical film forming method; and

performing a post process in which temperature in a film surface in the presence of oxygen becomes a temperature equal to or higher than a substrate temperature at the time of the film formation.