Field-effect transistor, and process for producing field-effect transistor

• US 8,530,891 B2
• Filed: 02/28/2008
• Issued: 09/10/2013
• Est. Priority Date: 04/05/2007
• Status: Active Grant

• Current Assignee: Idemitsu Kosan Company Limited
• Original Assignee: Idemitsu Kosan Company Limited
• Inventors: Inoue, Kazuyoshi, Yano, Koki, Kasami, Masashi
• Primary Examiner(s): NGUYEN, CUONG QUANG
• Application Number:
  US12/594,432
• Publication Number:
  US 20100117071A1
• Time in Patent Office: 2,021 Days
• Field of Search: 257/43, 257192-195, 257E29247-252
• US Class Current: 257/43
• 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 29/7869 having a semiconductor body comprising an oxide semiconductor material, e.g. zinc oxide, copper aluminium oxide, cadmium stannate

Abstract

To provide a field-effect transistor improved in transparency, electrical properties, stability, uniformity, reproducibility, heat resistance and durability, and as a reduced overlap capacity between electrodes.

A field-effect thin film transistor 1001 includes a gate electrode 1025, an active layer, a source electrode 1022 and a drain electrode 1023, wherein a crystalline oxide 1021 containing indium and having an electron carrier concentration of less than 10¹⁸/cm³ is used as the active layer, and the gate electrode 1025 is in self-alignment with the source electrode 1022 and the drain electrode 1023. The crystalline oxide 1021 contains a positive trivalent element different from a positive divalent element or indium.

Claims

1. A field-effect transistor comprising a gate electrode, an active layer, a source electrode and a drain electrode, wherein a crystalline oxide containing indium and having an electron carrier concentration of less than 10¹⁸/cm³ is used as the active layer, and the gate electrode is in self-alignment with the source electrode and the drain electrode, and the crystalline oxide has a bixbite structure and is polycrystalline.

2. The field-effect transistor according to claim 1, wherein the crystalline oxide further contains a positive divalent element.

3. The field-effect transistor according to claim 2, wherein the positive divalent element is at least one element of Zn, Mg, Ni, Co and Cu.

4. The field-effect transistor according to claim 2, wherein the electron mobility of the crystalline oxide logarithmically proportionally increases in a certain range with an increase in the electron carrier concentration, when the atomic ratio ([M2]/[A]) of the number of the atoms of the positive divalent element ([M2]) to the number of the atoms of all metal elements contained in the crystalline oxide ([A]) changes.

5. The field-effect transistor according to claim 1, wherein the crystalline oxide further contains a positive trivalent element different from indium.

6. The field-effect transistor according to claim 5, wherein the positive trivalent element is at least one element of B, Al, Ga, Sc, Y and a lanthanoid element.

7. The field-effect transistor according to claim 5, wherein the electron mobility of the crystalline oxide logarithmically proportionally increases in a certain range with an increase in electron carrier concentration, when the atomic ratio ([M3]/[A]) of the atom number of the positive trivalent element ([M3]) to the atom number of all metal elements contained in the crystalline oxide ([A]) changes.

8. The field-effect transistor according to claim 1, wherein the crystalline oxide is a nondegenerate semiconductor.

9. The field-effect transistor according to claim 1, wherein the crystalline oxide has a PAN resistance.

10. The field-effect transistor according to claim 1, wherein the field-effect transistor is a top-gate type transistor and the gate electrode is formed using the pattern of the source electrode and the drain electrode formed on a transparent substrate as a mask.

11. The field-effect transistor according to claim 1, wherein the field-effect transistor is a bottom-gate type transistor and the source electrode and the drain electrode are formed using the pattern of the gate electrode formed on a transparent substrate as a mask.

12. A method for producing a field-effect transistor according to claim 1, using a crystalline indium-containing oxide with an electron carrier concentration of less than 10¹⁸/cm³ as an active layer and having a bixbite structure and polycrystalline structure, comprising,

the active layer forming step of forming the crystalline oxide in an atmosphere containing oxygen and/or water.

13. The method for producing a field-effect transistor according to claim 12, wherein the atmosphere containing oxygen and/or water contains at least one of molecular oxygen, ozone gas, nitrogen oxide gas, oxygen-containing radicals, atomic oxygen, oxygen ions, oxygen radicals, water vapor and hydroxide ions.

14. The method for producing a field-effect transistor according to claim 12, wherein the film-forming temperature of the crystalline oxide is 150°

C. or more and 350°

C. or less.

15. The method for producing a field-effect transistor according to claim 12, wherein a sputtering method is used in the active layer forming step.

16. A method for producing a field-effect transistor according to claim 1, using a crystalline indium-containing oxide with an electron carrier concentration of less than 10¹⁸/cm³ as an active layer and having a bixbite structure and polycrystalline structure, comprising,

the thin film-forming step of forming an amorphous oxide film for the active layer, and

the crystallizing step of crystallizing the amorphous oxide to the crystalline oxide.

17. The method for producing a field-effect transistor according to claim 16, wherein the crystallizing step uses heating and/or irradiation of an oxygen-containing plasma.

18. The method for producing a field-effect transistor according to claim 16, wherein the crystallizing step uses heating and the temperature thereof is 150°

C. or more and 350°

C. or less.

19. The method for producing a field-effect transistor according to claim 16, wherein at least one of the thin film-forming step and the crystallizing step is conducted in an atmosphere containing oxygen and/or water, and the atmosphere containing oxygen and/or water contains at least one of molecular oxygen, ozone gas, nitrogen oxide gas, oxygen-containing radicals, atomic oxygen, oxygen ions, oxygen radicals, water vapor and hydroxide ions.

20. The method for producing a field-effect transistor according to claim 16, wherein a sputtering method is used in the thin film-forming step.

21. The method for producing a field-effect transistor according to claim 12, wherein the crystalline oxide contains a positive divalent element.

22. The method for producing a field-effect transistor according to claim 21, wherein the positive divalent element is at least one element of Zn, Mg, Ni, Co and Cu.

23. The method for producing a field-effect transistor according to claim 21, wherein the electron mobility of the crystalline oxide logarithmically proportionally increases in a certain range with an increase in the electron carrier concentration, when the atomic ratio ([M2]/[A]) of the number of the atoms of the positive divalent element ([M2]) to the number of the atoms of all metal elements contained in the crystalline oxide ([A]) changes.

24. The method for producing a field-effect transistor according to claim 12, wherein the crystalline oxide contains a positive trivalent element different from indium.

25. The method for producing a field-effect transistor according to claim 24, wherein the positive trivalent element is at least one element of B, Al, Ga, Sc, Y and a lanthanoid element.

26. The method for producing a field-effect transistor according to claim 24, wherein the electron mobility of the crystalline oxide logarithmically proportionally increases in a certain range with an increase in the electron carrier concentration, when the atomic ratio ([M3]/[A]) of the number of the atoms of the positive trivalent element ([M3]) to the number of the atoms of all metal elements contained in the crystalline oxide ([A]) changes.

27. The method for producing a field-effect transistor according to claim 12, wherein a substrate on which the active layer is to be formed is subjected to at least one treatment of ultraviolet irradiation in an ozone atmosphere, plasma irradiation and cleaning with a cleaning solution containg hydrogen peroxide.

28. The method for producing a field-effect transistor according to claim 12, wherein the crystalline oxide is a nondegenerate semiconductor.

29. The method for producing a field-effect transistor according to claim 12, wherein the crystalline oxide has a PAN resistance.

30. The method for producing a field-effect transistor according to claim 16, wherein the crystalline oxide contains a positive divalent element.

31. The method for producing a field-effect transistor according to claim 30, wherein the positive divalent element is at least one element of Zn, Mg, Ni, Co and Cu.

32. The method for producing a field-effect transistor according to claim 30, wherein the electron mobility of the crystalline oxide logarithmically proportionally increases in a certain range with an increase in the electron carrier concentration, when the atomic ratio ([M2]/[A]) of the number of the atoms of the positive divalent element ([M2]) to the number of the atoms of all metal elements contained in the crystalline oxide ([A]) changes.

33. The method for producing a field-effect transistor according to claim 16, wherein the crystalline oxide contains a positive trivalent element different from indium.

34. The method for producing a field-effect transistor according to claim 33, wherein the positive trivalent element is at least one element of B, Al, Ga, Sc, Y and a lanthanoid element.

35. The method for producing a field-effect transistor according to claim 33, wherein the electron mobility of the crystalline oxide logarithmically proportionally increases in a certain range with an increase in the electron carrier concentration, when the atomic ratio ([M3]/[A]) of the number of the atoms of the positive trivalent element ([M3]) to the number of the atoms of all metal elements contained in the crystalline oxide ([A]) changes.

36. The method for producing a field-effect transistor according to claim 16, wherein a substrate on which the active layer is to be formed is subjected to at least one treatment of ultraviolet irradiation in an ozone atmosphere, plasma irradiation and cleaning with a cleaning solution containg hydrogen peroxide.

37. The method for producing a field-effect transistor according to claim 16, wherein the crystalline oxide is a nondegenerate semiconductor.

38. The method for producing a field-effect transistor according to claim 16, wherein the crystalline oxide has a PAN resistance.

39. The field effect transistor according to claim 5, wherein the positive trivalent element is at least one of B or a lanthanoid element.