Oxide semiconductor field effect transistor and method for manufacturing the same

• US 8,461,583 B2
• Filed: 12/19/2008
• Issued: 06/11/2013
• Est. Priority Date: 12/25/2007
• Status: Active Grant

• Current Assignee: Idemitsu Kosan Company Limited
• Original Assignee: Idemitsu Kosan Company Limited
• Inventors: Yano, Koki, Kawashima, Hirokazu, Inoue, Kazuyoshi, Tomai, Shigekazu, Kasami, Masashi
• Primary Examiner(s): Chaudhuri, Olik
• Assistant Examiner(s): JEFFERSON, QUOVAUNDA
• Application Number:
  US12/810,189
• Publication Number:
  US 20100276688A1
• Time in Patent Office: 1,635 Days
• Field of Search: 438/29, 438/608, 438/609, 438/720, 438/722, 438/742, 438/754, 438/FOR.405, 257/43, 257/E33.064, 257/E31.126, 257/E21.28, 257/E23.155, 257/65, 257/66, 257/76, 257/E29.296, 257/E21.494, 252/500, 252/506, 252/508, 252/518.1, 252/519.15, 252/520.1, 252/521.1, 252/521.3, 252/521.4, 204/298.13, 204/192.25, 204/192.29
• US Class Current: 257/43
• CPC Class Codes: C23C 14/086 of zinc, germanium, cadmium, indium, tin, thallium or bismuth
• CPC Class Codes: H01L 29/263 Amorphous materials
• 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

A field effect transistor including a semiconductor layer including a composite oxide which contains In, Zn, and one or more elements X selected from the group consisting of Zr, Hf, Ge, Si, Ti, Mn, W, Mo, V, Cu, Ni, Co, Fe, Cr, Nb, Al, B, Sc, Y and lanthanoids in the following atomic ratios (1) to (3):
In/(In+Zn)=0.2 to 0.8  (1)
In/(In+X)=0.29 to 0.99  (2)
Zn/(X+Zn)=0.29 to 0.99  (3).

Claims

1. A field effect transistor comprising a gate electrode, a source electrode, a drain electrode and a semiconductor layer, said semiconductor layer comprising a composite oxide which comprises In, Zn, and one or more elements X selected from the group consisting of Zr, Hf, Ge, Si, Ti, Mn, W, Mo, V, Cu, Ni, Co, Fe, Cr, Nb, Al, B, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu in the following atomic ratios (1) to (3):

In/(In+Zn)=0.2 to 0.8 

 

(1)

In/(In+X)=0.29 to 0.99 

 

(2)

Zn/(X+Zn)=0.29 to 0.99 

 

(3).

2. The field effect transistor according to claim 1, wherein element X is one or more elements selected from the group consisting of Al, B, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu and the semiconductor layer comprises element X in the following atomic ratio (2)′

;

In/(In+X)=0.59 to 0.99 

 

(2)′

.

3. The field effect transistor according to claim 1, wherein element X is Al or B.

4. The field effect transistor according to claim 1, wherein element X is Sc or Y.

5. The field effect transistor according to claim 1, wherein element X is one or more elements selected from the group consisting of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu.

6. The field effect transistor according to claim 1, wherein element X is Zr.

7. The field effect transistor according to claim 1, wherein the semiconductor layer is an amorphous film which has an electron carrier concentration of 10¹³ to 10¹⁸/cm³ and a band gap of 2.0 to 6.0 eV.

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

9. The field effect transistor according to claim 1, wherein said semiconductor layer comprises a composite oxide which comprises In, Zn, and one or more elements X selected from the group consisting of Zr, Hf, Ge, Si, Ti, Mn, Mo, V, Cu, Co, Cr, Nb, Al, B, Sc, Y, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er, Tm, Yb and Lu.

10. The field effect transistor according to claim 1, wherein said semiconductor layer comprises a composite oxide which comprises In, Zn, and one or more elements X selected from the group consisting of Zr, Hf, Ge, Si, Ti, Al and Y.

11. The field effect transistor according to claim 1, wherein said field effect transistor has a mobility of 1 cm²/Vs or more.

12. The field effect transistor according to claim 1, wherein said field effect transistor has an on-off ratio of 10⁶ or more.

13. The field effect transistor according to claim 1, wherein said field effect transistor has an S value of 0.8 V/dec or less.

14. The field effect transistor according to claim 1, wherein said field effect transistor has an S value of 0.3 V/dec or less.

15. The field effect transistor according to claim 1, wherein said composite oxide comprises In, Zn, and one or more elements X in the following atomic ratios (1) to (3):

In/(In+Zn)=0.35 to 0.7 

 

(1)

In/(In+X)=0.45 to 0.98 

 

(2)

Zn/(X+Zn)=0.6 to 0.98 

 

(3).

16. A target comprising a composite oxide which comprises In, Zn, and one or more elements X wherein element X is one or more elements selected from the group consisting of Al, B, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu in the following atomic ratios (1) to (3):

In/(In+Zn)=0.2 to 0.8 

 

(1)

In/(In+X)=0.29 to 0.99 

 

(2)

Zn/(X+Zn)=0.29 to 0.99 

 

(3),

and wherein the target further comprises one or more elements selected from the group consisting of Sn, Ge, Si, Ti, Zr and Hf in an amount of 100 to 10000 atomic ppm.

17. A method for producing a field effect transistor comprising forming a semiconductor layer by DC or AC sputtering using a target comprising a composite oxide which comprises In, Zn, and one or more elements X selected from the group consisting of Zr, Hf, Ge, Si, Ti, Mn, W, Mo, V, Cu, Ni, Co, Fe, Cr, Nb, Al, B, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu in the following atomic ratios (1) to (3):

In/(In+Zn)=0.2 to 0.8 

 

(1)

In/(In+X)=0.29 to 0.99 

 

(2)

Zn/(X+Zn)=0.29 to 0.99 

 

(3),

and subjecting the semiconductor layer to a heat treatment at 70 to 350°

C.