Oxide semiconductor, thin-film transistor and method for producing the same

• US 7,807,515 B2
• Filed: 05/25/2007
• Issued: 10/05/2010
• Est. Priority Date: 05/25/2006
• Status: Expired due to Fees

• Current Assignee: Fuji Electric Company Limited (Fuji Electric Systems Company Limited)
• Original Assignee: Fuji Electric Holdings Company Limited (Fuji Electric Systems Company Limited)
• Inventors: Kato, Kyoko, Kato, Hisato, Sekine, Nobuyuki, Kawakami, Haruo
• Primary Examiner(s): Nhu; David
• Application Number:
  US12/086,628
• Publication Number:
  US 20090289249A1
• Time in Patent Office: 1,229 Days
• Field of Search: 438/30, 438/91, 438/96, 438/97, 438/149, 438/197, 438/509, 438/513, 257/359, 257/E21.051, 257/77, 257/81, 257/311, 257/352, 257/411
• US Class Current: 438/149
• CPC Class Codes: C01G 19/006 Compounds containing, besides tin, two or more other elements, with the exception of oxygen or hydrogen
• CPC Class Codes: C01P 2006/40 Electric properties
• 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 29/78693 the semiconducting oxide being amorphous

Abstract

Disclosed is an oxide semiconductor having an amorphous structure, wherein higher mobility and reduced carrier concentration are achieved. Also disclosed are a thin film transistor, a method for producing the oxide semiconductor, and a method for producing the thin film transistor. Specifically disclosed is an oxide semiconductor which is characterized by being composed of an amorphous oxide represented by the following a general formula: In_x+1MZn_y+1Sn_zO_{(4+1.5x+y+2z)} (wherein M is Ga or Al, 0≦x≦1, −0.2≦y≦1.2, z≧0.4 and 0.5≦(x+y)/z≦3). This oxide semiconductor is preferably subjected to a heat treatment in an oxidizing gas atmosphere after film formation. Also specifically disclosed is a thin film transistor which is characterized by comprising the oxide semiconductor.

Claims

1. A thin film transistor comprising an oxide semiconductor composed of amorphous oxide represented by general formula In_x+1MZn_y+1Sn_zO_{(4+1.5x+y+2z)} (in which M=Ga or Al, 0≦

x≦

1, −

0.2≦

y≦

1.2, z≧

0.4, and 0.5≦

(x+y)/z≦

3).

2. A thin-film transistor comprising an oxide semiconductor according to claim 1.

3. A method for producing an oxide semiconductor, comprising:

forming amorphous oxide represented by general formula In_x+1MZn_y+1Sn_zO_{(4+1.5x+y+2z)} (in which M=Ga or Al, 0≦

x≦

1, −

0.2≦

y≦

1.2, z≧

0.4, and 0.5≦

(x+y)/z≦

3); and

heat-treating the amorphous oxide under an oxidizing gas atmosphere.

4. A method for producing an oxide semiconductor according to claim 3, wherein the oxidizing gas at least contains oxygen radical, oxygen, water or ozone.

5. A method for producing a thin-film transistor, comprising:

forming amorphous oxide represented by general formula In_x+1MZn_y+1Sn_zO_{(4+1.5x+y+2z)} (in which M=Ga or Al, 0≦

x≦

1, −

0.2≦

y≦

1.2, z≧

0.4, and 0.5≧

(x+y)/z≧

3) on a gate insulating film or on source and drain electrodes; and

heat-treating the amorphous oxide under an oxidizing gas atmosphere.