Amorphous oxide semiconductor, semiconductor device, and thin film transistor

• US 8,154,017 B2
• Filed: 04/15/2008
• Issued: 04/10/2012
• Est. Priority Date: 04/25/2007
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Yabuta, Hisato, Kaji, Nobuyuki, Hayashi, Ryo, Endo, Ayanori
• Primary Examiner(s): Toledo, Fernando L
• Assistant Examiner(s): SINGAL, ANKUSH K
• Application Number:
  US12/594,629
• Publication Number:
  US 20100044703A1
• Time in Patent Office: 1,456 Days
• Field of Search: 257/43
• US Class Current: 257/43
• CPC Class Codes: H01L 29/247 Amorphous materials
• 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

An amorphous oxide semiconductor contains at least one element selected from In, Ga, and Zn at an atomic ratio of In_xGa_yZn_z, wherein the density M of the amorphous oxide semiconductor is represented by the relational expression (1) below:
M≧0.94×(7.121x+5.941y+5.675z)/(x+y+z)  (1)
where 0≦x≦1, 0≦y≦1, 0≦z≦1, and x+y+z≠0.

Claims

1. An amorphous oxide semiconductor containing at least one element selected from In, Ga, and Zn at an atomic ratio of In_xGa_yZn_z, wherein a mass density M of the amorphous oxide semiconductor is represented by a relational expression (1) shown below:

M≧

0.94×

(7.121x+5.941y+5.675z)/(x+y+z)  

 

(1)

where 0≦

x≦

1, 0≦

y≦

1, 0≦

z≦

1, and x+y+z≠

0.

2. The amorphous oxide semiconductor according to claim 1, wherein x>

0, y>

0, and z>

0.

3. The amorphous oxide semiconductor according to claim 1, wherein ratios x/(x+y+z), y/(x+y+z), and z/(x+y+z) are each not less than 0.2.

4. A thin film transistor comprising a source electrode, a drain electrode, a gate electrode, a gate insulating film and a channel layer, which employs the amorphous oxide semiconductor set forth in claim 1 as the channel layer.