Field effect transistor with amorphous oxide active layer containing microcrystals and gate electrode opposed to active layer through gate insulator

• US 7,601,984 B2
• Filed: 11/09/2005
• Issued: 10/13/2009
• Est. Priority Date: 11/10/2004
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.), Japan Science And Technology Agency, Tokyo Institute of Technology (National University Corporation Tokyo Institute of Technology)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.), Tokyo Institute of Technology (National University Corporation Tokyo Institute of Technology)
• Inventors: Sano, Masafumi, Kamiya, Toshio, Nomura, Kenji, Nakagawa, Katsumi, Hosono, Hideo
• Primary Examiner(s): LE, DUNG ANH
• Application Number:
  US11/269,600
• Publication Number:
  US 20060108636A1
• Time in Patent Office: 1,434 Days
• Field of Search: 438/761, 438/778, 438/482, 438/149, 438/166, 438/365, 257/635, 257 52- 59, 257 72- 75, 257/347, 257/646
• US Class Current: 257/57
• CPC Class Codes: H01L 21/02422 Non-crystalline insulating materials, e.g. glass, polymers
• CPC Class Codes: H01L 21/02554 Oxides
• CPC Class Codes: H01L 21/02565 Oxide semiconducting materials not being Group 12/16 materials, e.g. ternary compounds
• CPC Class Codes: H01L 21/02592 amorphous
• CPC Class Codes: H01L 21/02631 Physical deposition at reduced pressure, e.g. MBE, sputtering, evaporation
• CPC Class Codes: H01L 21/428 using electromagnetic radiation, e.g. laser radiation
• CPC Class Codes: H01L 27/1225 with semiconductor materials not belonging to the group IV of the periodic table, e.g. InGaZnO
• CPC Class Codes: H01L 27/124 with a particular composition, shape or layout of the wiring layers specially adapted to the circuit arrangement, e.g. scanning lines in LCD pixel circuits wiring structures per se H01L23/52
• 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
• CPC Class Codes: H01L 29/78693 the semiconducting oxide being amorphous
• CPC Class Codes: H01L 29/78696 characterised by the structure of the channel, e.g. multichannel, transverse or longitudinal shape, length or width, doping structure, or the overlap or alignment between the channel and the gate, the source or the drain, or the contacting structure of the channel H01L29/78612 takes precedence; transistors having a drain offset region or a lightly doped drain [LDD] H01L29/78621

Abstract

A novel amorphous oxide applicable, for example, to an active layer of a TFT is provided. The amorphous oxide comprises microcrystals.

Claims

1. A field effect transistor comprising an active layer of an amorphous oxide containing a microcrystal, wherein a grain boundary interface of the microcrystal is surrounded by the amorphous oxide and a gate electrode formed so as to face the active layer through a gate insulator.

2. The field effect transistor according to claim 1, wherein the transistor is a normally-off type transistor.

3. The field effect transistor according to claim 1, which provides a current of 10 microamperes or less between a source and a drain when no gate voltage is applied.

4. The field effect transistor according to claim 1, wherein the amorphous oxide containing the microcrystal controls entrapment of mobile electrons.

5. The field effect transistor according to claim 1, wherein the amorphous oxide containing the microcrystal decreases the number of conductive electrons.

6. The field effect transistor according to claim 1, wherein the amorphous oxide comprised in the active layer has an electron carrier density of less than 10¹⁸/cm³ and has a tendency to increase electron mobility as electron carrier density increases.