Oxide semiconductor thin film and thin film transistor

Patent metadata

Field	Value
Publication number	US-9768316-B2
Application number	US-201414905008-A
Country	US
Kind code	B2
Filing date	Jul 16, 2014
Priority date	Jul 16, 2013
Publication date	Sep 19, 2017
Grant date	Sep 19, 2017

Abstract

Provided is a crystalline oxide semiconductor thin film comprising only bixbyite-structured In 2 O 3 phase, suitable as a channel layer material for a thin film transistor, and having excellent etching properties in an amorphous state and a low carrier density and high carrier mobility in a crystalline state. An amorphous oxide thin film is formed using, as a target, an oxide sintered body which comprises indium, gallium, oxygen, and unavoidable impurities, the gallium content being in a range of 0.09 to 0.45 in terms of a Ga/(In+Ga) atomic ratio, has a In 2 O 3 phase having a bixbyite structure as the main crystal phase, and has a GaInO 3 phase having a β-Ga 2 O 3 -type structure, or a GaInO 3 phase having a β-Ga 2 O 3 -type structure and a (Ga, In) 2 O 3 phase finely dispersed therein. The amorphous oxide thin film is finely processed by performing etching using photolithography, and is annealed.

First claim

What is claimed is:

1. An oxide semiconductor thin film obtained from an oxide sintered body that comprises indium, gallium and unavoidable impurities and being crystalline; wherein
the oxide sintered body comprises a bixbyite-structured In 2 O 3 phase and a β-Ga 2 O 3 -structured GaInO 3 phase, or a bixbyite-structured In 2 O 3 phase, a β-Ga 2 O 3 -structured GaInO 3 phase and a (Ga, In) 2 O 3 phase; and
the gallium content expressed by the Ga/(In+Ga) atomic ratio is greater than 0.15 and less than or equal to 0.45, and the crystal phase is constructed only by bixbyite-structured In 2 O 3 phase.

2. The oxide semiconductor thin film according to claim 1 , wherein the gallium content expressed by the Ga/(In+Ga) atomic ratio is greater than 0.15 and less than or equal to 0.30.

3. The oxide semiconductor thin film according to claim 1 , wherein a carrier density is less than or equal to 5.0×10 17 cm −3 .

4. The oxide semiconductor thin film according to claim 1 , wherein a carrier mobility is greater than or equal to 10 cm 2 V −1 sec −1 .

5. The oxide semiconductor thin film according to claim 1 , wherein the crystallization temperature of amorphous film before crystallizing by an annealing process is greater than or equal to 225° C.

6. A thin-film transistor comprising a source electrode, a drain electrode, a gate electrode, a channel layer, and a gate insulation film, wherein the channel layer comprises the oxide semiconductor thin film according to claim 1 .

7. A display comprising the thin-film transistor according to claim 6 .

Assignees

• Sumitomo Metal Mining Co

Inventors

• Nakayama Tokuyuki
• Nishimura Eiichiro
• Iwara Masashi

Classifications

• H10P14/3434

  being oxide semiconductor materials (Group IIB-VIA semiconductor materials H10P14/3424) · CPC title

• H10P14/22

  using physical deposition, e.g. vacuum deposition or sputtering · CPC title

• H10D30/6757

  characterised by the structure of the channel, e.g. transverse or longitudinal shape or doping profile (TFTs having channel structures for preventing kink or snapback effects H10D30/6708; TFTs having lightly-doped source or drain extensions H10D30/6715) · CPC title

• H01L27/1285

  Electricity · mapped topic

• H01L27/1225

  Electricity · mapped topic