Fabrication of oxide nanostructure using Sidewall

Growth田中研　 M1

尾野篤志

VO2LPCMO

Backgroundstrongly correlated electron system( 強相関電子系 ) in nanosize

100nm100nm 100nm100nm100nmM. Fäth et al, Science 285 (1999)1540

Ferromagnetic

Anti-Ferromagnetic

M. M. Qazilbash et al, Science 318 (2007) 1750,

Metal

Insulator

(La, Pr,Ca)MnO3 filmSTM image

VO2 filmSNIM image

500nm

500nm

• Nanostructure lead to sharp phase transition

Backgroundstrongly correlated electron system( 強相関電子系 ) in nanosize

Nano-structure fabrication techniqueSize-control

Insulator Metal

Y. Yanagisawa et al Appl. PHYSICS LETTERS 89 (2006) 253121

500nm

Future advanced nano-deviceDimension-control

(La, Pr,Ca)MnO3 film

Charge Ordering Insulator 　　Ferromagnetic metal

1μm

Fabrication of nanostructureTop down and Bottom up

Top down Technique • Figure materials finely

For example―Nano Imprint Lithography―AFM Lithography

Bottom up Technique• Accumulate atoms by

depositionFor example―Pulsed Laser Deposition―Sputtering Deposition

　 Top down Bottom upComplex pattern

○ △

Size control △ (>101nm) ○(>10-1nm)

Our nanostructure fabrication methodCombination of Top down and Bottom up

Top Down• Nano Imprint Technology

Bottom up• Pulsed Laser Deposisiton

　 Top down Bottom up CombinationSize control △(>101nm) ○(>10-1nm) ○(>10-1nm)

Complex pattern

○ △ ○

Purpose- Fabrication of oxide nanostructures

and evaluation of their properties-• Establishment of fabrication method

ZnO nanobox

• Measurement of their physical properties• Application for devices

ZnO: Semiconductor, Optical Device

Amorphous @RT ⇒ Crystal @HT

Fabrication of the nanostructureFabrication of the nanostructure① Patterning by NIL ② Depositon using Sidewall growth

③ 　 Removing patterns ( Ion milling and Cleaning) ④ Crystallization by annealing

⑤ Measurement of their physical properties

Experimental method1. Deposition on Plane Substrate 1-1. Control thin film’s thickness 1-2. Optimize crystallization condition by

annealing

2. Deposition on Nano-pattaerne substrate ― Fabricate ZnO nanobox using sidewall

growth

Deposition@ Room temperature

Result1-1: Deposition of ZnO

time-dependency of sidewall thickness

Deposition time [min.]

Film’s thickness∝ Sidewall’s thickness

I measured thin films’ thickness

Sidewall thickness : controllable

Thickness[nm]

ZnO deposition: PLD methodSubstrate: Si(001)PO2=1.0×10-2PaDeposition time: 30-120min.

Evaluation method:Atomic Force Microscopyd: film’s thickness (nm)

t: deposition time (min)

d=1.30t

Result1-2: Crystallization condition

Optimize the condition of Crystallizing ZnO

by Annealing•ZnO crystallization: higher than 550℃

Annealing temperature: 550-950 ℃

Evaluation method: X-ray Diffraction

2θ [°]

Intensity (a.u.)

1μm 1μm

1μm 500nm45nm

Polymers on substrate

Ion Milling

Result2: Fabrication of ZnO nano-boxEvaluation method: Scanning Electron Microscopy

ZnO-deposited substrate

Acetone cleaning

Summary• I succeeded in fabrication of ZnO nanobox by the

combination Top down (imprint) and Bottom up (PLD) technique.

• The side wall thickness was 45nm.• I need to improve the accuracy and responsibility.

This technique can be applied for another system.Various patterns can be formed.

2 µm

100 nm

200 nm

200 nm

60nm

150 nm

150 nm

Examples of the various patterns: Mo, Au

Example of various patterns

N.-G. Cha et al. Nanotechnology 20 (2009) 395301

Next Step―I am trying to fabricate Fe3-xZnxO4 nanowire

500nm

50nm!!

MR effect 　⇒MRAM, Spin FET, …

Spintronics

Y. Yanagisawa et al Appl. PHYSICS LETTERS 89 (2006) 253121 FZO

1.Strongly correlated electron system2.Ferromagnetic semiconductor @ room temperature

Mag

netic

F

ield

Magnetic Field