NANOTECHNOLOGY

2008. 3. 13 (목)

이 길 선

나노 기술 (Nano Technology)( gy)“나노미터(1nm = 1x10-9 m : 10억분의 1미터) 크기의 물질을

조작하고 제어하는 기술”조작하고 제어하는 기술

나노: 그리스어로 난쟁이를 의미함

사람 적혈구 DNA 원자백두산지구 핀 머리

m nm(1/십억)

μm(1/백만)

mm(1/천)

km(천)

103 km(백만) (1)

나노기술의 응용

재미있는 나노 현상

크기에 따라 색깔이 바뀌는 나노입자

재미있는 나노 현상합성조건에 따른 다양한 모양의

나노입자

춤추는 자성액체: 콜로이드 상태의 액체 자석(지름 수십 f 로 안정화 $100/ )(지름 : 수십 nm, surfactant로 안정화, >$100/g)

나노기술역사

Si(111)-7x7fu

Si(111)-7x7

5 nm

나노 크기를 어떻게 관찰하는가?

주사형 터널 현미경(STM)

전자현미경

여러가지표면의원자배열

8x8 silicon nitride / Si(111)

fu

Si(111)-7x7 3 x 3Sb/Si(111)-

5 nm

5 3 x5 3Sb/Si(111) Sb/Si(111)-2x1 Si(100)-2x1-

전자의 터널링전자의 터널링

도체 도체절연체

분자주판 단분자의합성

C60 on stepped Cu surface Fe(CO)2

작은 것으로부터 나노크기로 (Bottom-up 방식)

E l Q t C lExample: Quantum Corral

D Ei l IBM

(1) STM manipulation(2) Visualization of the spatial D. Eigler, IBMof the spatial distribution of certain quantum states of thestates of the corral

• Surface state electrons on Cu(111) were confined to closed• Surface state electrons on Cu(111) were confined to closedstructures (corrals) defined by barriers built from Fe datoms.

• A circular corral of radius 71.3 Angstrom was constructed inthis way out of 48 Fe adatoms.

Atomic Manipulation by STMIron on Copper (111):

Circular corralradius= 71 3 Aradius= 71.3 A 48 Fe atoms

Quantum-mechanicalQuantum mechanicalinterference patterns

M.F. Crommie, C.P. Lutz, D.M. Eigler. Science 262, 218-220 (1993).

전자의 파동성 : STM 이미지

48 Fe atoms on Cu(111)( )

STM Manipulation of Atoms and MoleculesSTM Manipulation of Atoms and Molecules

Xenon/Ni(110)Xenon/Ni(110)

Iron/Cu(111)CO/Pt(111)

Atomic Force Microscope (AFM) and Lateral Force Microscope (LFM)

PhotodiodeL

~PiezoLaser

Feedback andx,y,z ScanControl

ImageControl

x,y,z PiezoDrum Scanner

Topography,LFM, etc.

×500 ×20000

< Microscope image > < FE-SEM image >

단분자의 정렬 모양 : AFM 이미지단분자의 정렬 모양 : AFM 이미지

Molecular Images of Au (111) and ODT on Au/micaTopography FFT filtered image Spacing

Au (111) 2 9 ÅAu (111) 2.9 Å

2 5 Å 2 5 Å

5.0 ÅODT 5.0 ÅODT on Au/mica Au (111)

4 0 Å4 0 Å

나노기술의 기술적 접근

□ T d 방식□ Top-down 방식

▶ 나노미터 수준의 가공을 통해 나노미터크기의 구조체를 인공적

으로 형성하는 기술 (거시적 → 미시적, 일반적인 반도체 공정)

□ Bottom-up 방식p

물질의 최소 단위인 원자나 분자를 자유자재로 조작하여 원하는

기능 구조체를 형성하는 기술(미시적 → 거시적 예를 들면 레고처럼기능, 구조체를 형성하는 기술(미시적 → 거시적, 예를 들면 레고처럼

각 조각을 조립하여 전체를 만드는 경우)

( )Dip Pen Lithography (DPN)

Dip-pen nanolithography의 개념

□ Mirkin박사는 AFM측정에서 극복해야 할 단점인 대기 중의 물분자의 기판으로의

이동을 이용하여 코팅하고자 하는 물질을 물과 함께 이동가능성을 생각

Fountain penAFM tip을 이용한 물질전달 개념도

□ 만년필과 DPN의 비교

Fountain pen

DPN Fountain pen

AFM tip Nib (end part of pen)

Solid substrate PaperSolid substrate Paper

Molecules Ink

Dip Pen Nanolithography (DPN)

Invention of DPN• Capillary forces between the AFM tip and the sample → Difficult to achieve molecular resolution in air (water condensation)

Mirkin at el, Science, 283, 1999.Advantages

Key Factors of DPN Resolution• The grain size of substrate

Advantages• Positive patterning • Delivery of different types of

• Interaction between molecules and substrate • The tip-substrate contact time and the scan speed• Relative humidity

molecules at specific sites• Not resist, stamp, complicated processing

Si l i i ( l AFM)Relative humidity • Simple instrumentation (general AFM)

Examples of Direct Nanopatterns by DPN (Mirkin’s group)

Au (111)Amorphous Au Amorphous AuAu (111)Amorphous Au Amorphous Au

HMDS (hexamethyldisilazane) : (H3C)3-Si-NH-Si-(CH3)y 3 3 3

On Oxide surfaces

Amorphous Au

Nanofabrication: Dip Pen NanolithographyNanofabrication: Dip Pen NanolithographyS. Hong and C.A. Mirkin, Northwestern Univ.

Multiple DPN - 8

Protein Detection using DPN

Multiple DPN - 55000

8773 dots

Electrochemical DPN (Liu’s group)

Ag, Ge, Pd, Cu nanowires Au nanowires

Lith hLithography

PhotolithographyPhotolithography

E-beam lithography

Microcontact Printing (uCP)Microcontact Printing (uCP)

Imprinting

Image Display Using Immobilized Vesicles

Immobilized diacetylene liposome

glass substrate

254 nm UV exposure

mask+ polymerization

p

M k P ttp yon exposed areas

Heating at 100 oC

Mask Pattern

blue-to-redcolor transition

Observe patternwith a fluorescence microscope

Patterned Polydiacetylene Image

Nano-meter spacing electrode fabricationp g

SiO / Si waferResist coatingPMMA 950K C2SiO2 / Si wafer

SiO2 thickness: 200 nmPMMA 950K C2Thickness: 80 nm

e-beam lithography& develop PMMA

Metallization 5 nm Ti/10 nm Au

Nano patternChannel width: 20 nm

thermal evaporation& lift off

iQUIPS Korea Univ.

Photo & E-beam Lithography Process

PMMA spin coatingPR spin coating

E-beam LithographyPhoto Lithography

PMMA spin coating(thickness: ~100 nm )

PR spin coating(thickness: ~1 μm )

UV or laser exposureiti ith k

e-beam exposuredi t iti

developmentdevelopmentwaferPRmask

writing with mask direct writing

metallization

lift-off

metallization

lift-off

maskPMMAexposed areametal

lift offlift off

• resist: photo sensitive polymer• light source: UV or ArF laser

• resist: PMMA• light source: e beam• light source: UV or ArF laser

• critical size: ~100 nm• light source: e-beam• critical size:

Nano Pattern Fabrication Process(Dr. Hwang, iQUIPS, Seoul University)( g Q y)

E-beam lithography for nano pattern fabrication

Photo lithography for pad pattern fabrication

SEM Images of Typical Nano-Electrode(Dr H ang iQUIPS Seo l Uni ersit )(Dr. Hwang, iQUIPS, Seoul University)

FE-SEM and AFM Images of Nanoelectrode

7 5 0 n m1 0 0 0 n m

E-beam patterning examplesp g p

D l ttDevelop patternLine width/spacing1. 200 nm/300 nm2. 100 nm/400 nm3 50 /450

12

34 D l tt3. 50 nm/450 nm

4. 100 nm/100 nm5. 50 nm/50 nm

4 5 Develop patternLine width/spacing20 nm/180 nm

Liftoff patternLiftoff pattern Liftoff patternLine width/spacing50 nm/50 nm

Liftoff pattern6 um diameter150 nm line width

iQUIPS Korea Univ.

세상에서 가장 작은 기타: 전자빔 식각 방법

Self-assembled monolayer (SAM) and μCP

▲ LFM images of a gold surface patterned with SAMs terminated in different head groups.

▲ SEM images of test patterns on layers of silver (A, B, C: 50 nm thick; D: 200 nm thick) that were fabricated by mCP with HDT

Angew. Chem. Int. Ed, 37, 550-575 (1998)

Self-assembled monolayer (SAM) and μCPCrystal growth

Whitesides et al., Nature, 398, 495 (1999)

21세기는 나노의 시대21세기는 나노의 시대

수학, 화학, 물리, 생물, 공학의융합 기술