NANOTECHNOLOGY 2008. 3. 13 ( 목 ) 이길선
나노기술 (Nano Technology) 나노미터 (1nm = 1x10-9 m : 10억분의 1미터 ) 크기의물질을조작하고제어하는기술 나노 : 그리스어로난쟁이를의미함 지구 백두산 사람핀머리적혈구 DNA 원자 10 3 km km m ( 백만 ) ( 천 ) (1) mm (1/ 천 ) μm (1/ 백만 ) nm (1/ 십억 )
나노기술의응용
크기에따라색깔이바뀌는나노입자 재미있는나노현상
합성조건에따른다양한모양의나노입자 재미있는나노현상
춤추는자성액체 : 콜로이드상태의액체자석 ( 지름 : 수십 nm, surfactant 로안정화, >$100/g)
나노기술역사 Si(111)-7x7 uf 5 nm
나노크기를어떻게관찰하는가? 주사형터널현미경 (STM) 전자현미경
여러가지표면의원자배열 Si(111)-7x7 8x8 silicon nitride / Si(111) Sb/Si(111)- 3 x 3 uf 5 nm 5 3 x5 3 Sb/Si(111) Sb/Si(111)-2x1 Si(100)-2x1 -
전자의터널링 도체 절연체 도체
분자주판 단분자의합성 C 60 on stepped Cu surface Fe(CO) 2
작은것으로부터나노크기로 (Bottom-up 방식 )
Example: Quantum Corral (1) STM manipulation (2) Visualization of the spatial distribution of certain quantum states of the corral D. Eigler, IBM Surface state electrons on Cu(111) were confined to closed Surface state electrons on Cu(111) were confined to closed structures (corrals) defined by barriers built from Fe datoms. A circular corral of radius 71.3 Angstrom was constructed in this way out of 48 Fe adatoms.
Atomic Manipulation by STM Iron on Copper (111): Circular corral radius= 71.3 A 48 Fe atoms Quantum-mechanical mechanical interference patterns M.F. Crommie, C.P. Lutz, D.M. Eigler. Science 262, 218-220 (1993).
전자의파동성 : STM 이미지 48 Fe atoms on Cu(111)
STM Manipulation of Atoms and Molecules Xenon/Ni(110) CO/Pt(111) Iron/Cu(111)
Atomic Force Microscope (AFM) and Lateral Force Microscope (LFM) Laser Photodiode Piezo ~ x,y,z Piezo Drum Scanner Feedback and x,y,z Scan Control Image Topography, LFM, etc. 500 20000 < Microscope image > < FE-SEM image >
단분자의정렬모양 :AFM 이미지
Molecular Images of Au (111) and ODT on Au/mica Topography FFT filtered image Spacing Au (111) 29Å 2.9 2 5 A 2 5 A ODT 5.0 Å on Au/mica Au (111) 4 0 A 4 0 A
나노기술의기술적접근 Top-down 방식 나노미터수준의가공을통해나노미터크기의구조체를인공적 으로형성하는기술 ( 거시적 미시적, 일반적인반도체공정 ) Bottom-up 방식 물질의최소단위인원자나분자를자유자재로조작하여원하는기능, 구조체를형성하는기술 ( 미시적 거시적, 예를들면레고처럼각조각을조립하여전체를만드는경우 )
Dip Pen Lithography (DPN)
Dip-pen nanolithography 의개념 Mirkin박사는 AFM측정에서극복해야할단점인대기중의물분자의기판으로의이동을이용하여코팅하고자하는물질을물과함께이동가능성을생각 AFM tip 을이용한물질전달개념도 Fountain pen 만년필과 DPN 의비교 DPN AFM tip Solid substrate Molecules Fountain pen Nib (end part of pen) Paper 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. Key Factors of DPN Resolution The grain size of substrate Interaction between molecules and substrate The tip-substrate contact time and the scan speed Relative humidity Advantages Positive patterning Delivery of different types of molecules at specific sites Not resist, stamp, complicated processing Simple instrumentation i (general AFM)
Examples of Direct Nanopatterns by DPN (Mirkin s group) Amorphous Au Au (111) Amorphous Au Amorphous Au HMDS (hexamethyldisilazane) : (H 3 C) 3 -Si-NH-Si-(CH 3 ) 3 3 3 On Oxide surfaces
Nanofabrication: Dip Pen Nanolithography S. 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
Lithographyh Photolithography E-beam lithography Microcontact Printing (ucp) Imprinting
Image Display Using Immobilized Vesicles Immobilized diacetylene liposome glass substrate 254 nm UV exposure mask + polymerization on exposed areas Mask Pattern Heating at 100 o C blue-to-red color transition Observe pattern with a fluorescence microscope Patterned Polydiacetylene Image
Nano-meter spacing electrode fabrication SiO 2 / Si wafer SiO 2 thickness: 200 nm Resist coating PMMA 950K C2 Thickness: 80 nm e-beam lithography & develop PMMA Nano pattern Channel width: 20 nm Metallization 5 nm Ti/10 nm Au thermal evaporation & lift off iquips Korea Univ.
Photo & E-beam Lithography Process Photo Lithography PR spin coating (thickness: ~1 μm ) E-beam Lithography PMMA spin coating (thickness: ~100 nm ) UV or laser exposure writing with mask development metallization lift-off e-beam exposure direct writing development metallization lift-off wafer PR mask PMMA exposed area metal resist: photo sensitive polymer light source: UV or ArF laser critical size: ~100 nm resist: PMMA light source: e-beam critical size: <10 nm PMMA (polymethylmethacrylate)
Nano Pattern Fabrication Process (Dr. Hwang, iquips, Seoul University) E-beam lithography for nano pattern fabrication Photo lithography for pad pattern fabrication
SEM Images of Typical Nano-Electrode (Dr. Hwang, iquips, Seoul University)
FE-SEM and AFM Images of Nanoelectrode 1 0 0 0 n m 7 5 0 n m
E-beam patterning examples 1 2 Develop pattern Line width/spacing 1. 200 nm/300 nm 2. 100 nm/400 nm 3 4 5 Develop pattern 3. 50 nm/450 nm 4. 100 nm/100 nm 5. 50 nm/50 nm Line width/spacing 20 nm/180 nm Liftoff pattern 6 um diameter 150 nm line width Liftoff pattern Line width/spacing 50 nm/50 nm iquips Korea Univ.
세상에서가장작은기타 : 전자빔식각방법
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 μcp Crystal growth Whitesides et al., Nature, 398, 495 (1999)
21 세기는나노의시대 수학, 화학, 물리, 생물, 공학의융합기술