KOSEN 한인과학기술자네트워크

다음의 내용은 포항공과대학교 newsletter에서 발췌한 것입니다. 도움이 되시길 바랍니다. 나노 도안을 parallel하게 수행할수 있는 DPN nanoplotter 개발(포항공대 화학과, 박준원 교수 정리) 나노 도안은 고집적 생물학적 소자나 전자 소자 등에 널리 사용될 수 있다. 하지만 지금까지의 기술로는 나노리소그래피의 연속적인 특성으로 인해 처리 속도가 느려, 넓은 지역을 도안하기에는 어려움이 있었다. 노스웨스턴 대학의 Mirkin 연구진에서는 자체 개발한 Dip-Pen Nanolithography(DPN) 방법을 이용하여 nanoplotter을 고안, 좀 더 빠른 처리 속도를 가지며, 나노 도안을 형성할 수 있는 방법을 개발하 였다(science 2000, 288, 1808). DPN 방법은 AFM 팁을 펜으로, 고체 기질을 종이로, 기질과 화학적 친화성이 있는 분자를 잉크라 했을 때, 팁과 기질 사이의 물 매니스커스를 매질로 하여 모세관 이동이라는 추진력을 통해 잉크가 팁에서 기질로 이동함으로써 도안을 형성 하는 방법이다. 이런 DPN 방법의 분해능이 팁의 접촉 힘과는 무관한 특징을 이용, 하나의 피드백 시스템으로 한번에 여러 개의 동일한 나노 도안 을 형성하였다. 이는 나노리소그래피에서 처리 속도를 증가시킬 수 있는 방법을 제시함으로써, 앞으로의 나노리소그래피 발전을 가속시키는 데 기여할 것이다. Words Writ--Very--Small by a Nanopen In a 1959 speech, physicist Richard Feynman wondered whether crafty researchers would one day find a way to write an encyclopedia on the head of a pin. Now, chemists at Northwestern University in Evanston, Illinois, have memorialized a paragraph of Feynman's speech in a most appropriate way, by writing it in an area just one-thousandth the size of a pinhead, using multiple "inks" that line up with one another to produce features as small as 5 nanometers. The work, reported in this week's Science (15 October 1999, p. 523), could pave the way for new nanotechnology applications, ranging from testing novel catalysts to creating nanoscale electronic devices. Previously, researchers have used either electron beam lithography or, more recently, the tiny styluslike arm of an atomic force microscope (AFM) to create nanometer-sized features on a surface. But these techniques can damage the surface or leave behind molecular contaminants, making it hard to add new, pristine layers that line up in perfect registry with the ones below, a typical requirement for making electronic devices. To get around these problems, a group led by Chad Mirkin came up with a technique called dip-pen nanolithography, which uses a water layer to transport organic ink on the AFM tip to a surface (Science, 29 January, p. 661). With just one ink, they could write simple structures, including letters. But making an electronically active nanostructure requires positioning different organic conductors, insulators, and semiconductors in different regions. The Mirkin team hasn't yet accomplished that, but it has taken a step in that direction by figuring out how to align a second set of ink marks with the first. They began by coating one AFM tip with an ink consisting of 16-mercaptohexadecanoic acid (MHA), an organic molecule capped with a water-attracting carboxylic acid group. They then used this ink to write a set of parallel lines 70 nanometers apart. Because they feared that their second AFM pass would damage these lines if they used it to locate them directly, they also put in cross-shaped alignment marks, which sit 2 micrometers on either side of the lines. Next, the researchers changed their AFM tip to one dipped in a second ink called 1-octadecanethiol (ODT), which is capped with a water-repelling methyl group, and scanned this tip across the surface to find the alignment marks. The computer then positioned the tip near the original set of parallel lines and wrote another set alongside the first. Finally, to view the patterns they created, the team switched to an uncoated AFM tip, which they used to scan the entire surface and create an image of the pattern. The method "seems like a real enabler" of nanotechnology, says Clifford Kubiak, a chemist and nanotechnology expert at the University of California, San Diego. While nanowriting could generate some interest among spies, Kubiak believes its real value will be in making numerous nanoscale electronic devices in a highly reproducible fashion. --ROBERT F. SERVICE >dip-pen nanolithography에 관련된 논문을 읽던중 >여러가지 의문점이 생겼는데요 ... >그중에서 특별이 흔히 ink라고 말하는 monomer등과 같은 >물질을 AFM tip에 doping시키는 방법을 알려주세요 >그밖에 전반적인 실험방법을 구체적으로 알려주세요.. >그 수고하세요...