AVS 49th International Symposium
    Organic Films and Devices Wednesday Sessions
       Session OF+EL-WeP

Paper OF+EL-WeP2
Nanolithography Technique Based on Dynamic Mode Atomic Force Microscopy and Organosilane Self-Assembled Monolayers

Wednesday, November 6, 2002, 11:00 am, Room Exhibit Hall B2

Session: Organic Films and Devices
Presenter: K. Hayashi, Nagoya University, Japan
Authors: K. Hayashi, Nagoya University, Japan
N. Saito, Nagoya University, Japan
H. Sugimura, Nagoya University, Japan
O. Takai, Nagoya University, Japan
Correspondent: Click to Email
Organosilane self-assembled monolayer (SAM) is a candidate for resist material in future nanolithography techniques. Although several techniques have been applied to patterning of the SAMs, scanning probe lithography using an atomic force microscope (AFM) is promising since the method has a high potential in archiving nanometer scale resolution. However, there has been a serious problem, that is, damages of the AFM-tip, when the AFM is operated in the contact mode. Here we report on nanopatterning of organosilane SAMs using a dynamic mode AFM in which tip damages are expected to be reduced. We observe AFM-tip induced chemical changes on the SAM surfaces by Kelvin-probe force microscopy (KFM) working in the dynamic mode as well. Onto cleaned silicon (Si) substrates covered with native oxide (SiO@sub 2@), a SAM was formed from n-octadecyltrimethoxysilane [ODS: CH@sub 3@(CH@sub 2@)@sub 17@Si(OCH@sub 3@)@sub 3@]. Thickness of this ODS-SAM was ca. 1.8 nm. While scanning a AFM-tip (Au coated Si tip), operated in the dynamic mode, on an ODS-SAM/Si sample, a DC bias voltage was applied between the conductive tip and the sample. After the patterning, the sample surface was characterized by KFM. Due to electrochemical reactions induced by the injected current, the modified region where current had been injected from the tip was found to show a more positive surface potential than the surrounding unmodified region. Through the surface potential images acquired by KFM, chemical changes of ODS-SAM could be detected, while such changes could hardly be confirmed in topographic images. KFM is a powerful means to characterize nanoscale patterns on the SAMs drawn by scanning probe lithography.