title: Fabrication of tungsten probe for hard tapping operation in atomic force microscopy.
abstract: We propose a method of producing a tungsten probe with high stiffness for atomic force microscopy (AFM) in order to acquire enhanced phase contrast images and efficiently perform lithography. A tungsten probe with a tip radius between 20nm and 50nm was fabricated using electrochemical etching optimized by applying pulse waves at different voltages. The spring constant of the tungsten probe was determined by finite element analysis (FEA), and its applicability as an AFM probe was evaluated by obtaining topography and phase contrast images of a Si wafer sample partly coated with Au. Enhanced hard tapping performance of the tungsten probe compared with a commercial Si probe was confirmed by conducting hard tapping tests at five different oscillation amplitudes on single layer graphene grown by chemical vapor deposition (CVD). To analyze the damaged graphene sample, the test areas were investigated using tip-enhanced Raman spectroscopy (TERS). The test results demonstrate that the tungsten probe with high stiffness was capable of inducing sufficient elastic and plastic deformation to enable obtaining enhanced phase contrast images and performing lithography, respectively.
authors.affiliation: Department of Physics and Optical Engineering, Rose-Hulman Institute of Technology, 5500 Wabash Avenue, Terre Haute, Indiana 47803, USA; Department of Mechanical Design and Robot Engineering, Seoul National University of Science and Technology, 232 Gongneung-ro, Nowon-gu, Seoul 139-743, Korea. Electronic address: hanguebum@live.co.kr.
authors.forename: Guebum
authors.initials: G
authors.lastname: Han
authors.affiliation: Manufacturing Systems and Design Engineering Programme, Seoul National University of Science & Technology, 232 Gongneung-ro, Nowon-gu, Seoul 139-743, Korea. Electronic address: hsahn@seoultech.ac.kr.
authors.forename: Hyo-Sok
authors.initials: HS
authors.lastname: Ahn
keywords: Electrochemical etching; Finite element analysis; High stiffness; Phase contrast image; Tip-enhanced Raman spectroscopy; Tungsten probe