• Proceedings of the Korean Vacuum Society Conference
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• 2008.02a
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• pp.75-75
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• 2008

• International Journal of Precision Engineering and Manufacturing
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• v.8 no.2
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• pp.54-58
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• 2007

This paper describes an atomic force microscope (AFM)-based instrument for measuring the nanoscale cutting edge profiles of diamond cutting tools. The instrument consists of a combined AFM unit and an optical sensor to align the AFM tip with the top of the diamond cutting tool edge over a submicron range. In the optical sensor, a aser beam is emitted from a laser diode along the Y-axis and focused to a small beam spot with a diameter of approximately $10{\mu}m$ at the beam waist, which is then received by a photodiode. The top of the tool edge is first brought into the center of the beam waist by adjusting it in the X-Z-plane while monitoring the variation in the photodiode output. The cutting tool is then withdrawn and its top edge position at the beam center is recorded. The AFM tip can also be positioned at the beam center in a similar manner to align it with the top of the cutting edge. To reduce electronic noise interference on the photodiode output and thereby enhance the alignment accuracy, a technique is applied that can modulate the photodiode output to an AC signal by driving the laser diode with a sinusoidal current. Alignment experiments and edge profile measurements of a diamond cutting tool were carried out to verify the performance of the proposed system.

• Tribology and Lubricants
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• v.35 no.4
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• pp.199-205
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• 2019

Two-dimensional materials such as graphene, h-BN, and $MoS_2$ have attracted increased interest as solid lubricant and protective coating layer for nanoscale devices owing to their superior mechanical properties and low friction characteristics. In this work, the frictional properties of single-layer graphene, h-BN, and $MoS_2$ are experimentally investigated under various normal forces using atomic force microscope (AFM) tips with a spherical and flat end, with the aim to gain a better understanding of frictional behaviors. The nonlinear relationship between friction and normal force friction was clearly observed for single-layer graphene, h-BN, $MoS_2$ specimens slid against the spherical and flat AFM tips. The results also indicate that single-layer graphene, h-BN, $MoS_2$ exhibit low frictional properties (e.g., friction coefficient below 0.1 under 70~100 nN normal force). In particular, graphene is found to be superior to h-BN and $MoS_2$ in terms of frictional properties. However, the friction of single-layer graphene, h-BN, $MoS_2$ against the flat tip is larger than that against the spherical tip, which may be attributed to the relatively large adhesion. Furthermore, it is shown that the fluctuation of friction is more significant for the flat tip than the spherical tip. The resutls of this study may be helpful to elucidate the feasibility of using two-dimensional materials as solid lubricant and protective coating layer for nanoscale devices.

• Journal of the Korean institute of surface engineering
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• v.47 no.6
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• pp.362-367
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• 2014

We report the design, fabrication of a $Si_3N_4$ probe and calculation of its mechanical properties for DPN(dip pen nanolithography), which consists of dual tips. Concept of dual tip probe is to employ individual tips on probe as either an AFM tip for imaging or a writing tip for nano patterning. For this, the dual tip probe is fabricated using low residual stress $Si_3N_4$ material with LPCVD deposition and MEMS fabrication process. On the basis of FEM analysis we show that the functionality of dual tip probe for imaging is dependent on the dimensions of dual tip probe, and high ratio of widths of beam areas is preferred to minimize curvature variation on probe.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.54-54
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• 2009

AFM anodic oxidation has the capability of patterning complex nano-patterns under relatively high speeds and low voltage. We report the fabrication using a atomic force microscopy (AFM) of silicon nano-ribbon and nano-field effect transistors (FETs). The fabricated nano-patterns have great potential characteristics in various fields due to their interesting electronic, optical and other profiles. The results shows that oxide width and the separation between the oxide patterns can be optimally controlled. The subsequently fabricated silicon nano-ribbon and nano-FET working devices were controled by various tip-sample bias-voltages and scan speed of AFM anodic oxidation. The results may be applied for highly integration circuits and sensitive optical sensor applications.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1778-1783
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• 2008

A compact and two-dimensional atomic force microscope (AFM) using an orthogonal sample scanner, a calibrated homodyne laser interferometer and a commercial AFM head was developed for use in the nanometrology field. The x and y position of the sample with respect to the tip are acquired by using the laser interferometer in the open-loop state, when each z data point of the AFM head is taken. The sample scanner which has a motion amplifying mechanism was designed to move a sample up to $100{\times}100{\mu}m^2$ in orthogonal way, which means less crosstalk between axes. Moreover, the rotational errors between axes are measured to ensure the accuracy of the calibrated AFM within the full scanning range. The conventional homodyne laser interferometer was used to measure the x and y displacements of the sample and compensated via an X-ray interferometer to reduce the nonlinearity of the optical interferometer. The repeatability of the calibrated AFM was measured to sub-nm within a few hundred nm scanning range.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.268-271
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• 2005

Etch resistance of mask layer on silicon substrate modified by AFM-based Tribo-Nanolithography (TNL) in Aqueous Solution in an aqueous solution was demonstrated. n consists or sequential processes, nano-scratching and wet chemical etching. The simple scratching can form a mask layer on the silicon substrate, which acting as an etching mask. For TNL, a specially designed cantilever with diamond tip, allowing the formation of mask layer on silicon substrate easily by a simple scratching process, has been applied instead of conventional silicon cantilever fur scanning. This study demonstrates how the TNL parameters can affect the etch resistance of mask layer, hence introducing a new process of AFM-based maskless nanolithography in aqueous solution.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.643-648
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• 2000

The AFM is an imaging tool or a profiler with unprecedented 3-D resolution for various surface types. The AFM technology, however, leaves a lot of room for improvement due to its delicate and fragile probing mechanism. The distance between probe tip and sample surface must be maintained in below the nano meter level in order to measure the sample surface in Angstrom resolution. In this paper, the mode analysis of AFM system, modification based on the mode analysis are performed and finally the sample surface is measured by the home-built AFM.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.461-462
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• 2006

This paper reports on the development of a scanning probe microscopy(SPM) tip with caborn nanotubes. We used an electric field which causes dielectrophoresis(DEP), to align and deposit CNTs on a metal-coated SPM tip. Using the CNT attached SPM tip, we have obtained an enhanced resolution and wear property compared to that from the bare silicon tip through the scanning of the surface of the bio materials. The carbon nanotube tip align toward the source of the ion beam allowing their orientation to be changed at precise angles. By this technique, metal coated carbon nanotube tips that are several micrometer in length are prepared for scanning probe microscopy.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.67-68
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• 2002

The properties and mechanism of silicon protuberance and groove processing by diamond tip sliding using atomic force microscope (AFM) in atmosphere were studied. To control the height of protuberance and the depth of groove, the processed height and depth depended on load and diamond tip radius were evaluated. Nanoprotuberances and grooves were fabricated on a silicon surface by approximately 100-nm-radius diamond tip sliding using an atomic force microscope in atmosphere. To clarify the mechanical and chemical properties of these parts processed, changes in the protuberance and groove profiles due to additional diamond tip sliding and potassium hydroxide (KOH) solution etching were evaluated. Processed protuberances were negligibly removed, and processed grooves were easily removed by additional diamond tip sliding. The KOH solution selectively etched the unprocessed silicon area. while the protuberances, grooves and flat surfaces processed by diamond tip sliding were negligibly etched. Three-dimensional nanofabrication is performed in this study by utilizing these mechanic-chemically processed parts as protective etching mask for KOH solution etching.