• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.59-62
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• 2005

Small force measurements ranging from 1 pN to $100{\mu}N$, we call it Nano Force, become the questions of common interests of biomechanics, nanomechanics, material researches, and so on. However, unfortunately, quantitative and accurate force measurements have not been taken so far. This is because there ,are no traceable force standards and a calibration scheme. This paper introduces a quantitative force metrology, which provides traceable link to SI (International Systems of Units). We realize SI traceable force ranging from 1 nN to $100{\mu}N$ using an electrostatic balance and disseminate it through transfer standards, which are self-sensing cantilevers that have integrated piezoresistive strain gages. We have been built a prototype electrostatic balance and Nano Force Calibrator (NFC), which is an AFM cantilever calibration system. As a first experiment, we calibrated normal spring constants of commercial AFM cantilevers using NFC. Calibration results show that the spring constants of them are quite differ from each other and nominal values provided by a manufacturer (up to 240% deviation).

• Journal of Photoscience
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• v.11 no.32
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• pp.47-53
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• 2004

A laser scanning fluorescence microscope system has been fabricated for single molecule detection (SMD). Problems associated with the system set-up have been discussed along with proper suggestions. Based on the SMD results obtained by using the apparatus, a statistical method has been suggested to determine the minimum number of required molecules to form a group of uniform average in a selected error range.

• International Journal of Precision Engineering and Manufacturing
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• v.9 no.4
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• pp.32-38
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• 2008

This paper describes a fast tool control (FTC)-based diamond turning process for fabricating large-area high-quality micro-lens arrays. The developed FTC unit has a stroke of $48{\mu}m$ and a resonance frequency of 4.9 kHz. Micro-lens arrays were fabricated using a micro-cutting tool with a nose radius of $50{\mu}m$. The FTC unit was integrated with a force sensor so that the initial position of the micro-cutting tool with respect to the workpiece surface could be detected through monitoring the contacting force. The length and depth of the designed parabolic micro-lens profile were $190{\mu}m$ and $20{\mu}m$, respectively. A micro-lens array was fabricated on a cylinder surface over an area of ${\phi}55 mm{\times}40 mm$.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.170.1-170.1
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• 2016

$Bi_2Te_3$ has long been studied for its excellent thermoelectric characteristics. Recently, this material has been known as a topological insulator (TI). The surface states within the bulk band gap of a TI, which are protected by the time reversal symmetry, contribute to the conduction at the surface, while the bulk is in insulating state. In contrast to the bulk defects tuning the chemical potential to the Dirac energy, the native defects near the surface are expected not to change the shape of the Fermi surface and the related spin structure. Using scanning tunneling microscopy (STM), we have systematically characterized surface or near surface defects in p- and n- doped $Bi_2Te_3$, and identified their structure by first principles calculations. In addition, bias-polarity dependences of STM images revealed the electron donor/acceptor nature of each defect. A detailed theoretical study of the surface states near the Dirac energy reveals the robustness of the Dirac point, which verifies the effectiveness of the disturbance on the backscattering from various kinds of defects.

• International Journal of Precision Engineering and Manufacturing
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• v.9 no.3
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• pp.27-32
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• 2008

This paper describes a contact atomic force microscope (AFM) that can be used for high-speed precision measurements of microstructured surfaces. The AFM is composed of an air-bearing X stage, an air-bearing spindle with the axis of rotation in the Z direction, and an AFM probe unit. The traversing distance and maximum speed of the X stage are 300 mm and 400 mm/s, respectively. The spindle has the ability to hold a sample in a vacuum chuck with a maximum diameter of 130 mm and has a maximum rotation speed of 300 rpm. The bandwidth of the AFM probe unit in an open loop control circuit is more than 40 kHz. To achieve precision measurements of microstructured surfaces with slopes, a scanning strategy combining constant height measurements with a slope compensation technique is proposed. In this scanning strategy, the Z direction PZT actuator of the AFM probe unit is employed to compensate for the slope of the sample surface while the microstructures are scanned by the AFM probe at a constant height. The precision of such a scanning strategy is demonstrated by obtaining profile measurements of a microstructure surface at a series of scanning speeds ranging from 0.1 to 20.0 mm/s.

• International Journal of Precision Engineering and Manufacturing
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• v.5 no.3
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• pp.19-25
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• 2004

Pitch measurements of 150 nm one-dimensional grating standards were carried out using a contact mode atomic force microscopy with a high resolution three-axis laser interferometer. This measurement technique was named as the 'nano-metrological AFM'. In the nano-metrological AFM, three laser interferometers were aligned precisely to the end of an AFM tip. Laser sources of the three-axis laser interferometer in the nano-metrological AFM were calibrated with an I$_2$ stabilized He-Ne laser at a wavelength of 633 nm. Therefore, the Abbe error was minimized and the result of the pitch measurement using the nano-metrological AFM could be used to directly measure the length standard. The uncertainty in the pitch measurement was estimated in accordance with the Guide to the Expression of Uncertainty in Measurement (GUM). The primary source of uncertainty in the pitch-measurements was derived from the repeatability of the pitch-measurements, and its value was about 0.186 nm. The average pitch value was 146.65 nm and the combined standard uncertainty was less than 0.262 nm. It is suggested that the metrological AFM is a useful tool for the nano-metrological standard calibration.

• Journal of Powder Materials
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• v.20 no.2
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• pp.129-133
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• 2013

In this paper we have studied the effect of water droplet size on nano-particle size distribution using SMPS(Scanning Mobility Particle Sizer)system. It can be seen that the unknown peak at >100 nm was caused by water droplets which did not dry completely when DI water was used as a solvent in the SMPS system. Therefore, it is important to dry water droplets generated from atomizer in the SMPS system when measuring the particle size distribution using less than 100 nm nano-particles in diameter. From this study, It can be concluded that the napion was a useful material as dryer ones and using EAG(Electro Aerosol Generator) as a particle generator was the most effective in reducing the effect of water droplets.

• JSTS:Journal of Semiconductor Technology and Science
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• v.12 no.2
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• pp.219-229
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• 2012

In the course of feasibility study the necessity of implementing electrochemical methods as an inline metrology technique to characterize semiconductor nano structures for a Deep Trench Dynamic Random Access Memory (DT-DRAM) (e.g. ultra shallow junctions USJ) was discussed. Hereby, the state of the art semiconductor technology on the advantages and disadvantages of the most recently used analytical techniques for characterization of nano electronic devices are mentioned. Various electrochemical methods, their measure relationship and correlations to physical quantities are explained. The most important issue of this paper is to prove the novel usefulness of the electrochemical micro cell in the semiconductor industry.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.6
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• pp.96-104
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• 2007

Calibration of the spring constants of atomic force microscopy (AFM) cantilevers is one of the issues in biomechanics and nanomechanies for quantified force metrology at pieo- or nano Newton level. In this paper, we present an AFM cantilever calibration system: the Nano Force Calibrator (NFC), which consists of a precision balance and a one-dimensional stage. Three types of AFM cantilevers (contact and tapping mode) with different shapes (beam and V) and spring constants (42, 1, 0.06 N $m^{-1}$) are investigated using the NFC. The calibration results show that the NFC can calibrate the micro cantilevers ranging from 0.01 ${\sim}$ 100 N $m^{-1}$ with relative uncertainties of less than 2%.

• Proceedings of the Korean Magnestics Society Conference
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• 2004.06a
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• pp.2-2
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• 2004