• Laser Solutions
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• v.7 no.3
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• pp.37-46
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• 2004

The shape and size variations of the nanopatterns produced on a polymer film using a near-field scanning optical microscope(NSOM) are investigated with respect to the process variables. A cantilever type nanoprobe having a 100nm aperture at the apex of the pyramidal tip is used with the NSOM and a He-Cd laser at a wavelength of 442nm as the illumination source. Patterning characteristics are examined for different laser beam power at the entrance side of the aperture($P_{in}$), scan speed of the piezo stage(V), repeated scanning over the same pattern, and operation modes of the NSOM(DC and AC modes). The pattern size remained almost the same for equal linear energy density. Pattern size decreased for lower laser beam power and greater scan speed, leading to a minimum pattern width of around 50nm at $P_{in}=1.2{\mu}W\;and\;V=12{\mu}m/s$. Direct writing of an arbitrary pattern with a line width of about 150nm was demonstrated to verify the feasibility of this technique for nanomask fabrication. Application on high-density data storage is discussed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.657-662
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• 2005

In this study, the deposition of micrometer-scale metallic interconnects on LCD glass for the repair of open-circuit type defects is investigated. Although there had been a few studies Since 1980 s for the deposition of metallic interconnects by laser-induced chemical vapor deposition, those studies mostly used continuous wave lasers. In this work, a third harmonic Nd:YLF laser (351nm) of high repetition rates, up to 10 KHz, was used as the illumination source and $W(CO)_6$ was selected as the precursor. General characteristics of the metal deposit (tungsten) such as height, width, morphology as well as electrical properties were examined for various process conditions. Height of the deposited tungsten lines ranged from 35 to 500 nm depending on laser power and scan speed while the width was controlled between $3\~50{\mu}$ using a slit placed in the beam path. The resistivity of the deposited tungsten lines was measured to be below 1 $O\cdot{\mu}m$, which is an acceptable value according to the manufacturing standard. The tungsten lines produced at high scan speed had good surface morphology with little particles around the patterns. Experimental results demonstrated that it is likely that the deposit forms through a hybrid process, namely through the combination of photolytic and pyrolytic mechanisms.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.8 s.173
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• pp.165-173
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• 2005

This paper presents the results for deposition of micrometer-scale metal lines on glass for the development of TFT-LCD circuit repair-system. Although there had been a few studies in the late 1980's for the deposition of metallic interconnects by laser-induced chemical vapor deposition, those studies mostly used continuous wave lasers. In this work, a third harmonic Nd:YLF laser (351nm) of high repetition rates, up to 10 KHz, was used as the illumination source and W(CO)s was selected as the precursor. General characteristics of the metal deposit (tungsten) such as height, width, morphology as well as electrical properties were examined for various process conditions. Height of the deposited tungsten lines ranged from 35 to 500 m depending on laser power and scan speed while the width was controlled between 50um using a slit placed in the beam path. The resistivity of the deposited tungsten lines was measured to be below $1{\Omega}{\cdotu}um$, which is an acceptable value according to the manufacturing standard. The tungsten lines produced at high scan speed had good surface morphology with little particles around the patterns. Experimental results demonstrated that it is likely that the deposit forms through a hybrid process, namely through the combination of photolytic and pyrolytic mechanisms.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.05a
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• pp.638-640
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• 2018

In this paper, FBG sensor is fabricated using 800nm femtosecond laser. The sensor was irradiated with a cumulative dose of 100 kGy gamma ray, and the effect of radiation on the FBG coating material was evaluated.

• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.3
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• pp.343-351
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• 1988

Planar optical waveguides are fabricated on a Y-cut LiNbO3 single crystal substrate by Ti indiffusion method. From data measured by the bright M-line spectroscopy, refractive index profiles are reconstructed by WKB approximation method. Then, single strip, X-crossing strip, and Y-brinch strip optical waveguides are fabricated on X-cut LiNbO3 single crystal substrate, with waveguide patterns made by the laser beam direct writing method. And their near-field intensity profiles are observed after coupling the light to the waveguide edges.

• Korean Journal of Materials Research
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• v.34 no.3
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• pp.144-151
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• 2024

This work focuses on the fabrication of excellent magnetic structures for trapping breast cancer cells. Micromagnetic structures were patterned for trapping cancer cells by depositing 30 nm of permalloy on a silicon substrate. These structures were designed and fabricated using two fabrication techniques: electron beam lithography and laser direct writing. Two types of magnetic structures, rectangular wire and zig-zagged wire, were created on a silicon substrate. The length of each rectangular wire and each straight line of zig-zagged wire was 150 ㎛ with a range of widths from 1 to 15 ㎛ for rectangular and 1, 5, 10 and 15 ㎛ for zigzag, respectively. The magnetic structures showed good responses to the applied magnetic field despite adding layers of silicon nitride and polyethylene glycol. The results showed that Si + Si₃N₄ + PEG exhibited the best adhesion of cells to the surface, followed by Si + Py + Si₃N₄ + PEG. concentration of 5-6 with permalloy indicates that this layer affected silicon nitride in the presence of Polyethylene glycolPEG.

• Journal of the Microelectronics and Packaging Society
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• v.25 no.1
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• pp.35-40
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• 2018

Nd:YAG laser was used to carbonize polyimide films to produce carbon films. This is a simple manufacturing process to fabricate low cost sensors. By applying this method, we studied characteristics of flexible and low-cost piezoresistive. Previously, many studies focused on carbonization of polyimide using $CO_2$ laser with wavelength of $10.6{\mu}m$. In this paper, carbonization (carbonization process) was performed on polyimide films using an Nd:YAG laser with a wavelength of $1.064{\mu}m$. In order to increase the resolution, we optimized the laser conditions of the power density ($W/cm^2$) and the beam scan rate. In previous studies using $CO_2$ laser, the minimum line width was $140{\sim}220{\mu}m$ but in this study, carbon line width was reduced to $35{\sim}40{\mu}m$. The initial sheet resistance of the carbon sensor was $100{\sim}300{\Omega}/{\square}$. The resistance decreased by 30% under stretched with a curvature radius of 21 R. The calculated gauge factor was 56.6. This work offers a simple, highly flexible, and low-cost process to fabricate piezoresistive sensors.

• Journal of the Optical Society of Korea
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• v.9 no.1
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• pp.16-21
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• 2005

Using a cantilever type nanoprobe having a 100㎚m aperture at the apex of the pyramidal tip of a near-field scanning optical microscope (NSOM), nanopatterning of polymer films are conducted. Two different types of polymer, namely a positive photoresist (DPR-i5500) and an azopolymer (Poly disperse orange-3), spincoated on a silicon wafer are used as the substrate. A He-Cd laser with a wavelength of 442㎚ is employed as the illumination source. The optical near-field produced at the tip of the nanoprobe induces a photochemical reaction on the irradiated region, leading to the fabrication of nanostructures below the diffraction limit of the laser light. By controlling the process parameters properly, nanopatterns as small as 100㎚ are produced on both the photoresist and azopolymer samples. The shape and size variations of the nanopatterns are examined with respect to the key process parameters such as laser beam power, irradiation time or scanning speed of the probe, operation modes of the NSOM (DC and AC modes), etc. The characteristic features during the fabrication of ordered structures such as dot or line arrays using NSOM lithography are investigated. Not only the direct writing of nano array structures on the polymer films but also the fabrication of NSOM-written patterns on the silicon substrate were investigated by introducing a passivation layer over the silicon surface. Possible application of thereby developed NSOM lithography technology to the fabrication of data storage is discussed.