• Laser Solutions
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• v.14 no.3
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• pp.17-20
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• 2011

We fabricated a multi-layer diffraction grating inside fused silica glass by using a femtosecond laser direct writing method. The femtosecond laser with a wavelength of 515 nm, a pulse width of 250 fs, a repetition rate of 100 kHz, and an average output power of 6 W was used. Two layer diffraction grating with a grating period of $6{\mu}m$ was successfully fabricated with the layer gap of 0.5, 1, 2, 3, and $5{\mu}m$, respectively. Also, we investigated the diffraction pattern by illuminating a He-Ne laser beam. Finally, we demonstrated the diffraction grating with a grating period of $3{\mu}m$ by adjusting the gap of each layer with a grating period of $6{\mu}m$. Femtosecond laser direct writing technology of multi-layer has a potential to fabricate the diffraction grating with a grating period of below $1.5{\mu}m$.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.65-66
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• 2010

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.663-666
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• 2000

Laser direct writing of micro-patterned copper lines has been achieved by pyrolytic decomposition of copper formate films (Cu(HCOO)$_2$$.$4H$_2$O), as a precursor, using a focused Ar$\^$+/ laser beam ($\lambda$= 514 nm) on PCB boards and glass substrates. The linewidth and thickness of the lines were investigated as a function of laser power and scan speed. The profiles of the lines were measured by scanning electron microscope (SEM), surface profiler (${\alpha}$-step) and atomic force microscopy (AFM). The electrical resistivities of the patterned lines were also investigated as a function of laser parameter using probe station and semiconductor analyzer. we compared resistivities of the patterned lines with that of the Cu bulk, respectively.

• Laser Solutions
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• v.10 no.2
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• pp.17-24
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• 2007

We have studied a laser direct writing lithography(LDWL). This is more important to apply to micro patterning using UV laser. We demonstrate the possibility of LDWL and construct the fabrication system. We use Galvano scanner to process quickly micro patterns from computer data. And laser beam is focused with $F-{\theta}$ lens. AZ5214 and SU-8 photoresist are chosen as experimental materials and a kind of well-known positive and negative photoresist respectively. Laser ablation mechanism depends on the optical properties of polymer. In this paper, therefore we investigate the phenomenon of laser ablation according to the laser fluence variation and measure the shape profile of micro patterned holes. From these experimental results, we show that LDWL is very useful to process various micro patterns directly.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.10a
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• pp.319-320
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• 2012

• Journal of Sensor Science and Technology
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• v.24 no.4
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• pp.215-218
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• 2015

As several innovative technologies for flexible electric devices are being realized, demand for in-situ strain monitoring for flexible electric devices is being emphasized. Because flexible devices are commonly influenced by substrate strain, suitable strain sensors for flexible devices are essential for the sophisticated maneuvering of flexible devices. In this study, a flexible strain sensor based on an Ag electrode is prepared on a polyimide substrate using the LDW (laser direct writing) process. In this process, first, the Ag nanoparticles are coated on the substrate and selectively sintered using a focused laser. Because of the advantages of the LDW process (such as being mask-less, using low temperatures, and having non-vacuum characteristics), the entire fabrication process has been dramatically simplified; as a final outcome, a highly reliable strain sensor has been fabricated. Using this strain sensor, various strain conditions that arise from different bending radii can be detected by measuring real-time electrical signals.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1889-1892
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• 2003

The fabrication of micro-size patterning on alumina substrate is generated by laser direct writing, which has high precision and selectivity of various laser beam energies. The depth and width of patterns is affected by laser parameter such as laser power, scan rate. Through the chemical and mechanical polishing Pd seeds was effectively got rid of alumina substrate for selectivity electroless Ni plating. Thermal treatment is good method for changing electrical property of conductor line, because the treatment can control of the grain size.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.11a
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• pp.279-280
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• 2008

• Proceedings of the Korean Society of Laser Processing Conference
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• 2002.11a
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• pp.91-94
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• 2002

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.11
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• pp.969-975
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• 2000

Laser direct writing of micro-patterned copper lines has been achieved by pyrolytic decomposition of copper formate films (Cu(HCOO)$_2$.4$H_2O$), as a metallo-organic precursor, using a focused CW Ar$^{+}$ laser beam (λ=514nm) on PCB boards and glass substrates. The linewidth and thickness of the lines wee investigated as a functin of laser power and scan speed. The profiles of the lines were measured by scanning electron microscope (SEM), surface profiler ($\alpha$-step) and atomic force measured by scanning electron microscope (SEM), surface profiler ($\alpha$-step) and atomic force microscopy (AFM). The electrical resistivities of the patterned lines were also investigated as a function of laser parameters using probe station and semiconductor analyzer. We compared resistivities of the patterned copper lines with these of the Cu bulk. Resistivities decreased due to changes in morphology and porosity of the deposit, which were about 3.8 $\mu$$\Omega$cm and 12$\mu$$\Omega$cm on PCB and glass substrates after annealing at 30$0^{\circ}C$ for 5 minutes.s.