• Korean Journal of Materials Research
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• v.13 no.5
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• pp.279-284
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• 2003

The $CoSi_2$ process is widely employed in a salicide as well as an ohmic layer process. In this experiment, we investigated the characteristics of $CoSi_2$ films by combinations of I-type (TiN 100$\AA$/Co 150$\AA$), II-type(TiN 100$\AA$/Co 150$\AA$/Ti 50$\AA$), III-type(Ti 100$\AA$/Co 150$\AA$/Ti 50$\AA$), and IV-type(Ti 100$\AA$/Co 150$\AA$/Ti 100$\AA$). Sheet resistances of $CoSi_2$ show the lowest resistance with 2.9 $\Omega$/sq. in a TiN/Co condition and much higher resistances in conditions simultaneously applying Ti capping layers and Ti interlayers. Though we couldn't observe a $CoSi_2$roughness dependence on the film stacks from RMS values, Ti capping layers turned into 78∼94$\AA$ thick TiN layers of (200) preferred orientation at $N_2$ambient. In addition, Ti interlayers helped to form the epitaxial $CoSi_2$with (200) preferred orientation and ternary compounds of Co-Ti-Si. We propose that film structures of II-type and III-type may be appropriate in the salicide process and the ohmic layer process from the viewpoint of Co diffusion kinetics and the CoSi$_2$epitaxy.

• Journal of the Korean Ceramic Society
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• v.46 no.1
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• pp.86-93
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• 2009

The crack formation and the resistance of ITO film on PET substrate with a thickness of 20 nm were investigated as a function of strain. The onset strain for the increase of resistance increased with increasing strain rate, suggesting the crack initiation is dependent on the strain rate. Electrical resistance increased at the strain of 1.6% at the strain rates below $10^{-4}/sec$ while it increased at ${\sim}2%$ at the strain rates above $10^{-3}/sec$. The critical strain at which the cracks were formed is close to the proportional limit. Upon loading, the initial cracks perpendicular to the tensile axis were observed and propagated the whole sample width with increasing strain. The spacing between horizontal cracks is thought to be determined by the fracture strength and the interfacial strength between ITO and PET. The crack density increased with increasing strain. However, the effect of the strain rate on the crack density was less pronounced in ITO/PET with 20 nm ITO thickness than ITO/PET with 125 nm ITO thickness, the strength of ITO film is thought to increase as the thickness on ITO film decreases. The absence of cracks on ITO film at a strain as close as 1.5% can be attributed to the compressive residual stress of ITO film which was developed during cooling after the coating process. The higher critical strain for the onset of the resistance increase and the crack initiation of ITO/PET with a thinner ITO film (20 nm) can be linked with the higher strength of the thinner ITO film.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.39-42
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• 2002

Recently, CMP (chemical mechanical polishing) technology has been widely used for global planarization of multi-level interconnection for ULSI applications. However, COO (cost of ownership) and COC (cost of consumables) were relatively increased because of expensive slurry. In this paper, we have studied the possibility of recycle of reused silica slurry in order to reduce the costs of CMP slurry. The post-CMP thickness and within-wafer non-uniformity(WIWNU) were measured as a function of different slurry composition. As a experimental result, the performance of reused slurry with annealed silica abrasive of 2 wt% contents was showed high removal rate and low non-uniformity. Therefore, we propose two-step CMP process as follows In the first-step CMP, we can polish the thick and rough film surface using remaked slurry, and then, in the second-step CMP, we can polish the thin film and fine pattern using original slurry. In summary, we can expect the saving of high costs of slurry.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.9
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• pp.759-764
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• 2003

Recently, CMP (chemical mechanical polishing) technology has been widely used for global planarization of multi-level interconnection for ULSI applications. However, COO (cost of ownership) and COC (cost of consumables) were relatively increased because of expensive slurry. In this paper, we have studied the possibility of recycle of roused silica slurry in order to reduce the costs of CMP slurry. The post-CMP thickness and within-wafer non-uniformity (WIWNU) wore measured as a function of different slurry composition. As an experimental result, the performance of reused slurry with annealed silica abrasive of 2 wt％ contents was showed high removal rate and low non-uniformity. Therefore, we propose two-step CMP process as follows , In tile first-step CMP, we can polish the thick and rough film surface using remaked slurry, and then, in the second-step CMP, we can polish the thin film and fine pattern using original slurry. In summary, we can expect the saying of high costs of slurry.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.240-245
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• 2004

Tensile properties of hard coating material, TiN, were evaluated using micro-tensile testing system. TiN has been known as a hard coating material commonly used today. Micro-tensile testing system consisted of a micro tensile loading system and a micro-ESPI(Electronic Speckle Pattern Interferometry) system. Micro-tensile loading system had a maximum load capacity of 500mN and a resolution of 4.5 nm in stroke. TiN thin film $1{\mu}m$ thick was deposited on the Si wafer pre-deposited of $Si_3N_4$ film substrate by the closed field unbalanced magnetron sputtering (CFUBMS) process. Three kinds of micro-tensile specimen with the respective width of $50{\mu}m$, $100{\mu}m$ and $500{\mu}m$ were fabricated by MEMS process. The mechanical properties including tensile strength and elastic modulus were determined using the micro-tensile testing system and compared by those obtained by nano-indentation

• Journal of Sensor Science and Technology
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• v.13 no.1
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• pp.35-40
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• 2004

A thin-film multijunction thermal converter was fabricated through the process using 6 inch silicon wafer semiconductor process and bulk micromachining. Evanohm R alloy and chromel-constantan were used as a heater and thermocouple materials, respectively. The temperature coefficient of resistance of Evanohm R heater was about 75.12 ppm/$^{\circ}C$ and the voltage sensitivity of the thermal converter indicated about 5.75 mV/mW in air. The transfer differences, measured by FRDC-DC method in the frequency range from 20 Hz to 10 kHz, showed the value under about 1.36 ppm, 0.83 ppm for the film thickness of 500, 200 nm, respectively. And in case of a 200 nm-thick thermal converter, the AC-DC transfer differences seems to be stabilized below the value of 1 ppm in the frequency range from 1 kHz to 500 kHz.

• Geosystem Engineering
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• v.21 no.6
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• pp.318-325
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• 2018

Eight tight sandstone reservoir samples from $He_8$ and $Shan_1$ Formations of the Sulige Gas field were selected to perform gas-water micro-displacement experiment based on authentic sandstone micro-model. The gas pressure-relief experiment was proposed for the first time to simulate the pressure change and gas-water percolation characteristics in the process of gas exploitation. The experiment results show that: (1) In the process of gas accumulation, the gas preferentially flows into the well-connected pores and throats with large radius, but rarely flows into the area without pores and throats. (2) Under sufficient gas drive, the water in pores and throats usually exists in the forms of 'thin water film', 'thick water film', and 'water column', but under insufficient gas drive, gas fails to flow into new pathways in time, so that the reservoirs with large pores and throats are high in water cut. (3) Under the same water saturation, the reservoirs with better petrophysical properties has higher gas recovery factor within unit time. Under the same petrophysical conditions, the reservoirs with lower water saturation show higher gas recovery factor within unit time. The higher the permeability, the stronger the liquid carrying capacity of reservoirs.

• Korean Journal of Materials Research
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• v.29 no.2
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• pp.73-78
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• 2019

Lead free $(Ba_{0.7}Ca_{0.3})TiO_3$ thick films with nano-sized grains are prepared using an aerosol deposition (AD) method at room temperature. The crystallinity of the AD thick films is enhanced by a post annealing process. Contrary to the sharp phase transition of bulk ceramics that has been reported, AD films show broad phase transition behaviors due to the nano-sized grains. The polarization-electric hysteresis loop of annealed AD film shows ferroelectric behaviors. With an increase in annealing temperature, the saturation polarization increases because of an increase in crystallinity. However, the remnant polarization and cohesive field are not affected by the annealing temperature. BCT AD thick films annealed at $700^{\circ}C/2h$ have an energy density of $1.84J/cm^3$ and a charge-discharge efficiency of 69.9 %, which is much higher than those of bulk ceramic with the same composition. The higher energy storage properties are likely due to the increase in the breakdown field from a large number of grain boundaries of nano-sized grains.

• Korean Journal of Materials Research
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• v.28 no.4
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• pp.235-240
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• 2018

We propose a speedy two-step deposit process to form an Au electrode on hole transport layer(HTL) without any damage using a general thermal evaporator in a perovskite solar cell(PSC). An Au electrode with a thickness of 70 nm was prepared with one-step and two-step processes using a general thermal evaporator with a 30 cm source-substrate distance and $6.0{\times}10^{-6}$ torr vacuum. The one-step process deposits the Au film with the desirable thickness through a source power of 60 and 100 W at a time. The two-step process deposits a 7 nm-thick buffer layer with source power of 60, 70, and 80 W, and then deposits the remaining film thickness at higher source power of 80, 90, and 100 W. The photovoltaic properties and microstructure of these PSC devices with a glass/FTO/$TiO_2$/perovskite/HTL/Au electrode were measured by a solar simulator and field emission scanning electron microscope. The one-step process showed a low depo-temperature of $88.5^{\circ}C$ with a long deposition time of 90 minutes at 60 W. It showed a high depo-temperature of $135.4^{\circ}C$ with a short deposition time of 8 minutes at 100 W. All the samples showed an ECE lower than 2.8 % due to damage on the HTL. The two-step process offered an ECE higher than 6.25 % without HTL damage through a deposition temperature lower than $88^{\circ}C$ and a short deposition time within 20 minutes in general. Therefore, the proposed two-step process is favorable to produce an Au electrode layer for the PSC device with a general thermal evaporator.

• Korean Journal of Materials Research
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• v.16 no.3
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• pp.151-156
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• 2006

A method for fabrication of nano-scale GaN structure by inductively coupled plasma etching is proposed, exploiting a thermal dewetting of Pt thin film as an etch mask. The nano-scale Pt metal islands were formed by the dewetting of 2-dimensional film on $SiO_2$ dielectric materials during rapid thermal annealing process. For the case of 30 nm thick Pt films, pattern formation and dewetting was initiated at temperatures greater $600^{\circ}C$. Controlling the annealing temperature and time as well as the thickness of the Pt metal film affected the size and density of Pt islands. The activation energy for the formation of Pt metal island was calculated to be 23.2 KJ/mole. The islands show good resistance to dry etching by a $CF_4$ based plasma for dielectric etching indicating that the metal islands produced by dewetting are suitable for use as an etch mask in the fabrication of nano-scale structures.