• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2006.10a
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• pp.14-17
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• 2006

This paper describes a novel processing technique for fabrication of polymer-derived SiCN (silicone carbonitride) microstructures for super-temperature MEMS applications. PDMS (polydimethylsiloxane) mold is fabricated on SU-8 photoresist using standard UV photolithographic process. Liquid precursor is injected into the PDMS mold. Finally, solid polymer structure is cross-linked using HIP (hot isostatic pressure) at $400^{\circ}C$, 205 bar Optimum pyrolysis and anneal ins conditions are determined to form a ceramic microstructure capable of withstanding over $1400^{\circ}C$. The fabricated SiCN ceramic microstructure has excel lent characteristics, such as shear strength (15.2 N), insulation resistance ($2.163{\times}10^{14}\;{\Omega}$) and BDV (min. 1.2 kV) under optimum process condition.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.12
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• pp.597-600
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• 2002

Film Bulk Acoustic wave Resonator (FBAR) using thin piezoelectric films can be made as monolithic integrated devices with compatibility to semiconductor process, leading to small size and low cost, high Q RF circuit elements with wide applications in communications area. This paper presents a MMIC compatible suspended FBAR using surface micromachining. Membrane is composed $Si_3N_4SiO_2Si _3N_4$ multi layer and air gap is about 50${\mu}{\textrm}{m}$. Firstly, We perform one dimensional simulation applying transmission line theorem to verify resonance characteristic of the FBAR. Process of the FBAR is used MEMS technology. Fabricated FBAR resonate at 2.4GHz, $K^2_{eff}$ and Q are 4.1% and 1100.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.147-150
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• 2003

In this paper, We fabricated a high temperature pressure sensor using SBD(silicon- direct-bonding) wafer of $Si/SiO_2$/Si-sub structure. This sensor was very sensitive because the piezoresistor is fabricated by single crystal silicon of the first layer of SDB wafer. Also, it was possible to operate the sensor at high temperature over $120^{\circ}C$ which is the temperature limitation of general silicon sensor because the piezoresistor was dielectric isolation from silicon substrate using silicon dioxide of the second layer. The sensitivity of this sensor is very high as the measured result of D2200 shows $183.6\;{\mu}V/V{\cdot}kPa$. Also, the output characteristic of linearity was very good. This sensor was available at high temperature as $300^{\circ}C$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.3
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• pp.236-240
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• 2012

Limiting thermal exposure time using rapid thermal processing(RTP) has emerged as promising simplified process for manufacturing of solar cell in a continuous way. This paper reports the simplification of co-firing using RTP. Actual temperature profile for co-firing after screen printing is a key issue for high-quality metal-semiconductor contact. The plateau time during the firing process were varied at $450^{\circ}C$ for 10~16 sec. Glass frit in Ag paste etch anti-reflection layer with plateau time. Glass frit in Ag paste is important for the Ag/Si contact formation and performances of crystalline Si solar cell. We achieved 17.14% efficiency with optimum conditions.

• Electrical & Electronic Materials
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• v.9 no.7
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• pp.727-732
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• 1996

In the present paper, the Cu films 4.mu.m thick were deposited by RF magnetron sputtering method on Si wafer. The Cu films deposited at a condition of 100W, 10mtorr exhibited a low electrical resistivity of 2.3.mu..ohm..cm and densed microstructure, poor adhesion. The Cu films grown by 200W, 20mtorr showed a good adhesion property and higher electrical resistivity of 7.mu..ohm..cm because of porous columnar microstructure. Therefore, The Cu films were deposited by double layer deposition method using RF magnetron sputtering on Si wafer. The dependence of the electrical resistivity, adhesion, and reflectance in the CU films [C $U_{4-d}$(low resistivity) / C $U_{d}$(high adhesion) / Si-wafer] on the thickness of d has been investigated. The films formed with this deposition methods had the low electrical resistivity of about 2.6.mu..ohm..cm and high adhesion of about 700g/cm.m.m.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.835-838
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• 1992

The $TiN/TiSi_2$ bilayer has been studied for contact barrier layer at ULSI recently. The $TiN/TiSi_2$ bilayer was formed by RTA in $NH_3$ ambient simultaneously after the Ti film was deposited on silicon substrate. In this paper, properties of $TiN/TiSi_2$ bilayer was evaluated according to $BF_2$ dopant concentration and dopant redistribution in $TiN/TiSi_2$ bilayer was also analyzed. In this experiment, the composition and structure of $TiN/TiSi_2$ bilayer were constant even though dopant concentration increased but silicide growth rate decreased. Boron atoms were redistributed within TiN film and at $TiSi_2Si$ interface during the bilayer formation.

• Journal of Sensor Science and Technology
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• v.6 no.6
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• pp.483-490
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• 1997

Thin film Si has been used in sensors, radiation detectors, and solar cells. The carrier mobility of thin film Si influences the device behavior through its frequency response or time response. Since poly-Si shows the higher mobility value, a-Si:H films on Mo substrate were subjected to various crystallization treatments. Consequently, we need to find an appropriate method in mobility measurement before and after the anneal treatment. This paper investigates the carrier mobility improvement with anneal treatments and summarizes the mobility measurement methods of the a-Si:H and poly-Si film. Various techniques were investigated for the mobility determination such as Hall mobility, HS, TOF, SCLC, TFT, and TCO method. We learned that TFT and TCO method are suitable for the mobility determination of a-Si:H and poly-Si film. The measured mobility was improved by $2{\sim}3$ orders after high temperature anneal above $700^{\circ}C$ and grain boundary passivation using an RF plasma rehydrogenation.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.1076-1078
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• 2004

In this paper, we report $Eu^{2+}$ activated green phosphor $Ba_2CaMgSi_2O_8:Eu^{2+}$. This phosphor absorbs ultroviolet radation and emits a green visible light. The phosphors were synthesized by conventional solid state reaction method. Reagent grade $BaCO_3$, $CaCO_3$, MgO, $SiO_2$, $Eu_2O_3$ were used as raw materials. The raw materials were mixed thoroughly with an appropriate amount of ethanol in an agate mortar and then dried at 90 $^{\circ}C$ for 2 hours. The mixture was sintered at 900 $^{\circ}C$ for 2 hours and reheated at the mild reducing atmosphere 5% $H_2$ gas mixed with 95% $N_2$ gas at about 900 $^{\circ}C$ to 1250 $^{\circ}C$ for 2 hours. The photoluminescence spectra of the phosphor powders were measured by a fluorescent spectrophotometer. The crystal structure of phosphor powders were investigated by X-ray diffractometer.

• Journal of Electrical Engineering and information Science
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• v.2 no.5
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• pp.108-113
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• 1997

In this paper, the optimum condition of (110) Si etching with the potassium hydroxide(KOH) etchant is presented. Although several researches on (110) Si anisotropic etching have been studied, there has been lack of effects of mask quality and etching conditions on the selectivity and the roughness o the etched surface. Three kinds of masks (film, emulsion and E-beam mask) were used in order to verify the effect of etching properties. Anisotropic bulk etching depends on the crystalline orientation and the concentration and temperature of the etchant. In order to investigate the effect of etching conditions on selectivity and the roughness of the etched surface, the concentration of the etchant was varied from 35 to 45 per cent in weight with increments by 5 per cent and the temperature was changed from 70 to 90$^{\circ}C$ with increments by 10$^{\circ}C$. The combination of the temperature of 70$^{\circ}C$ and the concentration of 40wt.% was found to be the optimum etching condition for high selectivity. Etched surfaces show minimum surfaces show minimum surface roughness at a temperature of 80$^{\circ}C$ and a concentation of 40wt.%. Comb structures with various comb widths were fabricated and the lengths of the combs wree measured with several etching time durations. A micro comb structure 525$\mu\textrm{m}$ high was fabricated for MEMS application.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.323-324
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• 2007

Investigation of improving the properties of UV photodetector which uses the wide bandgap of ZnO are under active progress. In this paper, transparent conducting aluminum-doped Zinc oxide films(AZO) were prepared by rf magnetron sputtering on glass(corning 1737) and p-Si substrate, were then annealed at temperature $400^{\circ}C$ for 2hr. The AZO thin films were deposited by RF sputtering system. HF power and work pressure is 120 W and 15 mTorr, respectively, and the purity of AZO target is 5N. The AZO thin films were deposited at 300, 400, $500^{\circ}C$, and $600^{\circ}C$. For sample deposited at $400^{\circ}C$, we observed best $V_r-I_{ph}$ of 0.94 mA and good transmittance.