• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.6
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• pp.1099-1103
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• 2007

TFT's have been intensively researched for possible electronic and display applications. Through tremendous engineering and scientific efforts, a-Si:H TFT fabrication process was greatly improved. In this paper, the reason on defects occurring at a-Si:H TFT fabrication process is analyzed and solved, so a-Si:H TFT's yield is increased and reliability is improved. The a-Si:H TFT of this paper is inverted staggered type TFT. The gate electrode is formed by patterning with length of $8{\mu}m{\sim}16{\mu}m$ and width of $80{\sim}200{\mu}m$ after depositing with gate electrode (Cr). We have fabricated a-SiN:H, conductor, etch-stopper and photo-resistor on gate electrode in sequence, respectively. We have deposited n+a-Si:H, NPR(Negative Photo Resister) layer after forming pattern of Cr gate electrode by etch-slower pattern. The NPR layer by inverting pattern of upper Sate electrode is patterned and the n+a-Si:H layer is etched by the NPR pattern. The NPR layer is removed. After Cr layer is deposited and patterned, the source-drain electrode is formed. The a-Si:H TFT made like this has problems at photo-lithography process caused by remains of PR. When sample is cleaned, this remains of PR makes thin chemical film on surface and damages device. Therefor, in order to improve this problem we added ashing process and cleaning process was enforced strictly. We can estimate that this method stabilizes fabrication process and makes to increase a-Si:H TFT's yield.

• JSTS:Journal of Semiconductor Technology and Science
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• v.10 no.4
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• pp.300-308
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• 2010

This paper describes the development of a low-power electrocardiogram (ECG) touch sensor intended for the use with two dry metal electrodes. An equivalent ECG extraction circuit model encountered in a ground-free two-electrode configuration is investigated for an optimal sensor read-out circuit design criteria. From the equivalent circuit model, (1) maximum sensor resolution is derived based on the electrode's background thermal noise, which originates from high electrode-skin contact impedance, together with the input referred noise of instrumentation amplifier (IA), (2) 60 Hz electrostatic coupling from mains and motion artifact are also considered to determine minimum requirement of common mode rejection ratio (CMRR) and input impedance of IA. A dedicated ECG read-out front end incorporating chopping scheme is introduced to provide an input referred circuit noise of 1.3 ${\mu}V_{rms}$ over 0.5 Hz ~ 200 Hz, CMRR of IA > 100 dB, sensor resolution of 7 bits, and dissipating only 36 ${\mu}W$. Together with 8 bits synchronous successive approximation register (SAR) ADC, the sensor IC chip is implemented in 0.18 ${\mu}m$ CMOS technology and integrated on a 5 cm $\times$ 8 cm PCB with two copper patterned electrodes. With the help of proposed touch sensor, ECG signal containing QRS complex and P, T waves are successfully extracted by simply touching the electrodes with two thumbs.

• Proceedings of the Korean Magnestics Society Conference
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• 2004.12a
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• pp.80-80
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• 2004

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.1463-1465
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• 2008

We report all-ink-jet printed inorganic/organic hybrid TFTs on plastic substrates. We have investigated the optimal printing conditions to make uniform patterned layers of gate electrode, dielectrics, source/drain electrodes, and semiconductor as a coplanar type TFT in a successive manner. All ink-jet printed devices have good mechanical flexibility and current modulation characteristic even when bent.

• Journal of the Korean Vacuum Society
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• v.9 no.4
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• pp.379-381
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• 2000

Organic materials have potential advantages to be utilized as semiconductors in field effect transistors and light emmiting diodes. Gold, Aluminium, Silver, Chromium and Indium are used by electrodes. Gold is ohmic contact and the others are schottky contact. In this study, Pentacene and various electrode materials were deposited by Organic Molecular Beam Deposition (OMBD) and vacuum evaporation respectively. Those films were photolithographically patterned for measurements. These devices showed no degration after a 15 days of storage in laboratory environment.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1119-1122
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• 2005

A selective deposition of Co thin films for thin film transistor gate electrode has been carried out by the growth with combination of micro-contact printing and metal organic chemical vapor deposition (MOCVD). This results in the elimination of optical lithography process. MOCVD has been employed to selectively deposit Co films on preformed OTS gate pattern by using micro-contact printing (${\mu}CP$). A hydrogenated amorphous silicon TFT with a Co gate selectively formed on SAMs patterned structure exhibited a subthreshold slope of 0.88V/dec, and mobility of $0.35cm^2/V-s$, on/off current ratio of $10^6$, and a threshold voltage of 2.5V, and thus demonstrating the successful application of the novel bottom-up approach into the fabrication of a-Si:H TFTs.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.8
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• pp.731-735
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• 2003

Ti-indiffused LiNbO$_3$waveguide have been used to various high speed optical device based on electro-optic effect such as modulators, switches, and sensor, etc. In order to high speed modulation of optical modulator have, one of the further devices, needed to increasing of electrode surrounding air by LiNbO$_3$dry etching because of impedance matching for optical and RF phase velocity between waveguide and electrode. We studied property of LiNbO$_3$dry etching after waveguide patterning lot optical modulation by using neutral loop discharge (NLD) plasma.

• Proceedings of the KIEE Conference
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• 2006.10a
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• pp.101-102
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• 2006

PZT thin films, which are the representative ferroelectric materials in ferroelectric random access memory (FRAM), have some serious problem such as the imprint, retention and fatigue which ferroelectric properties are degraded by repetitive polarization. BL T thin film capacitors were fabricated by plasma etching, however, the plasma etching of BLT thin film was known to be very difficult. In our previous study, the ferroelectric materials such as PZT and BLT were patterned by chemical mechanical polishing (CMP) using damascene process to top electrode/ferroelectric material/bottom electrode. It is also possible to pattern the BLT thin film capacitors by CMP, however, the CMP damage was not considered in the experiments. The properties of BLT thin films were changed by the change of polishing pressure although the removal rate was directly proportional to the polishing pressure in CMP process.

• Proceedings of the KIEE Conference
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• 1999.07g
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• pp.3292-3294
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• 1999

In this paper, electrostatic scanner mirror for optical pick-up head is designed and fabricated. The mirror size is $20{\mu}m{\times}2400{\mu}m{\times}2400{\mu}m$ and torsional beam size is $10{\mu}m{\times}20{\mu}m{\times}500{\mu}m$. Static deflection angle is calculated ${\pm}0.4$ degrees when the maximum driving voltage is 20 V. Silicon mirror was fabricated using KOH etching and deep RIE. For passivation of the patterned mirror from KOH solution, parylene thin film was used and its usefulness has been verified. Driving electrode was fabricated using UV LIGA process. Mirror and electrode were bonded.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.377-382
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• 2000

Film bulk acoustic resonator (FBAR) using AIN reactively sputtered at room temperature was fabricated. The FBAR is composed of a piezoelectric aluminium nitride thin film, top electrode of Al and bottom electrode of Au connected by a short (200${\mu}{\textrm}{m}$) transmission line on both sides and reflector layers of SiO$_2$- W Pair. The active areas of Al and Au were patterned using 150${\mu}{\textrm}{m}$ diameter shadow mask. The series resonance frequency (fs) and the parallel resonance frequency (fp) were measured at 1.976 GHz and 2.005 GHz, respectively. The minimum insertion loss and return loss were 6.1 dB and 37.19 dB, and the quality factor (Q) was 4261.