• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.409-412
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• 2006

A high data accuracy and low power consumption driving method and output stage of the source driver are proposed for the LTPS TFT-LCD in mobile applications. The proposed driving method is insensitive to the variations of the electrical characteristics of TFTs, which enables the output errors of the source driver are under 1/2 LSB in all gray levels. In addition, the power consumption of the driver with the method is decreased to 9.9mW which is 55.9% of that of the conventional source driver by reducing unnecessary charge waste.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1123-1126
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• 2005

For creation of low temperature polycrystallinesilicon (LTPS) the line beam excimer laser annealing (ELA) is a well known and established technique in mass production. With introduction of Sequential Lateral Solidification (SLS) some aspects such as crystalline quality, throughput and flexibility regarding the substrate size could be improved, but for OLED manufacturing still further process development is necessary. This paper discusses line beam ELA and SLS techniques that might enable process engineers to make polycrystalline-silicon (poly-Si) films with a high degree of uniformity and quality as required for system on glass (SOG) and active matrix organic light emitting displays (AMOLED). Equipment requirements are discussed and compared to previous standards. SEM images of process examples are shown in order to demonstrate the viability.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.338-338
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• 2011

최근 FPD (Flat Pannel Display) 시장이 커짐에 따라 고효율, 저비용 제작 공정이 화두로 떠오르고 있다. ELA (Excimer Laser Annenling)을 이용한 LTPS (Low Temperature Poly Silicon) 공정은 mobility와 전류 점멸비 등에서 장점을 가지지만, 고비용, 대면적과 short-range에서 uniformity가 어렵다는 단점이 있다. 이를 극복하기 위한 방법으로 dLTA (diode Laser Thermal Annealing) 공정에 대한 연구가 진행되고 있다. 본 연구에서는 Flexible Display을 만들기 위한 방법으로 dLTA 공정을 진행하였다. 이 방법은 PI (Poly imide) 기판 위에 a-Si을 ICP CVD로 증착시킨 후, Diode Laser (980 nm)를 이용한 annealing을 통하여 a-Si이 poly-Si으로 결정화가 되는 것을 확인하였고, 에너지 조사량에 따른 grain boundary와 grain size을 통하여 비교 분석하였다. 실험 결과 ELA 공정을 이용한 것과 버금가는 실험 결과를 얻을 수 있었다.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.7-7
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• 2007

Laser-irradiation-induced crystallization of as-deposited amorphous precursor films constitutes an integral step in fabricating LTPS TFTs. Consideration of various factors leads one to conclude that, for display manufacturers, choosing how to crystallize the films can be identified as being tactically and strategically significant. This paper will begin by reviewing the fundamental aspects of laser crystallization, and then present noteworthy advances and progress, which have recently been accomplished in the field. In particular, we will focus on communicating the evolving status associated with the sequential lateral solidification (SLS) method, which can be presently identified as the most strategically enabling crystallization method.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.429-429
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• 2010

TFT 제조 방법 중 LTPS (Low Temperature Polycrystalline Silicon)는 저온과 저비용 등의 이점으로 인하여 flat panel display 제작에 널리 사용된다. 이동도와 전류 점멸비 등에서 이점을 가지는 ELA(Excimer Laser Annealing)가 널리 사용되고 있지만, 이 방법은 uniformity 등의 문제점을 가지고 있다. 이를 극복하기 위한 방법으로 MICC(Metal Induced Capping Crystallization)이 사용되고 있다. 이 방법은 $SiN_x$, $SiO_2$, SiON등의 capping layer를 diffusion barrier로 위치시키고, Ni 등의 금속을 capping layer에 도핑 한 뒤, 다시 한번 열처리를 통하여 a-Si에 Ni을 확산시키킨다. a-Si 층에 도달한 Ni들이 seed로 작용하여 Grain size가 매우 큰 film을 제작할 수 있다. 채널의 grain size가 클 경우 grain boundary에 의한 캐리어 scattering을 줄일 수 있기 때문에 MIC 방법을 사용하였음에도 ELA에 버금가는 소자의 성능과 안정성을 얻을 수있었다. 본 연구에서는 large grain TFT의 Gate bias stress에 따른 소자의 안정성 측정 및 분석에 목표를 두었다.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.11
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• pp.48-55
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• 2016

Ambient-light sensor system, which changes the brightness of a display as ambient light change, was studied to reduce the power consumption of the mobile applications such as note PC, tablet PC and smart phone. The ambient-light sensor system should be integrated on a display panel to improve the complexity and cost of mobile applications, so the ambient-light sensor and readout circuit was integrated on a display panel using low-temperature poly-silicon thin film transistors (LTPS-TFT). We proposed the new compensation method to correct the panel-to-panel variation of the ambient-light sensors, without additional equipment. We designed and investigated the new readout circuit with the proposed compensation method and the analog-to-digital converter for the final digital output of ambient light. The readout circuit has very simple structure and control timing to be integrated with LTPS-TFT, and the input luminance ranges from 10 to 10,000 lux. The readout rate is 100 Hz, and maximum differential non-uniformity with 20 levels of the final output below 0.5 LSB.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.2 s.344
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• pp.76-83
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• 2006

We proposed a new level shifter circuit architecture. The prposed circuit can provide high output voltage upto 15V by taking 3.3V logic signal compared to the conventional level shifter. The unposed circuit has compatible speed, low power consumption and chip size. We have confirmed the operation by conducting HSPICE simulation.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1071-1074
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• 2007

6Mask CMOS process in low temperature polycrystalline silicon thin film transistors (poly-Si TFTs) has been developed and verified by manufacturing a 6Mask CMOS AMLCD panel. The novel 6Mask CMOS process is realized by eliminating the storage mask, gate mask and via open mask of conventional structure.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.696-699
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• 2008

A 10-bit source driver using low temperature poly-silicon(LTPS) TFTs is developed. To reduce the DAC area, the DAC structure including two 5-bit resistor-string DACs and analog buffer, which has analog adder is proposed. The source driver is fabricated using LTPS process and its one channel area is $3,200{\mu}m\;{\times}\;260{\mu}m$. The simulated INL and DNL of output voltages are less than 3 LSB and 1 LSB, respectively.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.550-552
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• 2009

The negative bias temperature instability on LTPS TFTs in a darkened and an illuminated environment was investigated. Experimental results reveal that the generation of interface state density showed no change between the different NBTI stresses. The degradation of the grain boundary trap under illumination was more significant than for the darkened environment.