• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1772-1775
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• 2000

We have fabricated poly-Si TFTs by two-step crystallizaton. Poly-Si films have been prepared by furnace annealing(FA) and rapid thermal annealing(RTA) followed by subsequent the post-annealing, excimer laser annealing. The measured crystallinity of RTA and FA annealed poly-Si film is 77% and 68.5%, respectively. For two-step annealed poly-Si film, the crystallinity has been drastically to 87.7% and 86.3%. The RMS surface roughness from AFM results have been improved from 56.3${\AA}$ to 33.5${\AA}$ after post annealing. The measured transfer characteristics of the two-step annealed poly-Si TFTs have been improved significantly for the both FA-ELA and RTA-ELA. Leakage currents of two-step annealed poly-Si TFTs are lower than that of the devices by FA and RTA. From these results, we can describe the fact that the intra-grain defects has been cured drastically by the post-annealing.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.630-633
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• 2003

Integrating the driver circuitry directly onto the glass substrate would be one of the advantages of polycrystalline Si (poly-Si) TFT-(LCD). Low-temperature poly-Si TFT(LTPS) is well-suited for higher-definition display applications due to its intrinsically superior electrical characteristics. In order to improve LTPS electrical characteristics, currently the excimer laser-induced crystallization (ELC) processes and sequential lateral solidification method were developed. Grain size of the poly-Si is mainly affected by beam pitch and energy density. Key parameter for making a larger poly-Si using excimer laser annealing(ELA) and increasing a throughput is due to increase in beam pitch and energy density to a certain degree. Furthermore, thin $SiO_{2}$ capping is effective to suppress the protrusion of the poly-Si thin films and to reduce the interface state density. From the ELA process, we are able to control grain size by varying different parameters such as number of shots and energy density.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.413-418
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• 2006

Highly stable thin-film transistor (TFT) pixel employing both low temperature polycrystalline silicon (LTPS) and amorphous silicon (a-Si) for active matrix organic light emitting diode (AMOLED) is discussed. ELA (excimer laser annealing) LTPS-TFT pixel should compensate $I_{OLED}$ variation caused by the non-uniformity of LTPS-TFT due to the fluctuation of excimer laser energy and amorphous silicon TFT pixel is desired to suppress the decrease of $I_{OLED}$ induced by the degradation of a-Si TFT. We discuss various compensation schemes of both LTPS and a-Si TFT employing the voltage and the current programming.

• 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 KIEE Conference
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• 1996.07c
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• pp.1440-1442
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• 1996

The laser annealing effects on the TEOS (Tetra-Ethyl-Ortho-Silicate) oxide of MOS (Al/TEOS/n+ Silicon) structures was investigated with different initial oxide conditions, such as breakdown field. The breakdown field increased up to the 170 $mJ/cm^2$ with increasing laser energy density and decreased at 220 $mJ/cm^2$. It is considered that the increase of breakdown field is originated from the restore of strains which exist mainly at the metal/oxide interface.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1400-1402
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• 2002

금속유도 측면 결정화 (Metal Induced Lateral Crystallization; MILC)를 통하여 형성한 다결정 실리콘 박막에 엑시머 (excimer) 레이저를 조사하여 우수한 특성을 갖는 박막 트랜지스터를 제작하였다. MILC 공정 중에 형성되는 금속 유도 결정화 (Metal Induced Crystallization; MIC) 실리콘 박막은 다량의 Ni을 함유하고 있기 때문에, 이에 인접한 MILC 실리콘 박막 내에는 니켈 농도의 점진적인 차이가 발생한다. MILC 다결정 실리콘 박막 내의 Ni 농도 차이는 실리콘 박막의 용융점 차이를 유발하여 레이저 결정화 시에 매우 큰 실리콘 결정립의 성장을 유도한다. 새로운 다결정 실리콘 박막 트랜지스터는 기존의 레이저 결정화 방식으로 제작한 다결정 실리콘 박막 트랜지스터에 비하여 40% 향상된 전계효과 이동도를 나타내었다.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1239-1242
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• 1994

We have characterized XeCl excimer-laser-induced crystallization of thin amorphous silicon films deposited by PECVD (${\alpha}-Si:H$) and LPCVD(${\alpha}-Si$). The electrical and optical properties and surface roughness of crystallized thin films have been measured. The dc conductivities, crystallinity and surface roughness of the films increased as the laser energy density and shot density were increased. Also, we have investigated the effects of 2-step annealing employing SPC and ELA. The properties of 2-step annealed films were better than those of films annealed by ELA only.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.12
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• pp.559-561
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• 2003

We report a new excimer laser annealing method which successfully results in a single grain boundary formation in the channel of polycrystalline silicon thin film transistor. The proposed method is based on lateral grain growth and employs aluminum patterns which act as selective beam mask and lateral heat sink. The maximum grain size obtained by the proposed method is about 1.6${\mu}{\textrm}{m}$ in the length. The grainboundaries should be arranged parallel with the direction of current flow for the best device performance, so we propose a new device fabrication method and a new poly-Si TFT structure. Poly-Si TFT fabricated by the proposed method exhibits considerably improved electrical characteristics, such as high field effect mobility exceeding 240 $cm^2$/Vsec.

• Journal of the Korean Electrochemical Society
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• v.3 no.1
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• pp.19-24
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• 2000

It is increasingly necessary to use poly-Si n's as high resolution and integration of Tn for LCD. Excimer Laser Crystallization (ELC) of a-Si is mainly used as a low temperature process. But the ELC method for the fabrication of poly-Si has the eruption problems associated with hydrogen in the a-Si film. So we need a dehydro-genation process additionally. Hydrogen in a-Si film can degrade the quality of poly-Si film and electrical properties of device due to the hydrogen eruption and voids which occur during the excimer laser annealing. In this study, we propose mesh-type PECVD as the a-Si film deposition method for achieving the low concentration hydrogen. Mesh-type PECVD was found to reduce the hydrogen content substantially. We could obtain a as-deposited a-Si film with hydrogen contents less than $1\%$ at $300^{\circ}C$. We also investigated the behavior by XeCl excimer laser annealing of a-Si fabricated by mesh-type PECVB. As a result, we were able to confirm the broad process window in contrast to the narrow process range typically obtained in ELC. Hydrogen eruption was not observed in poly-Si films after ELC These results suggests that mesh-type PECVD is a viable method to achieve the low hydrogen content a-Si and improve the process windows for ELC.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.412-414
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• 2004

We have developed nucleation control methods applicable to a zone-melting recrystallization excimer laser annealing process for poly-Si films. Ribbon-shaped Si grains of 2 ${\mu}m$-width were successfully aligned side by side by means of a comb-shaped beam, and we have successfully fabricated TFTs with channels formed in those grains. Electron mobility in the TFTs is as high as 677-$cm^2$/Vs.