• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.5
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• pp.315-318
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• 1999

We have proposed and fabricated the new bottom-gated polycrystalline silicon (poly-Si) thin film transistor (TFT) with a partial amorphous-Si region by employing the selective laser annealing. The channel layer of the proposed TFTs is composed of poly-Si region in the center and a-Si region in the edge. The TEM image shows that the local a-Si region is successfully fabricated by the effective cut out of the incident laser light in the upper a-Si layer. Our experimental results show that the ON/OFF current ratio is increased significantly by more than three orders in the new poly-Si TFT compared with conventional poly-Si TFT. The leakage current is decreased significantly due to the highly resistive a-Si re TFTs while the ON-series resistance of the local a-Si is reduced significantly due to the considerable inducement of electron carriers by the positive gate bias, so that the ON-current is not decreased much.

• Korean Journal of Materials Research
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• v.24 no.9
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• pp.443-450
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• 2014

Amorphous (a-Si) films were epitaxially crystallized on a very thin large-grained poly-Si seed layer by a silicide-enhanced rapid thermal annealing (SERTA) process. The poly-Si seed layer contained a small amount of nickel silicide which can enhance crystallization of the upper layer of the a-Si film at lower temperature. A 5-nm thick poly-Si seed layer was then prepared by the crystallization of an a-Si film using the vapor-induced crystallization process in a $NiCl_2$ environment. After removing surface oxide on the seed layer, a 45-nm thick a-Si film was deposited on the poly-Si seed layer by hot-wire chemical vapor deposition at $200^{\circ}C$. The epitaxial crystallization of the top a-Si layer was performed by the rapid thermal annealing (RTA) process at $730^{\circ}C$ for 5 min in Ar as an ambient atmosphere. Considering the needle-like grains as well as the crystallization temperature of the top layer as produced by the SERTA process, it was thought that the top a-Si layer was epitaxially crystallized with the help of $NiSi_2$ precipitates that originated from the poly-Si seed layer. The crystallinity of the SERTA processed poly-Si thin films was better than the other crystallization process, due to the high-temperature RTA process. The Ni concentration in the poly-Si film fabricated by the SERTA process was reduced to $1{\times}10^{18}cm^{-3}$. The maximum field-effect mobility and substrate swing of the p-channel poly-Si thin-film transistors (TFTs) using the poly-Si film prepared by the SERTA process were $85cm^2/V{\cdot}s$ and 1.23 V/decade at $V_{ds}=-3V$, respectively. The off current was little increased under reverse bias from $1.0{\times}10^{-11}$ A. Our results showed that the SERTA process is a promising technology for high quality poly-Si film, which enables the fabrication of high mobility TFTs. In addition, it is expected that poly-Si TFTs with low leakage current can be fabricated with more precise experiments.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.385-386
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• 2008

This paper reports the design of the ultra low power consumption microhotplates for high temperatures. The microhotplates consisting of a platinum-based heating element on AlN/poly 3C-SiC layers were designed. The microhotplate is a $600\times600{\mu}m^2$ square shaped membrane made of $1{\mu}m$ thick ploy 3C-SiC suspended by four legs. The microhotplate was compared with $Si_3N_4/SiO_2/Si_3N_4$(NON) structure microhotplate by COMSOL simulation system. Thermal uniformity, power consumption and thermal characterizations of microhotplates based on 3C-SiC thin film are better than microhotplates with NON structure.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.5
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• pp.48-53
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• 1998

Poly-Si TFT's could be fabricated on glass substrates by metal induced lateral crystallization (MILC) method at 450.deg. C. Channel area of the poly-Si TFT's was laterally crystallized from source and drain areas, where a thn nickel film was deposited. Dopants activation for the formation of source and drain region could be achieved by thermal annealing at 450.deg. C after the ion mass doping of phosphorus. The field effect mobility of thus formed N-channel poly-Si TFT's was 76cm$^{2}$/Vs, and the on/off current ratio was higher than 7E6.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.752-755
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• 2006

Reverse annealing was observed in $P^+/B^+$ ion shower doped poly-Si upon activation annealing. Phosphorous or boron was implanted by ion shower doping using a source gas mixture of $PH_3/H_2$ or $B_2H_6/H_2$. Activation annealing was conducted using a tube furnace in the temperature ranges from $350^{\circ}C$ to $650^{\circ}C$. Hall measurement revealed that reverse annealing begins at different annealing temperatures for poly-Si implanted with P and B, respectively. It was observed that reverse annealing starts at $550^{\circ}C$$ in $P^+$ ion shower doped poly-Si, while at $350^{\circ}C$ in the case of B-doping.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.5
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• pp.237-241
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• 2004

Amorphous silicon (a-Si) films are used in a broad range of solar cell, flat panel display, and sensor. Because of the greater ease of deposition and lower processing temperature, thin films are widely used for thin film transistors (TFTs). However, they have lower stability under the exposure of visible light and because of their low field effect mobility ($\mu$$_{FE}$ ) , less than 1 c $m^2$/Vs, they require a driving IC in the external circuits. On the other hand, polycrystalline silicon (poly-Si) thin films have superiority in $\mu$$_{FE}$ and optical stability in comparison to a-Si film. Many researches have been done to obtain high performance poly-Si because conventional methods such as excimer laser annealing, solid phase crystallization and metal induced crystallization have several difficulties to crystallize. In this paper, a new crystallization process using a molybdenum substrate has been proposed. As we use a flexible substrate, high temperature treatment and roll-to-roll process are possible. We have used a high temperature process above 75$0^{\circ}C$ to obtain poly-Si films on molybdenum substrates by a rapid thermal annealing (RTA) of the amorphous silicon (a-Si) layers. The properties of high temperature crystallized poly-Si studied, and poly-Si has been used for the fabrication of TFT. By this method, we are able to achieve high crystal volume fraction as well as high field effect mobility.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.28A no.12
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• pp.24-30
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• 1991

As a study to use Ti-silicides as interconnection material, the formation of Ti-silicides and the behavior of dopants were investigated for specimens where dopants are introduced on both single-Si substrate and poly-Si that was deposited on the single-Si. Result showed that stable C54 TiSiS12T formed above $700^{\circ}C$ and the formed TiSiS12T had bad surface roughness. And arsenics were chiefly redistributed in TiSiS12T while boron was accumulated near the interface between TiSiS11T and Si during RTA treatment.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.275-275
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• 2008

This paper describe the fabrication of a Pd/polycrystalline 3C-SiC schottky diode and its characteristics, in which the polycrystalline 3C-SiC layer and Pd Schottky contact were deposited by using APCVD and sputter, respectively. Crystalline quality, uniformity, and preferred orientations of the Pd thin film were evaluated by SEM and XRD, respectively. Pd/poly 3C-SiC Schottky diodes were fabricated and characterized by I-V and C-V measurements. Its electric current density Js and barrier height voltage were measured as $2\times10^{-3}$ A/$cm^2$ and 0.58 eV, respectively. These devices were operated until about $400^{\circ}C$. Therefore, from these results, Pd/poly 3C-SiC Schottky devices have very high potential for high temperature chemical sensor applications.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1999.05a
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• pp.403-406
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• 1999

The influence of temperature variation (25～125$^{\circ}C$) on poly-Si thin-film transistors (TFT's) was investigated by examining the electrical properties change of poly-Si films formed by solid phase crystallization (SPC). The n-channel poly-Si TFT's fabricated by SPC with channel length of 1.5 and loon ,respectively, exhibit good characteristics with a high ${\mu}$$\sub$FE/ ($\geq$82 and $\geq$60$\textrm{cm}^2$/V-s in 1.5 and 10$\mu\textrm{m}$, respectively), low V$\sub$t/, ($\leq$1.52 and $\leq$ 2.75V in 1.5 and 10$\mu\textrm{m}$, respectively), low S$\sub$t/, and good ON-OFF characteristics in spite of temperature variation. Thus, poly-Si films formed by SPC can be applied for the application to poly-Si TFT liquid crystal display with peripheral integrated circuits.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.235-235
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• 2009

This paper describes the influence of a polycrystalline (poly) 3C-SiC buffer layer on the surface acoustic wave (SAW) properties of poly aluminum nitride (AlN) thin films by comparing the center frequency, insertion loss, the electromechanical coupling coefficient ($k^2$), andthetemperaturecoefficientoffrequency(TCF) of an IDT/AlN/3C-SiC structure with those of an IDT/AlN/Si structure, The poly-AlN thin films with an (0002)-preferred orientation were deposited on a silicon (Si) substrate using a pulsed reactive magnetron sputtering system. Results show that the insertion loss (21.92 dB) and TCF (-18 ppm/$^{\circ}C$) of the IDT/AlN/3C-SiC structure were improved by a closely matched coefficient of thermal expansion (CTE) and small lattice mismatch (1 %) between the AlN and 3C-SiC. However, a drawback is that the $k^2(0.79%)$ and SAW velocity(5020m/s) of the AlN/3C-SiC SAW device were reduced by appearing in some non-(0002)AlN planes such as the (10 $\bar{1}$ 2) and (10 $\bar{1}$ 3) AlN planes in the AlN/SiC film. Although disadvantages were shown to exist, the use of the AlN/3C-SiC structure for SAW applications at high temperatures is possible. The characteristics of the AlN thin films were also evaluated using FT-IR spectra, XRD, and AFM images.