• Korean Journal of Metals and Materials
• /
• v.50 no.4
• /
• pp.331-337
• /
• 2012

Electrical properties as a function of composition in silicon nitride ($SiN_x$) films grown at low temperatures ($<200^{\circ}C$) were studied for applications to photonic devices and thin film transistors. Both silicon-rich and nitrogen-rich compositions were successfully produced in final films by controlling the source gas mixing ratio, $R=[(N_2\;or\;NH_3)/SiH_4]$, and the RF plasma power. Depending on the film composition, the dielectric and optical properties of $SiN_x$ films varied substantially. Both the resistivity and breakdown field strength showed the maximum value at the stoichiometric composition (N/Si = 1.33), and degraded as the composition deviated to either side. The electrical properties degraded more rapidly when the composition shifted toward the silicon-rich side than toward the nitrogen-rich side. The composition shift from the silicon-rich side to the nitrogen-rich side accompanied the shift in the photoluminescence characteristic peak to a shorter wavelength, indicating an increase in the band gap. As long as the film composition is close to the stoichiometry, the breakdown field strength and the bulk resistivity showed adequate values for use as a gate dielectric layer down to $150^{\circ}C$ of the process temperature.

• Proceedings of the IEEK Conference
• /
• 2004.08c
• /
• pp.801-803
• /
• 2004

The current drive in an MOSFET is limited by the intrinsic channel resistance. All the other parasitic elements in a device structure playa significant role and degrade the device performance. These other resistances need to be less than $10{\%}-20{\%}$ of the channel resistance. To achieve the requirements, we should investigate the methodology of separation and quantification of those resistances. In this paper, we developed the extraction method of resistances using calibrated TCAD simulation. The resistance of the extension region is also partially determined by the formation of a surface accumulation region that forms under the gate in the tail region of the extension profile. This resistance is strongly affected by the abruptness of the extension profile because the steeper the profile is, the shorter this accumulation region will be.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2010.06a
• /
• pp.371-371
• /
• 2010

In this paper, the stress induced leakage currents of thin silicon oxides is investigated in the MEMS implementation with nano structure. The stress and transient currents associated with the on and off time of applied voltage were used to measure the distribution of high voltage stress induced traps in thin silicon oxide films. The oxide current for the thickness dependence of stress current, transient current, and stress induced leakage currents has been measured in oxides with thicknesses between $41{\AA}$, which have the gate area $10^{-3}cm^2$. The stress current, transient current is used to estimate to fundamental limitations on oxide thicknesses.

• ETRI Journal
• /
• v.20 no.2
• /
• pp.241-249
• /
• 1998

The structure and electrical characteristics of metal-ferroelectric-semiconductor FET(MFSFET) for a single transistor memory are presented. The MFSFET was comprised of polysilicon islands as source/drain electrodes and $BaMgF_4$ film as a gate dielectric. The polysilicon source and drain were built-up prior to the formation of the ferroelectric film to suppress a degradation of the film due to high thermal cycles. From the MFS capacitor, the remnant polarization and coercive field were measured to be about $0.6{\mu}C/cm^2$ and 100 kV/cm, respectively. The fabricated MFSFETs also showed good hysteretic I-V curves, while the current levels disperse probably due to film cracking or bad adhesion between the film and the Al electrode.

• Proceedings of the Optical Society of Korea Conference
• /
• 1998.08a
• /
• pp.192-193
• /
• 1998

At Rutherford Appleton Laboratory(RAL), a high-repetition rate ps exicmer laser-plasma x-ray source has been developed for x-ray lithography with a calibrated output of up to 1 watt X-ray average power at 1nm wavelength. In a previous reports this compact x-ray source was used to print 0.18$\mu$m lines for a gate on Si-FET devices and deep three-dimensional structure with 100$\mu$m length, 25$\mu$m width, and 48 $\mu$m depth for a nanotechnology. The deep X-ray lithography is called as LIGA thchnology and getting a wide interest as a new technology for a nano-device. In this report all this works are summarized.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.07a
• /
• pp.428-431
• /
• 2003

In this paper, the stress induced leakage currents of thin silicon oxides is investigated in the ULSI implementation with nano structure transistors. The stress and transient currents associated with the on and off time of applied voltage were used to measure the distribution of high voltage stress induced traps in thin silicon oxide films. The stress and transient currents were due to the charging and discharging of traps generated by high stress voltage in the silicon oxides. The transient current was caused by the tunnel charging and discharging of the stress generated traps nearby two interfaces. The stress induced leakage current will affect data retention in electrically erasable programmable read only memories. The oxide current for the thickness dependence of stress current, transient current, and stress induced leakage currents has been measured in oxides with thicknesses between $113.4{\AA}$ and $814{\AA}$, which have the gate area 10-3cm2. The stress induced leakage currents will affect data retention and the stress current, transient current is used to estimate to fundamental limitations on oxide thicknesses.

• Journal of the Korean Society for Precision Engineering
• /
• v.27 no.9
• /
• pp.43-51
• /
• 2010

Speed, accuracy and smoothness are the important properties of pan-tilt camera. In the case of a high ratio zoom lens system, low vibration characteristic is a crucial point in driving pan-tilt mechanism. In this paper, a novel micro-stepping controller with a function of reducing vibration was designed using field programmable gate arrays (FPGA) technology for high zoom ratio pan-tilt camera. The proposed variable reference current (VRC) control scheme reduces vibration decently and optimizing coil current in order to prevent the step motor from occurring missing steps. By employing VRC control scheme, the vibration in low speed could be significantly minimized. The proposed controller can also make very high speed of 378kpps micro-step driving, and increase maximum acceleration in motion profiles.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2009.05a
• /
• pp.22.1-22.1
• /
• 2009

차세대 CMOS 공정에서 유전상수가 높은 게이트 절연막과 함께 게이트 전극이 관심을 끌고 있다. 게이트 전극은 전도도가 높아야 하고 p-MOS, n-MOS에 맞는 일함수를 가져야 하며 열적 특성이 안정해야 한다. 탄탈룸 계열 탄화물이나 질화물은 게이트 전극으로 관심을 끌고 있는 물질이며 이를 원자층 화학증착법으로 박막화 하는 공정이 관심을 끌고 있다. 원자층 화학공정에서는 전구체의 역할이 중요하며 이의 기상반응 메카니즘, 표면 반응 메카니즘을 제대로 이해해야 한다. 본 연구에서는 TBTDET (tert-butylimido tris-diethylamido tantalum) 전구체의 반응 메커니즘을 FTIR(Fourier Transform Infrared)을 이용해 진단하였다. 또한 수소, 암모니아, 메탄을 이용한 열화학 원자층 증착, 플라즈마 원자층 증착 공정을 수행하여 박막을 얻고 이들의 특성을 평가하였다. 각 공정에 따라 반응 메커니즘이 달라지고 박막의 조성이 달라지며 또한 박막의 물성도 달라진다. 특히 박막에 형성되는 TaC, TaN, Ta3N5, Ta2O5 (증착 후 산소의 유입에 의해 형성됨) 등의 조성이 공정에 따라 달라지며 박막의 물성도 달라진다. 반응메카니즘의 연구를 통해 각 공정에서 어떠한 조성의 박막이 얻어지는 지를 규명하였고 박막의 밀도에 따라 산소유입량이 어떻게 달라지는 지를 규명하였다.

• International Journal of Computer Science & Network Security
• /
• v.23 no.3
• /
• pp.203-207
• /
• 2023

A frequency reconfigurable antenna based on graphene and used for multi-band wireless communications is presented in this article. The proposed antenna, which consists of two radiating rectangular loops with a graphene extension, is analyzed for Global Positioning System (GPS) and Iridium applications. Its operating frequency is tuned through the implementation of a layer of graphene and thereby adjusting the applied gate bias. Furthermore, the results show a novel use of graphene for microwave frequencies while achieving a frequency reconfiguration with an improvement of the impedance matching and the gain. The results also prove the importance of graphene, with its exceptional properties, for a promising future in nano-electronics.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2016.02a
• /
• pp.268-268
• /
• 2016

Chemical sensors have attracted much attention due to their various applications such as agriculture product, cosmetic and pharmaceutical components and clinical control. A conventional chemical and biological sensor is consists of fluorescent dye, optical light sources, and photodetector to quantify the extent of concentration. Such complicated system leads to rising cost and slow response time. Until now, the most contemporary thin film transistors (TFTs) are used in the field of flat panel display technology for switching device. Some papers have reported that an interesting alternative to flat panel display technology is chemical sensor technology. Recent advances in chemical detection study for using TFTs, benefits from overwhelming progress made in organic thin film transistors (OTFTs) electronic, have been studied alternative to current optical detection system. However numerous problems still remain especially the long-term stability and lack of reliability. On the other hand, the utilization of metal oxide transistor technology in chemical sensors is substantially promising owing to many advantages such as outstanding electrical performance, flexible device, and transparency. The top-gate structure transistor indicated long-term atmosphere stability and reliability because insulator layer is deposited on the top of semiconductor layer, as an effective mechanical and chemical protection. We report on the fabrication of InGaZnO TFTs with silver nanowire as the top gate electrode for the aim of chemical materials detection by monitoring change of electrical properties. We demonstrated that the improved sensitivity characteristics are related to the employment of a unique combination of nano materials. The silver nanowire top-gate InGaZnO TFTs used in this study features the following advantages: i) high sensitivity, ii) long-term stability in atmosphere and buffer solution iii) no necessary additional electrode and iv) simple fabrication process by spray.