• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.326-326
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• 2010

The dielectric properties of continuous composition spreaded (CCS) $BaTiO_3-SrTiO_3$ (BST) thin filmsgrown at room temperature and annealed at different temperature ($350^{\circ}C$ and $550^{\circ}C$) were investigated. Moreover, electrical properties (leakage current and breakdown voltage) of CCS BST thin films were also investigated. The aluminum top-electrode, sized by $200{\times}200\;{\mu}m2$ and apart from each other by $300\;{\mu}m$, were deposited on the CCS BST thin films by the DC sputtering system. The dielectric properties of the CCS BST thin films were significantly influenced depending on the distance from $BaTiO_3$ and $SrTiO_3$ targets which was attributed to the $BaTiO_3-SrTiO_3$ composition ratio. The maps of dielectric constants and loss tangents were plotted via $1500\;{\mu}m$ - step measuring. The specific points showing the dielectric constant (k: ~300) and loss tangent (tand: ~0.008) at 1 MHz were found.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.285-285
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• 2011

EUVL (Extreme Ultra Violet Lithography) is one of competitive lithographic technologies for sub-30nm fabrication of nano-scale Si devices that can possibly replace the conventional photolithography used to make today's microcircuits. Among the core EUVL technologies, mask fabrication is of considerable importance since the use of new reflective optics having a completely different configuration compared to those of conventional photolithography. Therefore new materials and new mask fabrication process are required for high performance EUVL mask fabrication. This study investigated the etching properties of SnO2 (Tin Oxide) as a new absorber material for EUVL binary mask. The EUVL mask structure used for etching is SnO2 (absorber layer) / Ru (capping / etch stop layer) / Mo-Si multilayer (reflective layer) / Si (substrate). Since the Ru etch stop layer should not be etched, infinitely high selectivity of SnO2 layer to Ru ESL is required. To obtain infinitely high etch selectivity and very low LER (line edge roughness) values, etch parameters of gas flow ratio, top electrode power, dc self - bias voltage (Vdc), and etch time were varied in inductively coupled Cl2/Ar plasmas. For certain process window, infinitely high etch selectivity of SnO2 to Ru ESL could be obtained by optimizing the process parameters. Etch characteristics were measured by on scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analyses. Detailed mechanisms for ultra-high etch selectivity will be discussed.

• Journal of the Korean institute of surface engineering
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• v.48 no.6
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• pp.297-302
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• 2015

Nanocrystalline diamond(NCD) coated aluminium plates were prepared and applied as heat sinks for LED modules. NCD films were deposited on 1 mm thick Al plates for times of 2 - 10 h in a microwave plasma chemical vapor deposition reactor. Deposition parameters were the microwave power of 1.2 kW, the working pressure of 90 Torr, the $CH_4/Ar$ gas ratio of 2/200 sccm. In order to enhance diamond nucleation, DC bias voltage of -90 V was applied to the substrate during deposition without external heating. NCD film was identified by X-ray diffraction and Raman spectroscopy. The Al plates with about 300 nm thick NCD film were attached to LED modules and thermal analysis was carried out using Thermal Transient Tester (T3ster) in a still air box. Thermal resistance of the module with NCD/Al plate was 3.88 K/W while that with Al plate was 5.55 K/W. The smaller the thermal resistance, the better the heat emission. From structure function analysis, the differences between junction and ambient temperatures were $12.1^{\circ}C$ for NCD/Al plate and $15.5^{\circ}C$ for Al plate. The hot spot size of infrared images was larger on NCD/Al than Al plate for a given period of LED operation. In conclusion, NCD coated Al plate exhibited better thermal spreading performance than conventional Al heat sink.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.1
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• pp.29-35
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• 2016

We have demonstrated a $Ti:LiNbO_3$ electro-optic electric-field sensors utilizing a $1{\times}2$ Y-fed balanced-bridge Mach-Zehnder interferometric (YBB-MZI) modulator which uses a 3-dB directional coupler at the output and dipole patch antenna. The operation and design were proved by the BPM simulation. A dc switching voltage of ~16.6 V and an extinction ratio of ~14.7 dB are observed at a wavelength of $1.3{\mu}m$. For a 20 dBm rf power, the minimum detectable electric-fields are ~1.12 V/m and ~3.3 V/m corresponding to a dynamic range of about ~22 dB and ~18 dB at frequencies 10 MHz and 50 MHz, respectively. The sensors exhibit almost linear response for the applied electric-field intensity from 0.29 V/m to 29.8 V/m.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.168-168
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• 2008

Dimension of a transistor has rapidly shrunk to increase the speed of device and to reduce the power consumption. However, it is accompanied with several problems like direct tunneling through the gate dioxide layer and low conductivity characteristic of poly-Si gate in nano-region. To cover these faults, study of new materials is urgently needed. Recently, high dielectric materials like $Al_2O_3$, $ZrO_2$, and $HfO_2$ are being studied for equivalent oxide thickness (EOT). However, poly-Si gate is not compatible with high-k materials for gate-insulator. Poly Si gate with high-k material has some problems such as gate depletion and dopant penetration problems. Therefore, new gate structure or materials that are compatible with high-k materials are also needed. TiN for metal/high-k gate stack is conductive enough to allow a good electrical connection and compatible with high-k materials. According to this trend, the study on dry etching of TiN for metal/high-k gate stack is needed. In this study, the investigations of the TiN etching characteristics were carried out using the inductively coupled $BCl_3$-based plasma system and adding $Cl_2$ gas. Dry etching of the TiN was studied by varying the etching parameters including $BCl_3$/Ar gas mixing ratio, RF power, DC-bias voltage to substrate, and $Cl_2$ gas addition. The plasmas were characterized by optical emission spectroscopy analysis. Scanning electron microscopy was used to investigate the etching profile.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.11
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• pp.826-830
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• 2013

In this paper, we carried out the investigations of both etch characteristics and mechanisms for the $SnO_2$ thin films in $O_2/BCl_3/Ar$ plasma. The dry etching characteristics of the $SnO_2$ thin films was studied by varying the $O_2/BCl_3/Ar$ gas mixing ratio. We determined the optimized process conditions that were as follows: a RF power of 700 W, a DC-bias voltage of - 150 V, and a process pressure of 2 Pa. The maximum etch rate was 509.9 nm/min in $O_2/BCl_3/Ar$=(3:4:16 sccm) plasma. From XPS analysis, the etch mechanism of the $SnO_2$ thin films in the $O_2/BCl_3/Ar$ plasma can be identified as the ion-assisted chemical reaction while the role of ion bombardment includes the destruction of the metal-oxide bonds as well as the cleaning of the etched surface form the reaction products.

• Korean Journal of Optics and Photonics
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• v.17 no.2
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• pp.181-185
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• 2006

A novel 60GHz optical carrier generator with a polarization domain-inverted structure is suggested and is demonstrated. The two arms of the Mach-Zehnder optical waveguide are periodically poled for quasi-phase velocity matching between the optical wave at 1550nm and the RF wave at 30 GHz. The center frequency of band-pass modulation and the 3 dB bandwidth of the fabricated modulator were measured to be 30.3 GHz and 5.1 GHz, respectively. Sub-carriers with the frequency difference of 60GHz waeregenerated under appropriate DC biac voltage application while the carrier was suppressed to lead to the power ratio between the modulated sub-carrier and the suppressed fundamental carrier of 28 dB, which proves that double sideband- suppressed carrier(DSB-SC) operation can be realized by the suggested single device.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.41-43
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• 1999

Among the feffoelectric thin films that have been widely investigated for ferroelectric random access memory (FRAM) applications, SrBi$_2$Ta$_2$$O_{9}$ thin film is appropriate to memory capacitor materials for its excellent fatigue endurance. However, very few studies on etch properties of SBT thin film have been reported although dry etching is an area that demands a great deal of attention in the very large scale integrations. In this study, the a SrBi$_2$Ta$_2$$O_{9}$ thin films were etched by using magnetically enhanced inductively coupled Ar/CHF$_3$ plasma. Etch properties, such as etch rate, selectivity, and etched profile, were measured according to gas mixing ratio of CHF$_3$(Ar$_{7}$+CHF$_3$) and the other process conditions were fixed at RF power of 600 W, dc bias voltage of 150 V, chamber pressure of 10 mTorr. Maximum etch rate of SBT thin films was 1750 A77in, under CHF$_3$(Ar+CHF$_3$) of 0.1. The selectivities of SBT to Pt and PR were 1.35 and 0.94 respectively. The chemical reaction of etched surface were investigated by X-ray photoelectron spectroscopy (XPS) analysis. The Sr and Ta atoms of SBT film react with fluorine and then Sr-F and Ta-F were removed by the physical sputtering of Ar ion. The surface of etched SBT film with CHF$_3$(Ar+CHF$_3$) of 0.1 was analyzed by secondary ion mass spectrometer (SIMS). Scanning electron microscopy (SEM) was used for examination of etched profile of SBT film under CHF$_3$(Ar+CHF$_3$) of 0.1 was about 85˚.85˚.˚.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.6
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• pp.454-459
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• 2020

In this study, a TiO₂/TiO_2-x-based resistance variable memory was fabricated using a DC/RF magnetron sputtering system and ALD. In order to analyze the effect of oxygen plasma treatment on the performance of resistance random access memory (ReRAM), the TiO₂/TiO_2-x-based ReRAM was evaluated by applying RF power to the TiO_2-x oxygen-holding layer at 30, 60, 90, 120, and 150 W, respectively. The ReRAM was fabricated, and the electrical and surface area performances were compared and analyzed. In the case of ReRAM without oxygen plasma treatment, the I-V curve had a hysteresis curve shape, but the width was very small, with a relatively high surface roughness of the oxygen-retaining layer. However, in the case of oxygen plasma treatment, the HRS/LRS ratio for the I-V curve improved as the applied RF power increased; stable improvement was also noted in the surface roughness of the oxygen-retaining layer. It was confirmed that the low voltage drive was not smooth due to charge trapping in the oxygen diffusion barrier layer owing to the high intensity ReRAM applied with an RF power of approximately 150 W.

• Journal of Advanced Navigation Technology
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• v.27 no.4
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• pp.463-468
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• 2023

In this paper, we proposed reconfigurable dual polarization patch array antenna that can select two polarizations(Vertical, RHCP) using defected ground structure and Pin diode. The proposed antenna was designed arranging a circular polarization patch antenna implemented with a square microstrip patch and two slots 3x3 at 25.8mm placed, a half-wavelength of 5.8 GHz. Conect the pin diode and the capacitor to the slot diagonally placed on the ground of each antennas, and select polarization using the open/short operating according to the application of DC voltage to the pin diode. As a result of the design, the gain of the antenna is 11.7 dBi at vertical polarization and 11.6 dBic at RHCP. The axial ratio is 20.3 dB at 1.8 dB vertical polarization at RHCP. Mutual Coupling is Maximum to -20.8 dB for vertical polarization and Maximum to -30.1 dB for RHCP.