Moonkeun Kim

A Model-Based Analysis of Plasma Parameters and Composition in HBr/X ( X = Ar , He , N2 ) Inductively Coupled Plasmas

D A Model-Based Analysis of Plasma Parameters and Composition in HBr/X „X = Ar, He, N2... Inductively Coupled Plasmas Kwang-Ho Kwon,* Alexander Efremov, Moonkeun Kim, Nam Ki Min, Jaehwa Jeong, and Kwangsoo Kim Department of Control and Instrumentation Engineering, Korea University, Chungnam 339-700, Korea Department of Electronic Devices and Materials Technology, State University of Chemistry and Technology, 153000 Ivanovo, Russia Sogang Institute of Advanced Technology, Sogang University, Seoul 121-742, Korea

Design, fabrication, and experimental demonstration of a piezoelectric cantilever for a low resonant frequency microelectromechanical system vibration energy harvester

Abstract. We compare the performances of vibration-powered microelectromechanical system (MEMS) electrical generators using a Pb(Zr,Ti)O3 (PZT) material. With the aid of a finite element method simulation, we have designed a PZT cantilever-based energy-harvesting system that uses mechanical vibration. We fabricate cantilevers on the MEMS scale with an integrated variable Si proof mass to obtain a low resonant frequency and high current. Based on simulation results, we fabricate cantilever devices with integrated Si proof masses with volumes of about 0.32 and 0.53  mm3. These devices compare favorably to the data obtained through simulation. Further, by comparing variable mass volumes, we obtain a high current and low resonant frequency. Similar results are obtained by simulation and experiment. Therefore, we offer a new and predictable means of obtaining a low resonant frequency for application to a micropower source area. Furthermore, from the size effect of the proof mass volume, we obtain the current and resonant frequency of these energy harvester systems. The possibility of a MEMS-scale power source for energy conversion experiments is also tested.

Etch mechanism of In2O3 and SnO2 thin films in HBr-based inductively coupled plasmas

The investigations of etch characteristics and mechanisms for both In2O3 and SnO2 thin films in the HBr-based inductively coupled plasmas were carried out. The etch rates were measured as functions of gas mixing ratio (0%–100% Ar), input power (400–700 W), and gas pressure (4–10 mTorr) at fixed bias power (200 W) and gas flow rate [40 SCCM (SCCM denotes cubic centimeter per minute at STP)]. Plasma parameters and composition were determined using a combination of plasma diagnostics by double Langmuir probe and global (zero-dimensional) plasma model. The correlations between the behaviors of etch rates and fluxes of plasma active species allow one to infer both In2O3 and SnO2 etch mechanisms as the transitional regime of ion-assisted chemical reaction, which is controlled by neutral and charged fluxes together.

Etching Characteristics of In2O3 and SnO2 Thin Films in an Inductively Coupled HBr/Ar Plasma: Effects of Gas Mixing Ratio and Bias Power

An investigation of the etching characteristics and mechanisms of both In2O3 and SnO2 in a HBr/Ar inductively coupled plasma was carried out. The etching rates were measured in the range of 0–100% Ar and 100–300 W bias power at a fixed gas flow rate (40 sccm), total gas pressure (6 mTorr), and input power (700 W). The plasma parameters and composition were determined using a combination of plasma diagnostics by a double Langmuir probe and a global (zero-dimensional) plasma model. It was found that both In2O3 and SnO2 etching rates are mainly controlled by the Br atom flux, with some sensitivity to the ion energy flux corresponding to the transitional regimes of the ion-assisted chemical reaction.

Effect of Gas Mixing Ratio on Etch Behavior of Y2O3 Thin Films in Cl2/Ar and BCl3/Ar Inductively Coupled Plasmas

This paper reports the results of a model-based analysis of the etch mechanism for the Y2O3 thin films in the Cl2/Ar and BCl3/Ar inductively coupled plasma. It was found that the BCl3/Ar plasma provides higher etch rate (except the case of pure BCl3 and Cl2 gases) as well as shows the non-monotonic dependence of the etch rate on the Ar mixing ratio. Plasma diagnostics by Langmuir probes indicated the noticeable influence of Ar mixing ratio on electron temperature and total density of positive ions. Using the model-based analysis of plasma chemistry and etch kinetics, it was demonstrated that the behavior of the Y2O3 etch rate in both gas mixtures generally corresponds to the neutral-flux-limited etch regime of the ion-assisted chemical reaction while the obtained differences cannot be explained assuming the Cl atoms to be the main chemically active species. Probably, in the BCl3-bases plasmas, the etch kinetics is significantly influenced by the BClx radicals.

Fabrication and Characteristics of Micro PZT Cantilever Energy Harvester Using MEMS Technologies

In this work, we designed and fabricated a multilayer thin film Pb(Zr,Ti)O3 cantilever with a Si proof mass for low frequency vibration energy harvesting applications. A mathematical model of a mu lti-layer composite beam was derived and applied in a parametric analysis of the piezoelectric cantilever. Finally, the dimensions of the cantilever were determined for the resonant frequency of the cantilever. W e fabricated a device with beam dimensions of about 4,930 μm × 450 μm × 12 μm, and an integrated Si proof mass with dimensions of about 1,410 μm × 450 μm × 450 μm. The resonant frequency, maximum peak voltage, and highest average power of the cantilever device were 84.5 Hz, 88 mV, and 0.166 μWat 1.0 g and 23.7 Ω, respectively. The dimensions of the cantilever were determined for the resonance frequ ency of the cantilever.

Influence of Nitrogen Plasma Treatment on Low Temperature Deposited Silicon Nitride Thin Film for Flexible Display

Department of Electrical and Electronic Engineering, Anyang University, Anyang 430-714, Korea(Received October 8, 2013; Revised December 9, 2013; Accepted December 11, 2013)Abstract: Silicon nitride thin film deposited with Plasma Enhanced Chemical Vapor Deposition was treated by a nitrogen plasma generated by Inductively Coupled Plasma at room temperature. The treatment was investigated by Fourier Transform Infrared Spectroscopy and Atomic Force Microscopy on the surface at various RF source powers at two RF bias powers. The amount of hydrogen was reduced and the surface roughness of the films was decreased remarkably after the plasma treatment. In order to understand the causes, we analyzed the plasma diagnostics by Optical Emission Spectroscopy and Double Langmuir Probe. Based on these analysis results, we show that the nitrogen plasma treatment was effective in the improving of the properties silicon nitride thin film for flexible display.Keywords: Plasma nitridation, Silicon nitride, Thin film, Low temperature, Flexible display, ICP, PECVD, FT-IR, AFM, OES, DLP

The Characteristics of Silicon Nitride Films Grown at Low Temperature for Flexible Display

We investigated the characteristics of the silicon oxy-nitride and nitride films grown by plasma-enhanced chemical vapor deposition (PECVD) at the low temperature with a varying mixing ratio and a fixed flow rate. The deposition temperature was held at which was the temperature compatible with the plastic substrate. The composition and bonding structure of the nitride films were investigated using Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Nitrogen richness was confirmed with increasing optical band gap and increasing dielectric constant with the higher fraction. The leakage current density of the nitride films with a high NH3 fraction decreased from to at 1.5 MV/cm). This results showed that the films had improved electrical properties and could be acceptable as a gate insulator for thin film transistors by deposited with variable mixing ratio.

A Study on the Surface Modification Mechanism of Copper Foil Using O2 / Ar Plasma

In this study, the surface modification of copper foil using an inductively coupled / Ar plasma as gas fraction (0~100%) was investigated in order to improve the surface characteristics. After plasma treatment, the measurement of the surface roughness, surface contact angle and surface energy were performed for the surface analysis of copper foil. As a result, the surface roughness and the surface energy were increased. And plasma diagnostics was performed by a double Langmuir probe (DLP) and optical emission spectroscopy (OES). Using these results, the plasma surface modification mechanism was investigated.

A Study on the Fabrication and Characterization of Micro Pb(Zr,Ti)O 3 Film Piezoelectric Cantilever Using MEMS Process for Energy Harvesting

(PZT) film piezoelectric cantilever with a Si proof mass and dual beams through MEMS process. The size of the beam and the integrated Si proof mass were about 4,320 μm × 290 μm × 12 μm and 1,380 μm × 880 μm × 450 μm each. To reduce the air damping and have the larger displacement of dual beams was used for design. After mounting micro PZT film piezoelectric cantilever on shaker, we measured the resonance frequency and a output voltage while making resonant frequency changed. The resonant frequency and the highest average power of the cantilever device were 110.2 Hz and 0.36 μW each, at 0.8 g acceleration and 23.7 kΩ load resistance, respectively. Keywords: MEMS, Cantilever, Energy harvesting, PZT, Resonance frequency