• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.320-320
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• 2013

Film thickness monitoring with plasma impedance monitoring (PIM) is demonstrated for small area $SiO_2$ RF plasma etching processes in this work. The chamber conditions were monitored by the impedance signal variation from the I-V monitoring system. Moreover, modified principal component analysis (mPCA) was applied to estimate the $SiO_2$ film thickness. For verification, the PIM was compared with optical emission spectroscopy (OES) signals which are widely used in the semiconductor industry. The results indicated that film thickness can be estimated by 1st principal component (PC) and 2nd PC. Film thickness monitoring of small area $SiO_2$ etching was successfully demonstrated with RF plasma harmonic impedance monitoring and mPCA. We believe that this technique can be potentially applied to plasma etching processes as a sensitive process monitoring tool.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.153-153
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• 2012

Endpoint detection with plasma impedance monitoring and self-plasma optical emission spectroscopy is demonstrated for dielectric layers etching processes. For in-situ detecting endpoint, optical-emission spectroscopy (OES) is used for in-situ endpoint detection for plasma etching. However, the sensitivity of OES is decreased if polymer is deposited on viewport or the proportion of exposed area on the wafer is too small. To overcome these problems, the endpoint was determined by impedance signal variation from I-V monitoring (VI probe) and self-plasma optical emission spectroscopy. In addition, modified principal component analysis was applied to enhance sensitivity for small area etching. As a result, the sensitivity of this method is increased about twice better than that of OES. From plasma impedance monitoring and self-plasma optical emission spectroscopy, properties of plasma and chamber are analyzed, and real-time endpoint detection is achieved.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.182-182
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• 2012

Plasma etching is used in various semiconductor processing steps. In plasma etcher, optical- emission spectroscopy (OES) is widely used for in-situ endpoint detection. However, the sensitivity of OES is decreased if polymer is deposited on viewport or the proportion of exposed area on the wafer is too small. Because of these problems, the object is to investigate the suitability of using plasma impedance monitoring (PIM) and self plasma optical emission spectrocopy (SPOES) with statistical approach for in-situ endpoint detection. The endpoint was determined by impedance signal variation from I-V monitor (VI probe) and optical emission signal from SPOES. However, the signal variation at the endpoint is too weak to determine endpoint when $SiO_2$ and SiNx layers are etched by fluorocarbon on inductive coupled plasma (ICP) etcher, if the proportion of $SiO_2$ and SiNx area on Si wafer are small. Therefore, modified principal component analysis (mPCA) is applied to them for increasing sensitivity. For verifying this method, detected endpoint from impedance monitoring is compared with optical emission spectroscopy.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.32-32
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• 2011

Plasma etching is used in microelectronic processing for patterning of micro- and nano-scale devices. Commonly, optical emission spectroscopy (OES) is widely used for real-time endpoint detection for plasma etching. However, if the viewport for optical-emission monitoring becomes blurred by polymer film due to prolonged use of the etching system, optical-emission monitoring becomes impossible. In addition, when the exposed area ratio on the wafer is small, changes in the optical emission are so slight that it is almost impossible to detect the endpoint of etching. For this reason, as a simple method of detecting variations in plasma without contamination of the reaction chamber at low cost, a method of measuring plasma impedance is being examined. The object in this research is to investigate the suitability of using plasma impedance monitoring (PIM) with statistical approach for real-time endpoint detection of $SiO_2$ etching. The endpoint was determined by impedance signal variation from I-V monitor (VI probe). However, the signal variation at the endpoint is too weak to determine endpoint when $SiO_2$ film on Si wafer is etched by fluorocarbon plasma on inductive coupled plasma (ICP) etcher. Therefore, modified principal component analysis (mPCA) is applied to them for increasing sensitivity. For verifying this method, detected endpoint from impedance analysis is compared with optical emission spectroscopy (OES). From impedance data, we tried to analyze physical properties of plasma, and real-time endpoint detection can be achieved.

• Applied Science and Convergence Technology
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• v.23 no.6
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• pp.328-339
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• 2014

In this article, plasma monitoring tools and mulivariate analysis techniques were reviewed. Optical emission spectroscopy was reviewed for a chemical composition analysis tool and RF V-I probe for a physical analysis tool for plasma monitoring. Multivariate analysis techniques are discussed to the sensitivity improvement. Principal component analysis (PCA) is one of the widely adopted multivariate analysis techniques and its application to end-point detection of plasma etching process is discussed.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.2
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• pp.70.3-70.3
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• 2019

We present a method to estimate 3-component plasma velocity (Vx, Vy and Vz) at solar photosphere near solar disk center, using the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO) called Space-weather HMI Active Region Patch (SHARP). In Heliocentric-Cartesian Coordinates, the component of Vz is obtained from Dopplergram while the components of Vx and Vy are derived from the relation of $B_z{\overrightarrow{u}}=B_z{\overrightarrow{{\nu}_t}}-{\nu}_z{\overrightarrow{B_t}}$ (Demoulin & Berger 2003) using a series of vector magnetograms by an optical flow technique NAVE (Nonlinear Affine Velocity Estimator). This velocity measurement method is applied to AR 12158 producing an X1.6 flare along with a coronal mass ejection. We find noticeable upflow motions at both ends of flux ropes which become a major eruption part, and strong transverse motions nearby them before the eruption. We will discuss the change of plasma motions and magnetic fields before and after the eruption.

• Journal of Magnetics
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• v.11 no.4
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• pp.160-163
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• 2006

We have prepared crystalline Ag nanoparticles with an average size of 4 nm in diameter by using an inductively coupled plasma reactor equipped with the liquid nitrogen cooling system. Our magnetic data show that the nano-sized effect of Ag nanoparticles on the magnetic properties is ferromagnetic, instead of a diamagnetic component of the Ag bulk and a superparamagnetic component of magnetic nanoparticles. We have also studied the magnetic properties of Ag-Cu nanocomposites with an opposite concentration profile between surface and core. These comparisons indicate that the ferromagnetic component strongly depends on the surface of Ag nanoparticles, while the paramagnetic component is strongly affected by the outer oxide layer, with the background of a diamagnetic component from the core of Ag.

• 전기의세계
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• v.24 no.1
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• pp.75-85
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• 1975

In order to develop the commercial frequency (60Hz) plasma torch of small capacity for material cutting, welding and other industrial heating, the A.C plasma jet generator of non-transfered type is made domestically and the electrode configurations of plasma torch are composed of two kinds of electrodes W-C and W-Cu, combined by thermal emission and field emission electrode materials. In this paper, the characteristics of input power, thermal efficiency, electrode consumption, the flame and forms of arc voltage and arc current for A.C plasma torch are investigated in relation to such variables as arc current, argon flow and magnetic field intensity to obtain the basic design data necessary to A.C plasma jet generator. The result are as follows; (1)The input power, thermal efficiency and electrode consumption are influenced greatly by argon flow, magnetic field intensity and nozzle materials. (2)A.C arc voltage and current are non-symmetrial, involving D.C Component. Due to this current of D.C Component, transformer core is saturated and a large abnormal current flows into the primary winding coil. In order to prevent this abnormal current flow, a condenser must be connected in series to the main discharge circuit. (3)The stability and sharpness of jet flame are improved more in the torch of W-C electrode configuration than in the torch of W-Cu electrode configuration.

• Textile Coloration and Finishing
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• v.34 no.2
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• pp.102-108
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• 2022

The physicochemical properties of stainless steel fibers which were modified by oxygen plasma treatment were analyzed through microscopy and XPS analysis. The wettability of the surface of the stainless steel fiber was observed by measuring water contact angle to find out the effect of the plasma treatment time on the surface characteristics of the stainless steel fiber. In addition, in order to understand the effect of oxygen plasma treatment on the deterioration of the stainless steel fiber properties, the physical properties due to plasma treatment was investigated by measuring the weight reduction, tensile strength, elongation, tensile modulus of the stainless steel fibers according to the treatment time. As a result, the stainless steel fiber surface was etched by the oxygen plasma and the surface became more wettable by the introduction of hydrophilic functional groups. However the physical properties of the stainless steel fiber were not significantly deteriorated even if the surface of the stainless steel fiber made hydrophilic.

• Journal of the Semiconductor & Display Technology
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• v.21 no.3
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• pp.57-62
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• 2022

The plasma resistance of multi-component glasses containing La, Gd, Ti, Zn, Y, Zr, Nb, and Ta was analyzed in this study. The plasma etching was performed via inductively coupled plasma-reactive ion etching (ICP-RIE) using CF₄/O₂/Ar mixed gas. After the reaction, the glass with a low fluoride sublimation temperature and high content of P, Si, and Ti elements showed a high etching rate. On the other hand, the glass containing a high fluoride sublimation temperature component such as Ca, La, Gd, Y, and Zr exhibited high plasma resistance because the etch rate was lower than that of sapphire. Glass with low plasma resistance increased surface roughness after etching or nanoholes were formed on the surface, but glass with high plasma resistance showed little change in surface microstructure. Thus, the results of this study demonstrate the potential for the development of plasma-resistant glasses (PRGs) with other compositions besides alumino-silicate glasses, which are conventionally referred to as plasma-resistant glasses.