• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.77-77
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• 2011

These days, a growing demand for memory device is filled up with the flash memory and the dynamic random access memory (DRAM). Although DRAM is a reasonable solution for current demand, the universal novel memory with high density, high speed and nonvolatility, needs to be developed. Among various new memories, the magnetic random access memory (MRAM) device is considered as one of good candidate memories because of excellent features including high density, high speed, low operating power and nonvolatility. The etching of MTJ stack which is composed of magnetic materials and insulator such as MgO is one of the vital process for MRAM. Recently, MgO has attracted great interest in the MTJ stack as tunneling barrier layer for its high tunneling magnetoresistance values. For the successful realization of high density MRAM, the etching process of MgO thin films should be investigated. Until now, there were some works devoted to the investigations on etch characteristics of MgO thin films. Initially, ion milling was applied to the etching of MgO thin films. However, ion milling has many disadvantages such as sidewall redeposition and etching damage. High density plasma etching containing the magnetically enhanced reactive ion etching and high density reactive ion etching have been employed for the improvement of etching process. In this work, inductively coupled plasma reactive ion etching (ICPRIE) system was adopted for the improvement of etching process using MgO thin films and etching gas mixes of $CH_4$/Ar and $CH_4$/$O_2$/Ar have been employed. The etch rates are measured by a surface profilometer and etch profiles are observed using field emission scanning emission microscopy (FESEM). The effects of gas concentration and etch parameters such as coil rf power, dc-bias voltage to substrate, and gas pressure on etch characteristics will be systematically explored.

• Journal of the Semiconductor & Display Technology
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• v.17 no.4
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• pp.97-100
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• 2018

$NF_3$ Plasma etching of silicon was conducted by injecting only $NF_3$ gas into reactive ion etching. $NF_3$ Plasma etching was done in intermediate pressure. Silicon etching by $NF_3$ plasma in reactive ion etching was diagnosed through residual gas analyzer and optical emission spectroscopy. In plasma etching, optical emission spectroscopy is generally used to know what kinds of species in plasma. Also, residual gas analyzer is mainly to know the byproducts of etching process. Through experiments, the results of optical emission spectroscopy during silicon etching by $NF_3$ plasma was analyzed with connecting the results of etch rate of silicon and residual gas analyzer. It was confirmed that $NF_3$ plasma etching of silicon in reactive ion etching accords with the characteristic of reactive ion etching.

• Proceedings of the Materials Research Society of Korea Conference
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• 1992.05b
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• pp.63-63
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• 1992

• Proceedings of the Materials Research Society of Korea Conference
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• 1992.05a
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• pp.32-32
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• 1992

• Journal of Magnetics
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• v.15 no.3
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• pp.132-137
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• 2010

Plasma etching of $SiO_2$ contact holes was statistically analyzed by a fractional factorial experimental design. The analysis revealed the dependence of the etch rate and DC self-bias voltage on the input factors of the magnetically enhanced reactive ion etching reactor, including gas pressure, magnetic field, and the gas flow rates of $CHF_3$, $CF_4$, and Ar. Empirical models of the DC self-bias voltage and etch rate were obtained. The DC self-bias voltage was found to be determined mainly by the operating pressure and the magnetic field, and the etch rate was related mainly to the pressure and the flow rates of Ar and $CHF_3$.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.985-989
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• 2005

본 논문에서는 비정질 반도체 및 절연체의 etching을 RIE를 사용하여 etching 조건을 결정하는 요인(chamber pressure, gas flow rate, rf power, 온도 등)들을 변화시켜 실험하였고, gas는 비정질 실리콘 박막의 reactive ion etching에 주로 사용되는 $CF_4,\; CF_4+O_2,\;CCl_2F_2,\;CHF_3\;gas$ 등을 사용하였다. 여기서 실리콘 박막의 식각은 $CF_4,\;CCl_2F_2,\;gas$를 그리고 insulator 막인 SiNx 박막의 식각은 $CF_4+O_2,\;CHF_3\;gas$를 사용하였다. 특히 $CCl_2F_2$ gas는 insulator 막인 SiNx 박막과의 식각 selectivity가 6:1로서 우수하기 때문이다. 정확한 control에 의해 높은 수율 (Yield) 을 얻을 수 있어 cost를 절감할 수 있다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.5
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• pp.962-969
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• 2006

To address the importance of the process fault detection for productivity, support vector machines (SVMs) is employed to assist the decision to determine process faults in real-time. The reactive ion etching (RIE) tool data acquired from a production line consist of 59 variables, and each of them consists of 10 data points per second. Principal component analysis (PCA) is first performed to accommodate for real-time data processing by reducing the dimensionality or the data. SVMs for eleven steps or etching m are established with data acquired from baseline runs, and they are further verified with the data from controlled (acceptable) and perturbed (unacceptable) runs. Then, each SVM is further utilized for the fault detection purpose utilizing control limits which is well understood in statistical process control chart. Utilizing SVMs, fault detection of reactive ion etching process is demonstrated with zero false alarm rate of the controlled runs on a run to run basis.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.247-250
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• 2006

Maximizing the productivity in reactive ion etching, early detection of process equipment anomaly became crucial in current high volume semiconductor manufacturing environment. To address the importance of the process fault detection for productivity, support vector machines (SVMs) is employed to assist the decision to determine process faults in real-time. SVMs for eleven steps of etching runs are established with data acquired from baseline runs, and they are further verified with the data from controlled (acceptable) and perturbed (unacceptable) runs. Then, each SVM is further utilized for the fault detection purpose utilizing control limits which is well understood in statistical process control chart. Utilizing SVMs, fault detection of reactive ion etching process is demonstrated with zero false alarm rate of the controlled runs on a run to run basis.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.05a
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• pp.140-143
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• 2006

차세대 반도체 공정을 위한 많은 노력 중 미세가공의 중요성이 날로 증가함에 따라 reactive ion etching (RIE)에 대한 연구 또한 그 중요성이 커지고 있으며, 현재 제조공정 라인에서는 공정상의 오류를 줄이는 노력에 주목하고 있다. 본 논문에서는 RIE 과정에서 etch rate과 uniformity에 영향을 줄 수 있는 요인 4 가지 즉, $CHF_3$, $O_2$ chamber pressure, RF power의 변화에 대해 실험 계획법 (DOE)을 통해 실험을 계획하고, 실험한 후 neural networks. 를 통해 학습함으로서 RIE 공정상의 최적화률 모색하였다.

• Current Photovoltaic Research
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• v.5 no.4
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• pp.105-108
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• 2017

The reactive ion etching (RIE) technology which enables nano-texturatization of surface is applied on monocrystalline silicon solar cell. The additional RIE process on alkalized textured surface further improves the blue response and short circuit current. Such parameter is characterized by surface reflectance and quantum efficiency measurement. By varying the RIE process time and matching the subsequent processes, the absolute efficiency gain of 0.13% is achieved. However, the result indicates potential efficiency gain could be higher due to process integration. The critical etch process time is discussed which minimizes both front surface reflectance and etching damage, considering the challenges of required system throughput in industry.