• 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 Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.12S
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• pp.1187-1194
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• 2003

A BCl$_3$/Ne plasma chemistry was used to etch Ga-based (GaAs, AIGaAs, GaSb) and In-based (InGaP, InP, InAs and InGaAsP) compound semiconductors in a Planar Inductively Coupled Plasma (ICP) reactor. The addition of the Ne instead of Ar can minimize electrical and optical damage during dry etching of III-V semiconductors due to its light mass compared to that of Ar All of the materials exhibited a maximum etch rate at BCl$_3$ to Ne ratios of 0.25-0.5. Under all conditions, the Ga-based materials etched at significantly higher rates than the In-based materials, due to relatively high volatilities of their trichloride etch products (boiling point CaCl$_3$ : 201 $^{\circ}C$, AsCl$_3$ : 130 $^{\circ}C$, PCl$_3$: 76 $^{\circ}C$) compared to InCl$_3$ (boiling point : 600 $^{\circ}C$). We obtained low root-mean-square(RMS) roughness of the etched sulfate of both AIGaAs and GaAs, which is quite comparable to the unetched control samples. Excellent etch anisotropy ( > 85$^{\circ}$) of the GaAs and AIGaAs in our PICP BCl$_3$/Ne etching relies on some degree of sidewall passivation by redeposition of etch products and photoresist from the mask. However, the surfaces of In-based materials are somewhat degraded during the BCl$_3$/Ne etching due to the low volatility of InCl$_{x}$./.

• Proceedings of the Materials Research Society of Korea Conference
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• 1997.10a
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• pp.103-103
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• 1997

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 1998.05a
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• pp.39-40
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• 1998

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.6
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• pp.447-452
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• 1998

The selective dry etching of GaAs to Al\ulcornerGa\ulcornerAs using $BCI_3/SF_6$ gas mixture in electron cyclotron resonance(ECR) plasma is investigated. A selectivity of GaAs to AlGaAs of more than 100 and maximum etch rate of GaAs are obtained at a gas ratio $SF_6/BCI_3+SF_6$ of 25%. We verified the formation of $AlF_3$ on $Al_{0.25}Ga_{0.75}As$from the Auger spectra which enhanced the etch selectivity. In order to investigate surface damage of AlGaAs caused by ECR plasma, we performed a low temperature photoluminescence(PL) measurement as a function of RF power. As the RF power. As the RF power increases, the PL intensity decreases monotonically from 50 to 100 Wand then repidly decreases until 250 W. This behavior is due to surface damage by plasma treatment. This dry etching technique using $BCI_3/SF_6$ gas mixture in ECR plasma is suitable for gate recess formation on the GaAs based pseudomorphic high electron mobility transistor(PHEMT)

• Journal of the Semiconductor & Display Technology
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• v.19 no.4
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• pp.28-33
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• 2020

Plasma etching process employs high density plasma to create surface chemistry and physical reactions, by which to remove material. Plasma chamber includes silicon-based materials such as a focus ring and gas distribution plate. Focus ring needs to be replaced after a short period. For this reason, there is a need to find materials resistant to erosion by plasma. The developed chemical vapor deposition processing to produce silicon carbide parts with high purity has also supported its widespread use in the plasma etch process. Silicon carbide maintains mechanical strength at high temperature, it have been use to chamber parts for plasma. Recently, besides the structural aspects of silicon carbide, its electrical conductivity and possibly its enhanced life time under high density plasma with less generation of contamination particles are drawing attention for use in applications such as upper electrode or focus rings, which have been made of silicon for a long time. However, especially for high purity silicon carbide focus ring, which has usually been made by the chemical vapor deposition method, there has been no study about quality improvement. The goal of this study is to reduce surface roughness and depth of damage by diamond tool grit size and tool dressing of diamond tools for precise dimensional assurance of focus rings.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.4
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• pp.319-324
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• 2002

In this study, the reduce of plasma etching damage in PZT thin film with addictive gas and re-annealing after etching have been investigated. The PZT thin films were etched as a function of $Cl_2/CF_4$ with addition of Ar and $O_2$ with inductively coupled plasma. The etch rates of PZT thin films were 1450 ${\AA}/min$ at 30% additive Ar and 1100 ${\AA}/min$ at 10% auditive $O_2$ into $Cl_2/CF_4$ gas mixing ratio of 8/2. In order to reduce plasma damage of PZT thin films after etching, the etched PZT thin films were re-annealed at various temperatures at $O_2$ atmosphere. From the hysteresis curries, the ferroelectric properties are improved by $O_2$ re-annealing process. The improvement of ferroelectric behavior at annealed PZT films is consistent wish the increase of the (100) and (200) PZT peaks revealed by x-ray diffraction (XRD). From x ray photoelectron spectroscopy (XPS) analysis, the intensity of Pb-O, Zr-O and Ti-O peak are increased and the chemical residue peak is reduced by $O_2$ re-annealing. The ferroelectric behavior consistent with the dielectric nature of $Ti_xO_y$ is recovered by $O_2$ recombination during rapid thermal annealing process.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.477-477
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• 2008

For more than three decades, the gate dielectrics in CMOS devices are $SiO_2$ because of its blocking properties of current in insulated gate FET channels. As the dimensions of feature size have been scaled down (width and the thickness is reduced down to 50 urn and 2 urn or less), gate leakage current is increased and reliability of $SiO_2$ is reduced. Many metal oxides such as $TiO_2$, $Ta_2O_4$, $SrTiO_3$, $Al_2O_3$, $HfO_2$ and $ZrO_2$ have been challenged for memory devices. These materials posses relatively high dielectric constant, but $HfO_2$ and $Al_2O_3$ did not provide sufficient advantages over $SiO_2$ or $Si_3N_4$ because of reaction with Si substrate. Recently, $HfO_2$ have been attracted attention because Hf forms the most stable oxide with the highest heat of formation. In addition, Hf can reduce the native oxide layer by creating $HfO_2$. However, new gate oxide candidates must satisfy a standard CMOS process. In order to fabricate high density memories with small feature size, the plasma etch process should be developed by well understanding and optimizing plasma behaviors. Therefore, it is necessary that the etch behavior of $HfO_2$ and plasma parameters are systematically investigated as functions of process parameters including gas mixing ratio, rf power, pressure and temperature to determine the mechanism of plasma induced damage. However, there is few studies on the the etch mechanism and the surface reactions in $BCl_3$ based plasma to etch $HfO_2$ thin films. In this work, the samples of $HfO_2$ were prepared on Si wafer with using atomic layer deposition. In our previous work, the maximum etch rate of $BCl_3$/Ar were obtained 20% $BCl_3$/ 80% Ar. Over 20% $BCl_3$ addition, the etch rate of $HfO_2$ decreased. The etching rate of $HfO_2$ and selectivity of $HfO_2$ to Si were investigated with using in inductively coupled plasma etching system (ICP) and $BCl_3/Cl_2$/Ar plasma. The change of volume densities of radical and atoms were monitored with using optical emission spectroscopy analysis (OES). The variations of components of etched surfaces for $HfO_2$ was investigated with using x-ray photo electron spectroscopy (XPS). In order to investigate the accumulation of etch by products during etch process, the exposed surface of $HfO_2$ in $BCl_3/Cl_2$/Ar plasma was compared with surface of as-doped $HfO_2$ and all the surfaces of samples were examined with field emission scanning electron microscopy and atomic force microscope (AFM).

• Journal of the Korean institute of surface engineering
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• v.34 no.5
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• pp.516-521
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• 2001

Dry etching of Si wafer and $SiO_2$ layers was performed using He/Cl$_2$ mixture plasma by diode-type reactive ion etcher (RIE) system. For Si etching, the Cl molecules react with the Si molecules on the surface and become chemically stable, indicating that the reactants need energetic ion bombardment. During the ion assisted desorption, energetic ions would damage the photoresist (PR) and produce the bad etch Si-profile. Moreover, we have examined the characteristics of the Cl-Si reaction system, and developed the new fabrication procedures with a $Cl_2$/He mixture for Si and $SiO_2$-etching. The developed novel fabrication procedure allows the RIE to be unexpensive and useful a Si deep etching system. Since the etch rate was proved to increase linearly with fHe and the selectivity of Si to $SiO_2$ etch rate was observed to be inversely proportional to fHe.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.5 no.4
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• pp.408-413
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• 1995

We investigated the effect of mechanical backside damage upon minority carrier recombination lifetime measurement in Czochralski silicon substrate by laser excitation/microwave reflection photoconductance decay method. The intensity of mechanical damage was evaluated by X-ray double crystal rocking curve, X-ray section topography and wet oxidation/preferential etch methods. The data indicate that the higher the mechanical damage intensity, the lower the minority carrier lifetime, and the threshold full width at half maximum value which affect minority carrier lifetime measurement is about 13 secs.