• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.169-169
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• 2008

To keep pace with scaling trends of CMOS technologies, high-k metal oxides are to be introduced. Due to their high permittivity, high-k materials can achieve the required capacitance with stacks of higher physical thickness to reduce the leakage current through the scaled gate oxide, which make it become much more promising materials to instead of $SiO_2$. As further studying on high-k, an understanding of the relation between the etch characteristics of high-k dielectric materials and plasma properties is required for the low damaged removal process to match standard processing procedure. There are some reports on the dry etching of different high-k materials in ICP and ECR plasma with various plasma parameters, such as different gas combinations ($Cl_2$, $Cl_2/BCl_3$, $Cl_2$/Ar, $SF_6$/Ar, and $CH_4/H_2$/Ar etc). Understanding of the complex behavior of particles at surfaces requires detailed knowledge of both macroscopic and microscopic processes that take place; also certain processes depend critically on temperature and gas pressure. The choice of $BCl_3$ as the chemically active gas results from the fact that it is widely used for the etching o the materials covered by the native oxides due to the effective extraction of oxygen in the form of $BCl_xO_y$ compounds. In this study, the surface reactions and the etch rate of $Al_2O_3$ films in $BCl_3/Cl_2$/Ar plasma were investigated in an inductively coupled plasma(ICP) reactor in terms of the gas mixing ratio, RF power, DC bias and chamber pressure. The variations of relative volume densities for the particles were measured with optical emission spectroscopy (OES). The surface imagination was measured by AFM and SEM. The chemical states of film was investigated using X-ray photoelectron spectroscopy (XPS), which confirmed the existence of nonvolatile etch byproducts.

• 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.

• 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).

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.62-62
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• 2003

고밀도 유도결합 플라즈마(high density inductively coupled plasma) 식각은 GaAs 이종접합 양극성 트랜지스터(HBTs)와 고속전자 이동도 트랜지스터(HEMTs)와 같은 GaAs 기반 반도체의 정교한 패턴을 형성하는데 더욱 많이 이용되고 있다 본 연구는 고밀도 플라즈마 소스(source)인 평판형(planar) 고밀도 유도결합 플라즈마 식각장치를 이용하여 $BCl_3$ 와 $BCl_3/Ar$ 가스에 따른 GaAs 식각결과를 비교 분석하였다. 공정변수는 ICP 소스 파워를 0-500W, RIE 척(chuck) 파워를 0-150W, 공정압력을 0-15 mTorr 이었다. 그리고 가스 유량은 20sccm(standard cubic centimeter per minute)으로 고정시킨 상태에서 Ar 첨가 비율에 따른 GaAs의 식각결과를 관찰하였다. 공정 결과는 식각률(etch rate), GaAs 대 PR의 선택도(selectivity), 표면 거칠기(roughness)와 식각후 표면에 남아 있는 잔류 가스등을 분석하였다. 20 $BCl_3$ 플라즈마를 이용한 GaAs 식각률 보다 Ar이 첨가된 (20-x) $BC1_3/x Ar$ 플라즈마의 식각률이 더 우수하다는 것을 알 수 있었다. 식각률 증가는 Ar 가스의 첨가로 인한 GaAs 반도체와 Ar 플라즈마의 충돌로 나타난 결과로 예측된다. $BCl_3$ 와 $BC1_3/Ar$ 플라즈마에 노출된 GaAs 반도체 모두 표면이 평탄하였고 수직 측벽도 또한 우수하였다. 그리고 표면에 잔류하는 성분은 Ga와 As 이외에 $Cl_2$ 계열의 불순물이 거의 발견되지 않아 매우 깨끗함을 확인하였다. 이번 발표에서는 $BCl_3$ 와 $BCl_3/Ar$ 플라즈마를 이용한 GaAs의 건식식각 비교에 대해 상세하게 보고 할 것이다.

• Transactions on Electrical and Electronic Materials
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• v.15 no.3
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• pp.164-169
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• 2014

We investigated the etching characteristics of $HfAlO_3$ thin films in $O_2/Cl_2/Ar$ and $O_2/BCl_3/Ar$ gas, using a high-density plasma (HDP) system. The etch rates of the $HfAlO_3$ thin film obtained were 30.1 nm/min and 36 nm/min in the $O_2/Cl_2/Ar$ (3:4:16 sccm) and $O_2/BCl_3/Ar$ (3:4:16 sccm) gas mixtures, respectively. At the same time, the etch rate was measured as a function of the etching parameter, namely as the process pressure. The chemical states on the surface of the etched $HfAlO_3$ thin films were investigated by X-ray photoelectron spectroscopy. Auger electron spectroscopy was used for elemental analysis on the surface of the etched $HfAlO_3$ thin films. These surface analyses confirm that the surface of the etched $HfAlO_3$ thin film is formed with nonvolatile by-product. Also, Cl-O can protect the sidewall due to additional $O_2$.

• Journal of the Korean institute of surface engineering
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• v.41 no.3
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• pp.83-87
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• 2008

This study described the effects of RF power, DC bias voltage, chamber pressure and gas mixing ratio on the etch rates of TiN thin film and selectivity of TiN thin film to $SiO_2$ with $BCl_3$/Ar gas mixture. When the gas mixing ratio was $BCl_3$(20%)/Ar(80%) with other conditions were fixed, the maximum etch rate of TiN thin film was 170.6 nm/min. When the DC bias voltage increased from -50 V to -200 V, the etch rate of TiN thin film increased from 15 nm/min to 452 nm/min. As the RF power increased and chamber pressure decreased, the etch rate of TiN thin film showed an increasing tendency. When the gas mixing ratio was $BCl_3$(20%)/Ar(80%) under others conditions were fixed, the intensity of optical emission spectra from radical or ion such as Ar(750.4 nm), $Cl^+$(481.9 nm) and $Cl^{2+}$(460.8 nm) was highest. The TiN thin film was effectively removed by the chemically assisted physical etching in $BCl_3$/Ar ICP plasma.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.3
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• pp.188-192
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• 2000

In this study PZT etching was performed using planar inductively coupled Ar/Cl$_2$/BCI$_3$ plasma. The etch rate of PZT film was 2450 $\AA$/min at Ar(20)/BCl$_3$(80) gas mixing ratio and substrate temperature of 8$0^{\circ}C$. X-ray photoelectron spectroscopy(XPS) analysis for films composition of etched PZT surface was utilized. The chemical bond of PbO is broken by ion bombardment and Cl radical, and the peak of metal Pb in a Pb 4f narrow scan begins to appear upon etching. As increasing additive BCl$_3$content the relative content of oxygen decreases rapidly in contrast with etch rate of PZT thin film. So we though that the etch rate of PZT thin film increased because abundant B and BCl radicals made volatile oxy-compound such as B$_{x}$/O$_{y}$ and/or BClO$_{x}$ bond. We achieved etch profile of about 80$^{\circ}$ at Ar(20)/BCl$_3$(80) gas mixing condition and substrate temperature of 8$0^{\circ}C$TEX>X>.

• Proceedings of the KIEE Conference
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• 2003.10a
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• pp.322-325
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• 2003

BST thin films were etched with inductively coupled plasmas. A chemically assisted physical etch of BST was experimentally confirmed by ICP under various gas mixtures. After a 20 % addition of $BCl_3$ to the $Cl_2/Ar$ mixture, resulting in an increased the chemical effect. As a increases of RF power, substrate power, and substrate temperature, and decrease of working pressure, the ion energy flux and chlorine atoms density increased. The maximum etch rate of the BST thin films was 90.1 nm/min at the RF power, substrate power, working pressure, and substrate temperature were 700 W, 300 W, 1.6 Pa, and 20 $^{\circ}C$, respectively. It was proposed that sputter etching is dominant etching mechanism while the contribution of chemical reaction is relatively low due to low volatility of etching product.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.135-136
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• 2009

The etching characteristics of Zinc Oxide (ZnO) and etch selectivity of ZnO to $SiO_2$ in $BCl_3/Ar/Cl_2$ plasma were investigated. It was found that ZnO etch rate shows a non-monotonic behavior with increasing both Ar fraction in $BCl_3$ plasma, RF power, and gas pressure. The maximum ZnO etch rate of 53 nm/min was obtained for $BCl_3$(16 sccm)/Ar(4 sccm)/$Cl_2$(3 sccm) gas mixture. The chemical state of etched surfaces was investigated with X-ray photoelectron spectroscopy (XPS). From these data, the suggestions on the ZnO etch mechanism were made.

• Applied Chemistry for Engineering
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• v.16 no.6
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• pp.853-856
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• 2005

Inductively coupled plasma reactive ion etching of magnetic tunnel junction (MTJ) stack, which is one of the key elements in magnetic random access memory, was studied. The MTJ stacks were patterned in nanometer size by electron(e)-beam lithography, and TiN thin films were employed as a hard mask. The etch process of TiN hard mask was examined using Ar, $Cl_2/Ar$, and $SF_6/Ar$. The TiN hard mask patterned by e-beam lithography was first etched and then the etching of MTJ stack was performed. The MTJ stacks were etched using Ar, $Cl_2/Ar$, and $BCl_3/Ar$ gases by varying gas concentration and pressure.