Chee Won Chung | Inha University (original) (raw)

Papers by Chee Won Chung

Korean Journal of Chemical Engineering, 2005

− Inductively coupled plasma reactive ion etching of CoTb and CoZrNb magnetic materials with the ... more − Inductively coupled plasma reactive ion etching of CoTb and CoZrNb magnetic materials with the photoresist mask was performed using Cl 2 /Ar and C 2 F 6 /Ar gas mixtures and characterized in terms of etch rate and etch profile. As the concentrations of Cl 2 and C 2 F 6 gases increased, the etch rates of magnetic films decreased and the etch slopes became slanted. The Cl 2 /Ar gas was more effective in obtaining fast etch rate and steep sidewall slope than the C 2 F 6 /Ar gas. As the coil rf power and dc bias increased, fast etch rate and steep etch slope were obtained but the redeposition on the sidewall was observed. This is due to the increase of ion and radical densities in plasma with increasing the coil rf power and the increase of incident ion energy to the substrate with increasing the dc bias voltage. By applying high density reactive ion etching to magnetic tunnel junction stack containing various magnetic films and metal oxide, steep etch slope and clean etch profile wit...

Journal of Nanoscience and Nanotechnology, 2021

Pulse-modulated plasma etching of copper masked using SIO2 films was conducted via a CH3COOH/Ar. ... more Pulse-modulated plasma etching of copper masked using SIO2 films was conducted via a CH3COOH/Ar. The etch characteristics were examined under pulse-modulated plasma. As the duty ratio of pulse decreased and the frequency of pulse increased, the etch selectivity and etch profile were improved. X-ray photoelectron spectroscopy and indicated that more copper oxides (Cu2O and CuO) and Cu(CH3COO)2 were formed using pulse-modulated plasma than those formed using continuous-wave (CW) plasma. As the concentration of CH3COOH gas in pulse-modulated plasma increased, the formation of these copper compounds increased, which improved the etch profiles. Optical emission spectroscopy confirmed that the active ingredients of the plasma increased with decreasing pulse duty ratio and increasing frequency. Therefore, the optimized pulsed plasma etching of copper via a CH3COOH/Ar gas provides better etch profile than that by CW plasma etching.

ECS Journal of Solid State Science and Technology, 2021

High density plasma reactive ion etching of copper thin films patterned with SiO2 masks was perfo... more High density plasma reactive ion etching of copper thin films patterned with SiO2 masks was performed via piperidine/ethanol/Ar gas mixture. The etch characteristics of the copper thin films were examined as functions of the gas concentrations in piperidine/Ar and piperidine/ethanol/Ar mixtures. As the piperidine concentration increased, the etch rates of the copper films decreased whereas the etch selectivities of the copper films to SiO2 mask increased and the etch profiles improved. Optical emission spectroscopy studies showed that the major active species in the plasmas of piperidine/Ar and piperidine/ethanol/Ar were CH and CN, which were responsible for the good etch profiles. Further, X-ray photoelectron spectroscopy revealed the formation of CuCN, copper compounds, and polymer layers. Finally, dry etching of copper thin films was successfully accomplished with the optimized piperidine/ethanol/Ar gas mixture, thereby obtaining good etch profiles with high degrees of anisotropy.

Current Applied Physics, 2018

Journal of Nanoscience and Nanotechnology, 2020

Magnetic tunnel junctions (MTJs) patterned with 70 × 70 nm2 square arrays were etched in a CH4/O2... more Magnetic tunnel junctions (MTJs) patterned with 70 × 70 nm2 square arrays were etched in a CH4/O2/Ar gas mixture by pulse-modulated inductively coupled plasma reactive ion etching (ICPRIE). A good etch profile of MTJs with etch slope of approximately 82° was achieved by adjusting the on–off duty ratio of the plasma and pulse frequency. Langmuir probe analysis and optical emission spectroscopy confirmed that the balance between the formation of the passivation layer as an etch byproduct and sputtering effect is responsible for the etch selectivity and etch profile with a high degree of anisotropy. It is concluded that the application of pulse-modulated plasma on ICPRIE can be an effective method to obtain the anisotropic etch profile of nanometer-scale MTJs.

ECS Journal of Solid State Science and Technology, 2018

Thin Solid Films, 2018

Inductively coupled plasma reactive ion etching of copper thin films patterned with SiO 2 masks w... more Inductively coupled plasma reactive ion etching of copper thin films patterned with SiO 2 masks was performed using CH 4 /O 2 /Ar gas mixture. The etch characteristics of copper films in CH 4 /Ar and O 2 /Ar gases were examined to determine the roles of CH 4 and O 2 , respectively. The etch rates and etch profiles of copper films were investigated by varying the O 2 concentration in CH 4 /O 2 /Ar gas mixture. In the optimized CH 4 /O 2 /Ar gas mixture, systematic etching of copper films was performed by changing the etch parameters, including ICP RF power, DC-bias voltage, and process pressure. As the ICP RF power and DC-bias voltage was increased and the process pressure was decreased, the etch rate increased and the etch profile improved. X-ray photoelectron spectroscopy and energy dispersive X-ray spectroscopy were used to determine the etch mechanism in the CH 4 / O 2 /Ar gas mixture. Finally, the etching of copper films in the optimized CH 4 /O 2 /Ar gas mixture was successfully achieved with good etch profile with a high degree of anisotropy.

Vacuum, 2016

Inductively coupled plasma reactive ion etching of Ta thin films masked with photoresist was perf... more Inductively coupled plasma reactive ion etching of Ta thin films masked with photoresist was performed using C 2 F 6 /Ar, HBr/Ar and Cl 2 /Ar gases. The etch characteristics such as etch rate, etch selectivity and etch profile were investigated in different gas concentrations of each gas. The Cl 2 chemistry showed high degree of anisotropy in etch profile as well as fastest etch rate and highest etch selectivity of Ta films among these gases. Optical emission spectroscopy revealed that the increase in chlorine radicals with increasing Cl 2 concentration was responsible for the increase in the Ta etch rate. The etch rate of Ta films increased with increasing ICP rf power and dc-bias voltage, and decreasing process pressure. Good etch profiles were obtained at high rf power and dc-bias voltage, and low process pressure. X-ray photoelectron spectroscopy confirmed the existence of a chemical reaction of Ta with chlorine radicals by forming tantalum chlorides. These results suggested that Ta etching in Cl 2 /Ar follows the typical reactive ion etching mechanism. It was concluded that a high degree of anisotropy and high etch rate of Ta films were achieved using Cl 2 /Ar gas.

Journal of Vacuum Science & Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phenomena, 2015

Thin Solid Films, 2011

Ti hard mask Magnetic tunnel junction Inductively coupled plasma reactive ion etching HBr/Ar gas ... more Ti hard mask Magnetic tunnel junction Inductively coupled plasma reactive ion etching HBr/Ar gas Etch characteristics of MgO thin films were investigated using an inductively coupled plasma reactive ion etcher in a HBr/Ar plasma. As the concentration of HBr gas increased, the etch rate of MgO thin films gradually decreased, but the etch rate of Ti hard mask showed initial decrease and then increased with increasing HBr concentration. The etch profile of MgO films was improved with increasing HBr concentration and a high degree of anisotropy in etch profile was achieved at 30% HBr/Ar gas. Based on the etch characteristics and surface analysis by X-ray photoelectron spectroscopy, it can be concluded that the etch mechanism of MgO thin films in a HBr/Ar gas does not follow the reactive ion etch mechanism but the sputter etching mechanism with the assistance of chemical reactions on the film surfaces.

Surface and Coatings Technology, 2010

Gallium indium zinc oxide (GIZO) thin films patterned with a photoresist (PR) were dry etched usi... more Gallium indium zinc oxide (GIZO) thin films patterned with a photoresist (PR) were dry etched using inductively coupled plasma (ICP) of HBr/Ar gas. The etch rate of the GIZO films and the etch selectivity of GIZO/PR decreased gradually as HBr gas was added to Ar. In addition, the etch rate increased with increasing ICP power and dc-bias voltage to the substrate. However, the etch rate was decreased with increasing gas pressure. X-ray photoelectron spectroscopy and atomic force microscopy revealed Br compounds on the film surface during the etching process. It can be concluded that the high density plasma etching of GIZO films using HBr/Ar gas follows a sputtering etching mechanism with the assistance of a chemical reaction on the films.

Vacuum, 2015

The inductively coupled plasma etching characteristics of Co 2 MnSi thin films patterned using a ... more The inductively coupled plasma etching characteristics of Co 2 MnSi thin films patterned using a TiN hard mask were investigated by the addition of CH 3 OH to Ar gas. As the CH 3 OH concentration increased, the etch rates of Co 2 MnSi magnetic thin films and TiN hard mask decreased, but the etch profile improved. The effects of rf power, dc-bias voltage and gas pressure on the etch rate and etch profile were also investigated. The etch rate and etch profile degree of anisotropy increased with increasing rf power and dc-bias voltage and decreasing gas pressure. Optical emission spectroscopy analysis revealed that [H], [O], [CO], [OH], [CH 3 O] and [Ar] species in the CH 3 OH/Ar plasma played a key role in achieving a good etch profile.

… OF INDUSTRIAL AND …, 2007

Abstract: The etch characteristics of Ni thin films masked with a photoresist were investigated u... more Abstract: The etch characteristics of Ni thin films masked with a photoresist were investigated using inductively coupled plasma reactive ion etching in a Cl2/Ar gas mix. As the Cl2 concentration increased, the etch rate of Ni films decreased and the redeposited materials ...

Thin Solid Films, 2011

Abstract Etch characteristics of L10 FePt thin films masked with TiN films were investigated usin... more Abstract Etch characteristics of L10 FePt thin films masked with TiN films were investigated using an inductively coupled plasma (ICP) reactive ion etching in a CH 3 OH/Ar plasma. As the CH 3 OH gas was added to Ar, the etch rates of FePt thin films and TiN hard mask gradually decreased, and the etch profile of FePt films improved with high degree of anisotropy. With increasing ICP rf power and dc-bias voltage to substrate and decreasing gas pressure, the etch rate increased and the etch profile becomes vertical without any redepositions or etch residues. Based on the etch characteristics and surface analysis of the films by X-ray photoelectron spectroscopy, it can be concluded that the etch mechanism of FePt thin films in a CH 3 OH/Ar gas does not follow the reactive ion etch mechanism but the chemically assisted sputter etching mechanism, due to the chemical reaction of FePt film with CH 3 OH gas.

Thin Solid Films, 2011

An inductively coupled plasma reactive ion etching of IrMn magnetic thin films patterned with Ti ... more An inductively coupled plasma reactive ion etching of IrMn magnetic thin films patterned with Ti hard mask was studied in a CH3OH/Ar gas mix. As the CH3OH concentration increased, the etch rates of IrMn thin films and Ti hard mask decreased, while the etch profiles improved with high degree of anisotropy. The effects of coil rf power, dc-bias voltage to substrate and gas pressure on the etch characteristics were investigated. The etch rate increased and the etch profile improved with increasing coil rf power, dc-bias voltage and decreasing gas pressure. X-ray photoelectron spectroscopy revealed that the chemical reaction between IrMn films and CH3OH gas occurred, leading to the clean and good etch profile with high degree of anisotropy of 90°.

physica status solidi c, 2007

The etch characteristics of magnetic tunneling junction (MTJ) related materials such as CoFeB, Mg... more The etch characteristics of magnetic tunneling junction (MTJ) related materials such as CoFeB, MgO, FePt, Ru, and W as hard mask have been investigated as functions of rf pulse biasing, substrate heating, and CH 4 /N 2 O gas combination in an inductively coupled plasma system. When CH 4 /N 2 O gas ratio was varied, at CH 4 /N 2 O gas ratio of 2:1, not only the highest etch rates but also the highest etch selectivity over W could be obtained. By increasing the substrate temperature, the linear increase of both the etch rates of MTJ materials and the etch selectivity over W could be obtained. The use of the rf pulse biasing improved the etch selectivity of the MTJ materials over hard mask such as W further. The surface roughness and residual thickness remaining on the etched surface of the CoFeB were also decreased by using rf pulse biasing and with the decrease of rf duty percentage. The improvement of etch characteristics by substrate heating and rf pulse biasing was possibly related to the formation of more stable and volatile etch compounds and the removal of chemically reacted compounds more easily on the etched CoFeB surface. Highly selective etching of MTJ materials over the hard mask could be obtained by using the rf pulse biasing of 30% of duty ratio and by increasing the substrate temperature to 200 C in the CH 4 /N 2 O (2:1) plasmas.

physica status solidi (a), 2004

... Byul Shin1, Young Soo Song1, Sang Jin Park2, Tae Wan Kim2, and Chee Won Chung*, 1 1 Departmen... more ... Byul Shin1, Young Soo Song1, Sang Jin Park2, Tae Wan Kim2, and Chee Won Chung*, 1 1 Department of Chemical Engineering and Institute of Clean Technology, Inha University, 253 Yonghyun-Dong, Nam-Ku, Incheon 402-751, Korea 2 Materials & ... [3] KB Jung, ES Lambers ...

Korean Journal of Chemical Engineering, 2003

− − − −High density plasma etching of polysilicon thin films was carried out in an inductively co... more − − − −High density plasma etching of polysilicon thin films was carried out in an inductively coupled plasma (ICP) for the formation of nanometer-sized patterns. The etch rate and etch selectivity of polysilicon films were investigated as a function of the concentration of Cl 2 and HBr etch gases. The fast etch rate of polysilicon films was obtained in Cl 2 /Ar gas, and the high selectivity of polysilicon to photoresist was found in HBr/Ar gas. Finally, the etching of polysilicon films masked with photoresists was attempted in HBr/Ar and Cl 2 /Ar gases. The good pattern profile of polysilicon films with 60 nm lines was achieved in an HBr/Ar plasma.

Korean Journal of Chemical Engineering, 2002

Ti 1 − x)O 3 thin films were etched in an inductively coupled plasma by using various etch gases ... more Ti 1 − x)O 3 thin films were etched in an inductively coupled plasma by using various etch gases such as Cl 2 /Ar, C 2 F 6 /Ar, Cl 2 /C 2 F 6 /Ar and HBr/Ar. The etch rates and etch profiles for each etch gas were investigated. Fast etch rates were obtained in chlorine-containing etch gases (e.g., Cl 2 /Ar and Cl 2 /C 2 F 6 /Ar), and clean and steep etch profiles were achieved in Cl 2 /C 2 F 6 /Ar or HBr/Ar gases. The gas mixture of Cl 2 and C 2 F 6 was proposed to give a fast etch rate and a steep sidewall angle of etched patterns. The optimum gas mixture of Cl 2 /C 2 F 6 /Ar was found by varying the gas ratio of Cl 2 to C 2 F 6. On the other hand, HBr/Ar gas as an alternative for etching of the Pb(Zr x Ti 1− x)O 3 films was examined. Cl 2 /C 2 F 6 /Ar and HBr/Ar etch gases were compared with respect to etch rate, etch profile and electrical properties.

Korean Journal of Chemical Engineering, 2005

− Inductively coupled plasma reactive ion etching of CoTb and CoZrNb magnetic materials with the ... more − Inductively coupled plasma reactive ion etching of CoTb and CoZrNb magnetic materials with the photoresist mask was performed using Cl 2 /Ar and C 2 F 6 /Ar gas mixtures and characterized in terms of etch rate and etch profile. As the concentrations of Cl 2 and C 2 F 6 gases increased, the etch rates of magnetic films decreased and the etch slopes became slanted. The Cl 2 /Ar gas was more effective in obtaining fast etch rate and steep sidewall slope than the C 2 F 6 /Ar gas. As the coil rf power and dc bias increased, fast etch rate and steep etch slope were obtained but the redeposition on the sidewall was observed. This is due to the increase of ion and radical densities in plasma with increasing the coil rf power and the increase of incident ion energy to the substrate with increasing the dc bias voltage. By applying high density reactive ion etching to magnetic tunnel junction stack containing various magnetic films and metal oxide, steep etch slope and clean etch profile wit...

Journal of Nanoscience and Nanotechnology, 2021

Pulse-modulated plasma etching of copper masked using SIO2 films was conducted via a CH3COOH/Ar. ... more Pulse-modulated plasma etching of copper masked using SIO2 films was conducted via a CH3COOH/Ar. The etch characteristics were examined under pulse-modulated plasma. As the duty ratio of pulse decreased and the frequency of pulse increased, the etch selectivity and etch profile were improved. X-ray photoelectron spectroscopy and indicated that more copper oxides (Cu2O and CuO) and Cu(CH3COO)2 were formed using pulse-modulated plasma than those formed using continuous-wave (CW) plasma. As the concentration of CH3COOH gas in pulse-modulated plasma increased, the formation of these copper compounds increased, which improved the etch profiles. Optical emission spectroscopy confirmed that the active ingredients of the plasma increased with decreasing pulse duty ratio and increasing frequency. Therefore, the optimized pulsed plasma etching of copper via a CH3COOH/Ar gas provides better etch profile than that by CW plasma etching.

ECS Journal of Solid State Science and Technology, 2021

High density plasma reactive ion etching of copper thin films patterned with SiO2 masks was perfo... more High density plasma reactive ion etching of copper thin films patterned with SiO2 masks was performed via piperidine/ethanol/Ar gas mixture. The etch characteristics of the copper thin films were examined as functions of the gas concentrations in piperidine/Ar and piperidine/ethanol/Ar mixtures. As the piperidine concentration increased, the etch rates of the copper films decreased whereas the etch selectivities of the copper films to SiO2 mask increased and the etch profiles improved. Optical emission spectroscopy studies showed that the major active species in the plasmas of piperidine/Ar and piperidine/ethanol/Ar were CH and CN, which were responsible for the good etch profiles. Further, X-ray photoelectron spectroscopy revealed the formation of CuCN, copper compounds, and polymer layers. Finally, dry etching of copper thin films was successfully accomplished with the optimized piperidine/ethanol/Ar gas mixture, thereby obtaining good etch profiles with high degrees of anisotropy.

Current Applied Physics, 2018

Journal of Nanoscience and Nanotechnology, 2020

Magnetic tunnel junctions (MTJs) patterned with 70 × 70 nm2 square arrays were etched in a CH4/O2... more Magnetic tunnel junctions (MTJs) patterned with 70 × 70 nm2 square arrays were etched in a CH4/O2/Ar gas mixture by pulse-modulated inductively coupled plasma reactive ion etching (ICPRIE). A good etch profile of MTJs with etch slope of approximately 82° was achieved by adjusting the on–off duty ratio of the plasma and pulse frequency. Langmuir probe analysis and optical emission spectroscopy confirmed that the balance between the formation of the passivation layer as an etch byproduct and sputtering effect is responsible for the etch selectivity and etch profile with a high degree of anisotropy. It is concluded that the application of pulse-modulated plasma on ICPRIE can be an effective method to obtain the anisotropic etch profile of nanometer-scale MTJs.

ECS Journal of Solid State Science and Technology, 2018

Thin Solid Films, 2018

Inductively coupled plasma reactive ion etching of copper thin films patterned with SiO 2 masks w... more Inductively coupled plasma reactive ion etching of copper thin films patterned with SiO 2 masks was performed using CH 4 /O 2 /Ar gas mixture. The etch characteristics of copper films in CH 4 /Ar and O 2 /Ar gases were examined to determine the roles of CH 4 and O 2 , respectively. The etch rates and etch profiles of copper films were investigated by varying the O 2 concentration in CH 4 /O 2 /Ar gas mixture. In the optimized CH 4 /O 2 /Ar gas mixture, systematic etching of copper films was performed by changing the etch parameters, including ICP RF power, DC-bias voltage, and process pressure. As the ICP RF power and DC-bias voltage was increased and the process pressure was decreased, the etch rate increased and the etch profile improved. X-ray photoelectron spectroscopy and energy dispersive X-ray spectroscopy were used to determine the etch mechanism in the CH 4 / O 2 /Ar gas mixture. Finally, the etching of copper films in the optimized CH 4 /O 2 /Ar gas mixture was successfully achieved with good etch profile with a high degree of anisotropy.

Vacuum, 2016

Inductively coupled plasma reactive ion etching of Ta thin films masked with photoresist was perf... more Inductively coupled plasma reactive ion etching of Ta thin films masked with photoresist was performed using C 2 F 6 /Ar, HBr/Ar and Cl 2 /Ar gases. The etch characteristics such as etch rate, etch selectivity and etch profile were investigated in different gas concentrations of each gas. The Cl 2 chemistry showed high degree of anisotropy in etch profile as well as fastest etch rate and highest etch selectivity of Ta films among these gases. Optical emission spectroscopy revealed that the increase in chlorine radicals with increasing Cl 2 concentration was responsible for the increase in the Ta etch rate. The etch rate of Ta films increased with increasing ICP rf power and dc-bias voltage, and decreasing process pressure. Good etch profiles were obtained at high rf power and dc-bias voltage, and low process pressure. X-ray photoelectron spectroscopy confirmed the existence of a chemical reaction of Ta with chlorine radicals by forming tantalum chlorides. These results suggested that Ta etching in Cl 2 /Ar follows the typical reactive ion etching mechanism. It was concluded that a high degree of anisotropy and high etch rate of Ta films were achieved using Cl 2 /Ar gas.

Journal of Vacuum Science & Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phenomena, 2015

Thin Solid Films, 2011

Ti hard mask Magnetic tunnel junction Inductively coupled plasma reactive ion etching HBr/Ar gas ... more Ti hard mask Magnetic tunnel junction Inductively coupled plasma reactive ion etching HBr/Ar gas Etch characteristics of MgO thin films were investigated using an inductively coupled plasma reactive ion etcher in a HBr/Ar plasma. As the concentration of HBr gas increased, the etch rate of MgO thin films gradually decreased, but the etch rate of Ti hard mask showed initial decrease and then increased with increasing HBr concentration. The etch profile of MgO films was improved with increasing HBr concentration and a high degree of anisotropy in etch profile was achieved at 30% HBr/Ar gas. Based on the etch characteristics and surface analysis by X-ray photoelectron spectroscopy, it can be concluded that the etch mechanism of MgO thin films in a HBr/Ar gas does not follow the reactive ion etch mechanism but the sputter etching mechanism with the assistance of chemical reactions on the film surfaces.

Surface and Coatings Technology, 2010

Gallium indium zinc oxide (GIZO) thin films patterned with a photoresist (PR) were dry etched usi... more Gallium indium zinc oxide (GIZO) thin films patterned with a photoresist (PR) were dry etched using inductively coupled plasma (ICP) of HBr/Ar gas. The etch rate of the GIZO films and the etch selectivity of GIZO/PR decreased gradually as HBr gas was added to Ar. In addition, the etch rate increased with increasing ICP power and dc-bias voltage to the substrate. However, the etch rate was decreased with increasing gas pressure. X-ray photoelectron spectroscopy and atomic force microscopy revealed Br compounds on the film surface during the etching process. It can be concluded that the high density plasma etching of GIZO films using HBr/Ar gas follows a sputtering etching mechanism with the assistance of a chemical reaction on the films.

Vacuum, 2015

The inductively coupled plasma etching characteristics of Co 2 MnSi thin films patterned using a ... more The inductively coupled plasma etching characteristics of Co 2 MnSi thin films patterned using a TiN hard mask were investigated by the addition of CH 3 OH to Ar gas. As the CH 3 OH concentration increased, the etch rates of Co 2 MnSi magnetic thin films and TiN hard mask decreased, but the etch profile improved. The effects of rf power, dc-bias voltage and gas pressure on the etch rate and etch profile were also investigated. The etch rate and etch profile degree of anisotropy increased with increasing rf power and dc-bias voltage and decreasing gas pressure. Optical emission spectroscopy analysis revealed that [H], [O], [CO], [OH], [CH 3 O] and [Ar] species in the CH 3 OH/Ar plasma played a key role in achieving a good etch profile.

… OF INDUSTRIAL AND …, 2007

Abstract: The etch characteristics of Ni thin films masked with a photoresist were investigated u... more Abstract: The etch characteristics of Ni thin films masked with a photoresist were investigated using inductively coupled plasma reactive ion etching in a Cl2/Ar gas mix. As the Cl2 concentration increased, the etch rate of Ni films decreased and the redeposited materials ...

Thin Solid Films, 2011

Abstract Etch characteristics of L10 FePt thin films masked with TiN films were investigated usin... more Abstract Etch characteristics of L10 FePt thin films masked with TiN films were investigated using an inductively coupled plasma (ICP) reactive ion etching in a CH 3 OH/Ar plasma. As the CH 3 OH gas was added to Ar, the etch rates of FePt thin films and TiN hard mask gradually decreased, and the etch profile of FePt films improved with high degree of anisotropy. With increasing ICP rf power and dc-bias voltage to substrate and decreasing gas pressure, the etch rate increased and the etch profile becomes vertical without any redepositions or etch residues. Based on the etch characteristics and surface analysis of the films by X-ray photoelectron spectroscopy, it can be concluded that the etch mechanism of FePt thin films in a CH 3 OH/Ar gas does not follow the reactive ion etch mechanism but the chemically assisted sputter etching mechanism, due to the chemical reaction of FePt film with CH 3 OH gas.

Thin Solid Films, 2011

An inductively coupled plasma reactive ion etching of IrMn magnetic thin films patterned with Ti ... more An inductively coupled plasma reactive ion etching of IrMn magnetic thin films patterned with Ti hard mask was studied in a CH3OH/Ar gas mix. As the CH3OH concentration increased, the etch rates of IrMn thin films and Ti hard mask decreased, while the etch profiles improved with high degree of anisotropy. The effects of coil rf power, dc-bias voltage to substrate and gas pressure on the etch characteristics were investigated. The etch rate increased and the etch profile improved with increasing coil rf power, dc-bias voltage and decreasing gas pressure. X-ray photoelectron spectroscopy revealed that the chemical reaction between IrMn films and CH3OH gas occurred, leading to the clean and good etch profile with high degree of anisotropy of 90°.

physica status solidi c, 2007

The etch characteristics of magnetic tunneling junction (MTJ) related materials such as CoFeB, Mg... more The etch characteristics of magnetic tunneling junction (MTJ) related materials such as CoFeB, MgO, FePt, Ru, and W as hard mask have been investigated as functions of rf pulse biasing, substrate heating, and CH 4 /N 2 O gas combination in an inductively coupled plasma system. When CH 4 /N 2 O gas ratio was varied, at CH 4 /N 2 O gas ratio of 2:1, not only the highest etch rates but also the highest etch selectivity over W could be obtained. By increasing the substrate temperature, the linear increase of both the etch rates of MTJ materials and the etch selectivity over W could be obtained. The use of the rf pulse biasing improved the etch selectivity of the MTJ materials over hard mask such as W further. The surface roughness and residual thickness remaining on the etched surface of the CoFeB were also decreased by using rf pulse biasing and with the decrease of rf duty percentage. The improvement of etch characteristics by substrate heating and rf pulse biasing was possibly related to the formation of more stable and volatile etch compounds and the removal of chemically reacted compounds more easily on the etched CoFeB surface. Highly selective etching of MTJ materials over the hard mask could be obtained by using the rf pulse biasing of 30% of duty ratio and by increasing the substrate temperature to 200 C in the CH 4 /N 2 O (2:1) plasmas.

physica status solidi (a), 2004

... Byul Shin1, Young Soo Song1, Sang Jin Park2, Tae Wan Kim2, and Chee Won Chung*, 1 1 Departmen... more ... Byul Shin1, Young Soo Song1, Sang Jin Park2, Tae Wan Kim2, and Chee Won Chung*, 1 1 Department of Chemical Engineering and Institute of Clean Technology, Inha University, 253 Yonghyun-Dong, Nam-Ku, Incheon 402-751, Korea 2 Materials & ... [3] KB Jung, ES Lambers ...

Korean Journal of Chemical Engineering, 2003

− − − −High density plasma etching of polysilicon thin films was carried out in an inductively co... more − − − −High density plasma etching of polysilicon thin films was carried out in an inductively coupled plasma (ICP) for the formation of nanometer-sized patterns. The etch rate and etch selectivity of polysilicon films were investigated as a function of the concentration of Cl 2 and HBr etch gases. The fast etch rate of polysilicon films was obtained in Cl 2 /Ar gas, and the high selectivity of polysilicon to photoresist was found in HBr/Ar gas. Finally, the etching of polysilicon films masked with photoresists was attempted in HBr/Ar and Cl 2 /Ar gases. The good pattern profile of polysilicon films with 60 nm lines was achieved in an HBr/Ar plasma.

Korean Journal of Chemical Engineering, 2002

Ti 1 − x)O 3 thin films were etched in an inductively coupled plasma by using various etch gases ... more Ti 1 − x)O 3 thin films were etched in an inductively coupled plasma by using various etch gases such as Cl 2 /Ar, C 2 F 6 /Ar, Cl 2 /C 2 F 6 /Ar and HBr/Ar. The etch rates and etch profiles for each etch gas were investigated. Fast etch rates were obtained in chlorine-containing etch gases (e.g., Cl 2 /Ar and Cl 2 /C 2 F 6 /Ar), and clean and steep etch profiles were achieved in Cl 2 /C 2 F 6 /Ar or HBr/Ar gases. The gas mixture of Cl 2 and C 2 F 6 was proposed to give a fast etch rate and a steep sidewall angle of etched patterns. The optimum gas mixture of Cl 2 /C 2 F 6 /Ar was found by varying the gas ratio of Cl 2 to C 2 F 6. On the other hand, HBr/Ar gas as an alternative for etching of the Pb(Zr x Ti 1− x)O 3 films was examined. Cl 2 /C 2 F 6 /Ar and HBr/Ar etch gases were compared with respect to etch rate, etch profile and electrical properties.