ICP RF Power Research Articles

Etch characteristics of cobalt thin films using high density plasma of CH3COCH3/Ar gas mixture

Co thin films masked with SiO2/Si3N4 layers were etched using a high-density plasma of a CH3COCH3/Ar gas mixture. As the concentration of CH3COCH3 increased, the etch rate of the Co thin films and etch selectivity decreased. Optimal etch profiles of the Co films without redeposition were achieved owing to the formation of Co compounds and a passivation layer, which facilitated a high degree of anisotropy. Moreover, the etch characteristics of the Co films were examined using the ICP RF power, dc-bias voltage to the substrate, and process pressure. The active species in plasmas and Co compounds formed during etching were investigated using optical emission spectroscopy and X-ray photoelectron spectroscopy. Finally, the Co thin films patterned with 300 nm lines were etched using a CH3COCH3/Ar gas mixture under optimized etch conditions. The findings suggest that a CH3COCH3/Ar gas mixture can serve as an effective etch gas for fabricating dry-etched Co thin films.

Etch Characteristics of Cobalt Thin Films in High Density Plasma of Cl2/O2/Ar Gas Mixture

Inductively coupled plasma reaction ion etching (ICP-RIE) of cobalt thin films patterned with SiO2 hard masks was performed using Cl2/O2/Ar gas mixture. The etch characteristics of cobalt films in Cl2/Ar gas were examined to determine the roles of Cl2 and O2, respectively. The etch rates and etch profiles of cobalt films were investigated by varying the O2 concentration in Cl2/O2/Ar gas mixture.In the optimized Cl2/Ar gas mixture, systematic etching of cobalt films was performed by changing the etch parameters including ICP RF power, DC-bias voltage, and process pressure. As the DC-bias voltage and process pressure was increased, the etch rate increased and the etch profile improved. Through the etching parameters variation experiment, the etching properties were investigated by adding O2 to Cl2/Ar under optimized conditions. X-ray photoelectron spectroscopy and optical emission spectroscopy were used to investigate the etch mechanism in the Cl2/O2/Ar gas mixture. In addition, scanning probe microscope was used to observe roughness on the etched cobalt surface. Finally, the etching of cobalt films patterned with nanometer-scale in the optimized Cl2/O2/Ar gas mixture was successfully achieved with good etch profile.AcknowledgmentThis research was supported by the Ministry of Trade, Industry & Energy (MOTIE) (20019504) and Korea Semiconductor Research Consortium (KSRC) support program for the development of future semiconductor devices. This work was supported by Korea Institute for Advancement of Technology (KIAT) grant funded by the Korea Government (MOTIE) (P0008458, HRD Program for Industrial Innovation).

A simple dilute-and-shoot approach using UV photochemical vapor generation for the determination of iodine in alcoholic beverages by ICP-MS

A novel method using photochemical vapour generation (PVG) for the determination of iodine in alcoholic beverages by inductively coupled plasma mass spectrometry (ICP-MS) is presented. The procedure consisted in simply diluting 1.0 mL of an alcoholic beverage (cachaça, vodka, whisky, brandy and gin were analyzed) to a final volume of 15 mL with deionized water prior to introduction in the PVG reactor for the generation of volatile iodine species. The native ethanol content in the samples (approximately 40 % v/v, before dilution) was proven sufficient to produce radicals upon UV irradiation, which ultimately resulted in the release of volatile iodine compounds to the gas phase. The process was systematically evaluated to reach the optimum operating conditions of 1.0 L min-1 Ar as the carrier gas, 1400 W ICP RF power, sample flow rate of 8.08 mL min-1 and 49 s of sample solution exposition to UV photons in the PVG reactor. Two distinct gas-liquid separators (GLS) with internal volumes of 3.1 and 6.5 mL were evaluated. The GLS with an internal volume of 6.5 mL was selected, as it resulted in higher sensitivity for the analyte. Matrix effects required standard addition calibration to be employed to determine the iodine concentrations, which ranged from ca. 21 to 386 μg L-1. Detection and quantification limits were determined as 0.1 and 0.3 μg L-1, respectively. The trueness was verified by comparing the results with those obtained by ICP-MS with pneumatic nebulization, following sample digestion in closed vessels. No significant statistical difference was observed when a paired t-test was applied and the sensitivity achieved from analyte introduction using PVG was 64 % higher when compared to the use of a pneumatic nebulizer. The samples were also spiked with known amounts of the analyte and recoveries ranged from 95 to 105 %, with relative standard deviations better than 9 %.

Etch characteristics of copper thin films in high density plasma of CH4/O2/Ar gas mixture

Inductively coupled plasma reactive ion etching of copper thin films patterned with SiO2 masks was performed using CH4/O2/Ar gas mixture. The etch characteristics of copper films in CH4/Ar and O2/Ar gases were examined to determine the roles of CH4 and O2, respectively. The etch rates and etch profiles of copper films were investigated by varying the O2 concentration in CH4/O2/Ar gas mixture. In the optimized CH4/O2/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 CH4/O2/Ar gas mixture. Finally, the etching of copper films in the optimized CH4/O2/Ar gas mixture was successfully achieved with good etch profile with a high degree of anisotropy.

Highly anisotropic etching of Ta thin films using high density plasmas of halogen based gases

Inductively coupled plasma reactive ion etching of Ta thin films masked with photoresist was performed using C2F6/Ar, HBr/Ar and Cl2/Ar gases. The etch characteristics such as etch rate, etch selectivity and etch profile were investigated in different gas concentrations of each gas. The Cl2 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 Cl2 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 Cl2/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 Cl2/Ar gas.

Investigation on etch characteristics of FePt thin films using a H2O/Ar plasma

• Development of a H 2 O/Ar gas to etch FePt magnetic films. • Films etched by inductively coupled plasma reactive ion etching. • Etch mechanism of FePt films in H 2 O/Ar plasma. • Etching of FePt films with high degree of anisotropy without redeposition or etch residue. The etch characteristics of FePt thin films patterned with a TiN hard mask were investigated using inductively coupled plasma reactive ion etching (ICPRIE) in a H 2 O/Ar plasma. As the H 2 O concentration increased, the etch rates of the FePt films and TiN hard mask decreased gradually, but the etch profile improved with a high degree of anisotropy without redepositions or etch residues. The improvement of etch profiles was attributed to the formation of a protective layer containing hydrogen species on the sidewall of the patterns and the formation of metal oxides during etching. The optical emission spectroscopy of H 2 O/Ar plasma revealed an increase of [H]/[Ar] and [O]/[Ar] ratios with increasing H 2 O concentration. As the ICP rf power and dc-bias voltage increased, and the gas pressure decreased, the etch rates of the FePt films increased and more vertical etch slopes were obtained. X-ray photoelectron spectroscopy of etched FePt films confirmed the existence of Fe oxide compounds formed by the etching. Overall, the results indicated that the etching of FePt films in a H 2 O/Ar plasma follows a chemically-affected sputtering etching mechanism.

Influence de la qualité du positionnement des prothèses discales sur leurs résultats fonctionnels et sur la mobilité des étages opérés

Inductively coupled plasma reactive ion etching of copper thin films patterned with SiO2 masks was performed using CH4/O2/Ar gas mixture. The etch characteristics of copper films in CH4/Ar and O2/Ar gases were examined to determine the roles of CH4 and O2, respectively. The etch rates and etch profiles of copper films were investigated by varying the O2 concentration in CH4/O2/Ar gas mixture. In the optimized CH4/O2/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 CH4/O2/Ar gas mixture. Finally, the etching of copper films in the optimized CH4/O2/Ar gas mixture was successfully achieved with good etch profile with a high degree of anisotropy.

Investigation on Etch Characteristics of Nanometer-Sized Magnetic Tunnel Junction Stacks Using a HBr/Ar Plasma

The etch characteristics of CoFeB magnetic films and magnetic-tunnel-junction (MTJ) stacks masked with Ti films were investigated using an inductively coupled plasma reactive ion etching in a HBr/Ar gas mix. The etch rate, etch selectivity, and etch profile of the CoFeB films were obtained as a function of the HBr concentration. As the HBr gas was added to Ar, the etch rate of the CoFeB films, and the etch selectivity to the Ti hard mask, gradually decreased, but the etch profile of the CoFeB films was improved. The effects of the HBr concentration and etch parameters on the etch profile of the MTJ stacks with a nanometer-sized 70 x 100 nm2 pattern were explored. At 10% HBr concentration, low ICP RF power, and low DC-bias voltage, better etch profiles of the MTJ stacks were obtained without redeposition. It was confirmed that the protective layer containing hydrogen, and the surface bombardment of the Ar ions, played a key role in obtaining a steep sidewall angle in the etch profile. Fine-pattern transfer of the MTJ stacks with a high degree of anisotropy was achieved using a HBr/Ar gas chemistry.

The Effect of Plasma Treatment on the SiO2 film fabricated without Substrate Heating for Flexible Electronics

ABSTRACTSilicon dioxide (SiO2) films were deposited on crystalline silicon substrate by inductively coupled plasma chemical vapor deposition (ICP-CVD). In this paper, various process parameter-gas flow rate, ICP RF power, Process pressure were discussed for the investigation of refractive index. And some properties of the SiO2 film are investigated. Since there was no external substrate heating during the deposition, the SiO2 film showed poor electrical characteristics, such as shifted flat-band voltage and high effective charge density. We have proposed He plasma pre-treatment in order to reduce the interface fixed charge and some post-treatment. Our experimental results shows that He plasma pre-treatment supply thermal energy for decomposition of reactant gas and to remove effective charges. Hydrogen post-treatment also enhances electrical characteristics. We measured the effect of the plasma treatment using FT-IR spectrum and C-V characteristics.

Optical emission studies of atomic and ionic species in the ionized sputter-deposition process of magnesium oxide thin films

Planar magnetron (PM) power and ICP-RF power dependences of the optical emission intensities of excited atomic and ionic species in the reactive ionized sputter-deposition of magnesium oxide (MgO) thin films were investigated. With the increase in PM power at constant ICP-RF power, Mg I emission intensity increased and Ar I emission intensity gradually decreased. With the increase in ICP-RF power at constant PM power, the Mg I emission intensity increased at lower ICP-RF power and then gradually decreased at higher ICP-RF power; on the contrary, Ar I emission intensity monotonically increased. Emission intensity of atomic oxygen was negligibly small compared with those of Mg I and Ar I under the metallic sputtering mode condition.

The etching properties of MgO thin films in Cl2/Ar gas chemistry

The metal–ferroelectric–semiconductor (MFS) structure is widely studied for nondestructive readout (NDRO) memory devices, but conventional MFS structure has two critical problems. First, the one that is difficult to obtain ferroelectric films like PZT on Si substrate without interdiffusion of impurities such as Pb, Ti and other elements. Diffusion of Pb or Ti induces increased trap density and Fermi-level pinning. The other one is that PZT/Si structure generates nonferroelectric and low-dielectric constant layer at the interface. In order to solve these problems, the metal–ferroelectric–insulator–semiconductor (MFIS) structure has been proposed with a buffer layer of high dielectric constant such as MgO, Y2O3, and CeO2. Buffer layer candidate should meet the following requirements of low lattice mismatch, low leakage current, low interface-state density, high dielectric constant, chemical stability, and prevention of interdiffusion.In this study, the etching characteristics (etch rate, selectivity) of MgO thin films were etched using Cl2/Ar plasma. The maximum etch rate of 85 nm/min for MgO thin films was obtained at Cl2(30%)/Ar(70%) gas mixing ratio. Moreover, the etch rate was measured by varying the etching parameters such as ICP rf power, dc-bias voltage, and chamber pressure. Plasma diagnostics was performed by Langmuir probe (LP) and optical emission spectroscopy (OES).

Effect of inductively-coupled plasma assist on the crystal orientation of magnesium oxide thin films produced by reactive sputtering

High-performance reactive sputter-deposition of magnesium oxide (MgO) thin films is investigated. In this research, planar magnetron (PM) sputtering of Mg target in argon/oxygen mixture is assisted by an inductively coupled plasma (ICP) that is located between the target and the substrate and is driven by an internal RF coil antenna at 13.56 MHz. The changes in deposition rates and X-ray diffraction patterns due to the independent power control of PM and ICP are investigated. As a result, we found that deposition rate of MgO films was predominantly controlled by the PM discharge power and that the crystallinity of deposited MgO films was controlled by the ICP-RF power.

Improving analytical precision by utilizing intrinsic internal standards for determining minor constituents by inductively coupled plasma atomic emission spectrometry

In order to improve analytical precision, intrinsic internal standardization was applied to two routine analyses. Matrix emission lines that closely matched the noise patterns of the emission lines of the analytes were chosen. These noise patterns were induced by varying the ICP rf power and argon carrier flow rate. The changes in these two experimental conditions affect the plasma temperature, amount of aerosol injected into the plasma and analyte residence time in the plasma. Consequently, they contribute significantly to the over-all variability. Two lighting materials were chosen for this study: potassium-doped tungsten powder and europium-activated Y2O2S powder. Experimental results showed that with the intrinsic internal standard lines, the precision for determining the minor constituents (potassium in tungsten powder and iron in Y2O2S powder) was improved by 25–50%.