Coil Rf Power Research Articles

Evolution of etch profile of copper thin films in high density plasmas of alcohol-based gases

Dry etching of copper thin films patterned with SiO2 masks was performed using inductively coupled plasmas of CH3OH/Ar, C2H5OH/Ar, and O2/C2H5OH gases. The etch rates of copper films in CH3OH/Ar plasma were slightly faster than those in C2H5OH/Ar plasma while the etch profiles in C2H5OH/Ar plasma were better than those in CH3OH/Ar plasma. Upon varying the etch parameters, high coil RF power, high dc-bias voltage to substrate, and low process pressure were found to cause increased redeposition of the etched materials on the copper sidewalls and increased etch slopes. Optical emission spectroscopy, energy dispersive X-ray spectroscopy, and the evolution of the etch profiles revealed the etch mechanism of copper films in C2H5OH/Ar gas. X-ray photoelectron spectroscopy confirmed that the etching of copper films by C2H5OH/Ar takes place via a chemical mechanism involving the formation of copper compounds and a sputtering mechanism by the ions, depending on the C2H5OH concentration. Good etch profiles of copper films without the redeposition were achieved using the optimized O2/C2H5OH gas.

Inductively coupled plasma reactive ion etching of CoFeB magnetic thin films in a CH3COOH/Ar gas mixture

The etch characteristics of TiN hard mask patterned CoFeB thin films were investigated using an inductively coupled plasma reactive ion etching in a CH3COOH/Ar gas mixture. The etch characteristics of CoFeB magnetic thin film and TiN hard masks were investigated as a function of gas mixture concentration, coil rf power, dc-bias voltage and gas pressure. As CH3COOH concentration in the CH3COOH/Ar gas mixture increased, the etch rates of CoFeB films and degree of anisotropy in the etch profile decreased, while increased coil rf-power and dc bias voltage and reduced gas pressure increased the etch rate and improved the etch profile. Additionally, a thick hydrocarbon layer was formed on the film surface at a dc-bias voltage of 100 V. X-ray photoelectron spectroscopy and optical emission spectroscopy analyses of the etched films at various CH3COOH concentrations suggest that CoFeB thin films etched in a CH3COOH/Ar gas mixture follow a physical sputtering etch mechanism assisted by oxidation of the film and formation of a protective inhibition layer on the film surface. Etching of TiN patterned CoFeB films with a high degree of anisotropy was accomplished without redepositions or etch residues when conducted under high sputtering conditions.

Inductively coupled plasma etching of ultra-shallow Si3N4 nanostructures using SF6/C4F8 chemistry

A reproducible inductively coupled plasma (ICP) etching process using simultaneously SF6/C4F8 gases for the fabrication of ultra-shallow Si3N4 nanostructures is presented. The effect of varying etching parameters such as the coil and platen RF power, the chamber pressure, the C4F8 flow rate and the platen temperature on Si3N4 and ZEP etch rates are investigated. The passivation and etching chemistry balance is used to slow down the Si3N4 etch rate to a limit of 6nm/min. For lower etch rates, the passivation regime is getting dominant and the surface roughness increases. 10nm deep Si3N4 nanostructures are patterned without inducing any additional roughness on etched surfaces.

Evolution of etch profile in etching of CoFeB thin films using high density plasma reactive ion etching

Inductively coupled plasma reactive ion etching of CoFeB magnetic thin films patterned with Ti hard mask was studied in a CH 3OH/Ar gas mix. As the CH 3OH concentration increased, the etch rates of CoFeB thin films and Ti hard mask decreased but the etch profiles improved with high degree of anisotropy. The effects of coil rf power, dc-bias voltage and gas pressure on the etch characteristics were investigated. The etch rate increased with increasing coil rf power, dc-bias voltage and decreasing gas pressure. The degree of anisotropy in the etch profile of CoFeB films improved with increasing coil rf power and dc-bias voltage. X-ray photoelectron spectroscopy revealed that the chemical compounds containing Co and Fe components were formed during the etching. However, it was expected that the formation of these compounds could not increase the etch rates of the films due to low volatile compounds despite the improvement in etch profile.

Etch characteristics of IrMn thin films using an inductively coupled plasma of CH 3OH/Ar

An inductively coupled plasma reactive ion etching of IrMn magnetic thin films patterned with Ti hard mask was studied in a CH 3OH/Ar gas mix. As the CH 3OH 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 CH 3OH gas occurred, leading to the clean and good etch profile with high degree of anisotropy of 90°.

SiO2 shallow nanostructures ICP etching using ZEP electroresist

We propose an inductively coupled plasma (ICP) process to etch nanometer scale patterns defined by electron beam lithography in ZEP520A. The nanoscale patterns have been successfully transferred in thermal SiO2 using a CF4 based etching chemistry and a resist post-bake after development. Firstly, we show that platen temperature have a significant effect on line edge roughness (LER). We also present the effect of coil and platen RF power and pressure on sidewall angle, oxide to resist selectivity and LER. We demonstrate that 20nm deep trenches with sidewall angles of 86° and LER of less than 1nm can be etched in an ICP system with a platen temperature of −20°C using an electroresist mask.

Inductively coupled plasma reactive ion etching of titanium thin films using a Cl 2/Ar gas

Inductively coupled plasma reactive ion etching of titanium thin films patterned with a photoresist using Cl 2/Ar gas was examined. The etch rates of the titanium thin films increased with increasing the Cl 2 concentration but the etch profiles varied. In addition, the effects of the coil rf power, dc-bias voltage and gas pressure on the etch rate and etch profile were investigated. The etch rate increased with increasing coil rf power, dc-bias voltage and gas pressure. The degree of anisotropy in the etched titanium films improved with increasing coil rf power and dc-bias voltage and decreasing gas pressure. X-ray photoelectron spectroscopy revealed the formation of titanium compounds during etching, indicating that Ti films etching proceeds by a reactive ion etching mechanism.

Inductively Coupled Plasma Reactive Ion Etching of Gallium Indium Zinc Oxide Thin Films Using Cl2/Ar Gas Mix

Inductively coupled plasma reactive ion etching of gallium indium zinc oxide (GIZO) thin films patterned with a photoresist was studied using a Cl2/Ar gas. As the Cl2 concentration was increased from pure Ar to 40% Cl2 concentration, the etch rate of GIZO films increased, and thereafter gradually decreased. The etch rate increased with increasing coil rf power and dc bias voltage. A high degree of anisotropy was achieved with increasing coil rf power and dc-bias voltage, and decreasing gas pressure. X-ray photoelectron spectroscopy of the etched films revealed that chemical compounds were formed during the etching process, indicating that the etching of GIZO films is governed by a reactive ion etching mechanism.

Etch characteristics of indium zinc oxide thin films in a C 2F 6/Ar plasma

Dry etching of indium zinc oxide (IZO) thin films was performed using inductively coupled plasma reactive ion etching in a C 2F 6/Ar gas. The etch characteristics of IZO films were investigated as a function of gas concentration, coil rf power, dc-bias voltage to substrate, and gas pressure. As the C 2F 6 concentration was increased, the etch rate of the IZO films decreased and the degree of anisotropy in the etch profile also decreased. The etch profile was improved with increasing coil rf power and dc-bias voltage, and decreasing gas pressure. An X-ray photoelectron spectroscopy analysis confirmed the formation of InF 3 and ZnF 2 compounds on the etched surface due to the chemical reaction of IZO films with fluorine radicals. In addition, the film surfaces etched at different conditions were examined by atomic force microscopy. These results demonstrated that the etch mechanism of IZO thin films followed sputter etching with the assistance of chemical reaction.

Etch characteristics of indium zinc oxide thin films using inductively coupled plasma of a Cl 2/Ar gas

Inductively coupled plasma reactive ion etching of indium zinc oxide (IZO) thin films masked with a photoresist was performed using a Cl 2/Ar gas. The etch rate of the IZO thin films increased as Cl 2 gas was added to Ar gas, reaching a maximum at 60% Cl 2 and decreasing thereafter. The degree of anisotropy in the etch profile improved with increasing coil rf power and dc-bias voltage. Changes in pressure had little effect on the etch profile. X-ray photoelectron spectroscopy confirmed the formation of InCl 3 and ZnCl 2 on the etched surface. The surface morphology of the films etched at high Cl 2 concentrations was smoother than that of the films etched at low Cl 2 concentrations. These results suggest that the dry etching of IZO thin films in a Cl 2/Ar gas occurs according to a reactive ion etching mechanism involving ion sputtering and a surface reaction.

Inductively coupled plasma reactive ion etching of titanium nitride thin films in a Cl 2/Ar plasma

An inductively coupled plasma reactive ion etching of TiN thin films was carried out using a Cl 2/Ar gas chemistry. The etch characteristics such as the etch rate and etch profile were investigated by varying gas concentration and etch parameters including coil radio frequency (rf) power, dc-bias voltage and gas pressure. As the Cl 2 concentration increased, the etch rates of TiN thin films increased while the sidewall slopes of the etched films became slanted without the redeposition or etch residues. With increasing coil rf power and dc-bias voltage, the etch rates increased and etch slope became steep. Gas pressure has a little effect on etch rate and better etch profile was obtained at low gas pressure. Finally, highly anisotropic etching of TiN thin a film using a photoresist mask was achieved at the optimized etch condition.

Etch characteristics of magnetic tunnel junction stack using a high density plasma in a HBr/Ar gas

AbstractEtch characteristics of magnetic tunnel junction (MTJ) stack masked with TiN thin films were investigated using an inductively coupled plasma reactive ion etching in HBr/Ar gas for the application of magnetic random access memory. The effect of HBr gas concentration on the etch profile of MTJ stacks was examined. As HBr gas concentration increased, the sidewall angles of etched patterns of MTJ stacks were slightly improved. The effect of etch parameters including coil rf power, dc‐bias voltage, and gas pressure on the etch profile of MTJ stack was explored. At low coil rf power, low dc‐bias voltage, and high gas pressure, the etching of MTJ stack displayed better etch profile. A high degree of anisotropic etching of MTJ stacks without redeposition was achieved using HBr/Ar gas at the optimized etch conditions. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Inductively coupled plasma reactive ion etching of ZnO films in HBr/Ar plasma

The etching characteristics of ZnO thin films were examined in an HBr/Ar gas mix using an inductively coupled plasma reactive ion etching system. The etch rate and etch profile were systematically investigated as a function of gas concentration. In addition, the effects of etch parameters such as coil rf power, dc-bias voltage, and gas pressure were studied. As the HBr concentration increased, the etch rate of the ZnO films gradually decreased while the etch profile was improved. Surface analyses including X-ray photoelectron spectroscopy and atomic force microscopy were employed to elucidate the etch mechanism of ZnO in an HBr/Ar chemistry.

Inductively Coupled Plasma Reactive Ion Etching of GeSbTe Thin Films in a HBr/Ar Gas

ABSTRACT Inductively coupled plasma reactive ion etching of GeSbTe (GST) thin films with a photoresist mask was performed using a HBr/Ar gas mixture. The etch rate of GST films increased up to 20% HBr concentration and began to decrease with further increase of HBr concentration. The etch profiles were improved with increasing HBr gas concentration. In particular, clean and vertical etch profiles were achieved at 80∼ 100% HBr gas concentrations. As the coil rf power and dc-bias voltage increased, the etch rates increased. The gas pressure had little influence on the etch rate. The good etch profiles were obtained at high coil power, low dc-bias and high gas pressure. The x-ray photoelectron spectroscopy analysis reveals that Te showed highest reactivity with HBr gas chemistry. A high degree of anisotropic etching of GST films was achieved using HBr/Ar gas mixture at the optimized etch conditions.

ETCH CHARACTERISTICS OF COFESIB MAGNETIC FILMS USING INDUCTIVELY COUPLED PLASMA REACTIVE ION ETCHING FOR MAGNETIC RANDOM ACCESS MEMORY

ABSTRACT Inductively coupled plasma reactive ion etching of CoFeSiB magnetic thin films was studied in a Cl2/O2/Ar gas mix. The etch rate, etch selectivity and etch profile of this magnetic film were examined on varying gas concentration, coil rf power, gas pressure and dc-bias voltage. As the Cl2 gas increased, the etch rate monotonously decreased and etch residues decreased but etch slope was slanted. The use of the TiN hard mask gave rise to high selectivity of CoFeSiB to the TiN mask due to large decrease in etch rate of TiN in Cl2/O2/Ar gas mix. The addition of O2 into the gas mix led to the anisotropic etching of CoFeSiB films without the etch residues.

INVESTIGATION ON ETCH CHARACTERISTICS OF GESBTE THIN FILMS FOR PHASE-CHANGE MEMORY

ABSTRACT Inductively coupled plasma reactive ion etching of GeSbTe (GST) thin films with a photoresist mask was carried out in a Cl2/Ar gas. The monotonous increase in etch rate with increasing Cl2 concentration indicates that the etching of GST films obeys the reactive ion etching mechanism. The etch rates increased with increasing coil rf power and dc-bias voltage. The etch profiles was improved with decreasing coil rf power and dc-bias voltage and gas pressure gave little influence on the etch profile. The x-ray photoelectron spectroscopy analysis reveals that the rate limiting step in GST etching study is the etching of Te. Anisotropic etching of GST films was achieved using a Cl2/Ar chemistry at the optimized etch conditions.

Optical Absorption Measurements of Sputtered Ti Ion Density and Discussion of Ionization Mechanisms in Inductively Coupled Plasma-Assisted DC Sputtering

This study discusses the ionization mechanisms of sputtered titanium (Ti) in inductively coupled plasma (ICP)-assisted dc magnetron sputtering based on measurements and model analyses. Ionic and atomic densities of sputtered titanium were measured using an optical absorption method under an Ar pressure of 3.5 Pa against rf(13.56MHz) power applied to the inserted coil. A Langmuir probe provided measurements of electron densities against coil rf power, giving input parameters for model analyses. We adopted a model analysis method presented by J. Hopwood and F. Qian [J. Appl. Phys. 78, 758 (1995)]. Variations of ionic and atomic densities and ionization fractions against electron density from model calculation agreed with those obtained by measurements. The results showed clearly that electron impact ionization dominates ionization of sputtered titanium in high er electron density regions compared to Penning ionization through Ar metastable atoms. Penning ionization played an important role at the lower electron density region because of the longer time for radiative decay of Ar metastable atoms.

Ion Densities and Ionization Fractions of Sputtered Titanium in Inductively Coupled Plasma Assisted Sputtering

Ion densities of sputtered titanium (Ti) in Inductively Coupled Plasma (ICP)-assisted magnetron sputtering biased by rf (13.56 MHz) and dc voltages were measured using an optical absorption method. A spectral line with the wavelength of 336.1 nm (z4G9/2° → a4F7/2) was used as the absorption line. In the case of rf sputtering, at Ar pressures of several Pa, the Ti ion density jumped to higher value at a certain coil rf power while at the same time Ti atom density decreased gradually with increasing coil rf power due to a decrease in the self-bias voltage. For instance, ionization fractions showed increases at the threshold coil rf power of 160 W and rose to a value of 0.29 for Ar pressure of 7.0 Pa. Even at the low pressure of 0.6 Pa, the ionization fraction was 0.08 at coil rf power of 240 W, twice as high as that in sputtering that are not ICP-assisted. The Ti ion density against axial distance from the target showed characteristic peaked profile with its maximum at z=20 mm in contrast with the change of Ti atom density, resulting maximum ionization fraction at a position around lower edge of the inserted coil, z=30 mm. In the case of dc sputtering biased with -600 V, ion density and ionization fraction of Ti were slightly higher than those of rf sputtering with the same coil rf power though self-bias voltage in rf sputtering was -560 V, at Ar pressure of 3.5 Pa. It was found that ionization fractions of Ti in the dc sputtering biased with -400 V were higher than in the dc sputtering biased with -600 V.

Growth of Highly Oriented CoCrTa films by Inductively Coupled Plasma-Assisted Sputtering

Inductively coupled plasma (ICP)-assisted sputtering using an internal coil was applied to the deposition of ferromagnetic Co-based alloy (CoCrTa) films intended for magnetic recording media. The growth of highly oriented crystalline Co films on both low-temperature Si and glass substrates was achieved. Pole figure measurements indicated the growth of face-centered cubic Co with a (111) plane parallel to the substrate, while a hexagonal close-packed crystalline film with c-axis perpendicular to the glass substrate was obtained by adjusting the rf power applied to the inserted coil and the substrate temperature. In the ICP-assisted sputtering at a coil rf power of 120 W, the deposition rate at a pressure of 1.3 Pa was more than two times higher than that of conventional sputtering at the same target rf power of 150 W. The deposition performance responsible for highly oriented crystalline growth and higher deposition rate at low pressures was discussed in terms of target self-bias voltage and plasma parameters measured using a Langmuir probe. The film properties characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and vibrating sample magnetometer (VSM) were also presented showing the superior capability of ICP-assisted sputtering for ferromagnetic targets.

Ion fraction and energy distribution of Ti flux incident to substrate surface in RF-plasma enhanced magnetron sputtering

Effects of plasma conditions on ion fraction and ion energy distribution of Ti flux have been investigated in RF-plasma enhanced magnetron sputtering. The ion fraction of Ti flux reaching to the substrate increases to >30% with increasing the coil RF power for an Ar pressure of 1.0 Pa, while it is nearly independent of the coil RF power for Ar pressure of 0.3 Pa. The electron density and temperature measured by a single-probe method increase with increasing the coil RF power. The increase in the ion fraction strongly correlates with the increase in electron density and temperature. This is more significant for a high Ar pressure. The peak energy of ion spectra of Ti + flux also increases with increasing the coil RF power in accordance with the increase in the plasma potential for a constant Ar pressure. As a result of the increase in the ion fraction and plasma potential, the energy delivered to the substrate as kinetic energy of the Ti ions arriving to the substrate increases drastically with increasing the coil RF power. The strong dependence of ion fraction on Ar pressure at a relatively low electron density emphasizes the role of Penning ionization mechanism in sputtered Ti ionization.