Ar Mixing Ratio Research Articles

Etching Characteristics and Mechanisms of Mo and Al2O3 Thin Films in O2/Cl2/Ar Inductively Coupled Plasmas: Effect of Gas Mixing Ratios

An investigation of etching behaviors for Mo and Al2O3 thin films in O2/Cl2/Ar inductively coupled plasmas at constant gas pressure (6 mTorr), input power (700 W) and bias power (200 W) was carried out. It was found that an increase in Ar mixing ratio for Cl2/Ar plasma results in non-monotonic etching rates with the maximums of 160 nm/min at 60 % Ar for Mo and 27 nm/min at 20 % Ar for Al2O3. The addition of O2 in the Cl2/Ar plasma causes the non-monotonic Mo etching rate (max. 320 nm/min at 40–45 % O2) while the Al2O3 etching rate decreases monotonically. The model-based analysis of etching kinetics allows one to relate the non-monotonic etching rates in Cl2/Ar plasma to the change in the etching regime from the ion-flux-limited mode (at low Ar mixing ratios) to the neutral-flux-limited mode (for high Ar mixing ratios). In the Cl2/O2/Ar plasma, the non-monotonic Mo etching rate is probably due to the change in reaction probability.

Stable isotope and gas properties of two climatically contrasting (Pleistocene and Holocene) ice wedges from Cape Mamontov Klyk, Laptev Sea, northern Siberia

Abstract. This paper presents and discusses the texture, fabric, water stable isotopes (δ18O, δD) and gas properties (total gas content, O2, N2, Ar, CO2, and CH4 mixing ratios) of two climatically contrasted (Holocene vs. Pleistocene) ice wedges (IW-26 and IW-28) from Cape Mamontov Klyk, Laptev Sea, in northern Siberia. The two ice wedges display contrasting structures: one being of relatively "clean" ice and the other showing clean ice at its centre as well as debris-rich ice on both sides (referred to as "ice-sand wedge"). Our multiparametric approach allows discrimination between three different ice facies with specific signatures, suggesting different climatic and environmental conditions of formation and various intensities and nature of biological activity. More specifically, crystallography, total gas content and gas composition reveal variable levels of meltwater infiltration and contrasting contributions from anaerobic and aerobic conditions to the biological signatures. Stable isotope data are drawn on to discuss changes in paleoenvironmental conditions and in the temporal variation of the different moisture sources for the snow feeding into the ice wedges infillings. Our data set also supports the previous assumption that the ice wedge IW-28 was formed in Pleistocene and the ice wedge IW-26 in Holocene times. This study sheds more light on the conditions of ice wedge growth under changing environmental conditions.

Modeling of an inductively-coupled Cl2/Ar plasma using neural network

In this study, a neural network model for an inductively-coupled Cl2/Ar plasma (ICP) process has been proposed. Plasma experiments were performed in a planar inductively coupled plasma reactor. The input parameters considered for plasma modeling were the gas mixing ratio, and the source and bias powers, which were varied in the ranges 0–100% Cl2/Ar, 500–800W, and 50–300W, respectively. Plasma diagnostics were performed by double Langmuir probe measurements. Analysis of voltage–current curves in order to obtain electron temperature and total positive ion density was carried out. A back propagation neural network model with a pre-processor was constructed. The prediction errors for the proposed model were shown to be very small compared to those of a conventional neural network model. In the experiments conducted, it was found that an increase in Ar mixing ratio or input source power resulted in an increase in the total positive ion density. An increase in the input bias power, however, corresponded to a decrease in the total positive ion density. The electron temperature increased as the Ar fraction, input source power, or input bias power increased.

유도결합형 BCl3/Ar 플라즈마를 이용한 Al2O3박막의 식각 특성

In this study, the etching characteristics of <TEX>$Al_2O_3$</TEX> thin films were investigated using an ICP (inductively coupled plasma) of <TEX>$BCl_3$</TEX>/Ar gas mixture. The etch rate of <TEX>$Al_2O_3$</TEX> thin films as well as the <TEX>$SiO_2/Al_2O_3$</TEX> etch selectivity were measured as functions of <TEX>$BCl_3$</TEX>/Ar mixing ratio (0~100% Ar) at a constant gas pressure (10 mTorr), total gas flow rate (40 sccm), input power (800 W) and bias power (100 W). The behavior of the <TEX>$Al_2O_3$</TEX> etch rate was shown to be quite typical for ion-assisted etch processes with a dominant chemical etch pathway. To analyze the etching mechanism using DLP (double langmuir probe), OES (optical emission spectroscopy) and surface analysis using XPS (x-ray photoelectron spectroscopy) were carried out.

HfO 2 etching mechanism in inductively-coupled Cl 2/Ar plasma

Etching characteristics and the mechanism of HfO 2 thin films in Cl 2/Ar inductively-coupled plasma were investigated. The etch rate of HfO 2 was measured as a function of the Cl 2/Ar mixing ratio in the range of 0 to 100% Ar at a fixed gas pressure (6 mTorr), input power (700 W), and bias power (300 W). We found that an increase in the Ar mixing ratio resulted in a monotonic decrease in the HfO 2 etch rate in the range of 10.3 to 0.7 nm/min while the etch rate of the photoresist increased from 152.1 to 375.0 nm/min for 0 to 100% Ar. To examine the etching mechanism of HfO 2 films, we combined plasma diagnostics using Langmuir probes and quadrupole mass spectrometry with global (zero-dimensional) plasma modeling. We found that the HfO 2 etching process was not controlled by ion–surface interaction kinetics and formally corresponds to the reaction rate-limited etch regime.

Effect of Gas Mixing Ratio on Etch Behavior of Y2O3 Thin Films in Cl2/Ar and BCl3/Ar Inductively Coupled Plasmas

This paper reports the results of a model-based analysis of the etch mechanism for the Y2O3 thin films in the Cl2/Ar and BCl3/Ar inductively coupled plasma. It was found that the BCl3/Ar plasma provides higher etch rate (except the case of pure BCl3 and Cl2 gases) as well as shows the non-monotonic dependence of the etch rate on the Ar mixing ratio. Plasma diagnostics by Langmuir probes indicated the noticeable influence of Ar mixing ratio on electron temperature and total density of positive ions. Using the model-based analysis of plasma chemistry and etch kinetics, it was demonstrated that the behavior of the Y2O3 etch rate in both gas mixtures generally corresponds to the neutral-flux-limited etch regime of the ion-assisted chemical reaction while the obtained differences cannot be explained assuming the Cl atoms to be the main chemically active species. Probably, in the BCl3-bases plasmas, the etch kinetics is significantly influenced by the BClx radicals.

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An investigation of a VO2 etch mechanism in Cl2/Ar inductively coupled plasma under the condition of low ion bombardment energy is carried out. It is found that an increase in Ar mixing ratio results a nonmonotonic VO2 etch rate, which reaches a maximum of 70 to 80 nm/min at 70 to 75% Ar. The model-based analysis of the etch mechanism shows that the VO2 etch kinetics correspond to the ion-flux-limited etch regime. This is most likely due to the domination of low volatile VCl3 and/or VCl2 in the reaction products.

Model-Based Analysis of the ZrO2 Etching Mechanism in Inductively Coupled BCl3/Ar and BCl3/CHF3/Ar Plasmas

The etching mechanism of ZrO 2 thin films and etch selectivity over some materials in both BCl 3 /Ar and BCl 3 /CHF 3 /Ar plasmas are investigated using a combination of experimental and modeling methods. To obtain the data on plasma composition and fluxes of active species, global (0-dimensional) plasma models are developed with Langmuir probe diagnostics data. In BC 3 /Ar plasma, changes in gas mixing ratio result in nonlinear changes of both densities and fluxes for Cl, BCl 2 , and BCl 2 + . In this work, it is shown that the non-monotonic behavior of the ZrO 2 etch rate as a function of the BCl 3 /Ar mixing ratio could be related to the ion-assisted etch mechanism and the ion-flux-limited etch regime. The addition of up to 33% CHF 3 to the BCl 3 -rich BCl 3 /Ar plasma does not influence the ZrO 2 etch rate, but it non-monotonically changes the etch rates of both Si and SiO 2 . The last effect can probably be associated with the corresponding behavior of the F atom density.

Effect of gas mixing ratio on etch behaviors of Ba 2Ti 9O 20 (BTO) and Pt thin films in Cl 2/Ar inductively coupled plasma

An investigation of the Ba 2Ti 9O 20 (BTO) and Pt thin films etch mechanism in the Cl 2/Ar inductively coupled plasma was carried out. It was found that an increase in Ar mixing ratio at fixed gas pressure and input power causes a fast decrease in the BTO etch rate (26.9–1.2 nm/min for 0–100% Ar) while the Pt etch rate increases slightly from 17.4–23.0 nm/min. Langmuir probe diagnostics and zero-dimensional plasma modeling provided the data on plasma parameters, steady-state composition and fluxes of active species on the etched surface. From the model-based analysis of etch kinetics, it was shown that the behavior of the BTO etch rate corresponds to the reaction-rate-limited etch regime, where the etch rate is limited neither by physical sputtering of the main material nor by the ion-stimulated desorption of low-volatile reaction products. The etch process of Pt appears in the transitional regime and is controlled by the neutral and ion fluxes together.

Etching characteristics and mechanism of Ge2Sb2Te5 thin films in inductively coupled Cl2∕Ar plasma

This work reports the investigations of both etch characteristics and mechanisms for the Ge2Sb2Te5 (GST) thin films in the Cl2∕Ar inductively coupled plasma. The GST etch rates and etch selectivities over SiO2 were measured as functions of the Cl2∕Ar mixing ratio (43%–86% Ar), gas pressure (4–10mTorr), and source power (400–700W). Langmuir probe diagnostics and zero-dimensional (global) plasma modeling provided the information on plasma parameters and behaviors of plasma active species. From the model-based analysis of surface kinetics, it was found that with variations of the Cl2∕Ar mixing ratio and gas pressure, the GST etch rate follows the changes of Cl atom density and flux but contradicts with those for positive ions. The GST etch mechanism in the Cl2-containing plasmas represents a combination of spontaneous and ion-assisted chemical reactions with no limitation by ion-surface interaction kinetics such as physical sputtering of the main material or the ion-stimulated desorption of low volatile reaction products.

Etching Characteristics of (Na0.5K0.5)NbO3 Thin Films in an Inductively Coupled Cl2/Ar Plasma

The investigation of etch characteristics for (Na 0.5 K 0.5 )NbO 3 (NKN) thin films in Cl 2 /Ar inductively coupled plasma was carried out. It was found that the NKN etch rate is a monotonic function of both input power and negative dc bias as it generally expected from the corresponding variations of plasma parameters. At the same time, NKN etch rate shows a non-monotonic behavior as a function of Cl 2 /Ar mixing ratio with a maximum of 750 Å/min at Cl 2 (80%)/Ar (20%). The analysis of these data togeter with the XPS results for both as-deposited and etched NKN films allowed one to assume ion assisted etch mechanism and defined a concurence of chemical and physical etch pathways as a most probable reason for etch rate maximum.

On the etching mechanism of ZrO 2 thin films in inductively coupled BCl 3/Ar plasma

The etching mechanism of ZrO 2 thin films in BCl 3/Ar plasma was investigated using a combination of experimental and modeling methods. It was found that an increase in the Ar mixing ratio causes the non-monotonic behavior of the ZrO 2 etch rate which reaches a maximum of 41.4 nm/min at about 30–35% Ar. Langmuir probe measurements and plasma modeling indicated the noticeable influence of a BCl 3/Ar mixture composition on plasma parameters and active species kinetics that results in non-linear changes of both densities and fluxes for Cl, BCl 2 and BCl 2 + . From the model-based analysis of surface kinetics, it was shown that the non-monotonic behavior of the ZrO 2 etch rate can be associated with the concurrence of chemical and physical pathways in ion-assisted chemical reaction.

Etching Mechanism of ZnO Thin Films in Inductively Coupled Plasma

The etching properties of the ZnO thin films in the inductively coupled Cl2/Ar plasma (ICP) were studied in the terms of etch rate and selectivity as functions of gas mixing ratio, ICP coil power and dc bias voltage. The maximum etch rate of 129.3 nm/min was obtained for the mixture of 20% Ar/80% Cl2. The X-ray photoelectron spectroscopy (XPS) analyses of the ZnO surfaces etched at various Cl2/(Cl2+Ar) mixing ratios revealed the formation of the ZnClx and ClOx reaction by-products as a result of the increased etch rate with increasing Cl2 addition, compared with 100% Ar+ sputter etching. From the analysis of these data, it was proposed that the maximum on the etch rate may be explained by the concurrence of chemical and physical pathways in the ion assisted chemical reaction.

Direct FTIR high resolution probe of small and medium size Ar n(CO 2) m van der Waals complexes formed in a slit supersonic expansion

A slit nozzle continuous expansion of argon seeded with carbon dioxide is probed using a Bruker IFS 120 HR FTIR spectrometer operating at 0.05 cm −1 or 0.01 cm −1 spectral resolution. About 250 individual rovibrational transitions are assigned which belong to the asymmetric stretch of the CO 2 moiety in Ar–CO 2 and (CO 2) 2 complexes. This made it possible to refine the set of spectroscopic constants characterizing these van der Waals species. Analysis of the observed spectral features allowed for evaluation of the number densities of complexes formed in a jet. The manifold of rovibrational lines of van der Waals complexes (along with the monomer lines) sits on an unresolved pedestal, the shape of which varies dramatically as a function of reservoir pressure and initial CO 2–Ar mixing ratios. Thorough examination of these variations allows for the observed features to be assigned to Ar n (CO 2) m clusters formed in CO 2 seeded Ar expansion.

Etching characteristics of ZnO thin films in chlorine-containing inductively coupled plasmas

This study examined the plasma etching characteristics of ZnO thin films etched in BCl 3/Ar, BCl 3/Cl 2/Ar and Cl 2/Ar plasmas with a positive photoresist mask. The ZnO etch rates were increased in a limited way by increasing the gas flow ratio of the main etch gases in the BCl 3/Ar, BCl 3/Cl 2/Ar and Cl 2/Ar plasmas at a fixed dc self-bias voltage ( V dc). However, the ZnO etch rate was increased more effectively by increasing the V dc. Optical emission spectroscopy (OES) and X-ray photoelectron spectroscopy (XPS) analyses of the ZnO surfaces etched at various Cl 2/(Cl 2 + Ar) mixing ratios revealed the formation of the ZnO x Cl y reaction by-products as a result of the increased etch rate with increasing Cl 2 addition, compared with 100% Ar + sputter etching. This suggests that at Cl 2/Ar flow ratios ⩾20%, the ZnO etch process is controlled by an ion-assisted removal mechanism where the etch rate is governed by the ion-bombardment energy under the saturated chlorination conditions.

Effect of gas mixing ratio on MgO etch behaviour in inductively coupled BCl 3/Ar plasma

The etching behaviour of MgO thin films in BCl 3/Ar plasma was investigated. It was found that the increasing Ar mixing ratio under the constant total pressure conditions causes the monotonic decrease of MgO etch rate, which falls from 93 to 17 nm/min. Plasma diagnostics combined with a 0-dimensional plasma model showed the noticeable sensitivity of both electron temperature and electron density to the process parameters as well as monotonic changes of both densities and fluxes of active species. The analysis of etching kinetics and mechanisms was performed. The results showed in the BCl 3-rich plasma the etching process is dominantly supplied by the chemical pathway through the ion-assisted chemical reaction.

Etching mechanism of MgO thin films in inductively coupled Cl2∕Ar plasma

The etching mechanism of MgO thin films in Cl2∕Ar plasma was investigated. It was found that the increasing Ar in the mixing ratio of Cl2∕Ar plasma causes nonmonotonic MgO etch rate, which reaches a maximum value at 70%Ar+30%Cl2. Langmuir probe measurement showed the noticeable influence of Cl2∕Ar mixing ratio on electron temperature and electron density. The zero-dimensional plasma model indicated monotonic changes of both densities and fluxes of active species. At the same time, analyses of surface kinetics showed the possibility of nonmonotonic etch rate behavior due to the concurrence of physical and chemical pathways in ion-assisted chemical reaction.

Etching characteristics and mechanisms of SrBi 2Ta 2O 9 thin films in CF 4/Ar and Cl 2/Ar inductively coupled plasmas

We investigated etching mechanism of the SrBi 2Ta 2O 9 (SBT) thin films using Cl 2/Ar and CF 4/Ar plasmas. The investigations were carried out through the analysis of the influence of gas mixing ratio on etch rate, plasma parameters and volume and surface chemistries. In both gas mixtures, increasing the Ar mixing ratio leads to an increase of the SBT etch rate, which reaches a maximum value at 80% Ar. The maximum etch rates are 970 and 1100 Å/min for Cl 2/Ar and CF 4/Ar plasmas, respectively. CF 4/Ar plasma exhibits higher electron temperature but lower electron density while for Cl 2/Ar plasma, these parameters are more sensitive to gas composition. The increase of Ar content in both gas mixtures causes monotonic changes of fluxes for all kinds of active species. Simplified description of ion-assisted etching mechanism indicates that a combination of physical sputtering and chemical etching activated by ion bombardment can account for the experimental data explaining the appearance of etch rate maximum as well as the differences in SBT etch rate in Cl 2/Ar and CF 4/Ar plasmas.

Simple Model for Ion-Assisted Etching Using&amp;lt;tex&amp;gt;$hboxCl_2hbox--hboxAr$&amp;lt;/tex&amp;gt;Inductively Coupled Plasma: Effect of Gas Mixing Ratio

In this paper, we investigated the relationships between Cl/sub 2/--Ar mixing ratio, plasma parameters, plasma chemistry and etching kinetics using a combination of experimental investigations and modeling. Modeling of plasma chemistry was represented by zero-dimensional quasi-stationary model assuming electron energy distribution to be close to Maxwellian. For the surface kinetics, we used the simplified model based on the theory of active surface sites. The model confirmed the possibility of nonmonotonic behavior of etch rate behavior in the system with monotonic changes of fluxes of active species.

Etching characteristics and mechanism of Pb(Zr,Ti)O 3 thin films in CF 4/Ar inductively coupled plasma

The effect of the CF 4/Ar mixing ratio on the etching behaviour and mechanisms for Pb(Zr,Ti)O 3 (PZT) thin films in an inductively coupled plasma was carried out. It was found that an increase of Ar mixing ratio causes non-monotonic behaviour of the PZT etch rate, which reaches a maximum of 2.38 nm/s at 80% Ar. Investigating the plasma parameters, we found a weak sensitivity of both electron temperature and electron density to the change of CF 4/Ar mixing ratio. A combination of zero-dimensional plasma model with the model of surface kinetics shows the possibility of a non-monotonic etch rate behaviour due to the concurrence of physical and chemical pathways in the ion-assisted chemical reaction.