Surface properties of etched ITO thin films using high density plasma

The etching characteristics of ITO in a BCl₃/Ar plasma, including the etch rate and selectivity of ITO, were investigated. The maximum etch rate of 62.8 nm/min for the ITO thin films was obtained at a BCl₃/Ar gas mixing ratio of 25%/75%. Ion bombardment by physical sputtering was required to obtain such high etch rates, due to the relatively low volatility of the by-products formed during the etching. The chemical reactions on the etched surfaces were investigated using X-ray Photoelectron Spectroscopy (XPS) and the preferential losses on the etched surfaces were investigated using Atomic Force Microscopy (AFM).     

Etch characteristics of HfO2 thin films by using CF4/Ar inductively coupled plasma

In this study, we carried out an investigation of the etching characteristics (etch rate, selectivity) of HfO₂ thin films in the CF₄/Ar inductively coupled plasma (ICP). The maximum etch rate of 54.48 nm/min for HfO₂ thin films was obtained at CF₄/Ar (=20:80%) gas mixing ratio. At the same time, the etch rate was measured as function of the etching parameters such as ICP RF power, DC-bias voltage, and process pressure. The X-ray photoelectron spectroscopy analysis showed an efficient destruction of the oxide bonds by the ion bombardment as well as an accumulation of low volatile reaction products on the etched surface. Based on these data, the chemical reaction was proposed as the main etch mechanism for the CF₄-containing plasmas.     

Dry etch properties of IZO thin films in a CF4/Ar adaptively coupled plasma system

In this study, we investigated to the etch characteristics of indium zinc oxide (IZO) thin films in a CF₄/Ar plasma, namely, etch rate and selectivity toward SiO₂. A maximum etch rate of 76.6 nm/min was obtained for IZO thin films at a gas mixture ratio of CF₄/Ar (25:75%). In addition, etch rates were measured as a function of etching parameters, including adaptively coupled plasma chamber pressure. X-ray photoelectron spectroscopy analysis showed efficient destruction of the oxide bonds by ion bombardment, as well as accumulation of low volatile reaction products on the surface of the etched IZO thin films. Field emission Auger electron spectroscopy analysis was used to examine the efficiency of ion-stimulated desorption of the reaction products.     

Infinitely high etch selectivity during CH4/H2/Ar inductively coupled plasma (ICP) etching of indium tin oxide (ITO) with photoresist mask

Under certain conditions during ITO etching using CH₄/H₂/Ar inductively coupled plasmas, the etch rate selectivity of ITO to photoresist (PR) was infinitely high because the ITO films continued to be etched, but a net deposition of the α-C:H layer occurred on the top of the PR. Analyses of plasmas and etched ITO surfaces suggested that the continued consumption of the carbon and hydrogen in the deposited α-C:H layer by their chemical reaction with In and Sn atoms in the ITO resulting in the generation of volatile metal-organic etch products and by the ion-enhanced removal of the α-C:H layer presumably play important roles in determining the ITO etch rate and selectivity.     

Dry etching properties of TiO2 thin films in O2/CF4/Ar plasma

In this work, the etching properties of titanium dioxide (TiO₂) thin film in additions of O₂ at CF₄/Ar plasma were investigated. The maximum etch rate of 179.4 nm/min and selectivity of TiO₂ of 0.6 were obtained at an O₂/CF₄/Ar (=3:16:4 sccm) gas mixing ratio. In addition, the etch rate and selectivity were measured as a function of the etching parameters, such as the RF power, DC-bias voltage, and process pressure. The efficient destruction of the oxide bonds by ion bombardment, which was produced from the chemical reaction of the etched TiO₂ thin film, was investigated by X-ray photoelectron spectroscopy. To determine the re-deposition of sputter products and reorganization of such residues on the surface, the surface roughness of TiO₂ thin film were examined using atomic force microscopy.     

Dry etching characteristics of HfAlO3 thin films in BCl3/Ar plasma using inductively coupled plasma system

In this study, we monitored the HfAlO₃ etch rate and selectivity to SiO₂ as a function of the etch parameters (gas mixing ratio, RF power, DC-bias voltage, and process pressure). A maximum etch rate of 52.6 nm/min was achieved in the 30% BCl₃/(BCl₃ + Ar) plasma. The etch selectivity of HfAlO₃ to SiO₂ reached 1.4. As the RF power and the DC-bias voltage increased, the etch rate of the HfAlO₃ thin film increased. As the process pressure decreased, the etch rate of the HfAlO₃ thin films increased. The chemical state of the etched surfaces was investigated by X-ray Photoelectron Spectroscopy (XPS). According to the results, the etching of HfAlO₃ thin films follows the ion-assisted chemical etching mechanism.     

Comparative study on dry etching of polycrystalline diamond thin films

The reactive ion etching (RIE) technique was used to etch polycrystalline diamond thin films. In this study we investigate the influence of process parameters (total pressure, rf power, gas composition) of standard capacitively coupled plasma RIE system on the etching rate of diamond films. The surface morphology of etched diamond films was characterized by Scanning Electron Microscopy and the chemical composition of the etched film part was investigated by Raman Spectroscopy.We found that the gas composition had a crucial effect on the diamond film morphology. The use of CF₄ gas resulted in flatter surfaces and lateral-like etching, while the use of pure O₂ gas resulted in needle-like structures. Addition of argon to the reactant precursors increased the ion bombardment, which in turn increased the formation of non-diamond phases. Next, increasing the rf power from 100 to 500 W increased the etching rate from 5.4 to 8.6 μm/h. In contrast to this observation, the rise of process pressure from 80 to 150 mTorr lowered the etching rate from 5.6 down to 3.6 μm/h.     

Etch characteristics of indium zinc oxide thin films in a C2F6/Ar plasma

Dry etching of indium zinc oxide (IZO) thin films was performed using inductively coupled plasma reactive ion etching in a C₂F₆/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 C₂F₆ 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 InF₃ and ZnF₂ 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 silver by inductively coupled fluorine-based plasmas

In this study, thin films of Ag deposited onto glass substrates were etched using inductively coupled fluorine-based plasmas. The effects of various process conditions on the Ag etch characteristics were evaluated to ascertain whether it would be possible to etch patterned Ag films with high etch rates and smooth sidewalls free of involatile etch products. It was found that involatile etch products remained on the substrate when films were etched in CF₄-based gas mixtures possessing either O₂ or N₂ as an additive. However, when Ar was added to either NF₃ or CF₄, a residue-free etch was obtained provided the partial pressure of Ar was no less than 50%. It is proposed that the residue-free Ag etch mechanism involves the formation of silver fluoride, which is physically sputtered by Ar⁺ ions. A Ag etch rate of 160 nm/min with a Ag to photoresist etch selectivity exceeding 1.1 was achieved with an inductive power of 1500 W, a d.c. bias voltage of −180 V and a chamber pressure of 0.8 Pa with 50-50 CF₄/Ar partial pressures obtained with 60 sccm CF₄/60 sccm Ar flows. In addition, these conditions produced smooth Ag sidewall etch profiles.     

The dry etching property of TiO2 thin films using metal-insulator-metal capacitor in inductively coupled plasma system

In this work, we investigated the etching characteristics of TiO₂ thin films and the selectivity of TiO₂ to SiO₂ in a BCl₃/Ar inductively coupled plasma (ICP) system. The maximum etch rate of 84.68 nm/min was obtained for TiO₂ thin films at a gas mixture ratio of BCl₃/Ar (25:75%). In addition, etch rates were measured as a function of etching parameters, such as the RF power, DC-bias voltage and process pressure. Using the X-ray photoelectron spectroscopy analysis the accumulation of chemical reaction on the etched surface was investigated. Based on these data, the ion-assisted physical sputtering was proposed as the main etch mechanism for the BCl₃-containing plasmas.     

Dry etching of TaN thin film using CH4/Ar inductively coupled plasma

In this research, we investigated the TaN etch rate and selectivity with under layer (HfO₂) and mask material (SiO₂) in inductively coupled CH₄/Ar plasma. As the CH₄ content increased from 0% to 80% in CH₄/Ar plasma, the TaN etch rate was increased from 11.9 to 22.8 nm/min. From optical emission spectroscopy (OES), the intensities for CH [431 nm] and H [434 nm] were increased with the increasing CH₄ content from 0% to 100% in CH₄/Ar plasma. The results of x-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) showed no accumulation of etch by-products from the etched surface of TaN thin film. As a result of OES, AES and XPS analysis, we observed the etch by-products from the surfaces, such as Ta-N-CH and N-CH bonds. Based on the experimental results, the TaN etch was dominated by the chemical etching with the assistance of Ar sputtering in reactive ion etching mechanism.     

Dry etching of TaN thin film using CH4/Ar inductively coupled plasma

In this research, we investigated the TaN etch rate and selectivity with under layer (HfO₂) and mask material (SiO₂) in inductively coupled CH₄/Ar plasma. As the CH₄ content increased from 0% to 80% in CH₄/Ar plasma, the TaN etch rate was increased from 11.9 to 22.8 nm/min. From optical emission spectroscopy (OES), the intensities for CH [431 nm] and H [434 nm] were increased with the increasing CH₄ content from 0% to 100% in CH₄/Ar plasma. The results of x-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) showed no accumulation of etch by-products from the etched surface of TaN thin film. As a result of OES, AES and XPS analysis, we observed the etch by-products from the surfaces, such as Ta–N–CH and N–CH bonds. Based on the experimental results, the TaN etch was dominated by the chemical etching with the assistance of Ar sputtering in reactive ion etching mechanism.     

Etching characteristics and mechanism of Pb(Zr,Ti)O3 thin films in CF4/Ar inductively coupled plasma

The effect of the CF₄/Ar mixing ratio on the etching behaviour and mechanisms for Pb(Zr,Ti)O₃ (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 CF₄/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.     

Effect of etching on dielectric constant and surface composition of SiCOH low-k films in inductively coupled fluorocarbon plasmas

SiCOH low-k (k = 2.8) film etched in fluorocarbon (CF₄ and CHF₃) inductively coupled plasmas was characterized in this work. The surface composition and molecular structures of the low-k films after etching in the CF₄, CHF₃, CF₄/Ar, and CHF₃/Ar plasmas were characterized. A higher etch rate was observed with the CF₄ plasmas than with the CHF₃ plasmas. The etch rate of the low-k film in the CF₄ plasmas was decreased and the etch rate in the CHF₃ plasmas was increased by the Ar addition. After etching the low-k films, a decrease in the dielectric constant of up to 0.19 was observed. The thickness of the fluorocarbon (CF_x) layer and CF_x (x = 1, 2, 3)-to-carbon ratio obtained from the XPS C 1s peak increased with decreasing etch rate. The k-value was correlated with amount of Si-CH₃ and Si-O related groups determined from the Fourier transform infrared (FT-IR) spectrum. The Si-O related peaks were markedly decreased after etching in the CF₄ and CF₄/Ar plasmas. The lower k-value was attributed to the increase of the Si-CH₃/Si-O ratio after etching low-k film.     

Etch characteristics of indium zinc oxide thin films using inductively coupled plasma of a Cl2/Ar gas

Inductively coupled plasma reactive ion etching of indium zinc oxide (IZO) thin films masked with a photoresist was performed using a Cl₂/Ar gas. The etch rate of the IZO thin films increased as Cl₂ gas was added to Ar gas, reaching a maximum at 60% Cl₂ 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 InCl₃ and ZnCl₂ on the etched surface. The surface morphology of the films etched at high Cl₂ concentrations was smoother than that of the films etched at low Cl₂ concentrations. These results suggest that the dry etching of IZO thin films in a Cl₂/Ar gas occurs according to a reactive ion etching mechanism involving ion sputtering and a surface reaction.     

Etch characteristics of TiN/Al2O3 thin film by using a Cl2/Ar adaptive coupled plasma

In this study, we carried out an investigation in the etching characteristics of TiN thin films in a C1₂/Ar adaptive coupled plasma. The maximum etch rate of the TiN thin films was 768 nm/min at a gas mixing ratio of C1₂ (75%)/Ar (25%). At the same time, the etch rate was measured as functions of the various etching parameters. The X-ray photoelectron spectroscopy analysis showed the efficient destruction of the oxide bonds by the ion bombardment as well as the accumulation of low volatile reaction products on the etched surface. Field emission Auger electron spectroscopy analysis was used to examine the efficiency of the ion-stimulated desorption of the reaction products.     

Etch characteristics of TiN/Al2O3 thin film by using a Cl2/Ar adaptive coupled plasma

In this study, we carried out an investigation in the etching characteristics of TiN thin films in a C1₂/Ar adaptive coupled plasma. The maximum etch rate of the TiN thin films was 768 nm/min at a gas mixing ratio of C1₂ (75%)/Ar (25%). At the same time, the etch rate was measured as functions of the various etching parameters. The X-ray photoelectron spectroscopy analysis showed the efficient destruction of the oxide bonds by the ion bombardment as well as the accumulation of low volatile reaction products on the etched surface. Field emission Auger electron spectroscopy analysis was used to examine the efficiency of the ion-stimulated desorption of the reaction products.     

A study on the etch characteristics of HfAlO3 dielectric thin film in Cl2/Ar gas chemistry using inductively coupled plasma system

Thin films of HfAlO₃, a high-k material, were etched using inductively-coupled plasma. The dry etching mechanism of the HfAlO₃ thin film was studied by varying the Cl₂/Ar gas mixing ratio, RF power, direct current bias voltage, and process pressure. The maximum etch rate of the HfAlO₃ thin film was 16.9 nm/min at a C1₂/(C1₂ + Ar) ratio of 80%. Our results showed that the highest etch rate of the HfAlO₃ thin films was achieved by reactive ion etching using Cl radicals, due to the high volatility of the metal-chlorides. Consequently, the increased chemical effect caused an increase in the etch rate of the HfAlO₃ thin film. Surface analysis by x-ray photoelectron spectroscopy showed evidence that Hf, Al and O reacted with Cl and formed nonvolatile metal-oxide compounds and volatile metal-chlorides. This effect may be related to the concurrence of chemical and physical pathways in the ion-assisted chemical reaction.     

Inductively coupled plasma reactive ion etching of titanium thin films using a Cl2/Ar gas

Inductively coupled plasma reactive ion etching of titanium thin films patterned with a photoresist using Cl₂/Ar gas was examined. The etch rates of the titanium thin films increased with increasing the Cl₂ 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.     

High density plasma etching of amorphous CoZrNb films for thin film magnetic devices

Inductively coupled plasma reactive ion etching of CoZrNb magnetic thin films was studied using a TiN hard mask in a Cl₂/O₂/Ar gas mix. The etch rates of CoZrNb films and TiN hard mask gradually decreased with increasing Cl₂ or O₂ gas concentrations. When O₂ gas was added in the Cl₂/Ar gas mix, the etch rate of TiN hard mask was suppressed effectively so that the etch selectivity of CoZrNb film to TiN hard mask was enhanced. The addition of O₂ into the gas mix also led to the anisotropic etching of the CoZrNb films and it was confirmed by Auger electron spectroscopy that there were no redeposited materials on the sidewall of the etched films. Highly anisotropic etching of CoZrNb films was achieved at room temperature under the optimized etching conditions.