Papers by Keyword: Etching

Abstract: Wet etching of Si₃N₄ was conducted in superheated water at 160 °C with different additives type and concentration. In general, etching rate of Si₃N₄ increased with the pH of solution. However, it is difficult to fully explain the Si₃N₄ etching behavior just with the pH of solution. The OH^- concentration (or pH) in superheated water at 160 °C are different from the pH of solution at room temperature. Therefore, the OH^- concentrations in superheated water at 160 °C were calculated using van't Hoff equation, equilibrium constant equations, mass and charge balance equations. The calculated OH^- concentration at 160 °C showed better correlation with Si₃N₄ etching rate than that of initial pH of solution.

Abstract: Indium gallium arsenide (InGaAs) is one of the candidate materials to overcome the physical limitation of Si due to its excellent electrical properties. The effect of surface oxidation on the etching characteristics of InGaAs surface in acidic solutions were investigated. InGaAs surfaces was etched in HCl/H₂O₂/H₂O (CPM) and HNO₃/H₂O₂/H₂O (NPM), while there was no thickness change in diluted HCl or HNO₃. The CPM-treated InGaAs surface had a lower etching rate than the NPM-treated one, while etching rate of oxidized layer was higher in diluted HCl than in HNO₃. NaCl added in the NPM acts as an etching inhibitor for InGaAs and the etching rate was significantly suppressed. It is thought that Cl⁻ anion inhibits the formation of hydroxyl radical (OH∙) or consumes OH∙ in acidic solution, inhibiting surface oxidation of InGaAs and suppressing its material loss.

Abstract: Amorphous SiC and 4H-SiC were etched by chlorine fluoride (ClF), chlorine trifluoride (ClF₃), fluorine (F₂) and chlorine (Cl₂) gases, in order to evaluate the etching capability of various reactive gases. The gaseous byproducts of SiC etching were observed by the quadrupole mass spectrometry. The ClF showed slow etching rate of amorphous SiC and 4H-SiC, while ClF₃ and F₂ quickly etched them. By the ClF gas, the etching rate of amorphous SiC was 120 nm/min at 400 °C. The ClF gas was expected to be suitable for a shallow etching, because of its moderate etching rate even at high temperatures.

Abstract: High-carbon high-strength JIS-SUJ2 bearing steel is one of the alloys used as rolling contact applications which need high wear resistance. This high hardness material is broken from non-metallic inclusions under fatigue stress. In this work, we developed a new observation method “fracture surface etching (FSE)” in order to observe the material microstructure on the fracture surface. We succeeded to draw clear grain boundaries on the fracture surfaces and closely observed the material microstructure around the crack origins by the FSE method. We concluded that the crack initiation area boundary is not formed by only the grain boundary, and the grain size around the Al2O3 inclusion on the fracture surface was similar to that of the flat surface which does not have inclusions before fatigue testing.

Abstract: Epilayers grown on substrates etched by various etching conditions were studied for stacking fault defects. Substrates were etched by H₂, H₂+ HCl and H₂ + C_xH_y gases prior to epilayer growth for comparison. High density of SF was observed in the epilayers when H₂+HCl or H₂+C_xH_y gas mixtures were used. On the other hand, much lower density of stacking faults (SF) (<1 cm^-2) was observed in the epilayer grown on the surface etched by only H₂ gas. However, a high number of pits were generated in the epilayer grown on substrate etched by H₂ only, which can be considered to be tradeoff of achieving low SF in epilayer by substrate etching. We also conclude from our experimental results that C rich surface is more favorable to generate SF in epilayer compared to Si rich surface.

Abstract: The effect of surface topography in combination with chemical composition on hydrophobicity and static coefficient-of-friction between steel and ice was studied. Polished stainless steel blocks were etched to introduce a roughness, and further treated with octadecanethiol. Carbon rich inclusions, identified by energy-dispersive X-ray spectroscopy, and scratches acted as the exposure centers to promote etching. Due to heterogeneities in steel, rounded cavities and parallel troughs were found on the surface after etching. Etched blocks with a lowered surface energy were studied under various ambient conditions to determine the influence of ice temperature and humidity on the static coefficient-of-friction. Blocks modified with octadecanethiol showed improved hydrophobicity. Warmer ice conditions led to a lower friction, regardless of the surface modification.

Abstract: The paper presents the design of the etching unit, the experiment procedure to remove a thin surface layer of metal and fixing the elastic discharge of the pipe along its length. The value of elastic discharge is necessary to calculate the residual stresses of a thin surface layer, as well as the distribution of residual stresses of the pipe wall.

Abstract: The integration of III-V and Ge materials on Si surface causes many issues with complexity such as lattice mismatch with silicon. In particular, the surface preparation and passivation of InGaAs is very challenging, because the formation of InGaAs/high-K interface is important, but not well understood. For the systematical study of InGaAs surface during wet processes, the effect of various wet etching processes on the surfaces of binary III-V compound semiconductors (GaAs, InAs, GaSb and InSb) was studied from the viewpoints of surface oxidation, material loss (dissolution), and passivation. Based on that, further effort to understand the surface reactions on ternary InGaAs compound semiconductor was made. In addition, process sequential effect on the InGaAs surface was investigated.

Abstract: We report on the (electro) chemical etching behavior, surface morphology and composition of n-type Ge (100) in acidic halide solutions using various analytical and spectroscopic techniques. The use of an integrated (electro) chemical etching chamber connected to X-ray photoelectron spectroscopy instrument to exclude the effect of oxygen from atmosphere is highlighted.

Abstract: The article evaluates the toxicity of the spent acid etching solution (SAES) formed in production of titanium products when etched with a mixture of hydrofluoric and hydrochloric acids. The SAES contained TiF₃, HF and HCl in the amount of 21.9 g/l, 1.7 g/l and 6.2 g/l, respectively. To determine the toxicity of SAES the phytotesting method was used. As a phytoecological indicator, a cress of Zabava variety was used. The experiment was carried out according to the method for determining the toxicity of drinking, ground, surface and sewage water, chemical solutions by measuring the germination index, average length and average dry weight of seedlings of cress seeds (Lepidium sativum). The SAES toxicity was determined before its neutralization with alkali and after neutralization with alkali. It is shown that SAES has an acute toxic effect both before neutralization and after neutralization with alkali. To determine the safe dilution factor, the effect of SAES dilution on seed germination, average length and average dry weight of seedlings was investigated. It was found that “seedlings average length – dilution factor” equations most reliably describe the experimental data. The safe dilution factor calculated from these dependencies is 669.2 for non-neutralized SAES and 382.5 for neutralized SAES.