• Applied Science and Convergence Technology
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• v.24 no.6
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• pp.289-292
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• 2015

The etching processes of glass in aqueous hydrofluoric acid (HF) solutions were used to improve the current density of solar cell. In this study, the textured glass substrate has been etched by solution and the $TiO_2$ thin films have been prepared on this textured glass. After the $TiO_2$ film deposition the surface has been etched by HF under different concentration and the etched $TiO_2$ thin films had a longer electron lifetime and higher haze ratio as well as light scattering, resulting in 1.7 times increment of dye-sensitized solar-cell(DSSC) efficiency. Increases in the surface root-mean-square roughness of glass substrates from 80 nm to 1774 nm enhanced haze ratio in above 300 nm wavelength. In particular, haze ratio of etched $TiO_2$ films on textured glass showed gradually increasing tendency at 550 nm wavelength by increasing of HF concentration up to 10M, suggesting a formation of crater with various sizes on its surface.

• Transactions on Electrical and Electronic Materials
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• v.8 no.6
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• pp.229-233
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• 2007

In this study, we carried out an investigation of the etching characteristics(etch rate, selectivity) of $HfO_2$ thin films in the $CH_4/Ar$ inductively coupled plasma. It was found that variations of input power and negative dc-bias voltage are investigated by the monotonic changes of the $HfO_2$ etch rate as it generally expected from the corresponding variations of plasma parameters. At the same time, a change in either gas pressure or in gas mixing ratio result in non-monotonic etch rate that reaches a maximum at 2 Pa and for $CH_4(20%)/Ar(80%)$ gas mixture, respectively. The X-ray photoelectron spectroscopy analysis showed an efficient destruction of the oxide bonds by the ion bombardment as well as showed an accumulation of low volatile reaction products on the etched surface. Based on these data, the ion-assisted chemical reaction was proposed as the main etch mechanism for the $CH_4-containing$ plasmas.

• The Journal of Korean Academy of Prosthodontics
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• v.30 no.1
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• pp.73-83
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• 1992

Now composite resin restoration is clinically accepted in the repair of fractured PFM case, many mechanical surface treatment methods are performed to increase retentive force. The main purpose of this study was to compare the retentive force among the possible surface treatments and to insure the best method for the clinical application to the fractures porecelain and the exposed metal surface. To compare and to analyze the retentive force of repair resin, porcelain specimen were divided into 2 groups, etching group and non-etching group, and etching group were treated with 37% $H_3PO_4$, 1.23% APF, 10% HF and non-etching groups were treated with diamond bur, micro-sandblasasting. Also, metal specimens were divided by 2 groups : one was non-precious metal group which was treated with diamond bur, micro-sandblasting and tin plating and electrolytic etching, the other was precious metal group which was composed of micro-sandblasting treatment only and tin plating treatment with micro-sandblasting. Each specimen had been restored for 48 hours and the bond strength of each specimen was calculated with Universal testing machine. The results were as follows : 1. Porcelain specimen had higher bonding strength than metal specimen for the repair resin(P<0.01). 2. In porcelain specimen, 10% HF etching group had the highest bonding strength among etching and non-etching group. 3. Metal specimen treated with micro-sandblasting had highest bonding strength among the non-sandblasting had hightest bonding strength among the non-precious group, tin plating group had higher bonding strength than micro-sandblasting group between the precious metal groups. 4. Bonding strength of tin plating was increased in precious metal group only.

• Applied Chemistry for Engineering
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• v.20 no.5
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• pp.557-560
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• 2009

In this study, a new wet etching method and the solution for thinning the glass with the thickness below $100{\mu}m$ were investigated. For the preparation of etching solution with low hydrofluoric acid, it was effective to use $NH_4F$ or $NH_4HF_2$ as a main ingredient with the addition of sulfuric acid or nitric acid. Influence of the composition of mixed acid solution and the temperature on the etching rate was investigated. The addition of anionic surfactant provides the function to prevent the adhesion of sludge generated by the etching reaction. A new wet etching pilot device equipped with streaming generation parts was used to test etching of commercial non-alkali glass and soda lime glass. The non-alkali glass with the thickness of 640 ${\mu}m$ and soda lime glass with the thickness of $500{\mu}m$ were etched to $45{\mu}m$ and $100{\mu}m$, respectively, by using the pilot device. After the etching by pilot device, the roughness degree of the glass surface was maintained at $0.01{\sim}0.02{\mu}m$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.9
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• pp.687-692
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• 2011

Hafnium oxide ($HfO_2$) was very advantageous for substitute material of gate on existing transistor. $HfO_2$ has been widely studied due to high contact with polysilicon and thermal stability and also, it is easily etched by using HF solution. In this study, $HfO_2$ and thermal oxide films were etched by wet etch method using chemical etchant. Etch rate of $HfO_2$ and thermal oxide was linearly increased with increasing concentration of HF and temperature but etch rate of $HfO_2$ was higher than thermal oxide due to $H^+$, $F^-$, and $HF_2^-$ ions at below 0.5% concentration of HF. And also, etch selectivity was improved by adding Hydrazine as additive.

• JSTS:Journal of Semiconductor Technology and Science
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• v.13 no.6
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• pp.668-675
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• 2013

We investigate the effect of the ageing time and etching time on the etching rate of SiGe mixed etching solution, namely 1 vp HF (6%), 2 vp $H_2O_2$ (30%) and 3 vp $CH_3COOH$ (99.8%). For this etching solution, we found that the etch rate of SiGe layer is saturated after the ageing time of 72 hours, and the selectivity of $Si_{0.8}Ge_{0.2}$ layer and Si layer is 20:1 at ageing time of 72 hours. The collapse was appeared at the etching time of 9min with etching solution of after saturation ageing time.

• Journal of Photoscience
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• v.10 no.3
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• pp.257-261
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• 2003

We have systematically studied the evolution of the photoluminescence(PL) tuning of porous silicon(PS) by electrochemical etching in various mixed electrolytes. The electrolytes employed as an etchants were mixtures of HF:CH$_3$COOH:HNO$_3$:C$_2$H$\_$5/OH solutions where the composition ratios (%) were varied from 10:1.98:0:88.02 to 10: 1.98:8.4:79.62 under constant concentration of HF and CH$_3$COOH with a total volume of 100 ml. Changes in the surface morphology of the samples caused by variations in the etching process were investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). After samples are etched in various mixed electrolytes, FTIR analyses show that there is the non-photoluminescent state and the photoluminescent state simultaneously. The PL spectra show the PL tuning in the ranging from 560 to 700 nm with the increase of HNO$_3$ concentration. An analysis of the subsequent PL relaxation mechanism was carried out by time-correlated single photon counting (TCSPC) method. Based on experimental results, it is assumed that a red shift of the main PL peak position is related to the HNO$_3$ activated formation of silicon oxygen compounds. Therefore, the use of electrolyte mixtures with composition ratios can be obtained adequate and reproducible results for PL tuning.

• Journal of the Korean Ceramic Society
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• v.46 no.6
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• pp.685-688
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• 2009

Surface Texturing is very important process for high cell efficiency in crystalline silicon solar cell. Anisotropic texturing with an alkali etchant was known not to be able to produce uniform surface morphology in multi-crystalline silicon (mc-Si), because of its different etching rate with random crystal orientation. In order to reduce surface reflectance of mc-Si wafer, the general etching tendency was studied with HF/HN$O_3$/De-ionized Water acidic solution. And the surface structures of textured mc-Si in various HF/HN$O_3$ ratios were compared. The surface morphology and reflectance of textured silicon wafers were measured by FE-SEM and UVvisible spectrophotometer, respectively. We obtained average reflectance of $16{\sim}19$% for wavelength between 400 nm and 900 nm depending on different etching conditions.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.30 no.6
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• pp.251-257
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• 2020

In order to quickly and clearly recognize characters or images through display glass, glare of the glass must be suppressed. In this study, we tried to reduce glare by analyzing changes in glass surface shape and optical properties through etching process. The etching process was performed as a function of concentrations of the etching solutions, BOE and HF. During the etching process, a compound containing F ion was generated on the surface of the glass, forming an irregular pattern in the form of a projection, and thus various optical properties of the glass were changed; reflectance of 2.5~4.6 %, haze of 4.5~6.6 %, transmittance of 77~92 %, and gloss of 82~107 GU. As a result, optimum etching condition was obtained to minimize the loss of other optical properties while suppressing glare of the glass.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.382-382
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• 2010

The etch characteristics of the $HfAlO_3$ thin films and selectivity of $HfAlO_3$ to $SiO_2$ in $Cl_2/BCl_3$/Ar plasma were investigated in this work. The maximum etch rate was 108.7 nm/min and selectivity of $HfAlO_3$ to $SiO_2$ was 1.11 at $Cl_2$(3sccm)/$BCl_3$(4sccm)/Ar(16sccm), RF power of 500 W, DC-bias voltage of - 100 V, process pressure of 1 Pa and substrate temperature of $40^{\circ}C$. As increasing RF power and DC-bias voltage, etch rates of the $HfAlO_3$ thin films increased. Whereas as decreasing of the process pressure, those of the $HfAlO_3$ thin films were increased. The chemical reaction on the surface of the etched the $HfAlO_3$ thin films was investigated with X-ray photoelectron spectroscopy (XPS).