This study investigates the effect of mask material and thickness on the silicon etching profile using a high-density plasma (HDP) etching system, aiming to reduce optical loss in silicon-based optical waveguides. As the mask thickness increased, the etching sidewall angle became steeper. An etching profile angle of 87° was obtained when tetraethyl orthosilicate (TEOS) was used as the mask material, while 80° was obtained for photoresist (PR). This is attributed to electron charging on the mask surface in the plasma. The charged mask modifies the distribution and strength of the electric field depending on its thickness, thereby affecting the trajectory of positive ions accelerated toward the substrate by the bias voltage. Furthermore, Plasma diagnostics using optical emission spectroscopy (OES) and surface composition analysis using field emission Auger electron spectroscopy (FE-AES) revealed that changes in the mask material also alter the reaction pathways and formation characteristics of active species and silicon by-products in the plasma. These results suggest that the mask material influences the overall plasma characteristics, including electron density and ion energy, and plays a critical role in the precise control of silicon etching profiles for high-performance optical device fabrication.

Molybdenum disulfide (MoS₂) is a promising 2D semiconductor material for low-power electronics due to its excellent electrical properties and compatibility with conventional processes. In this study, MoS₂ thin films deposited by RF sputtering were etched using Cl₂/Ar plasma in an ICP system. The effects of Cl₂ gas ratio, RF power, and process pressure on etch rate and MoS₂/SiO₂ selectivity were investigated. Optimal results were obtained at 25% Cl₂, achieving ~38 nm/min etch rate and selectivity of 3.0. Increased source power improved both etch rate and selectivity, while higher bias power enhanced etching but reduced selectivity due to stronger ion bombardment. XPS analysis confirmed Mo－Cl and S－Cl bond formation after etching, indicating chemical reactions and some by-product residue. These results provide insights into optimized plasma etching of sputtered MoS₂ films for advanced 2D device fabrication

This work focuses on improving the light-harvesting efficiency of thin-film silicon solar cells through innovative multi-architecture surface modifications. To create a regular optical structure, a lithographic process was performed to form it on a glass substrate through various etching processes, from Etch-1 to Etch-3. AZO was deposited on top of the structures and re-etched to create a multi-architectural surface. These surface-modified structures improved the light absorption and overall performance of the solar cell through changes in optical and physical properties, which we will analyze. In addition, we investigated the effect of post-cleaning on the etched glass structures through EDX analysis to understand the mechanism of the etching action. The results of this study are expected to provide important guidelines for the design and fabrication of solar cells and other photovoltaic devices.

Currently, semiconductor manufacturing industry heavily relies on a wide range of high global warming potential (GWP) gases, particularly during etching and cleaning processes, and their use and relevant carbon emissions are subject to global rules and regulations for achieving carbon neutrality by 2050. To replace high GWP gases in near future, dry etching using alternative low GWP gases is thus being under intense investigations. In this review, we report a current status and recent progress of the relevant research activities on dry etching processes using a low GWP gas. First, we review the concept of GWP itself and then introduce the difference between high and low GWP gases. Although most of the studies have concentrated on potentially replaceable additive gases such as C₄F₈, an ultimate solution with a lower GWP for main etching gases including CF₄ should be developed; therefore, we provide our own perspective in this regard. Finally, we summarize the advanced dry etch process research with low GWP gases and list up several issues to be considered in future research.

Inductively coupled plasma reactive ion etching (ICP-RIE) of copper thin films patterned with SiO₂ hard masks was carried out using piperidine/O₂/Ar gas mixture. The etch rate, etch selectivity, and etch profile of copper thin films were investigated by varying gas concentration in piperidine/O₂/Ar gas mixture. In addition, the etch parameters including ICP RF power, DC-bias voltage to substrate, and process pressure were varied to examine the etch characteristics. X-ray photoelectron spectroscopy and optical emission spectroscopy were employed to elucidate the etch mechanism under piperidine/O₂/Ar gas chemistry. Finally, 150 nm-line patterned copper thin films were successfully etched using piperidine/ O₂/Ar etch gas under the optimized etch conditions.

Randomly patterned and wet chemical etching processes were used to treat anti-glare of display cover glasses. The surface and optical properties of grain size and surface morphology controlled by randomly patterned etching and wet chemical solution etching were investigated. The surface morphology and roughness of the etched samples were examined using a spectrophotometer and a portable surface roughness (Ra) measuring instrument, respectively. The gloss caused by reflection from the glass surface was measured at 60° using a gloss meter. The surface of the sample etched by the doctor-blade process was more uniform than that obtained from a screen pattern etching process at gel state etching process of the first step. The surface roughness obtained from the randomly patterned etching process depended greatly on the mesh size, which in turn affected the grain size and pattern formation. The surface morphology and gloss obtained by the etching process in the second step depended primarily on the mesh size of the gel state etching process of the first step. In our experimental range, the gloss increased on decreasing the grain size at a lower mesh size for the first step process and for longer reaction times for the second step process.

In this study, effects of ICP (inductively coupled plasma) treatment on PAR thin film have been investigated. A maximum etch rate of the PAR thin films and the selectivity of PAR to PR were obtained as 110 nm/minand 1.1 in the CF₄/O₂ (5:15 sccm) gas mixture. We present the surface properties of PAR thin film with various treatment conditions. The surface morphology and cross section of the PAR thin film was observed by AFM (atomic force microscopy) and FE-SEM (filed emission scanning electron microscopy).

ITO/Ag/ITO conductive films on PET (polyethylene terephthalate) was etched by a Q-switched diode-pumped neodymiun-doped yttrium vanadate (Nd:YVO4, λ = 1064 ㎚) laser. During the laser direct etching, the laser beam was incident on the two different directions of PET and the etching patterns were investigated and analyzed. At a lower repetition rate of laser pulse, the larger laser etched patterns were obtained by laser beam incident on reverse side of PET substrate. On the contrary, at a higher repetition rate, it was possible to find the larger etched patterns in case of the laser beam incidence on forward side of PET substrate. For the laser beam incidence on reverse side, the laser beam is expected to be transferred and scattered through the PET substrate and the laser beam energy is thought to be dependent on the etch laser pulse beam energy.

Single-layered transition metal dichalcogenides (TMDs) exhibit more interesting physical properties than those of bulk TMDs owing to the indirect to direct bandgap transition occurring due to quantum confinement. In this research, we demonstrate that layer-by-layer laser etching of molybdenum diselenide (MoSe₂) flakes could be controlled by varying the parameters employed in laser irradiation (time, intensity, interval, etc.). We observed a dramatic increase in the photoluminescence (PL) intensity (1.54 eV peak) after etching the samples, indicating that the removal of several layers of (MoSe₂) led to a change from indirect to direct bandgap. The laser-etched (MoSe₂) exhibited the single (MoSe₂) Raman vibration modes at ~239.4 cm^-1 and ~295 cm^-1, associated to out-of-plane A_1g and in-plane E¹ _2g Raman modes, respectively. These results indicate that controlling the number of MoSe2 layers by laser etching method could be employed for optimizing the performance of nano-electronic devices.

A textured front surface is required in high efficiency silicon solar cells to reduce reflectance and to improve light trapping. Wet etching with alkaline solution is usually applied for mono crystalline silicon solar cells. However, alkali texturing method is not appropriate for multi-crystalline silicon wafers due to grain boundary of random crystallographic orientation. Accordingly, acid texturing method is generally used for multi-crystalline silicon wafers to reduce the surface reflectance. To reduce reflectivity of multi-crystalline silicon wafers, double texturing method with combination of acid and reactive ion etching is an attractive technical solution. In this paper, we have studied to optimize RIE condition by different RF power condition (100, 150, 200, 250, 300 W).

In this paper, we report that selective etching on N-polar face by EC (electro-chemical)-etching effect on the reduction of bowing and strain of FS (free-standing)-GaN substrates. We applied the EC-etching to concave and convex type of FS-GaN substrates. After the EC-etching for FS-GaN, nano porous structure was formed on N-polar face of concave and convex type of FS-GaN. Consequently, the bowing in the convex type of FS-GaN substrate was decreased but the bowing in the concave type of FS-GaN substrate was increased. Furthermore, the FWHM (full width at half maximum) of (1 0 2) reflection for the convex type of FS-GaN was significantly decreased from 601 to 259 arcsec. In the case, we confirmed that the EC-etching method was very effective to reduce the bowing in the convex type of FS-GaN and the compressive stress in N-polar face of convex type of FS-GaN was fully released by Raman measurement.

We investigated and compared two methods of in-situ oxidation and chemical etching treatment (CET) to remove the boron rich layer (BRL). The BRL is generally formed during boron doping process. It has to be controlled in order not to degrade carrier lifetime and reduce electrical properties. A boron emitter is formed using BBr3 liquid source at 930℃. After that, in-situ oxidation was followed by injecting oxygen of 1,000 sccm into the furnace during ramp down step and compared with CET using a mixture of acid solution for a short time. Then, we analyzed passivation effect by depositing Al2O3. The results gave a carrier lifetime of 110.9 ㎲, an open-circuit voltage (Voc) of 635 mV at in-situ oxidation and a carrier lifetime of 188.5 ㎲, an Voc of 650 mV at CET. As a result, CET shows better properties than in-situ oxidation because of removing BRL uniformly.

To provide the clear images from the direct light on electrical board and display devices, anti glare treatment of display cover glass is needed. In this study, the effects of surface treatment temperature, concentration, and etching solution coating thickness of the gel phase on optical elements control such as gloss, haze of reflected light and transmittance, were investigated. Cover glasses were treated at different coating thickness and additive concentration. The optical properties were examined using spectrophotometer, gloss and haze meter. The surface morphology and roughness were measured by the optical microscope and Ra measuring instrument. The etching rate and surface morphologies were dramatically affected by the concentration of acid additive in the viscous gel because of re-crystallization of components in the etching solution, hydrogel formation and coagulant after coating on glass substrate. In our experimental range, cover glass which is surface-treated with various optical properties as well as the morphology uniformity was obtained; in particular, optical properties could be controlled by etching solution coating thickness of the gel phase and the concentration of additive. The gloss was depended on the surface roughness and it showed the linear relationship between optical transmittance and haze of reflected light, respectively.

WO3, SiO2, and TiO2 films with hydrophilic property are deposited by rf-magnetron sputtering. Their wettability is strongly depends on the presence or absence of the oxygen plasma etching on the glass substrates. The TiO2 film of 50 nm-thick on the plasma etched glass shows a water contact angle (WCA) below 5o which means a super-hydrophilic surface. However, WCA values are gradually degraded when the films are exposed under atmosphere, especially WO3. In order to improve hydrophilic property, the degraded films can be again recovered by UV illumination for 10 sec using UV-light and the TiO2 film shows a super-hydrophilic surface about 3o.

Anodic aluminum oxides (AAO) fabricated by the two-step anodizing process have attracted much attention for the fabrication of nano template because of pore structure with high aspect ratio, low cost process and ease of fabrication. AAOs are characterized by a homogeneous morphology of parallelpores that grow perpendicular to the template surface with a narrow distribution of diameter, length and inter-pores spacing, all of which can be easily controlled by suitably choosing of the anodizingparameters such as pH of the electrolyte, anodizing voltage and duration of anodizing. In this study, AAOtemplates were characterized by X-ray diffraction and field-emission scanning electron microscope(FE-SEM). The dependence of the pore size change according to the amount of addition of phosphoric acid, which was used to remove the initial alumina oxide layer, was not observed.

As a method of simple patterning of transparent conductive oxide (TCO) films deposited on flexible substrates, laser direct etching was carried out on TCO films sputtered on polycarbonate (PC) substrates. As a result of different binding energies in TCO films, indium tin oxide (ITO) and indium gallium zinc oxide (IGZO) were more easily etched than zinc oxide with different Nd: YVO4 laser beam conditions.

Zinc oxide(ZnO) was sputtered on various glass and flexible substrates such as polyethylene terephthalate(PET) and polycarbonate(PC). A Q-switched Nd:YVO4 laser with a wavelength of 1,064 nm was used for the direct etching of ZnO films. It was possible to obtain laser etched line patterns on the ZnO films on PC substrate at some specific laser beam conditions. In the flexible substrates, more thermal energy of laser beam is expected to be spreaded for the etching process.

In this paper, we carried out the investigations of both etch characteristics and mechanisms for the SnO2 thin films in O2/BCl3/Ar plasma. The dry etching characteristics of the SnO2 thin films was studied by varying the O2/BCl3/Ar gas mixing ratio. We determined the optimized process conditions that were as follows: a RF power of 700 W, a DC-bias voltage of -150 V, and a process pressure of 2 Pa. The maximum etch rate was 509.9 nm/min in O2/BCl3/Ar=(3:4:16 sccm) plasma. From XPS analysis, the etch mechanism of the SnO2 thin films in the O2/BCl3/Ar plasma can be identified as the ion-assisted chemical reaction while the role of ion bombardment includes the destruction of the metal-oxide bonds as well as the cleaning of the etched surface form the reaction products.

We investigated the effect of etching time on the surface roughness, and electrical and optical properties of ZnO and 2 wt% Al-doped ZnO (AZO) films. The ZnO and AZO films were deposited on glass substrates by RF magnetron sputtering technique. The etching experiment was carried out using a solution of 5% HCl at room temperature. The surface roughness was characterized by Atomic Force Microscopy. The electrical property was measured by Hall measurement system and 4-point probe. The optical property was characterized by UV-vis spectroscopy. After the wet chemical etching, the surface textures were obtained on the surface of the ZnO and AZO films. With the increase of etching time, the surface roughness (RMS) of the films increased and the transmittance of the films was observed to decrease. For the AZO film, a low resistivity of 1.0×10-3 Ω·cm was achieved even after the etching.

Lowering surface reflectance of silicon wafer by texturization is one of the most important processes to improve the efficiency of silicon solar cells. Generally, the texturing of crystalline silicon was carried out using alkaline solution. The average reflectance of this method was 11% at the wavelength between 400 and 1,000 nm. In this study. the wafers were first texturing by NaOH solution at 80℃ for 35 min. Then the wafers were texturing by SF_6 and O_2 plasma in RIE (Reactive Ion Etching). The average reflectance of two step texturing was reduced to below 5% at the wavelength between 400 and 1,000 nm.

For integrated complementary metal oxide semiconductor (CMOS) circuits, the lateral spread for two-dimensional (2-D) impurity distributions are very important for the analyzing the devices. The measured two-dimensional SEM data obtained using the chemical etching-method matched very well with the results of the Gauss model for boron implanted samples. But the profiles in boron implanted silicon were deviated from the Gauss model. The profiles in boron implanted silicon were shown a little bit steep profile in the deep region due to backscattering effect on the near surface from the bombardments of light boron ions. From the simulated 3-D data obtained using an analytical model, the 1-D and 2-D data were compared with the experimental data and could be verified the justification from the experimental data. The data of 3-D model were also shown good agreements with the experimental and the simulated data. It can be used in the 3-D chip design and the analysis of microelectro-mecanical system (MEMS) and special devices.

The etching characteristics of ZnO and etch selectivities of ZnO to SiO2 in SF6/Ar plasma were investigated using Inductively-coupled-plasma (ICP). The maximum etch rates of ZnO were 6.5 nm/min at SF6(50%)/Ar(50%), Source power (700 W), Bias power (250 W), Working pressure(8 mTorr). The etch rate of ZnO showed a non-monotonic behavior with increasing from 0% to 50% Ar fraction in SF6/ Ar plasma. The plasma diagnostic were characterized using Optical Emission Spectroscopy (OES) analysis measurements.

The morphology of etch pits in commercial 4H-SiC epi-wafer were investigated by molten-KOH etching. The etching process was optimized in 525~570℃ at 2~10 min and the novel type of etch pits was revealed. This type of etch pits have been considered as TED (threading edge dislocation) II, its origin and nature, however, are not reported yet. In this work, the morphology and evolution of etch pits during epitaxial growth were analyzed and the different behavior between TED and TEDII was discussed.

In semiconductor wafer fabrication, etching is one of the most critical processes, by which a material layer is selectively removed. Because of difficulty to correct a mistake caused by over etching, it is critical that etch should be performed correctly. This paper proposes a new approach for etch endpoint detection of small open area wafers. The traditional endpoint detection technique uses a few manually selected wavelengths, which are adequate for large open areas. As the integrated circuit devices continue to shrink in geometry and increase in device density, detecting the endpoint for small open areas presents a serious challenge to process engineers. In this work, a high-resolution optical emission spectroscopy (OES) sensor is used to provide the necessary sensitivity for detecting subtle endpoint signal. Partial Least Squares (PLS) method is used to analyze the OES data which reduces dimension of the data and increases gap between classes. Support Vector Machine (SVM) is employed to detect endpoint using the data after PLS. SVM classifies normal etching state and after endpoint state. Two data sets from OES are used in training PLS and SVM. The other data sets are used to test the performance of the model. The results show that the trained PLS and SVM hybrid algorithm model detects endpoint accurately.

In this paper a printing process for patterning electrodes on large area substrate was developed by combining screen printing with reverse off-set printing. Ag ink was uniformly coated by screen printing. And then etching resist (ER) was patterned in the Ag film by reverse off-set printing, and then the non-desired Ag film was etched off by etchant. Finally, the ER was stripped-off to obtain the final Ag patterns. We extracted the suitable conditions of reverse Using the process we successfully fabricated gate electrodes and scan bus lines of OTFT-backplane used for e-paper, in which the diagonal size was 6 inch, the resolution 320x240, the minimum line width 30 um, and sheet resistance 1 Ω/□.

Even though nano-scale materials were very advantageous for various applications, there are still problems to be solved such as the stabilization of surface state and realization of low contact resistances between a semiconducting nanowire and electrodes in nano-electronics. It is well known that the effects of contacts barrier between nano-channel and metal electrodes were dominant in carrier transportation in individual nano-electronics. In this report, it was investigated the electrical properties of GaN nanorod devices after chemical etching and rapid thermal annealing for making good contacts. After KOH wet-etching of the contact area the devices showed better electrical performance compared with non-treated GaN individual devices but still didn`t have linear voltage-current characteristics. The shape of voltage-current properties of GaN devices were improved remarkably after rapid thermal annealing as showing Ohmic behaviors with further bigger conductivities. Even though chemical etching of the nanorod surfaces could cause scattering of carriers, in here it was shown that the most important and dominant factor in carrier transport of nano-electronics was realization of low contact barrier between nano-channel and metal electrodes surely.

The present study introduces a novel wet etching technique for nanostructure fabrications which usually requires low surface roughness. Using the current method, acquired profiles were smooth even in the nanoscale, which cannot be easily achieved with conventional wet or dry etching methods. As one of the most popular single crystal silicon etchant, potassium hydroxide (KOH) solution was used as a base solvent and two additives, antimony trioxide (Sb2O3) and ethyl alcohol were employed in. Four experimental parameters, concentrations of KOH, Sb2O3, and ethyl alcohol and temperature were optimized at 60 wt.%, 0.003 wt.%, 10 v/v%, and 23℃, respectively. Effects of additives in KOH solution were investigated on the profiles in both (110) and (111) planes of single crystal silicon wafer. The preliminary results show that additives play a critical role to decrease etch rate significantly down to ~2 nm/min resulting in smooth side wall profiles on (111) plane and enhanced surface roughness.

Sapphire substrate was patterned by a selective chemical wet etching technique, and GaN/InGaN structures were grown on this substrate by MOVPE (Metal Organic Vapor Phase Epitaxy). The surface of grown GaN on patterned sapphire substrate (PSS) has good morphology and uniformity. The patterned sapphire substrate LED showed better light output than conventional LED that improvement 50%. We think these results come from enhancement of internal quantum efficiency by decrease of threading dislocation and increase of light extraction efficiency. Also these LED showed more uniform emission distribution in angle than conventional LED.

In this work, the etching characteristics of ZnO thin films were investigated using an inductively coupled plasma(ICP) of HBr/Ar/CHF3 gas mixtures. The plasma characteristics were analyzed by a quadrupole mass spectrometer (QMS) and double langmuir probe (DLP). The surface reaction of the ZnO thin films was investigated using X-ray photoelectron spectroscopy (XPS). The etch rate of ZnO was measured as a function of the CHF3 mixing ratio in the range of 0-15% in an HBr:Ar=5:2 plasma at a fixed gas pressure (6mTorr), input power (700 W), bias power (200 W) and total gas flow rate(50sccm). The etch rate of the ZnO films decreased with increasing CHF3 fraction due to the etch-blocking polymer layer formation.

The etching characteristics of indium tin oxide (ITO) thin films in an O2/BCl3/Ar plasma were investigated. The etch rate of ITO thin films increased with increasing O2 content from 0 to 2 sccm in BCl3/Ar plasma, whereas that of ITO decreased with increasing O2 content from 2 sccm to 6 sccm in BCl3/Ar plasma. The maximum etch rate of 65.9 nm/m in for the ITO thin films was obtained at 2 sccm O2 addition. The etch conditions were the RF power of 500 W, the bias power of 200 W, the process pressure of 15 mTorr, and the substrate temperature of 40℃. The analysis of x-ray photo electron spectroscopy (XPS) was carried out to investigate the chemical reactions between the surfaces of ITO thin films and etch species.