Etching Behavior Research Articles

High Performance GAA SNWT with a Triangular Cross Section: Simulation and Experiments

In this paper, we present a gate-all-around silicon nanowire transistor (GAA SNWT) with a triangular cross section by simulation and experiments. Through the TCAD simulation, it was found that with the same nanowire width, the triangular cross-sectional SNWT was superior to the circular or quadrate one in terms of the subthreshold swing, on/off ratio, and SCE immunity, which resulted from the smallest equivalent distance from the nanowire center to the surface in triangular SNWTs. Following this, we fabricated triangular cross-sectional GAA SNWTs with a nanowire width down to 20 nm by TMAH wet etching. This process featured its self-stopped etching behavior on a silicon (1 1 1) crystal plane, which made the triangular cross section smooth and controllable. The fabricated triangular SNWT showed an excellent performance with a large Ion/Ioff ratio (~107), low SS (85 mV/dec), and preferable DIBL (63 mV/V). Finally, the surface roughness mobility of the fabricated device at a low temperature was also extracted to confirm the benefit of a stable cross section.

Effect of cupric ion concentration on the etching behavior of copper in Electrogenerated Chemical Polishing (EGCP)

Electrogenerated Chemical Polishing (EGCP) is a stress-free polishing method which has been verified to be an effective method to obtain an ultra-flat and ultra-smooth copper (Cu) surface without defects induced by mechanical force. However, the surface roughness deterioration and removal rate decline emerged after polishing for a long time which prevents the application of EGCP in Cu ultra-precision manufacturing. In this study, apparent activation energy experiments and energy dispersive spectrometer (EDS) analysis were carried out to explore the mechanism of the Cu surface roughness deterioration and removal rate decline. With the increasing of cupric ions (Cu2+) concentration, the apparent activation energy of the Cu/Cu2+ reaction increased which inhibited the material removal rate consequently. Furthermore, it was found that Cu micro bumps were generated on the surface which was speculated to result from the disproportionation reaction of cuprous ion (Cu+) induced by high concentration of Cu2+. Based on this study, lifting the working electrode (WE) with a fixed time interval was verified to be an effective way to avoid the deterioration of surface roughness and the decline of the material removal rate. This study contributes to a further understanding of the chemical etching mechanism of Cu in EGCP.

On the porosification of LTCC substrates with sodium hydroxide

Outstanding material properties of low temperature co-fired ceramics (LTCC) make them the technology of choice when targeting the realization of robust, highly integrated substrates or packaging solutions for micromachined devices. However, the relatively high permittivity limits their utilization in high-frequency applications, as in addition defined areas with reduced permittivity in one single LTCC layer would be most beneficial. The wet-chemical porosification method under alkaline conditions is a novel and most advantageous approach which can be applied for permittivity reduction through locally embedding air into the LTCC surface in its as-fired state with low impact on the surface characteristics. The resulting porosity of the LTCC substrates after the etching process is strongly affected by the LTCC tape composition as well as the etch parameters. Since the chemical composition of the tape is desired to be unaltered, optimizing the etching parameters, namely etchant concentration, etching time, and bath temperature is a reasonable procedure which allows tailoring the porosification process for the LTCC tapes in their as-fired state.In this work the etching behavior and surface morphology of the LTCC substrates have been studied, both qualitatively and quantitatively, and detailed gravimetric and roughness measurements, as well as porosification depth investigations, were carried out. The conducted analyses suggest a dominating reaction-controlled mechanism for the etching process. In addition to generating a tailored porosity in the surface-near region, overall thickness reduction of the LTCC through the overall dissolution of the LTCC surface under a defined etching condition was also possible. The experimental results were finally fitted into a nonlinear polynomial model for providing an experimental basis in order to identify the most crucial parameters to achieve a tailored porosity.

Optimization of Quartz Sand Leaching Process Using Design Experiments Method (DOE)

The present study aims at investigating the Algerian quartz sand from Djelfa deposit as a potential source to produce silicon. The sand from the Djelfa deposit has a high concentration but not enough to be used as raw material for pyrometallurgy (97%) of SiO2. Therefore, the quartz was treated using acid leaching process to increase the silica concentration up to 98.5%. Otherwise, we employ Design of Experiments Method Software (DOE) as numerical model to optimize the parameters of leaching and also to predict the etching behavior of sand grains during the primary step of the process. The results show that the effect of acid concentration has more influence than the grains particle sizes and leaching time to obtain the required silica purity. Using DOE numerical method in the first step of leaching, optimal response of purity $\left (\mathrm {{\Delta } P} \right )$ about 98.48% is obtained. In this context, the optimal grain sizes of sand and the optimal acid concentration are respectively, 276.9 µm and 21.15%, for 6 hours leaching time. The obtained response is very close to the experimental values and can be used for the next stage of the silicon production chain.

Chemically Derived Kirigami of WSe2.

Layered metal dichalcogenides have shown intriguing physical phenomena depending on their complex layer stackings and unique architectures. Here, we report novel microscale kirigami structures of multilayered WSe2 formed by a simple chemical vapor deposition and etching method. Scanning electron microscopy and atomic force microscopy reveal the unusual structure features of curved concave edges, panhandles, and sawtooth corners of these intricate multilayer architectures that result from etching. The structure-symmetry relationship and layer stackings of these WSe2 kirigami were elucidated by second-harmonic generation imaging and micro-Raman spectroscopy. We propose an etching model in which the etching behaviors of WSe2 multilayers are governed by the layer stacking of the bottom trilayer, which can successfully explain the formation process of WSe2 kirigami. This chemical etching approach could be applied to other metal dichalcogenide materials and open up new possibilities for creating novel and complex platforms for studying the rich physical properties in two-dimensional materials.

Unexpected Pyramid Texturization of n-Type Ge (100) via Electrochemical Etching: Bridging Surface Chemistry and Morphology

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.

Formation and Dissolution of Mesoporous Layer during Metal-Assisted Etching of Silicon

Metal-assisted etching of silicon (Si) is one of the methods to fabricate porous Si.1 In this method, Si surface can be selectively etched without electrical bias by immersing metal-modified Si in a hydrofluoric acid (HF) solution containing an oxidizing agent, such as hydrogen peroxide (H2O2)2 or oxygen3. The dissolution of Si proceeds under the metal catalysts due to the injection of positive holes generated by the reduction of oxidizing agent on the metal catalysts. The etching behavior can be controlled by changing experimental conditions.1 In the previous work, the catalytic activity of different metal species was studied.3 Recently, we investigated the mass reduction and the porous structure obtained for different metal particles under a constant condition.4 The depth of pores estimated from the mass reduction was much larger than that observed when gold or platinum (Pt) particles were used. This result could be explained by the dissolution of mesoporous layer formed at the top-surface of Si (Fig. 1a). In this study, we directly observed the dissolution of the top-surface using a Si substrate on which Pt particles are partly deposited. As a Si substrate, single-crystalline n-type Si wafer (CZ, (100), 0.5–10 Ω cm) was used. A part of the Si substrate was covered by a masking tape. Pt particles were deposited by immersing the partly masked Si substrate in a 1.0 mM K2PtCl4 + 0.15 M HF aq. at 313 K for 90 s. After removing the masking tape, the Pt-deposited Si substrate was etched in a 0.08 M H2O2 + 6.6 M HF aq. at 298 K for 2 h in the dark. Step measurement was performed using a stylus-type surface texture measuring instrument (Tokyo Seimitsu Co., Ltd., Surfcom 570A). The cross-sectional observation was performed using scanning electron microscopes (SEM) (JEOL Ltd., JSM-7001F and JSM-7800F). Figure 1b shows the result of step measurement. A height difference of 7.5 µm was clearly observed between the deposited area and the un-deposited area. This indicates that general corrosion occurred at the deposited area. Figure 1c shows the cross-sectional SEM image of the boundary between Pt-deposited and un-deposited areas. The mesoporous layer with a thickness of 10 µm was observed at the top-surface of Si at the deposited area, suggesting that the general corrosion occurred due to the dissolution of mesoporous layer. The mesoporous layer was also observed at the un-deposited area and it was thinner than that observed at the deposited area. This could be an evidence that the mesoporous layer was formed due to the diffusion of the excess positive holes and the reaction with HF at the top-surface of Si.5 Considering the mass reduction, depth of macropores, thickness of mesoporous layer, and depth of general corrosion, the porosity of mesoporous layer was estimated to be about 0.5. In addition, we found that the depth of macropores, thickness of mesoporous layer, and depth of general corrosion increased with etching time in the range from 10 min to 2 h. This indicates that the reactions proceed faster in the order of the formation of macropores, formation of mesoporous layer, and general corrosion. In conclusion, the general corrosion occurs during the metal-assisted etching of Pt-deposited Si. The general corrosion would be explained by the formation and dissolution of mesoporous layer. Acknowledgements This work was partly supported by JSPS KAKENHI Grant number JP26289276. We are grateful to Prof. K. Okuda and Prof. M. Nunobiki, University of Hyogo, for their kind support in the step measurement. References Z. Huang, N. Geyer, P. Werner, J. de Boor, and U. Gösele, Adv. Mater., 23, 285 (2011).X. Li and P. W. Bohn, Appl. Phys. Lett., 77, 2572 (2000).S. Yae, Y. Morii, N. Fukumuro, and H. Matsuda, Nanoscale. Res. Lett., 7, 352 (2012).A. Matsumoto, M. Eguchi, H. Son, and S. Yae, book of Porous Semiconductor - Science and Technology 2018 (PSST 2018), 263 (2018).O. Hildreth and C. P. Wong, in Materials for Advanced Packaging, D. Lu and C. P. Wong, Editors, p. 879, Springer, New York (2009). Figure 1

(Invited) Atomic Layer Deposition and Etching of 2D Transition Metal Dichalcogenide Materials

Ultra-thin layer of two dimensional (2D) materials mainly transition metal dichalcogenide (TMD) semiconductor possess exceptional properties such as electrical, optical, magnetic, mechanical and chemical. This allows the exploration of internal quantum degrees of freedom of electrons and their potential for use in optoelectronic, energy, and sensor applications. At present, research on 2D-layered TMDs mostly rely on (i) flakes produced by exfoliation from bulk, (ii) synthesis by high temperature (800-1000oC) mostly by chemical vapor deposition or (iii) solution based methods. Although exciting results are being obtained, but all these methods have limitations such as poor quality of the material, lack of precise control of thickness, interface or ability to integrate them into complex 3D devices. Nevertheless, the biggest challenge in realizing their full potential has been the lack of doable material synthesis methods of such films with high uniformity, conformality and interfacing with other materials such as oxides and metals. Among the various thin film growth methods, atomic layer deposition (ALD) offers the best combination of a controlled layer-by-layer growth of the material with high conformality and suitable integration with other oxides such as dielectrics and metals. At the same time, precisely control thermal-based etching method for 2D-TMD materials are needed. Secondly at present, there are tremendous attention and efforts on development of the thermal vapor based well control etching methods especially on atomic layer etching (ALEt). The successful combination of both ALD and ALEt of 2D-TMD can pave the way to control the synthesis of 2D-TMD layers over large areas. This will be important for 2D-TMD material integration for future successful large-scale complex device structures fabrication. Here we will first discuss the ALD growth of 2D-TMDs (e.g. MoS2, HfS2 and MgS2) on metals (e.g. Mo, W and TiN), dielectric oxides (e.g. Al2O3, MgO, HfO2, and TiO2) and vice versa. Then precise control etching processes based on molybdenum hexafluoride (MoF6) and H2O vapor will be discussed. The MoF6-H2O precursors based etching process offer several advantages including low cost, low processing temperature, rapid and effective etching spanning the range from continuous etching to atomic layer etching (ALEt). We have used in-situ quartz crystal microbalance (QCM) and Fourier-transform infrared spectroscopy (FTIR) measurements to monitor the deposition and etching 2D-TMDs layers. Next, the deposited and etched 2D-TMDs thin films were analyzed by spectroscopic ellipsometry to determine the thickness and refractive index, and the composition was determined by X-ray photoelectron spectroscopy (XPS). These ex-situ measurements confirmed the 2D-TMDs deposition and etching behavior findings from our in-situ studies.

On-site SiH4 generator using hydrogen plasma generated in slit-type narrow gap

We have been developing an on-site silane (SiH4) generator based on use of the chemical etching reaction between solid silicon (Si) and the high-density H atoms that are generated in high-pressure H2 plasma. In this study, we have developed a slit-type plasma source for high-efficiency SiH4 generation. High-density H2 plasma was generated in a narrow slit-type discharge gap using a 2.45 GHz microwave power supply. The plasma’s optical emission intensity distribution along the slit was measured and the resulting distribution was reflected by both the electric power distribution and the hydrogen gas flow. Because the Si etching rate strongly affects the SiH4 generation rate, the Si etching behavior was investigated with respect to variations in the experimental parameters. The weight etch rate increased monotonically with increasing input microwave power. However, the weight etch rate decreased with increasing H2 pressure and an increasing plasma gap. This reduction in the etch rate appears to be related to shrinkage of the plasma generation area because increased input power is required to maintain a constant plasma area with increasing H2 pressure and the increasing plasma gap. Additionally, the weight etch rate also increases with increasing H2 flow rate. The SiH4 generation rate of the slit-type plasma source was also evaluated using gas-phase Fourier transform infrared absorption spectroscopy and the material utilization efficiencies of both Si and the H2 gas for SiH4 gas formation were discussed. The main etch product was determined to be SiH4 and the developed plasma source achieved a SiH4 generation rate of 10 sccm (standard cubic centimeters per minute) at an input power of 900 W. In addition, the Si utilization efficiency exceeded 60%.

Visualization of Mechanochemically-Assisted Degrafting of Surface-Tethered Poly(Acrylic Acid) Brushes.

We report visualization of mechanochemically assisted degrafting of surface-tethered poly(acrylic acid) (PAA) brushes in a basic aqueous buffer at nanometer to micrometer length scale by monitoring changes in local etching of silicon substrates. PAA brushes were prepared by surface-initiated atom transfer radical polymerization and incubated in 0.1 M ethanolamine buffer (pH 9.0) with 0.5 M NaCl. Morphological changes of the underlying substrates were monitored by scanning electron microscopy and atomic force microscopy. The appearance of regular-shaped pits indicated etching of the substrate, and both their number and size grew with increasing incubation time. We compared the etching behaviors for PAA, poly(methyl methacrylate) (PMMA), and poly(poly(ethylene glycol) methacrylate) (PPEGMA) brushes grafted on silicon substrates. After incubation for 7 days, the substrate of PMMA brush remained intact. In PAA brush systems, we detected the formation of a few large pits whose size grew in time. Many pits showed up on the substrate of PPEGMA brush but with substantially smaller size compared to PAA. Our findings suggest that hydrophobicity and stability of the grafted polymers play an important role in the morphological changes of the underlying silicon substrates under given incubation conditions.

Yttrium oxide film for protecting quartz glass surface from etching by long-term exposure to chlorine trifluoride gas at room temperature

The anticorrosive property of yttrium oxide was evaluated using chlorine trifluoride gas. After the exposure to chlorine trifluoride gas at room temperature for the total time longer than 1000 min, the yttrium oxide film, formed on a quartz glass surface, did not show any etching behavior and surface morphology change, while the non-coated quartz glass showed a rough surface with the etching depth of nearly 0.1 mm. Because yttrium oxide had no chemical reaction with chlorine trifluoride gas at temperatures less than 300 °C, yttrium oxide film is expected to protect the quartz glass from etching by chlorine trifluoride gas at room temperature for a significantly long time.

Fluoropolymer-based nanostructured membranes created by swift-heavy-ion irradiation and their energy and environmental applications

We have realized the importance of developing micro/nanofabrication techniques for fluoropolymers in order to further pursue their potential for future applications. This paper is devoted to the following two topics, i.e., ion-track membranes and ion-track-grafted electrolyte membranes for fuel cell applications, both of which include the creation of fluoropolymer-based nanostructured membranes with swift heavy ions. Latent tracks of the MeV-GeV heavy ions in an organic polymer foil can sometimes be chemically etched out to form a membrane with micro- and nano-sized through-pores, the so-called ion-track membrane. Our focus is on ion-track membranes of poly(vinylidene fluoride) (PVDF), which have also been considered as a matrix of functionalized polymer membranes. Although the PVDF-based ion-track membranes have already been reported, their preparation methods have never been optimized. The etching behavior mainly depended on the energy deposition of the ion beams, and thus its depth distribution, estimated by a theoretical simulation, was successfully applied to control the shapes and diameters of the etched pores. The electrolyte membranes for fuel cell applications were prepared by the direct ion-track grafting method. The membrane preparation involves (i) irradiation of a fluoropolymer (mostly the poly(ethylene-co-tetrafluoroethylene)) base film to create reactive species, (ii) graft polymerization of styrene or its derivative monomer into latent tracks, and (iii) sulfonation of the graft polymers. Interestingly, the resulting membranes exhibited an anisotropic proton transport, i.e., higher conductivity in the thickness direction. Based on microscopic observations, this is probably because the nearly columnar electrolyte phase with a width of tens-to-hundreds of nanometers extended through the membrane. Other excellent membrane properties, e.g., a high dimensional stability, should also be due to such a controlled structure.

(Invited) The Impact of the Phase and Stacking of 2D Materials on Their Properties and Applications

The interesting and tunable properties of layered metal dichalcogenides (MX2) and other layered materials heavily depend on their phase and layer stacking. We discovered that chemical exfoliation of layered MX2 nanosheets and simultaneous conversion from the semiconducting 2H polymorph to the metallic 1T polymorph grants greatly enhanced activity for electrocatalytic hydrogen evolution reaction (HER). We have also developed layer-controlled vertical heterostructures of MX2 by van der Waals epitaxy that have strong electronic interactions across the heterojunctions. We explain how the layer stacking and physical properties of MX2 are influenced by screw dislocations. A one-to-one correlation of atomic force microscopy and high- and low-frequency Raman spectroscopy of many dislocated WSe2 nanoplates reveals variations in the number and shapes of dislocation spirals and different layer stackings that are determined by the number, rotation, and location of the dislocations. These lead to three class of behaviors: plates with triangular dislocation spirals have non-centrosymmetric stacking that gives rise to strong second-harmonic generation, plates with hexagonal dislocation spirals form the bulk 2H layer stacking commonly observed, and plates containing mixed dislocation shapes have intermediate non-centrosymmetric stackings with mixed properties. We also explain layer stackings also determine the etching behaviors of multilayer WSe2 materials that result in complex chemically derived kirigami structures.

Effect of Surface Preparation on the Residual Oxide Thickness and Material Loss of InGaAs Layer

Indium gallium arsenide (InGaAs) can be introduced as a new channel material for improving device performance due to its high electron mobility. Surface preparation of InGaAs in wet chemical processes should be controlled because InGaAs is not as robust as Si against the wet chemistries. In this work, oxidation and etching behavior on InGaAs surface were investigated for acidic and basic treatments. It was observed that the oxidation states decreased after HCl treatment as compared to as-received InGaAs surface, while they increased after NH4OH treatment. The oxidation states increased after addition of H2O2 in both acidic and basic solutions. It is suggested that dissolution of the oxidized InGaAs layer is dominant in acidic solution, while it is a rate limiting step in the basic solution. Therefore, the concentration of oxidant such as H2O2 in acidic solution is important factor to determine residual oxidation and overall etching rate of InGaAs layer.

Catalytic Etching of Multi‐Walled Carbon Nanotubes Controlled by Oxygen Gas Pressure

AbstractWe examined the catalytic behavior of platinum nanoparticles supported directly on a multi‐walled carbon nanotube with environmental scanning transmission electron microscopy. The catalytic etching behavior of the platinum nanoparticles toward the carbon nanotube was found to depend on the oxygen gas pressure. We supposed that direction of catalytic etching could be involved with amount of adsorbed oxygen onto catalytic nanoparticles. In situ observations give new insight of morphological control of carbon nanotube etched by catalytic nanoparticles.

Effect of Ti3AlC2 precursor on the electrochemical properties of the resulting MXene Ti3C2 for Li-ion batteries

The presented work compared the etching behavior between combustion synthesized Ti3AlC2 (SHS-Ti3AlC2) and pressureless synthesized Ti3AlC2 (PLS-Ti3AlC2). Because the former had a more compact structure, it was harder to be etched than PLS-Ti3AlC2 under the same conditions. When served as anode material for Li-ion batteries, SHS-Ti3C2 showed much lower capacity than PLS-Ti3C2 at 1 C (52.7 and 87.4 mAh g−1, respectively) due to the smaller d-spacing. Furthermore, Potentiostatic Intermittent Titration Technique (PITT) was used to determine the Li-ion chemical diffusion coefficient (DLi+) of Ti3C2 in the range of 10−10 − 10−9 cm2 s−1, indicating that Ti3C2 could exhibit an excellent diffusion mobility for Li-ion.

Polymer etching by atmospheric‐pressure plasma jet and surface micro‐discharge sources: Activation energy analysis and etching directionality

Treatments of polymer films using either a MHz atmospheric pressure plasma jet (APPJ) or an atmospheric pressure surface micro‐discharge (SMD) plasma are investigated. While the typical approach to determine relevant reactive species is to correlate surface effects with gas phase species measurement, this does not capture potential synergistic or other complex effects that may be occurring. Activation energy and directionality of the etching process can characterize what is occurring at the surface for these processes in more detail. The APPJ source shows an apparent activation energy of ∼0.18 eV at 8 mm distance and up to ∼0.34 eV at 16 mm distance for a temperature range of 20–80 °C tested with thin polymer films. The APPJ source shows directional etching at 8 mm distance with less anisotropy the more distance is increased. The SMD source has an apparent activation energy of ∼0.8–0.9 eV at a distance of 3 mm. The SMD also only shows isotropic etching behavior. However the SMD surface chemistry changes significantly to less oxidation with increased temperature while the APPJ source induced modifications remain very similar with temperature change. The lower apparent activation energy of the APPJ‐induced etching reactions as compared with low pressure work (0.5 eV) and observation of line‐of‐sight contribution to etching suggests the involvement of a directional species at closer distances facilitating the etching which falls off with increasing distance. The high activation energy of the SMD suggests that species with less capability for etching is responsible compared to the APPJ and low pressure plasma. The high surface oxidation from low temperature SMD treatments shows that the surface is being oxidized but not sufficiently to reach the desorption step of the etching process.

Low-Temperature Material Stacking of Ultrathin Body Ge (110)-on-Insulator Structure via Wafer Bonding and Epitaxial Liftoff From III–V Templates

In this brief, we fabricated Ge (110)-on-insulator (-OI) structures on Si substrates via wafer bonding and epitaxial lift-off (ELO) process using Ge layer grown on GaAs for low-temperature layer stacking toward monolithic 3-D integration. We also systematically investigated the lateral etching behaviors of AlAs, which was used as a sacrificial layer in the ELO process, on GaAs (110) substrates. Fabricated Ge (110)-OI was analyzed by surface atomic force microscopy, X-ray diffraction, Raman shift, and transmission electron microscope analyses. We found that the 40-nm-thick ultrathin-body Ge (110)-OI has very high crystal quality, indicating our Ge stacking process is very stable.

Ion track etching revisited: I. Correlations between track parameters in aged polymers

Abstract Some yet poorly understood problems of etching of pristine and swift heavy ion track-irradiated aged polymers were treated, by applying conductometry across the irradiated foils during etching. The onset times of etchant penetration across pristine foils, and the onset times of the different etched track regimes in irradiated foils were determined for polymers of various proveniences, fluences and ages, as well as their corresponding etching speeds. From the results, correlations of the parameters with each other were deduced. The normalization of these parameters enables one to compare irradiated polymer foils of different origin and treatment with one another. In a number of cases, also polymeric gel formation and swelling occur which influence the track etching behaviour. The polymer degradation during aging influences the track etching parameters, which differ from each other on both sides of the foils. With increasing sample age, these differences increase.

Modeling the characteristic etch morphologies along specific crystallographic orientations by anisotropic chemical etching

To improve the advanced manufacturing technology for functional materials, a sophisticated control of chemical etching process is highly demanded, especially in the fields of environment and energy related applications. In this study, a phase-field-based model is utilized to investigate the etch morphologies influenced by the crystallographic characters during anisotropic chemical etching. Three types of etching modes are inspected theoretically, including the isotropic, <100> and <111> preferred oriented etchings. Owing to the specific etching behavior along the crystallographic directions, different characteristic surface structures are presented in the simulations, such as the pimple-like, pyramidal hillock and ridge-like morphologies. In addition, the processing parameters affecting the surface morphological formation and evolution are also examined systematically. According to the numerical results, the growth mechanism of surface morphology in a chemical etching is revealed distinctly. While the etching dynamics plays a dominant role on the surface formation, the characteristic surface morphologies corresponding to the preferred etching direction become more apparent. As the atomic diffusion turned into a determinative factor, a smoothened surface would appear, even under the anisotropic etching conditions. These simulation results provide fundamental information to enhance the development and application of anisotropic chemical etching techniques.