Etching Temperature Research Articles

CMOS-Compatible Catalyst for MacEtch: Titanium Nitride-Assisted Chemical Etching in Vapor phase for High Aspect Ratio Silicon Nanostructures

Metal-assisted chemical etching (MacEtch) is an emerging anisotropic chemical etching technique that has been used to fabricate high aspect ratio semiconductor micro- and nanostructures. Despite its advantages in unparalleled anisotropy, simplicity, versatility, and damage-free nature, the adaptation of MacEtch for silicon (Si)-based electronic device fabrication process is hindered by the use of a gold (Au)-based metal catalyst, as Au is a detrimental deep-level impurity in Si. In this report, for the first time, we demonstrate CMOS-compatible titanium nitride (TiN)-based MacEtch of Si by establishing a true vapor-phase (VP) MacEtch approach in order to overcome TiN-MacEtch-specific challenges. Whereas inverse-MacEtch is observed using conventional liquid phase MacEtch because of the limited mass transport from the strong adhesion between TiN and Si, the true VP etch leads to forward MacEtch and produces Si nanowire arrays by engraving the TiN mesh pattern in Si. The etch rate as a function of etch temperature, solution concentration, TiN dimension, and thickness is systematically characterized to uncover the underlying nature of MacEtching using this new catalyst. VP MacEtch represents a significant step toward scalability of this disruptive technology because of the high controllability of gas phase reaction dynamics. TiN-MacEtch may also have direct implications in embedded TiN-based plasmonic semiconductor structures for photonic applications.

Effect of Etching Time and Temperature on Plating Adhesion of Acrylonitrile Butadiene Styrene (ABS)-Based Material.

In this study, the effects of etching time and temperature on the adhesion of plated layers of acrylonitrile butadiene styrene (ABS) were investigated. The ABS surface micropores, which act as anchors to improve the adhesion of the plated layer, increased in numbers as the etching temperature increased. Adhesion was maximum at the etching time of 9 min at etching temperatures of 60 and 70 °C. For the etching times of 12 and 15 min, micropores on the ABS surface were incompletely filled during electroplating because the pores were both deep and narrow. The adhesion strength was decreased by these unfilled micropores, which further reduced the anchor effect. The ratio of the increased surface area ratio of the ABS to that of the plated surface was maximized at 9 min etching time, at which point the plating adhesion was also maximized.

Study and analysis the Cu nanoparticle assisted texturization forming low reflective silicon surface for solar cell application

Monocrystalline silicon solar cells with photo-absorbing morphology can amplify light-trapping properties within the absorber layer and help to fabricate cost-effective solar cells. In this paper, the effect of different parameters namely temperature and time of Cu-assisted chemical etching was thoroughly investigated for the optimization of the light absorption properties. P-type monocrystalline wafers were selectively treated with Cu(NO3)2.3H2O:HF:H2O2:DI water solution at 50 °C for five different time duration. The entire process was repeated at five different temperatures for 20min as well to study the relation between etching temperature and surface reflectance. Sonication bathing was used for the removal of the deposited Cu atoms from the surface with the variation of time and the effect was examined using energy dispersive spectroscopy (EDS). Field emission scanning electron microscopy (FESEM) and UV/VIS spectroscopy were conducted to study the surface morphology and light absorbance respectively. Inverted shapes almost similar to inverted pyramids or porous surface were found randomly on the surface of the wafer. The effect of temperature was found more significant compared to the effect of time variation. An optimum light reflectance was found at 50 °C for 20 min of texturization. Atomic force microscopy (AFM) of the textured sample revealed the average depth of pyramidal shape was about 1.58 μm. EDS results showed a proportional relation between time and Cu removal process, and a complete Cu atoms free textured surface after 25 min of sonication bathing. Therefore, a suitable Cu-assisted texturization technique was found, which could enable lowering the photo-reflectance below 1% without any antireflection coating.

Convex grid-patterned microstructures on silicon induced by femtosecond laser assisted with chemical etching

The convex grid-patterned microstructures were fabricated on a silicon substrate by using femtosecond laser assisted with chemical etching in this study. Along the femtosecond laser scanning traces, the isosceles trapezoidal microstructures were generated. According to Raman spectra and elemental distribution, the formation of the convex microstructures is investigated. Also, the effect of experimental parameters including laser power, scanning speed, etching duration and etching temperature on the microstructures’ three-dimensional size is discussed in detail. In addition, the hydrophobic property of a surface with large-area convex grid-patterned microstructures was explored.

The effect of residual stresses, grain size, grain orientation, and hardness on the surface quality of Co–Cr L605 alloy in Photochemical Machining

This paper presents the study of surface integrity of Co–Cr alloy in Photochemical machining (PCM). The surfaces were selected from different manufacturing processes such as forged, machined and, rolled. The responses such as surface roughness (Ra) and depth of etch were studied in correlation with PCM process parameters like etching temperature for a constant time and concentration. Further, characterization techniques viz. XRD, EBSD, hardness test and SEM were employed to evaluate residual stresses, grain size, grain orientation, hardness, local intergranular misorientation, and surface topography of the Co–Cr L605 alloy. These metallurgical parameters were corroborated with experimental results. The order of Ra and depth of etch for three conditions are: forged > machined > rolled.

Rapid preparation, thermal stability and electromagnetic interference shielding properties of two-dimensional Ti3C2 MXene

Abstract Two-dimensional (2D) MXenes have attracted much attention due to their unique structural characteristics and novel performance in a variety of functions. The fabrication of 2D Ti3C2 MXene by acid etching usually requires a long period of over 10 h. In this work, we report on the rapid preparation, thermal stability and electromagnetic interference (EMI) shielding effectiveness of 2D Ti3C2 MXene. With the processing conditions optimized by adjusting the etching time and temperature, Ti3C2 MXene with a scattered accordion-like structure has been successfully achieved by etching Ti3AlC2 powders with 40% HF at 50 °C for only 0.5 h. The as-synthesized Ti3C2 was stable at temperatures up to 300 °C in air, but stable in vacuum at temperatures up to 800 °C. The as-synthesized Ti3C2 MXene has good EMI shielding performance. The total shielding effectiveness of Ti3C2 in a WAX matrix exceeded 20 dB in the whole frequency ranging from 2 to 18 GHz. The maximum shielding effectiveness value achieved to 34 dB at 18 GHz as the Ti3C2 content was up to 70 wt%. This work provides an approach for the large scale preparation of the Ti3C2 MXene.

Controllable fabrication of polygonal micro and nanostructures on sapphire surfaces by chemical etching after femtosecond laser irradiation

We fabricate two different types of micro and nanostructures with either pyramid-like or tetrahedron-like geometry on the sapphire surface, through the use of thechemical etching process after femtosecond laser irradiation. The distinct features of the structures are measured with both scanning electron microscopy and atomic force microscopy. The dynamic regions for the formation of the two surface structures are experimentally obtained to indicate their tunability by varying the laser average fluence and etching temperature. With the help of discussions and analyses, we propose a model to explain the formation mechanisms of the two kinds of structures, in which the competition between the growth of the alunogen (Al2 (SO4)3·17H2O) crystals and the anisotropic etching rate of the sapphire material plays an important role. In addition, it is confirmed that the tetrahedron-like structures can be used to activate the sapphire substrate for the enhancement of Raman scattering and the hydrophobic properties.

Efficient etching of oxygen-incorporated molybdenum disulfide nanosheet arrays for excellent electrocatalytic hydrogen evolution

Abstract Molybdenum disulfide (MoS2) has attracted considerable attention in electrocatalysis for hydrogen evolution reaction (HER). Nevertheless, its HER activity is far from that of platinum-containing electrocatalysts. Therefore, it is urgent to develop a novel strategy to simultaneously increase the number of active sites (NAC) and decrease charge-transfer resistance (RCT) to favor HER. Herein, we have demonstrated an efficient approach to etching oxygen-incorporated MoS2 (O-MoS2) nanosheet arrays on carbon cloth for excellent electrocatalytic hydrogen evolution. The influence of temperature (T) at the etching stage and the concentration of ammonium fluoride ([NH4F]) on the micro-structure and HER activity of the as-obtained catalysts have been systematically investigated. The higher etching temperature or [NH4F] is achieved; the faster etching kinetics is obtained. At slow etching kinetics, the etching degree of O-MoS2 nanosheets is relatively low, which cannot supply sufficient unsaturated sulfur atoms for HER. At fast etching, the balance between active site and electron transfer for these etched nanosheets is achieved, which is available to efficient HER. However, excessive etching leads to inefficient HER because of the unsatisfactory RCT. The optimized elctrocatalysts exhibit the superior HER activity among all samples, accompanied by excellent catalytic stability. Therefore, this work promises important application in production of hydrogen.

Fabrication of ternary Ge–Se–Sb chalcogenide microlens arrays using thermal reflow

Ternary Ge–Se–Sb chalcogenide glasses have attractive optical properties for fabrication of micro optical components. This paper reports a thermal reflow method to fabricate Ge–Se–Sb chalcogenide microlens arrays (MLAs). By heating the chalcogenide to melting state, the surface tension of the melting chalcogenide contracts the liquid chalcogenide into spherical shape, forming microlenses automatically. Key processes including chalcogenide evaporation, dry etching, and thermal reflow temperature and time are investigated systematically, and microlenses with smooth surfaces, uniform profiles, and small F numbers have been fabricated successfully using the optimized processes. These preliminary results demonstrate the feasibility of using thermal reflow as a simple and low cost method to fabricate Ge–Se–Sb chalcogenide microlenses. The process parameters and the key influencing factors can be used as a baseline for process optimization.

Pengaruh Temperatur dan Waktu Etching Terhadap Karakeristik Fisik dan Mekanik Pelapisan Nikel pada Plastik ABS dengan Metode Elektrolessplating

ABS Plastic (Acrylonitrile Butadiene Stiren) is one type of plastic that is often used because of the many properties that are beneficial to humans. ABS plastic is widely used in engineering, for example in the electronics and automotive fields. But there are still disadvantages of ABS plastic, including low hardness, no friction resistance, and no heat resistance, so surface treatment is needed. Electrolessplating is a coating process that does not use electricity in the coating process. This study aims to determine the effect of temperature and time variation of nickel electrolessplating etching on roughness, wear, hardness, and thickness. The variation in etching temperature is 30; 40; 50; 60; and 70oC and the etching time is 15, 20, 25, 30 and 35 minutes followed by electrolesplating using nickel for 10 minutes. The tests carried out were surface roughness test, disk on block method wear test, hardness using Shore Durometer tool, and layer thickness using micro photos and scanning electron microscopy (SEM). The results showed that the etching process from electrolyplating affected the specimen surface to be coated with nickel metal. The longer the etching time causes the surface to become coarser from 0.435 μm at 15 minutes to 0.949 μm in 35 minutes. The temperature addition of the etching process will increase the surface surface to a temperature of 50oC at 0.499 μm and then drop. Increasing etching time from 15 minutes to 35 minutes will reduce specific wear, from 1.268 x 10-4 mm2 / kg to 0.465 x 10-4 mm2 / kg. Likewise, the etching temperature from 30oC to 70oC decreases the specific wear from 2.10 x 10-4 mm2 / kg to 0.255 x 10-4 mm2 / kg. The addition of etching and temperature etching time does not significantly increase the hardness value of electrolessplating results. Hardness of raw material is 83.5 shore D after coating the hardness value to 84.7 shore D. The electrolessplating process for 10 minutes produces a layer thickness of 1 μm to 2 μm.

Metal-Assisted Chemical Etching for Simple, Cost-Effective, and Large-Scale III-V Semiconductor Nanofabrication

Nanostructured semiconductor architectures have been the topic of extensive research for decades due to their advantages over their bulk or planar counterparts. However, many III-V materials are often plagued by a host of nanofabrication difficulties stemming from incompatible or inefficient top-down etching, or expensive bottom-up growth techniques. Metal-assisted chemical etching (MacEtch) and inverse MacEtch (I-MacEtch) are powerful and solution-based nanofabrication alternatives that combine many attractive processing advantages, including the simplicity and cost-efficiency of conventional wet-chemical etching, and the ability to yield high aspect-ratio structures that are typically generated via reactive-ion etching. Furthermore, MacEtch is not hindered by many common fabrication limitations, such as the isotropic or crystallographic tendency of traditional wet etching, and the detrimental sidewall damage and lattice defects that stem from high energy ion bombardment during dry etching. MacEtch samples consist of a thin metallic catalyst layer (e.g., Au, Ag, or Pt) in intimate contact with a semiconductor. The metal-interfaced semiconductor is then submerged in an etching solution containing an acid (e.g., hydrofluoric acid or sulfuric acid) and an oxidant (e.g., hydrogen peroxide or potassium permanganate). Fundamentally, MacEtch mechanisms are modelled after a galvanic cell; that is, cathodic and anodic half reactions occur at the solution/catalyst and catalyst/semiconductor interfaces, respectively. The metal catalyzes the reduction of oxidant species within the solution, thereby locally injecting holes into the interfaced substrate. Preferential dissolution of the selectively oxidized material realizes high aspect-ratio structures using solution-based processing. While this process is commonly applied to Si and binary III-V systems, MacEtch fabrication of two key ternary compound III-V material systems is demonstrated here for the first time, including Au-enhanced InGaP and AlGaAs. Firstly, I-MacEtch of heteroepitaxial InGaP/GaAs is presented, and differential etch rates between epilayer and substrate are exploited as a viable method to produce suspended III-V nanofoils. Secondly, I-MacEtch of AlGaAs is reported for fabrication of ordered nanopillar arrays, whose aspect-ratio is shown to be tunable with Al fraction (x) and etching temperature (T). Finally, an entirely solution-based and lithography-free MacEtch process is demonstrated for fabrication of black GaAs composed of sub-wavelength dimension nanostructures. The work detailed here provides simple, low-cost, and efficient means to customize nanofabrication processes for specific needs. It is anticipated that these methods can be utilized for adaptable and versatile processing of nanomaterials for LEDs, lasers, HEMTs, and solar cells. Fig. 1 – (a) false-colored cross-sectional SEM image and (b) schematic depicting overlapping hole distributions for Au-patterned I-MacEtch of suspended InGaP nanofoils [1]. False-colored tilted-view SEM images of Au-patterned I-MacEtch of AlGaAs (c) before and (d) after Au removal via mechanical exfoliation, and (e) a model illustrating the ability to tune the etch anisotropy with increasing Al content for a fixed etch temperature (x| T ) and increasing temperature for a fixed Al content (T| x ) [2]. [1] – T. S. Wilhelm et al., ACS Appl. Mater. Interfaces, 10, 2058 (2018) [2] – T. S. Wilhelm et al., ACS Appl. Mater. Interfaces, 10, 27488 (2018) Figure 1

Effect and optimization of photochemical machining process parameters for manufacturing array of micro-hole

The stainless steel-304 is used in various surgical instruments due to its low carbon content and better corrosion resistance. SS-304 is machined using photochemical machining process (PCM) to obtain the components with micro-dimensions. The statistical methods of signal-to-noise (S/N) ratio and the analysis of variance (ANOVA) are applied to investigate effect of concentration of etchant, time of etching and temperature of etchant using DoE (L27) orthogonal array. The performance characteristics like material removal rate (MRR), surface roughness (Ra), undercut (UC) and etch factor (EF) are optimized during the investigation. The ANOVA technique is used to evaluate significance and percentage contribution of each parameter. The regression model for PCM of SS-304 is developed. The ANN technique is used to compare the predicted and experimental results of machining. The MRR, Ra, EF and UC are showing improvement of 0.38 mm3/min, 1.271 µm, 0.11 and 0.028 mm, respectively, after the confirmatory test. The developed model is used to manufacture the array of micro-holes (5 × 5) with hole size of 220 µm, 280 µm and 370 µm which are used for metering of medicine in biomedical applications.

Parametric Optimization in Photochemical Machining of Aluminium Using Taguchi Method

The objective of this study was to investigate the optimal process parameters of photochemical machining on aluminium workpiece. The input parameters considered were etching concentration, etching temperature and etching time. The study revealed their effects over Material Removal Rate, Surface Roughness and Edge Deviation. L9 Taguchi design was used to formulate the experimental layout. ANOVA and average S/N ratio were performed for the optimal setting of the process parameters. For larger-the-better characteristics the optimal conditions for MRR was obtained at etching concentration of 600g/L, etching temperature of 60°C and etching time of 8 minutes. For, smaller-the-better characteristics, the optimal setting for surface roughness was obtained at etching concentration of 400g/L, etching temperature of 40°C and etching time of 4 minutes and for edge deviation obtained at etching concentration of 400g/L, etching temperature of 40°C and etching time of 8 minutes.

Effect of the Thermal Etching Temperature and SiO2/Al2O3 Ratio of Flexible Zeolite Fibers on the Adsorption/desorption Characteristics of Toluene

Effect of the Thermal Etching Temperature and SiO2/Al2O3 Ratio of Flexible Zeolite Fibers on the Adsorption/desorption Characteristics of Toluene

Droplet etching with indium – Intermixing and lattice mismatch

In contrast to Indium droplets the usage of Ga or Al droplets for the local droplet etching (LDE) technique is well established. It has been shown previously that In-droplets or In-alloys can be used for LDE with focus on small hole-depths at low etching temperatures. With our recent experiments we reveal that In-LDE is also well suited for the creation of very deep nanoholes (exceeding 100 nm) and very low densities in the range of 106 cm−2 for large average distances of several micrometers. The unexpected high thermal stability of the etching process itself as well as the formed wall-like structures clearly points to an intermixing between etching and substrate material during the LDE-process. This can be related to the lack of As during LDE. Additional experiments with capping layers also reveal high surface-roughness probably caused by a lattice mismatch, which can be also explained by intermixing. A second LDE step with Al can be applied to avoid roughening effects.

Acetic Acid Etching of Mg-xGd Alloys

Mg-xGd alloys show potential to be used for degradable implants. As rare earth containing alloys, they are also of special interest for wrought products. All applications from medical to engineering uses require a low and controlled degradation or corrosion rate without pitting. Impurities from fabrication or machining, like Fe inclusions, encourage pitting, which inhibits uniform material degradation. This work investigates a suitable etching method to remove surface contamination and to understand the influence of etching on surface morphology. Acetic acid (HAc) etching as chemical surface treatment has been used to remove contamination from the surface. Extruded Mg-xGd (x = 2, 5 and 10) discs were etched with 250 g/L HAc solution in a volume of 5 mL or 10 mL for different times. The microstructure in the near surface region was characterized. Surface characterization was done by SEM, EDS, interferometry, and ToF-SIMS (time-of-flight secondary ion mass spectrometry) analysis. Different etching kinetics were observed due to microstructure and the volume of etching solution. Gd rich particles and higher etching temperatures due to smaller etchant volumes promote the formation of pits. Removal of 2–9 µm of material from the surface was sufficient to remove surface Fe contamination and to result in a plain surface morphology.

Facile fabrication of superhydrophobic alloy surface based on room temperature vulcanized silicone modification

Superhydrophobicity of alloy surfaces is generally determined by the low-energy chemical composition and geometric structure of the surface. The appropriate geometry on alloy surfaces can be easily constructed via chemical etching methods. However, the subsequent low-energy modifications for pre-etched alloys are time-consuming or expensive, thus preventing their further application. Here, we prepared superhydrophobic alloy surfaces based on combining wet chemical etching and room temperature vulcanized (RTV) silicone treatment. Compared to traditional immersion methods, RTV silicone treatment for superhydrophobic 6061 Al alloy surfaces needs only 30 s, which is several thousand times faster than stearic acid or polymethyl triethoxy silane solution treatment. Mechanisms of RTV silicone treatment were investigated. The results show that dip-coating modification is different from these traditional methods. We found that the optimized proportion for RTV silicone rubber is HPDMS, PMTSi, and DBTDL with hexane solvent (HPDMS:PMTSi:DBTDL:hexane = 4:3:1:46, weight ratio), and the water contact angles of treated surfaces of pre-etched 6061 Al alloy, pure Al, and steels are 159° ± 2.7°, 168° ± 1.2°, and 169° ± 1.5°, respectively. Herein, our results demonstrate a facile, low-cost strategy to fabricate superhydrophobic alloy surface that is notable and easy to scale up for industrial applications.

Experimental investigation in photochemical machining process through response surface methodology for manufacturing of micro mould

Photochemical machining (PCM) is used as one of the best micromachining technique for machining of difficult-to-cut material with appropriate machining parametric combinations. Ferric chloride is used as etchant for machining of Stainless Steel-304. In the present study, the effect of process parameters such as time of etching, temperature of etchant and concentration of etchant on material removal rate (MRR), surface roughness (Ra), undercut (Uc) and etch factor (EF) in PCM of SS-304 is evaluated by using response surface methodology (RSM) and the optimum machining condition is evaluated. The central composite design (L20) is used to understand the behaviour of responses with change in levels of machining parameters. The optimum machining parameters evaluated are temperature of etchant at 54.65°C, time of etching at 47.14 min. and concentration of etchant at 727.80 g/l. The confirmatory result shows the improvement in performance quality with setting of machining parameter at optimum level. The optimum machining parameters are used to manufacture the array of micro mould with size of 139 µm, 204 µm and depth of 15 µm, 13 µm used in different engineering and biomedical application.

Experimental investigation in photochemical machining process through response surface methodology for manufacturing of micro mould

Photochemical machining (PCM) is used as one of the best micromachining technique for machining of difficult-to-cut material with appropriate machining parametric combinations. Ferric chloride is used as etchant for machining of Stainless Steel-304. In the present study, the effect of process parameters such as time of etching, temperature of etchant and concentration of etchant on material removal rate (MRR), surface roughness (Ra), undercut (Uc) and etch factor (EF) in PCM of SS-304 is evaluated by using response surface methodology (RSM) and the optimum machining condition is evaluated. The central composite design (L20) is used to understand the behaviour of responses with change in levels of machining parameters. The optimum machining parameters evaluated are temperature of etchant at 54.65°C, time of etching at 47.14 min. and concentration of etchant at 727.80 g/l. The confirmatory result shows the improvement in performance quality with setting of machining parameter at optimum level. The optimum machining parameters are used to manufacture the array of micro mould with size of 139 µm, 204 µm and depth of 15 µm, 13 µm used in different engineering and biomedical application.

Effect of Etching Temperature on Surface Properties of Ti6Al4V Alloy for Use in Biomedical Applications

The objective of this study is to evaluate the surface physicochemical properties of Ti6Al4V alloy after etching with a piranha’s solution at temperatures of 25 °C, 40 °C, and 60 °C for 30 min. Scanning electron microscopy with energy-dispersive X-ray spectroscopy, optical profilometry, X-ray diffraction, and wettability analyses were used to characterize the surface of the samples. In addition, corrosion tests were performed using potentiodynamic polarization and electrochemical impedance spectroscopy. The proposed surface treatment did not alter the wettability and surface chemistry (crystallinity), but the texture, surface roughness, superficial area, and corrosion resistance of the alloy could be changed by varying the etching temperature. Considering that these properties are indirect indicators of the alloy’s potential success in the osseointegration of a dental implant, the surface treatment of the Ti6Al4V alloy using a piranha solution while controlling the etching temperature has attractive biomedical applications.