Etching Temperature Research Articles

Synthesis of fluorine-free Ti3C2Tx MXenes via acidic activation for enhanced electrochemical applications

MXenes are a class of two-dimensional materials composed of carbides and nitrides, which possess tunable properties and thus suitable for electrochemical applications. The etching method of MXene plays an important role in defining the electrochemical properties. Here, a novel hydrothermal acidic etching process was introduced to synthesize fluorine free MXenes by varying etching time and temperature. As a result, highly effective fluorine free Ti3C2Tx MXenes with enhanced electrochemical properties were obtained. It is also noted that the synthesized Ti3C2Tx MXenes exhibit distinct charge-discharge performance and impressive battery-like characteristics when tested in a 1 M H2SO4 electrolyte. Especially, the 6D-160 °C sample shows relatively superior gravimetric capacity of 450 C g−1 with a retention rate of 114 % after 8000 cycles, compared to the HF-etched sample (only 75 % lower capacitance). This novel approach demonstrates a significant improvement in the electrochemical performance of Ti3C2Tx MXenes and suggests a highly effective technique for surface modification of MXenes.

Nanochannels in Fused Silica through NaOH Etching Assisted by Femtosecond Laser Irradiation

Sodium hydroxide (NaOH) is increasingly drawing attention as a highly selective etchant for femtosecond laser-modified fused silica. Unprecedented etching contrasts between the irradiated and pristine areas have enabled the fabrication of hollow, high-aspect-ratio structures in the bulk of the material, overcoming the micrometer threshold as the minimum feature size. In this work, we systematically study the effect of NaOH solutions under different etching conditions (etchant concentration, temperature, and etching time) on the tracks created by tightly focused femtosecond laser pulses to assess the best practices for the fabrication of hollow nanostructures in bulk fused silica.

Surface Texturing of Silicon Wafers by Two-step Ag-assisted Etching Process with New NSR Solution

Abstract: Solar cells made of monocrystalline silicon can convert more solar energy into electrical energy if the cells can absorb greater amounts of light. Recently, it has been observed that metal-assisted catalyzed etching (MACE) is a good technology for manufacturing micro and nanostructures on silicon substrates. In this work, we use silver as a catalyst in a two-step metal-assisted etching process followed by a rebuilding nanostructure (NSR). We study the effect of changing the parameters of the second step in the MACE process (concentrations of etching solution materials, temperature, and reaction time), where black silicon was obtained with a reduced reflection of 3% without the NSR process. We tested the effect of two types of alkaline solutions in the NSR process on the surface structure of silicon. After performing an NSR operation with sodium hydroxide solution, the field emission scanning electron microscopy (FESEM) image shows a surface with upright pyramidal structures intertwined with deep cavities, and with a reflectance of 10.74%. However, after performing the NSR process with a solution of sodium silicate, the FESEM image shows a rough surface with non-overlapping pores of small cross-sections, achieving a reflectance of 8.65% within the wavelength range of 550-850nm. Keywords: Texturing, Monocrystalline silicon, Ag-assistance chemical etching, Black silicon, Reflectance.

Fabrication of S-scheme graphdiyne (g-CnH2n-2)/carbon-nitrogen vacancies hollow Ni–Fe prussian blue analogues heterojunction for boosting wide spectrum photocatalytic hydrogen evolution

Efficient photocatalytic hydrogen evolution can be achieved by adjusting the morphology and constructing suitable heterojunction. In this work, an 2D/3D S-scheme graphdiyne (g-CnH2n-2)/carbon-nitrogen vacancies hollow Ni–Fe prussian blue analogues (Ni–Fe–CN PBA) heterojunction (GNF-CN) was prepared for photocatalytic hydrogen evolution. Ni–Fe–CN PBA were prepared by chemical etching and high temperature calcination. The hollow structure can realize multiple reflections of incident light and effectively improve the light utilization efficiency. The CN vacancy changes the band structure of Ni–Fe PBA and enhances its light absorption capacity. Graphdiyne nanosheets (GDY) prepared by load ball milling can increase the active site. The key lies in the construction of an S-scheme heterojunction between GDY and Ni–Fe–CN PBA, which effectively consume useless holes and increase the utilization rate of photogenerated electrons. The S-scheme electron transfer path are proved by DFT calculation, work function and in situ XPS. The GNF–CN–20 showed excellent photocatalytic hydrogen evolution activity (3755.02 μmol h−1 g−1) and photostability compared with GDY (1116.54 μmol h−1 g−1). The present study introduces a novel approach for the construction of an S-scheme heterojunction based on GDY and PBA, enabling wide‐spectrum‐responsive photocatalytic hydrogen evolution.

Heated-H3PO4 etching of (001) β-Ga2O3

β-Ga2O3 is a promising ultra-wide bandgap semiconductor with melt-grown substrates that are scalable, particularly in the (001) orientation. In this study, we report on the heated-phosphoric acid etching of (001) β-Ga2O3. A wagon wheel pattern with spokes aligned to a range of specific crystallographic directions was fabricated on (001) β-Ga2O3. At 160 °C, the (001) etch rate was 1.47 μm/h, which is comparable to etch rates obtained via dry etch techniques. The etched (001) surface had a morphology that was smoother than an inductively coupled plasma etched surface. All spokes possessed relatively smooth sidewalls. Spokes oriented along the [100] direction exhibited minimal SiO2 mask undercut rates at lower etch temperatures and symmetric trapezoidal profiles with near vertical (010)-like sidewalls, which are ideal for device structures with a trench geometry. Spokes oriented along the [010] direction exhibited significant SiO2 mask undercut rates and asymmetric trapezoidal profiles with different sidewall angles. These spokes also possessed reduced sidewall angles, which is favorable for field management at device corners and edges. The etch process was used to realize a dense array of [100]-oriented trenches with a height of 1.5 μm, a base width of 2.0 μm, and a mask width of 0.8 μm. The work highlights the potential for ion damage-free, standalone heated-H3PO4 etching as a viable alternative to the dry etching of (001) β-Ga2O3 for high-performance device applications.

Advancements in gas phase pollutant removal: A comprehensive study on the sorption of CO2 and SO2 on modified carbon monoliths

The synthesis of carbon monoliths using activated carbon treated with phenol-formaldehyde resin has been identified as a promising approach for the removal of pollutants from the gas phase. Monolithic adsorbents were synthesised and modified by adding silica, acid etching, and high temperature activation with CO2. Sorption capacities were determined by CO2 and SO2 adsorption tests. Preliminary findings indicated that the unmodified monoliths exhibited limited porosity. The activation process significantly altered the textural parameters, resulting in an increase in surface area and adsorption and desorption capacity. The modification yielded a monolith with a specific surface area of 598 m2/g and a pore volume of 438 mm3/g. The sorption capacity of the monoliths towards CO2 and SO2 was 1.64 mmol/g and 3.93 mmol/g, respectively. The modifications introduced developed the sorption capacity of the monoliths, enabling the regeneration process and its further use in subsequent measurement cycles.

Hierarchical porous cobalt nanoparticles encapsulated in heteroatom-doped hollow carbon as an enhancing multifunctional catalyst for hydrolysis of sodium borohydride and hydrogenation of bromate in water

Multifunctional heterogeneous catalysts have been consistently explored in recent years because of their distinctive catalytic activity in different catalysis areas at once. Here, a cobalt (Co) nanoparticles encapsulated in nitrogen-doped hollow carbon (denoted as Co@NHC) is prepared by two-step modifications of acid etching and high temperature carbonization in the inert atmosphere using a peculiar polyhedral configuration Co-ZIF as an initial template. Benefiting from an intriguing polyhedral configuration hollow structure with high specific surface area and pore volume supplying plentiful active sites, Co@NHC shows exceptional catalytic activity in catalyzing hydrolysis of NaBH4 and hydrogenation of toxic bromate in water. From experimental results, Co@NHC could efficiently enhance the generation of H2 with a H2 generation rate of 1515.4 mL min−1 gcat−1 meanwhile the activation energy (Ea) calculated from Co@NHC/NaBH4 system was only 12.6 kJ mol−1. Besides, the combination of Co@NHC and NaBH4 could further reduce toxic bromate ions into bromide via catalytic hydrogenation with a maximum bromate removal capacity of 390.6 μmol g−1. More importantly, due to its strong magnetization, Co@NHC could be simply recovered after reactions, making it well-preserve the unique structure as well as catalytic activity for multiple continuous recycles in both catalytic applications. Additionally, the plausible reaction mechanisms in catalyzing hydrolysis of NaBH4 and hydrogenation of bromate were also proposed. This work has pioneered a promising approach on preparing an engrossing magnetic heterogeneous Co-based catalyst that is practically applicable in various areas of catalysis.

Temperature Etching and Metallic Agent Concentration Effect on Structure, Morphology and Wettability of Silicon Nanowires

Abstract. Structural, Morphologycal and Wettability of SiliconNanowires (SiNWs) elaborated using Ag assisted electroless chemical etching are investigated. Prior the etching, Ag nanoparticles (AgNPs) were deposited at room temperature in a HF/AgNO3 solution with different concentration of AgNO3. The XRD spectra of the Ag NPs deposit show a good crystallinity. The effects of temperature etching bath and concentrations of AgNO3 on the etching process were examined. The morphological study, performed using a Scanning Electron Microscopy (SEM), shows porous silicon layer of 2µm for the lower temperature etching. For 25°C, perpendicular silicon nanowires about 15µm were formed. For the higher etching temperature (50°C), the silicon nanowire about 50 nm in diameter and 50µm in length were formed. The impact of Ag concentration on the SiNWs formation is examined in the second part of the present work. It is shown that the etching depth decreases as the Ag concentration decreases with values of 2.8 μm and 2 μm for concentrations of 0.025M and 0.0125M, respectively. The hydrophobicity of the samples was monitored by measuring the contact angle between a drop of water and the sample surface. It was established that the morphology is strongly influenced by etching conditions and their wettability changes from superhydrophilic to hydrophobic. FTIR analysis confirms the oxide-free silicon nanowires.

Molten Ba(OH)2.8H2O as an efficient and rapid etchant for detecting α-particles using a diallyl maleate-allyl diglycol carbonate detector

In the present study, for the first time, nuclear tracks of α-particles were created on diallyl maleate-allyl diglycol carbonate (DAM-ADC) using molten hydrated barium hydroxide (MBH). We used 17 DAM-ADC plates with dimensions of 1.0 cm × 1.0 cm × 0.1 cm. The bulk etching rate was calculated at various etching temperatures based on changes in the thickness of the DAM-ADC plates. DAM-ADC was irradiated with α-particles to etch at various temperatures for different durations in order to determine the characteristic etching parameters, such as the bulk and track etching rates, etching efficiency of the detector, and critical angle of etching. Photographs of the etched DAM-ADC samples were obtained with a calibrated optical microscope and analyzed with ImageJ software to calculate the track diameters of α-particles. The results demonstrated that MBH is a more efficient and rapid etchant for registering and detecting charged particles with various energies compared with conventional etching solutions (NaOH, KOH, etc.). DAM-ADC with MBH can be used in environmental applications for detecting radon and neutrons.

Study on the preparation of porous polyethylene glycol terephthalate film and the influencing factors of etching rate

AbstractPorous polyethylene glycol terephthalate (PET) film is a kind of mesopore structure template with pore size ranging from nanometer to micrometer by chemical etching after irradiation of heavy ions. The etching rate is an important factor affecting the pore morphology and quality of the membrane. In this paper, four stacked PET film were irradiated with 140 MeV 32S ions at room temperature and vacuum. During chemical etching of irradiated samples, the path etching rate Vt was determined by conduction method, and the bulk etching rate Vb was determined by weighing method. The relationship between etching temperature, concentration, sensitization time, and etching rate was studied. The results show that the etching rate is exponentially correlated with the etching temperature, and increases linearly with the increase of the etching solution concentration. When the concentration of NaOH is 3 mol·L−1 and the etching temperature is 75°C, the formation of cylindrical micropores is the most favorable. The pore size of porous PET film can be adjusted, and the relationship between pore size and etching time is . This is of great significance for the preparation of nanowires with uniform size and stable properties.Highlights We have obtained the optimal conditions for obtaining cylindrical holes. The relationship between the diameter of holes and etching time were determined.

Enhancing efficiency in photo chemical machining: a multivariate decision-making approach

Non-Traditional Machining (NTM) outperforms traditional processes by offering superior geometric and dimensional accuracy, along with a better surface finish. Photo Chemical Machining (PCM) represents one such NTM process, using chemical etching for material removal. PCM finds substantial application in the creation of microchannels in pharmaceutical, chemical and energy industries. Several input parameters—such as etchant concentration, etching time and etchant temperature—profoundly influence the machining’s quality and efficiency. Therefore, the optimization of these parameters is crucial. This study presents a comparative analysis of five Multiple Criteria Decision Making (MCDM) techniques—Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS), Multi-Objective Optimization on the basis of Ratio Analysis (MOORA), Additive Ratio Assessment (ARAS), Weighted aggregated sum product assessment method (WASPAS) and Multi-Attributive Border Approximation Area Comparison Method (MABAC)—for the optimization of the PCM process. Key performance metrics considered are Material Removal Rate (MRR), Surface Roughness (SR), Undercut (Uc) and etch factor (EF). The weights of these criteria were calculated using the Criterion-Induced Aggregation Technique (CRITIC) and was compared with other popular methods like MEREC, Entropy and equal weights. MRR and EF are seen as beneficial criteria, while SR and Uc are perceived as cost criteria. Optimum process parameters were identified as 850 g/L etchant concentration, 40 min etching time and 70°C etchant temperature. Two of the three employed MCDM techniques agreed on these optimal parameters, reinforcing the findings. Furthermore, a strong correlation was observed amongst the employed MCDM techniques, further validating the results.

Surface treatment of stainless steel (SUS) to improve interfacial adhesion of SUS/polymer hybrid bilayer composites

The use of hybrid metal/polymer structure is an efficient strategy for weight reduction in automotive applications. The poor interfacial adhesion between metals and polymers can be solved by using coupling agent (compatibilizer) and through surface treatments, adding new functionalities and a rough surface. In this study, the stainless steel (SUS) surface treatments were systematically examined using various etching and functionalizing solutions, such as hydrochloric acid (HCl), nitric acid (HNO3), acetic acid (CH3COOH), phosphoric acid (H3PO4), copper sulfate (CuSO4), ethanol (C2H5OH), fluorozirconic acid (H2ZrF6), sodium hydroxide (NaOH), acetone (C3H6O), and their mixtures. An HCl/CuSO4 aqueous solution was the most efficient surface treatment for SUS, resulting in the highest interfacial adhesion with polyamide 6,6 (lab shear strength: from 1.7 to 12.7 MPa, and toughness: from 4.9 to 35.4 N/m2). The etching process was further investigated by optimizing the etching time and temperature. The treated surfaces were characterized by surface roughness, morphology, contact angle, elemental analysis, and single–lap shear tests.

Reprint of “Characteristics and electrochemical performance of copper/graphite felt composite electrodes for vanadium redox flow battery”

BackgroundVanadium oxide is considered environmentally benign; however, its economic utilization is highly challenging due to the inability to control the size of etched holes. To address this limitation, it is crucial to regulate the depth of the hole by modifying the etching conditions. A controllable hole depth has the potential to enable its application in vanadium redox flow batteries (VRBs). MethodsIn this study, electrodeposition is used to deposit copper particles on the surface of graphite felt electrodes. The copper particles are then employed to etch the graphite felt surface under a reducing atmosphere, which produces porous copper/graphite felt composite electrodes that can be used in VRBs. The effect of etching temperature and time on the material characteristics and the electrochemical performance of this composite electrode were investigated. Significant FindingsThe holes on the graphite felt surface following a heat treatment are studied, especially as the temperature approaches 900 °C. The observed specific surface area is 16.59 m2/g. Upon grafting of oxygen functional groups, the O/C ratio of the composite electrodes reaches 0.12. After the annealing at 900 °C, the energy efficiency of the porous copper/graphite felt composite electrode is 67.40%, the voltage efficiency is 70.13%, and the current efficiency is 96.11%. Under long-term cyclic discharge, the composite electrode exhibits a good capacitance retention of 91% and a capacitance utilization of 63%.

Wet etch methods to achieve submicron active area self-aligned vertical Sb-heterostructure backward diodes

Sb-heterostructure backward diodes are attractive for passive millimeter-wave sensing techniques in Earth Observation applications, facilitating superior sensitivity (non-linearity) and low noise as compared to traditional zero-bias Schottky diodes. Reducing diode active area is imperative to achieve both increased sensitivity and operation at higher frequencies. In this work, we report a wet etch method utilizing citric acid, phosphoric acid, and hydrogen peroxide for simplified fabrication of vertical (250 nm height) Sb-heterostructure (InAs/AlSb/AlGaSb/GaSb) devices down to active area of 0.04 μm2 (critical dimensions 0.2 × 0.2 μm2). While conventional citric/peroxide etch chemistries are ineffective for removal of Sb-based etch products, including Sb2O5, the addition of phosphoric acid has shown to promote dissolution of etch stop layers, maintaining a linear etch rate throughout the device heterostructure. Furthermore, we found that citric acid plays a crucial role in the underlying etch mechanism which can be attributed to the formation of soluble Sb(V)-citrate complexes. Conducting the etching at reduced temperatures has also shown to promote slow-etching facets at reduced etch temperature (4 °C) drastically improving anisotropy. Finally, the etch method is evaluated by current-voltage characterization of the fabricated diodes achieving predictible active area scaling of performance-metrics across 190 devices indicating formation of defect free sidewalls.

Publisher note

BackgroundVanadium oxide is considered environmentally benign; however, its economic utilization is highly challenging due to the inability to control the size of etched holes. To address this limitation, it is crucial to regulate the depth of the hole by modifying the etching conditions. A controllable hole depth has the potential to enable its application in vanadium redox flow batteries (VRBs). MethodsIn this study, electrodeposition is used to deposit copper particles on the surface of graphite felt electrodes. The copper particles are then employed to etch the graphite felt surface under a reducing atmosphere, which produces porous copper/graphite felt composite electrodes that can be used in VRBs. The effect of etching temperature and time on the material characteristics and the electrochemical performance of this composite electrode were investigated. Significant FindingsThe holes on the graphite felt surface following a heat treatment are studied, especially as the temperature approaches 900 °C. The observed specific surface area is 16.59 m2/g. Upon grafting of oxygen functional groups, the O/C ratio of the composite electrodes reaches 0.12. After the annealing at 900 °C, the energy efficiency of the porous copper/graphite felt composite electrode is 67.40 %, the voltage efficiency is 70.13 %, and the current efficiency is 96.11 %. Under long-term cyclic discharge, the composite electrode exhibits a good capacitance retention of 91 % and a capacitance utilization of 63 %.

Study of surface etching of polycarbonate by environmentally friendly alkaline potassium permanganate system

This study examined the surface etching of polycarbonate (PC) using an environmentally friendly etching technique and an alkaline potassium permanganate system. On the surface morphology and roughness, the impacts of swelling circumstances, KMnO4-NaOH concentration, etching temperature, and time were examined. The PC substrate's average surface roughness (Ra) was enhanced by the etching process from 4 nm to 253 nm. The peel strength between the chemically coated copper film and the PC substrate also reached 0.91 KN/m. Using contact angle, Fourier transforms infrared spectrum (FT-IR), and X-ray photoelectron spectroscopy (XPS), the surface chemical structure of the PC substrate was compared before and after treatment. The PC surface turned hydrophilic after the etching process, and the contact angle dropped from 97.2° to 33.2°. The etching process increased the PC surface's roughness and hydrophilicity, which enhanced the adhesion strength between the polycarbonate (PC) substrate and the chemically coated copper film, according to FT-IR absorption spectroscopy, Atomic Force Microscope (AFM) and XPS analysis.

Photo-Enhanced Inverse Metal-Assisted Chemical Etching of α-Ga2O3 grown on Al2O3

Si-based semiconductor devices are not suitable for stable operations in the aerospace environments. Among the ultra-wide bandgap semiconductor materials, gallium oxide (Ga2O3) is attracting attention as the next-generation material for high-power semiconductor devices in extreme condition beyond Si, owing to its large band gap of 4.5-5.3 eV, high breakdown electric fields of 7-10 MV/cm, excellent chemical and thermal stability and radiation hardness. Alpha gallium oxide (α-Ga2O3) has the largest bandgap (4.8-5.3 eV) and the highest breakdown electric fields (~10 MV/cm) among the five Ga2O3 polymorphs, which facilitates the application of α-Ga2O3 as a high power device. However, the research on etching technology for α-Ga2O3 is rare. Etching technology is a crucial step of device fabrication. Chemical etching is free from plasma-induced damage which leads to superior device performance compared with dry etching, and high throughput with low cost is beneficial to industrial implementations. Chemical stability of Ga2O3 hinders the effective reaction with most chemical etchants. However, the photo-enhanced inverse metal assisted chemical (I-MAC) etching, where a noble metal with a high work function is utilized as a catalyst under UV irradiation, has emerged as a candidate for the chemical etching of Ga2O3. Deep-UV irradiation generates electron-hole pairs (EHPs) in the uncovered region of Ga2O3, and the metal electrode withdraws carriers from the photo-generated EHPs. The holes that are accumulated in the uncovered region of Ga2O3 react with gallium ions which produce gallium fluoride (GaF3) in a reaction with Hydrofluoric acid (HF). The etching process continues as the oxidant re-oxidizes the metal. The etch rate can be controlled by various parameter, including concentration and temperature of the etchant. In this work, for the I-MAC etch of α-Ga2O3 on sapphire substrate grown by halide vapor phase epitaxy, Pt was deposited on α-Ga2O3. Etch rate and surface roughness were characterized by atomic force microscopy after each step of the I-MAC etch. The I-MAC etch using HF and potassium persulfate (K2S2O8) solution with 185-nm UV irradiation was performed at constant durations under different etchant temperature conditions. The etch rates obtained at each temperature condition were fitted with the Arrhenius plot to estimate the activation energy of 0.898 eV. The etch depth showed a linear increase with time and the etch rate exhibits a direct dependency on the temperature of the etchant, indicating that the I-MAC etching of α-Ga2O3 is an activation-controlled reaction. As the I-MAC etching proceeded, surface roughness of α-Ga2O3 showed a tendency to increase. The rate at which the surface roughness increased increased with raising the etchant temperature. In the case of Pt there was no significant difference in the surface roughness after etching. After the completion of the I-MAC etch, the remaining Pt can be removed using aqua regia. The I-MAC etch process of α-Ga2O3 can allow us to fabricate α-Ga2O3 without plasma-damage. Figure 1

Enhancing photocathodic protection with Ti3C2-Decorated BiVO4 microspheres

In order to solve the problem of low carrier separation efficiency and large electron-transmission loss in transfer process of BiVO4; therefore, this study considered titanium carbide (Ti3C2) as a photoelectron-transfer agent for use in photocathodic protection (PCP) applications. Frist, SEM characterization proved that the typical accordion structure of Ti3C2 could be controlled by adjusting the etching time (36 h) and temperature (50 ℃). As-prepared Ti3C2 could reduced the volume resistivity of epoxy resin by four orders of magnitude and has excellent hydrophilicity. Second, different mass ratios of Ti3C2 to BiVO4 were also tested. When the ratio of BiVO4 to Ti3C2 was 1:2, the mixture self-assembled into BiVO4/Ti3C2 microspheres owing to the electrostatic adsorption of functional groups on the Ti3C2 surface. Third, the PEC test demonstrated that 304SS coupled with BiVO4/Ti3C2 (B:T = 1:2) photoanode showed an enhanced photocurrent density (154 μA•cm−2) and maximum potential drop (799 mV), which were equivalent to 3.5 times and 2.18 times that of the bare BiVO4, respectively. Mechanism study illustrated that enhanced performance of the BiVO4/Ti3C2 photoanode was attributed to Ti3C2 increased the hydrophilicity and conductivity, promoting the differentiation of the photocurrent in composite microspheres, and the interconnection structure helped maintain long-term stability.

Novel SiC-Based Power Device Bonding Materials of Nano Foam Sheet and Its Characteristic and Properties

Silicon carbide (SiC) has excellent characteristics such as high thermal and electrical conductivity. However, traditional bonding materials are difficult to serve lastingly at high temperature, which directly affects the performance of SiC-based devices. In this study, nano foam sheet was prepared by dealloying, and used to sinter chip and substrate at low temperature. Microstructure, interfacial composition, mechanical properties and fracture of the sintered joint were characterized and analyzed. The precursor was AgCu alloy, and the bicontinuous ligament/channel structure was formed on the precursor surface after dealloying. As the etching temperature increased from 80 °C to 90 °C, the ligament width of nano foam became large and channel diameter became small. With the extension of etching time from 2 h to 5 h, the etching depth gradually increased. The nano foam sheet could realize metallurgical reaction between substrate and chip at a sintering temperature of 300 °C. The joint had high shear strength, and could meet the strength requirement of standard.

Computational fluid dynamics modeling of a wafer etch temperature control system

Next-generation etching processes for semiconductor manufacturing exploit the potential of a variety of operating conditions, including cryogenic conditions at which high etch rates of silicon and very low etch rates of the photoresist are achieved. Thus, tight control of wafer temperature must be maintained. However, large and fast changes in the operating conditions make the wafer temperature control very challenging to be performed using typical etch cooling systems. The selection and evaluation of control tunings, material, and operating costs must be considered for next-generation etching processes under different operating strategies. These evaluations can be performed using digital twin environments (which we define in this paper to be a model that captures the major characteristics expected of a typical industrial process). Motivated by this, this project discusses the development of a computational fluid dynamics (CFD) model of a wafer temperature control (WTC) system that we will refer to as a “digital twin” due to its ability to capture major characteristics of typical wafer temperature control processes. The steps to develop the digital twin using the fluid simulation software ANSYS Fluent are described. Mesh and time independence tests are performed with a subsequent benchmark of the proposed ANSYS model with etch cooling system responses that meet expectations of a typical industrial cooling system. In addition, to quickly test different operating strategies, we propose a reduced-order model in Python based on ANSYS simulation data that is much faster to simulate than the ANSYS model itself. The reduced-order model captures the major features of the WTC system demonstrated in the CFD simulation results. Once the operating strategy is selected, this could be implemented in the digital twin using ANSYS to view flow and temperature profiles in depth.