Etching Process Parameters Research Articles

Controllable Fabrication of Gallium Ion Beam on Quartz Nanogrooves.

Nanogrooves with high aspect ratios possess small size effects and high-precision optical control capabilities, as well as high specific surface area and catalytic performance, demonstrating significant application value in the fields of optics, semiconductor processes, and biosensing. However, existing manufacturing methods face issues such as complexity, high costs, low efficiency, and low precision, especially in the difficulty of fabricating nanogrooves with high resolution on the nanoscale. This study proposes a method based on focused ion beam technology and a layer-by-layer etching process, successfully preparing V-shaped and rectangular nanogrooves on a silicon dioxide substrate. Combining with cellular automaton algorithm, the ion sputtering flux and redeposition model was simulated. By converting three-dimensional grooves to discrete rectangular slices through a continuous etching process and utilizing the sputtering and redeposition effects of gallium ion beams, high-aspect-ratio V-shaped grooves with up to 9.6:1 and rectangular grooves with nearly vertical sidewalls were achieved. In addition, the morphology and composition of the V-shaped groove sidewall were analyzed in detail using transmission electron microscopy (TEM) and tomography techniques. The influence of the etching process parameters (ion current, dwell time, scan times, and pixel overlap ratio) on groove size was analyzed, and the optimized process parameters were obtained.

Influence of Growth Process on Suppression of Surface Morphological Defects in 4H-SiC Homoepitaxial Layers.

To address surface morphological defects that have a destructive effect on the epitaxial wafer from the aspect of 4H-SiC epitaxial growth, this study thoroughly examined many key factors that affect the density of defects in 4H-SiC epitaxial wafer, including the ratio of carbon to silicon, growth time, application of a buffer layer, hydrogen etching and other process parameters. Through systematic experimental verification and data analysis, it was verified that when the carbon-silicon ratio was accurately controlled at 0.72, the density of defects in the epitaxial wafer was the lowest, and its surface flatness showed the best state. In addition, it was found that the growth of the buffer layer under specific conditions could effectively reduce defects, especially surface morphology defects. This provides a new idea and method for improving the surface quality of epitaxial wafers. At the same time, we also studied the influence of hydrogen etching on the quality of epitaxial wafers. The experimental results show that proper hydrogen etching can optimize surface quality, but excessive etching may lead to the exposure of substrate defects. Therefore, it is necessary to carefully control the conditions of hydrogen etching in practical applications to avoid adverse effects. These findings have important guiding significance for optimizing the quality of epitaxial wafers.

Research On Etching of Distributed Bragg Reflector

This study investigated the effect of etching process parameters on the sidewall morphology and bottom metal etching damage of Distributed Bragg Reflector (DBR), and analyzed the underlying mechanisms. By comparing the etching morphology under different RF power and pressure conditions, it was found that increasing RF power and reducing pressure can solve the problem of sidewall fracture and obtain a smooth sidewall morphology. By comparing the effect of different process gases on the sidewall angle, it was found that adding O2 can reduce the DBR/Photoresit selectivity and sidewall angle while adding BCl3 can increase the DBR/Photoresit selectivity and sidewall angle. Therefore, the sidewall angle can be adjusted by controlling the type and flow rate of the etching gas. By comparing the DBR/metal selectivity under different RF power, it was found that as the RF power decreases, the DBR/metal selectivity increases, which can prevent metal splashing caused by over-etching of metal. Therefore, in DBR etching, high RF power is used for main etching to obtain a smooth sidewall morphology and the sidewall angle can be adjusted by varying the gas type and flow rate, while low RF power is used for over-etching to improve the DBR/metal selectivity and prevent metal over-etching. This study has reference significance for the development of the inverted chip DBR process.

Influence of the Chemical Composition and Topography of the Ti6Al7Nb Surface Etched in Fluorine Plasma on Its Selected Properties

Herein, a new way of the surface modification of Ti6Al7Nb alloy in fluorine plasma is presented using the mask made of stainless steel and its influence on the selected properties, including chemical composition, topography, and tribological ones. Depending on the etching process parameters, different characteristics of the surfaces are obtained. The higher is the value of the negative bias, the less fluorine concentration on the etched surface and higher etching rates. Etching using the SF6 gas shows bigger etching rates in comparison to the etching using the CF4 gas. Chemical composition of the modified surfaces shows greater impact on tribological characteristics than topography parameters. The lowest wear rate is observed for the sample modified using the CF4 gas.

Study of the Pattern Preparation and Performance of the Resistance Grid of Thin-Film Strain Sensors.

The thin-film strain sensor is a cutting-force sensor that can be integrated with cutting tools. The quality of the alloy film strain layer resistance grid plays an important role in the performance of the sensor. In this paper, the two film patterning processes of photolithography magnetron sputtering and photolithography ion beam etching are compared, and the effects of the geometric size of the thin-film resistance grid on the resistance value and resistance strain coefficient of the thin film are compared and analyzed. Through orthogonal experiments of incident angle, argon flow rate, and substrate negative bias in the ion beam etching process parameters, the effects of the process parameters on photoresist stripping quality, etching rate, surface roughness, and resistivity are discussed. The effects of process parameters on etching rate, surface roughness, and resistivity are analyzed by the range method. The effect of substrate temperature on the preparation of Ni Cr alloy films is observed by scanning electron microscope. The surface morphology of the films before and after ion beam etching is observed by atomic force microscope. The influence of the lithography process on the surface quality of the film is discussed, and the etching process parameters are optimized.

Investigations on the fabrication of a patterned tool by chemical etching

ABSTRACT The present article introduces chemical etching for the fabrication of a patterned tool to manufacture micro-sized products. Further, a feasibility study is conducted to produce intricate features using the fabricated patterned tool. High depth with the desired width of geometric feature is required on the patterned tool for this study. Three etching process parameters, concentration, time, and temperature were varied to understand their effect on geometric features obtained, viz. depth and width. A three-level factorial design with three center points was applied to perform experiments. For chemical etching, ferric chloride is used as an etchant. The width and depth of geometric features were measured with the help of a stereomicroscope. The analysis of variance (ANOVA) showed the effective contribution of process variables to the desired geometric features. The desirability approach is used to obtain a set of optimal parametric settings. The optimum value of width (at concentration = 2 M, Temperature = 55°C and Time = 15 minutes) of the feature was 191.55 μm, while depth of feature obtained was 167.28 μm at optimum parametric conditions. The process shows its capability to produce complex features on the patterned tool, which was used as an EDM tool electrode to show the potential of the process.

Durable and Regenerable Superhydrophobic Coating on Steel Surface for Corrosion Protection

Corrosion limits the usage of steel and leads to the tremendous loss of the economy. Superhydrophobic coating is proven an effective way to prevent corrosion due to its excellent water repellent nature. Herein, we describe the successful preparation of superhydrophobic coating on steel surface which is synthesized by using chemical etching technique with mixture of hydrochloric and nitric acid followed by treatment with lauric acid. By optimizing the etching process parameters, superhydrophobicity with water static contact angle of 170° and tilt angle of 5° is successfully achieved. Coated steel is found to be thermal, chemical, and mechanical stable. Besides, coating has also good regenerability. Furthermore, coating exhibits the excellent self-cleaning and anti-fogging properties. The electrochemical study is revealed the enhancement of corrosion resistance of steel after coating. This facile strategy inspires the large-scale fabrication of multifunctional steel surfaces for practical applications in self-cleaning, anti-fogging, and corrosion protection.

Evaluation of Etching Process Parameter Optimization in the Objective Specific Microstructural Characterization of As-Cast and Heat Treated HCCI Alloy

Abstract The optimization of the etching process parameters in high chromium cast irons (HCCI) for general microstructural observation, eutectic and secondary carbide quantification and 3D analysis of the carbide network is indispensable for further microstructure-properties correlation. The main aim of the current work is to evaluate the efficacy of certain etchants to aid in ‘objective specific' microstructural characterization of a 26 % Cr HCCI alloy in the as-cast (AC) and heat treated (HT) state. Samples were etched with various solutions, including Vilella's reagent, Nital, Murakami's reagent and its modification, and two other etchants. It was seen that specific etchants are needed depending upon the final objective and the results are reliant on their selection and optimal usage. Etching the AC and HT samples with Vilella's reagent for 7 s was sufficient to develop a contrast between the phases which was observed both in confocal laser scanning microscope (CLSM) and scanning electron microscope (SEM). Murakami's reagent and a modification of the same, were used in successfully quantifying the eutectic and secondary carbide volume fraction (CVF) in the AC and HT samples, respectively. Consequently, the knowledge gained in this study will be used as a basis for further microstructural analyses of these alloys and be applied to other alloys in the family.

Selective etching of p-GaN over Al0.25Ga0.75N in Cl2/Ar/O2 ICP plasma for fabrication of normally-off GaN HEMTs

The article presents the results of development of selective etching of p-GaN over Al0.25Ga0.75N in Cl2/Ar/O2 ICP plasma for fabrication of normally-off p-GaN gate GaN HEMTs using a laser reflectometry system for precise control of the etched material thickness. By optimizing etching process parameters such as oxygen flow, ICP power and chamber pressure, high etching selectivity of p-GaN over Al0.25Ga0.75N were obtained, with values up to 56:1. High etching selectivity and the control of etch rates of p-GaN and Al0.25Ga0.75N layers withing a wide range by changing the ICP process parameters enabled application of developed etching processes in the technology of fabrication of normally-off AlGaN/GaN HEMTs with a p-GaN gate. High threshold voltage of around 1.6 V and current densities up to 400 mA/mm were obtained. Electrical measurements have shown that the shortest 1 min Al0.25Ga0.75N overetch time after selective etching of the p-GaN layer results in best electrical parameters of fabricated devices.

Novel fabrication of fixed suspended silicon nitride structure for MEMS devices with dry etching

A method of fabricating suspended LPCVD and PECVD silicon nitride structure is demonstrated for a wide range of MEMS (Micro-Electro-Mechanical Systems) applications. Low stress LPCVD and PECVD silicon nitride film of 1 μm thickness were selected for the structure separately. Optical Lithographic parameters, viz, photoresist (PR) thickness, PR variety and baking parameters were optimized to obtain the PR suitable for selective etching of silicon and silicon nitride. Parameters of the dry etching process were also optimized to achieve anisotropic etching of silicon nitride and isotropic etching of Si to release the silicon nitride beam. The silicon nitride structures, thus released, were characterized using Scanning Electron Microscope (SEM) and Laser Doppler Vibrometer (LDV). Finite Element Method (FEM) analysis was carried out using COMSOL, to compare with the experimental modes of vibration investigated using the Laser Doppler Vibrometer (LDV). Thus we demonstrate that the first mode at 30 kHz was indeed the optimum match.

Dry etching of silicon carbide in ICP with high anisotropy and etching rate

A detailed study of the influence of technological parameters of the plasma chemical etching process in inductively coupled plasma on the etching rate of single-crystal silicon carbide is presented. The physicochemical substantiation of experimentally revealed patterns is given. The optimal gas mixture was determined in terms of the etching rate of SiC. It was experimentally established that the dependence of the etching rate of silicon carbide on the percentage of oxygen in the total gas mixture is non-linear. Thus, with an increase in the percentage of O2 up to 23%, the etching rate of SiC gradually increases to 560 nm/min, a further increase in the percentage of O2 leads to a sharp decrease in the etching rate of SiC up to 160 nm/min at an oxygen content of 31%. The effect of the distance between the sample and the plasma generation zone on the etching rate of SiC was studied. It was shown that the greatest increase in speed is caused by an increase in the bias voltage, so at Ubias = - 50 V the etching rate is 300 nm/min, and at Ubias = - 150 V the value of the etching rate is 840 nm/min. The optimal parameters of the plasma-chemical etching process were selected for high-speed directional etching of single-crystal silicon carbide substrates.

Plasma Etching in InAlN/GaN Hemt Technology

The experimental data on the plasma etching of Si3N4 for sub-100 nm gate fabrication for high electron mobility transistors (HEMTs) based on InAlN/GaN heterostructures are analyzed. The influence of the plasma etching process parameters on the plasma-induced damage to the InAlN/GaN heterostructure is considered. The possibility of formation of a 70 nm-length gate InAlN/GaN HEMT using low damage reactive ion etching of Si3N4 is demonstrated.

Thin Film Encapsulation for RF MEMS in 5G and Modern Telecommunication Systems

In this work, SiNx/a-Si/SiNx caps on conductive coplanar waveguides (CPWs) are proposed for thin film encapsulation of radio-frequency microelectromechanical systems (RF MEMS), in view of the application of these devices in fifth generation (5G) and modern telecommunication systems. Simplification and cost reduction of the fabrication process were obtained, using two etching processes in the same barrel chamber to create a matrix of holes through the capping layer and to remove the sacrificial layer under the cap. Encapsulating layers with etch holes of different size and density were fabricated to evaluate the removal of the sacrificial layer as a function of the percentage of the cap perforated area. Barrel etching process parameters also varied. Finally, a full three-dimensional finite element method-based simulation model was developed to predict the impact of fabricated thin film encapsulating caps on RF performance of CPWs.

Reactive Ion Etching of Cytop and Investigation of Residual Microstructures

Reactive Ion Etching (RIE) of Cytop as the cladding material for optical waveguides and microfluidic channels is investigated. Different grades of Cytop (M, A and S), different mask materials including photoresist and metals, different RIE parameters, along with different substrate materials were investigated. Grass-like structure was observed at the bottom of etched channels, of height that depends on the etching process parameters. A comprehensive post-etch acid cleaning procedure was devised to effectively remove the grass structure. [2019-0232]

Analyzing the effect of the parameters of laser etching process influencing the corrosion resistance and surface roughness of marine grade 316 stainless steel

Laser etching process is used for marking those materials which cannot be marked by conventional machining processes. The aim of the current study attempts to investigate the effects of Laser etching parameters specially the scanning speed [ns], peak power [kW], frequency [kHz] and heat input [J/mm2] on the corrosion resistance and variations in surface roughness properties of the Marine grade 316 Stainless Steel. In the laser etching process the surface of the material is incident by a laser beam which heats up the marked area and subsequently vaporizes the material leading to formation of oxide layer on the surface, which when comes in contact with aggressive environment causes a chemical reaction on the bare steel leading to corrosion. The experiment was performed after marking on the material surface body with Nd: YAG Solid State UV Laser beam using Laser annealing process. Surface roughness is an important parameter that affects the tribological behavior of surfaces. In the food processing industry the '316′ grades are unofficially known as the 'food' grades because the lower the surface roughness, the better, since corrosive material and bacteria are less likely to stick to a very smooth surface. The samples were subjected to salt spray test to check corrosion resistance of materials. Taguchi method of orthogonal array based on Minitab 18 was used to determine the best factor level condition. Marking quality was evaluated by visual examination. Analysis of variance (ANOVA) has been applied on experimental data to identify the relative significance of process parameters on the response. The analysis shows that the laser beam scanning speed is the most influential operating factor.

Fabrication and characterisation of nanostructure step height sample

Step height calibration sample is a high-precision height (depth) standard transfer material for correcting the Z-axis characteristic parameter values of surface structure measuring instruments such as AFM, SEM and white light interferometer. It has the characteristics of accurate value transfer and small size structure. According to the traceability value of VLSI step height standard, step structure calibration samples with nominal height of 8 nm, 18 nm and 44 nm were fabricated by inductively coupled plasma (ICP) etching and lithography, and the height and surface roughness of the step structures are evaluated by AFM. The experimental results show that the standard deviation of the step height calculated by the algorithm is 0.820 nm, 0.770 nm, 1.786 nm, respectively. The upper surface roughness of the step structure was the surface roughness of the SiO2 film. The roughness of the bottom surface was related to the surface quality of SiO2 film, ICP etching process parameters.

Fabrication and characterisation of nanostructure step height sample

Step height calibration sample is a high-precision height (depth) standard transfer material for correcting the Z-axis characteristic parameter values of surface structure measuring instruments such as AFM, SEM and white light interferometer. It has the characteristics of accurate value transfer and small size structure. According to the traceability value of VLSI step height standard, step structure calibration samples with nominal height of 8 nm, 18 nm and 44 nm were fabricated by inductively coupled plasma (ICP) etching and lithography, and the height and surface roughness of the step structures are evaluated by AFM. The experimental results show that the standard deviation of the step height calculated by the algorithm is 0.820 nm, 0.770 nm, 1.786 nm, respectively. The upper surface roughness of the step structure was the surface roughness of the SiO2 film. The roughness of the bottom surface was related to the surface quality of SiO2 film, ICP etching process parameters.

The Effect of Inductively Coupled Plasma Etching on the I–V Curves of the Avalanche Photodiode with GaN/AlN Periodically Stacked Structure

Inductively coupled plasma (ICP) is widely used in dry etching of III‐nitride materials, wherein the etching parameters of GaN and AlN are very different. Herein, the ICP dry etching process parameters of GaN/AlN periodically stacked structure (PSS) for avalanche photodiode (APD) fabrication are intensively studied and optimized. The flow rate ratio of Cl2/BCl3/Ar plasma, bias voltage, and the GaN‐to‐SiNx selectivity of ICP etching are optimized to achieve excellent surface morphology and nearly vertical sidewalls. It is found that the etching rate and the etched surface roughness of GaN/AlN material are significantly influenced by the flow rate of Cl2. After optimizing the etching procedure, the root‐mean‐square roughness of the etched surface is measured to be 1.46 nm, which is close to the as grown surface. By using the optimized ICP dry etching in the fabrication of the GaN/AlN PSS APD, the dark current is suppressed from 3.6 to 8.2 × 10−3 A cm−2 at −90 V.

41.1: Invited Paper: Efficient pre‐treatment for improving the via hole profile in 4‐mask process TFT architecture

Ways to solve the passivation layer undercut in via hole were described in detail. By tuning the pretreatment before the passivation layer deposition, the passivation layer undercut in via hole was solved efficiently without any other side effects. Different from changing dry etching process parameters, we increasing the adhesion of the interface between metal layer and passivation layer to overcome undercut issue.

Optimization of KOH etching process for MEMS square diaphragm using response surface method

<em><span>KOH wet etching is widely used in realizing MEMS diaphragm due to its low cost, safe and easy handling. However, wet etching process parameters need to be studied thoroughly in order to realize the desired shape and size of MEMS devices. This paper presents the numerical study and optimization of KOH etching process parameters using the response surface method (RSM). Face central composite design (FCC) of RSM was employed as the experimental design to analyze the result and generate a mathematical prediction model. From the analysis, the temperature was identified as the most significant process parameter that affects the etching rate, thus affecting the thickness and size of the diaphragm. The results of RSM prediction for optimization were applied in this study. Particularly, 45% of KOH concentration, temperature of 80°C, 1735 µm2 of mask size, and 7.2 hours of etching time were implemented to obtain a square MEMS diaphragm with thickness of 120 µm and size of 1200 µm2. The results of RSM based optimization method for KOH wet etching offers a quick and effective method for realizing a desired MEMS device.</span></em>