Vertical Sidewalls Research Articles

Enhancing flow boiling using a microchannel with pillar–cavity mixed structures: A lattice Boltzmann study

Enhancement of flow boiling in microchannels through adjusting surface structures has attracted much attention in recent years. However, most of the existing studies focus on homogeneous surface structures. In the present study, a novel vertical microchannel with pillar–cavity mixed structures is conceived to enhance flow boiling heat transfer. In the mixed microchannel, cavities and pillars are distributed on the vertical sidewalls of the upstream and downstream flow channel, respectively. A multicomponent phase-change lattice Boltzmann model is employed to investigate the flow boiling performance of the mixed microchannel. Numerical results show that the cavities in the mixed microchannel can supply effective nucleation sites for timely departure of bubbles, while the pillars in the mixed microchannel can suppress the expansion of the vapor film from the outlet toward the inlet. Moreover, the bubbles from the upstream cavities can entrain the cold liquid to disrupt the vapor film covering the downstream pillars for the rewetting of the heated surface. As a result, the flow boiling performance can be significantly enhanced by the synergistic effect of the pillar and cavity structures, and the best flow boiling performance can be achieved by controlling the ratio of the number of cavities to the total number of structures in the mixed microchannel to optimize the synergistic effect. The influences of the structural parameters of pillars and cavities on the flow boiling performance have also been studied. It is found that the height of the pillars and the depth of the cavities have important influences on the flow boiling performance, while the boiling performance is not sensitive to the width of the pillars.

Using selective-area growth and selective-area etching on (−102) β-Ga2O3 substrates to fabricate plasma-damage-free vertical fins and trenches

We have demonstrated selective-area growth and selective-area etching on SiO2-masked (−102) β-Ga2O3 substrates using a HCl-based halide-vapor-phase epitaxy system that is capable of performing both growth and gas etching without plasma excitation. Since the surface of the (−102) substrate is perpendicular to the (100) plane, which has the lowest surface energy, we were able to use both methods to fabricate plasma-damage-free fins and trenches with (100)-faceted vertical sidewalls on windows striped along the [010] direction with high processing accuracy. Furthermore, since the [010] window direction is aligned parallel to the majority of dislocations and line-shaped voids in the substrate—which extend along the [010] direction and could potentially act as leakage paths—such crystal defects are unlikely to appear on the surfaces of the resulting fins and trenches. We believe that these selective-area growth/etching techniques can greatly accelerate research on, and the development of, β-Ga2O3-based vertical/lateral devices with fins or trenches.

Metalorganic Chemical Vapor Deposition of AlN on High Degree Roughness Vertical Surfaces for MEMS Fabrication

AbstractAluminum nitride (AlN) grown on vertical surfaces can be utilized for the fabrication of advanced piezoelectric microelectromechanical systems (MEMS). The in‐plane motion of the parts of a MEMS element is possible when AlN is deposited on the vertical surfaces of the moving structure. For the best device performance, AlN must have high crystal quality, uniform coverage of the vertical sidewalls, and c‐axis crystalline orientation perpendicular to the plane of a vertical surface. The impact of the surface roughness (Rq) of the vertical sidewalls formed in Si using wet and dry etching methods on the crystal quality, crystallographic orientation, and uniformity of the metalorganic chemical vapor deposited (MOCVD) AlN thin films is studied in this paper. In both cases, AlN films demonstrated full sidewall coverage and grew crystalline in the c‐axis direction. AlN films grown on vertical Si surfaces achieved using anisotropic wet etching are highly crystalline and oriented in [0001] direction, while the films grown on vertical surfaces achieved using dry etching displayed a lower level of alignment with the Si sidewalls.

Hydrodynamics and particle array optical characterizations of a high-performance Langmuir–Blodgett process

This paper describes the scientific features of an innovative technique to mass-produce monolayers of hexagonal close-packed structures (HCP) of particles (280–1100 nm). Our technique differs from a continuous roll-to-roll Langmuir–Blodgett (LB) process. It consists of a thin liquid film flowing down an inclined plane channel, the ramp, and entraining deposited particles floating on its surface to form a compact monolayer. Vertical sidewalls limit the entire flow. The main benefits of this technique in comparison with a standard LB process are a gentler push on the floating particles during the assembly and the prospect of better flexibility and scalability in the design of industrial applications. Our disruptive approach presents new control parameters and surprising but challenging hydraulic phenomena due to the flowing liquid. This paper investigates the hydrodynamics of this new LB-type design theoretically and experimentally. We propose an original theoretical prediction of the thickness of the liquid film flowing down the ramp without or with particles on its surface, including within the hydraulic jump region separating the liquid film whose surface is free of particles and the liquid film whose surface is particle-loaded. The experimental determinations of the film thickness obtained by a confocal chromatic technique and moiré topography agree well with our model. In addition, Bragg diffraction topography and false colour topography allow the HCP structure of the compact monolayer of particles to be quantified.

Plasma amplifiers: multiscale light-enhanced uniform SERS composite substrates for breaking through resonance limitations.

A phenomenon known as plasmon resonance constitutes a unique optical effect that can induce an enhancement in localized electromagnetic fields, resulting in a substantial increase in the electromagnetic field intensity surrounding metallic nanostructures. In this work, the coupling effect of excitation of surface plasmon polaritons and local surface plasmons in nanoparticles is deeply studied under the background of nanoparticles/one-dimension grating composite structures through grating matching. By employing finite-difference time-domain simulations as our methodological approach, we discern gratings with a periodicity of 1.5 μm support surface plasmon bound states between the gratings. Furthermore, the modulation of SPs along the vertical sidewalls of the grating due to standing wave effects exhibits oscillatory behavior with varying grating heights. Experimental results obtained from the nanoparticle/grating composite SERS substrate validate theoretical predictions, demonstrating higher enhanced Raman signals at 633 nm compared to 532 nm. Remarkably, this structure exhibits good performance, with R6G detection sensitivity down to concentrations as low as 10-10 M and mapping achieving a relative standard deviation of 7.79%, underscoring its uniformity and capability of electromagnetic field enhancement.

High aspect ratio silicon ring-shape micropillars fabricated by deep reactive ion etching with sacrificial structures

This paper presents the fabrication of widely-spaced high aspect ratio ring-shape pillars (i.e. hollow pillars). Lateral etching of the pillars during deep reactive ion etching is challenging. To reduce this problem, we proposed adding sacrificial structures surrounding the pillars such that the lateral etching mainly occurs on the sacrificial structures. We designed two different kinds of sacrificial structures, one is circular ring structures surrounding the pillars, the other one is two half circle structures with two small gaps. Both sacrificial structures could help to fabricate pillars with vertical sidewalls. When the width of the sacrificial structures was well designed for a given etching condition, the sacrificial structures could be removed by ultrasonic agitation after the process with clean surface because they had been weakened by the lateral etching. Using this method, 2D widely-spaced ring-shape pillar array with 470 μm high pillars (diameter 200 μm, aspect ratio 2.35) and 370 μm deep holes (diameter 80 μm, aspect ratio 4.63) was fabricated simultaneously.

Impact of Al2O3 spacers on the improvement in short-channel effects for the mesa-shaped vertical-channel In-Ga-Zn-O thin-film transistors with a channel length below 100 nm

To achieve a channel length scaling and an improvement in short-channel effect (SCE) for the mesa-shaped vertical thin-film transistors (VTFTs) using In-Ga-Zn-O (IGZO) channels prepared by atomic layer deposition (ALD), the impacts of two strategic approaches were investigated: the introduction of an ALD Al2O3 spacer and the modulation of ALD oxidants. The Al2O3 spacers were patterned with sound profiles by means of a hybrid-etching technique combining a wet- and plasma dry-etching processes to form vertical sidewalls corresponding to a channel length. For the cases when the Al2O3 spacers were prepared with H2O oxidant, the IGZO VTFT with an In/Ga ratio of 1.7 showed the degradations in device characteristics including a turn-on voltage (VON) of −8.0 V and a subthreshold swing (SS) of 1.50 V/dec. When the In/Ga ratio was increased to 2.9, the device failed to be operated with conductive properties. The excess hydrogen contained within the Al2O3 spacer was suggested to be thermally diffused into the IGZO from the back-channel interface, leading to marked increase in the number of conduction carriers within the channel. To suppress the doping effect of hydrogen from the spacer, the ALD oxidant was strategically modulated to O3. As results, the VON and SS of the IGZO VTFT were markedly improved to be −2.0 V and 0.483 V/dec, respectively. Additionally, the drain induced barrier lowering coefficient was also significantly enhanced from 2.9 to 0.13 V/V, demonstrating the excellent immunity against the SCE for the IGZO VTFTs with nanoscale channel lengths. It was concluded from these findings that the spacer engineering can be one of the most important guides for the implementation of IGZO VTFTs with channel lengths below 100 nm.

Model-Based XPS Technique for Characterization of Surface Composition on Nano-Scale SiCOH Sidewalls

The objective of this study is to develop an in-line metrology technique that employs X-ray Photoelectron Spectroscopy to measure photoelectron intensity from patterned trench surfaces of low-k dielectric film. A mathematical model uses linear regression method to separate the intensities into individual elemental compositions of the constituent surfaces. The initial segment of the model uses measured data from CD-SEM and spectroscopic Ellipsometry to determine the respective surface areas visible to the XPS electron analyzer. The second segment derives the surface composition of the line top, trench bottom, and vertical sidewalls based on a linear relationship between photoelectron intensity, emitting area, and characteristic elemental composition of each surface. The study has verified the predicted compositions from the model through physical measurements, demonstrating excellent agreement and concurrence with the physical mechanisms expected from the applied etch and ash chemistry in a commercial CCP RIE etch chamber.

Exploring oxide-nitride-oxide scalloping behavior with small gap structure and chemical analysis after fluorocarbon or hydrofluorocarbon plasma processing

The scalloping of oxide-nitride-oxide (ONO) stacked layers on vertical sidewalls during high-aspect-ratio contact etch is commonly seen and characterized by the horizontal etching of oxide and nitride layers at different etch rates. To understand the mechanisms of ONO scalloping in complex plasma chemistry, it is crucial to examine the surface chemistry of silicon dioxide and silicon nitride processed with single fluorocarbon (FC) or hydrofluorocarbon (HFC) gases. To simulate the isotropic etching of SiO2 and Si3N4 sidewalls, we use a horizontal trench structure to study the effect of neutral radicals produced by FC (Ar/C4F8), HFC (Ar/CH3F, CH2F2, or CH3F), FC/HFC (Ar/C4F8/CH2F2), or FC/H2 (Ar/C4F8/H2), plasma for aspect-ratio (AR) up to 25. To eliminate the effect of ions, oxide and nitride trench structures were treated by inductively coupled plasma. The changes in the film thickness as a function of AR were probed by ellipsometry. Additionally, x-ray photoelectron spectroscopy (XPS) measurements on oxide and nitride substrates processed by Ar/C4F8 and Ar/CH2F2 plasma were performed at various locations: outside of the trench structure, near the trench entrance (AR = 4.3), and deeper in the trench (AR = 12.9). We find a variety of responses of the trench sidewalls including both FC deposition and spontaneous etching which reflect (1) the nature of the FC and HFC gases, (2) the nature of the surfaces being exposed, and (3) the position relative to the trench entrance. Overall, both the etching and deposition patterns varied systematically depending on the precursor gas. We found that the ONO scalloping at different ARs is plasma chemistry dependent. Oxide showed a binary sidewall profile, with either all deposition inside of the trench (with FC and FC/H2 processing) or etching (HFC and FC/HFC). Both profiles showed a steady attenuation of either the deposition or etching at higher AR. On the nitride substrate, etching was observed near the entrance for HFC precursors, and maximum net etching occurred at higher AR for high F:C ratio HFC precursors like CHF3. XPS measurements performed with Ar/C4F8 and Ar/CH2F2 treated surfaces showed that Ar/C4F8 overall deposited a fluorine-rich film outside and inside of the trench, while Ar/CH2F2 mostly deposited a cross-linked film (except near the trench entrance) with an especially thin graphitic-like film deep inside the trench.

Stability analysis of wall‐attached Bénard–Marangoni convection in a vertical magnetic field

AbstractThe threshold for the onset of thermocapillary flow in a planar liquid layer heated from below is increased by a vertical magnetic field when the liquid is a good electric conductor. The magnetic damping effect is reduced when the induced eddy currents are blocked by insulating side walls. Neutral conditions for this specific Bénard–Marangoni stability problem with a vertical field and side walls are obtained numerically for three‐dimensional perturbations assumed periodic in one horizontal direction. The domain is bounded by a free‐slip wall at the bottom, a free surface at the top and two free‐slip lateral walls in the other horizontal direction. Buoyancy forces and surface deformations are neglected and a constant heat flux is imposed on the free surface. Upon increasing the magnetic induction, the least stable modes become localized near the side walls and the convective threshold increases at a lower rate than for the least stable bulk mode.

Lattice Boltzmann simulation of cavity flows driven by shear and internal heat generation for both Newtonian and viscoplastic fluids

Following our recent investigation [G. Kefayati, “Internally heated convection of viscoplastic fluids in enclosures using a lattice Boltzmann method,” Phys. Fluids 35, 013108 (2023)], this paper centers on exploring the influence of shear on internally heated convection and its flow within a square cavity. The study delves into the behavior of both Newtonian and viscoplastic fluids within this setup. The cavity features two vertical side walls that consistently maintain low temperatures, serving as isotherms. Meanwhile, the horizontal walls are adiabatic and provide thermal insulation. In this work, we present dimensional macroscopic equations and introduce innovative non-dimensional macroscopic equations. To generate shear, the top lid is continuously translated, and we quantify its intensity using the corresponding Richardson number. For investigating the viscoplastic behavior and defining the yielded (fluid) and unyielded (solid) zones, we employ an exact Bingham model, which relies on a unique tensor. To tackle the problem effectively, we develop a dimensionless lattice Boltzmann method to derive the specified macroscopic non-dimensional equations and subsequently solve the fluid motion scenario. Throughout the study, we introduce modified non-dimensional parameters, including the introduced yield number (Y), Reynolds number (R) ranging from 0 to 400, Prandtl number (Pr) ranging from 0 to 100, and the modified Grashof number (G) within the range of 104–106. By varying these parameters, we analyze their influence on streamlines, isotherms, and the regions of yield and unyielded zones. The obtained results revealed that shear plays a significant role in influencing fluid flow, heat transfer, and the behavior of the unyielded section within the enclosure.

Effects of multi-frequency ultrasound on inactivating Chironomus kiiensis eggs: Evidence from a case study in drinking water treatment plant

Chironomid is a type of arthropod that lay eggs on objects in stagnant waters. Vertical side walls of sedimentation tanks in drink water treatment plant (DWTP) are an ideal place for it, which often leads to outbreaks of the larvae booming. Poor hygiene of drinking water and high risk of vector-borne disease are often related to maggots and adult Chironomus, which need to be effectively inhibited. Herein, a study was performed to investigate the effects of single-, dual- and triple-frequency ultrasonic radiation for the stress responses of Chironomus eggs on their viabilities, stress-related protein concentrations and antioxidative enzyme activities. Compared to the single- and dual- frequency treatments, the maximum acoustic pressure ranged from −30 pa to 12 Pa was achieved by the triple - frequency treatment. Meanwhile, the lowest integrity (25.63 %) and hatching rate (2.6 %) of Chironomus eggs were recorded after 4-min of triple-frequency treatment with 10-cm exposure distance and 450 W power. As the introduction of different frequency ultrasound, hyperoxide was generated from the effect of transient cavitation, which significant reduced activities on acetylcholinesterase (AchE), cytochrome P450, and glutathione S-transferases (GSTs) (p < 0.05), and were responsible for lysis of eggs' periplasm and shells. The work provided a commercial-scale case study to inhibit Chironomus biomass and prevent its infestation in DWTP.

Enhancing shape precision in jet electrochemical additive micro-manufacturing process through confined electrolyte

This paper proposes a jet electrochemical additive micro-manufacturing (Jet-ECμAM) process with confined electrolyte to enhance the shape precision of micro structures. To achieve electrolyte confinement, a layer of dichloromethane is dispersed on the cathode workpiece. When the electrolyte is ejected out of nozzle and reaches onto the workpiece, it does not disperse freely on the workpiece but its extent of spread is restricted by dichloromethane due to their different densities and immiscibility. Consequently, the electrochemical reaction is confined to the processing zone and the distribution of current density in the confined zone is improved at the same time, which enhances the shape precision. To further analyze this method, a multi-physical simulation was performed to investigate the electrolyte flow characteristics and electric field distribution on the workpiece. The results showed that after electrolyte flow out of the nozzle, its extent of spread is restricted by dichloromethane leading to confinement within the processing zone on the workpiece. Moreover, the distance of radial spread of electrolyte is reduced from 241 μm to 133 μm with the inter-electrode gap (IEG) increased from 100 μm to 400 μm. On the other hand, there is an increased current density in the confined region, and the distribution of current density becomes uniform at the same time. Experiments were conducted to verify the proposed technique. The results indicate that the shape precision of a micro structure is significantly improved with the proposed method. Micro-pillars with vertical side walls were well deposited, and a reduction in diameter from 580 μm to 380 μm was observed with the increasing IEG. In addition, the surface quality improves when the current density increases from 30 A/dm2 to 70 A/dm2. At last, by controlling the IEG and the motion path of the nozzle, different kinds of micro structures were well deposited, demonstrating a flexible fabrication process based on Jet-ECμAM.

Granular Segregation in Gravity-Driven, Dense, Steady, Fluid–Particle Flows over Erodible Beds and Rigid, Bumpy Bases

Kinetic theory is used to propose and solve boundary value problems for fully developed, steady, dense gravity-driven flows of mixtures composed of identical inelastic spheres and water over both inclined erodible beds and rigid, bumpy bases confined by vertical sidewalls. We solve the boundary value problems assuming values of the mass density and of the size of the spheres typical of natural materials and show the numerical solutions for the profiles of the mean velocities of the particles and fluid, the intensity of the particle velocity fluctuations, and the granular concentration. In addition, we indicate how the features of the grain velocity fluctuations profile would influence segregation in three situations when the particle phase consists of two sizes of spheres: (1) the spheres are of the same material, and only gradients of temperature influence their segregation; (2) the mass densities of the material of the spheres are such that only gravity influences segregation; and (3) the mass densities are such that the coefficients of the temperature gradients and gravity segregation mechanisms are equal. For spheres of the same material, over a rigid bumpy base, the concentration of larger spheres increases from zero at the bed to the maximum value at the top of the flow; while over an erodible bed, this concentration has its maximum value at both the bed and the top of the flow.

Heat-Flux Effect on Fluid Flow and Convective Heat Transfer through a Rotating Curved Micro-Channel

The present paper investigates heat-flux effect and the dissemination of energy in a rotating bent square micro-channel (MC) subject to a temperature gradient between the vertical sidewalls. The flow structure prevailing the problem is solved by applying a highly accurate spectral-based numerical scheme. The flow controlling parameters are the Dean number (0&lt;Dn≤5000) and the Taylor number (-500 ≤ Tr ≤ 2000) for curvature 0.01 and the Grashof number, Gr=1000. After applying the arc-length path continuation technique to obtain steady solution (SS) curves, two branches of SS consisting of 2- to 8-vortex solutions are prevailed for the non-rotating case while a single branch with a symmetric 2-vortex solution is for positive rotation of the channel. Unsteady flow (UF) properties are simulated by the time-average of the solutions, and the transitional behavior is well predicted by contemplating the power spectrum and phase spaces of the solutions. Results manifest that the UF experiences a consequence ‘steady-state àmulti-periodic àsteady-state’ for no rotation of the channel as Dn is increased. For the rotating case, on the other hand, the flow advances in the scenario ‘steady-state àmulti-periodic àsteady-state’ for negative rotation and only a steady-state solution for rotation in the positive direction. Streamlines and isotherms of SS and UF for various values of the flow-controlling parameters are obtained. Centrifugal force impacts the fluid mixer, which then assists to turn the flow into chaos and prompts to intensify the convective heat transfer (CHT).&#x0D; J. of Sci. and Tech. Res. 4(1): 129-144, 2022

Investigating the sidewall's effects on [formula omitted]-shaped floating breakwaters interacting with water waves by the scaled boundary FEM

The effect of the existing vertical sidewall on the hydrodynamic characteristics of a π-shaped floating breakwater interacting with water waves in a fluid domain of finite, arbitrary water depth is analyzed. The Scaled Boundary Finite Element Method (SBFEM) is adopted to solve the Laplace governing equation based on the potential flow assumption in a two-dimensional vertical plane. The accuracy and efficiency of the SBFEM-based model are evaluated by comparing the calculated results of the current model with the literature. The presence of a sidewall generally produces more significant responses due to the creation of standing waves and the appearance of the resonance phenomenon, which synchronizes some wavelengths with the distance between the sidewall and the π-shape floating structure. Furthermore, the present model accurately predicts the hydrodynamic behavior, either with sharp corners or a few elements in the solution domain.

Role of pixel design and emission wavelength on the light extraction of nitride-based micro-LEDs.

Micro-light emitting diodes (µ-LEDs) suffer from a drastic drop in internal quantum efficiency that emerges with the miniaturization of pixels down to the single micrometer size regime. In addition, the light extraction efficiency (LEE) and far field characteristics change significantly as the pixel size approaches the wavelength of the emitted light. In this work, we systematically investigate the fundamental optical properties of nitride-based µ-LEDs with the focus on pixel sizes from 1 µm to 5 µm and various pixel sidewall angles from 0∘ to 60∘ using finite-difference time-domain simulations. We find that the LEE strictly increases with decreasing pixel size, resulting in a LEE improvement of up to 45% for a 1 µm pixel compared to a 20 µm pixel. The ideal pixel sidewall angle varies between 35∘ and 40∘, leading to a factor of 1.4 enhancement with respect to vertical pixel sidewalls. For pixel sizes in the order of 2µm and smaller, a substantial transition of far field properties can be observed. Here, the far field shape depends severely on the pixel sidewall angle and affects the LEE within a solid angle of ±15∘. Moreover, we investigate the impact of emission wavelength and observe major differences in optical characteristics for blue, green and red emitting pixels, which is relevant for real-world applications. Finally, we discuss the implications of the assumptions we made and their significance for the design of µ-LEDs.

Second law analysis of thermo-magneto-hydrodynamic couple-stress fluid flow in a cavity with heated fin

The objective of current study is to analyze the magnetohydrodynamic (MHD) natural convection flow of couple-stress fluid and entropy generation (second law analysis) inside the cavity with heated fin by using the Galerkin finite element method. The heated fin has been placed in middle of the heated bottom wall, the temperature T c is fixed on the vertical walls and an insulated situation is considered at the top wall. The irreversibility ratio and heat flux inside the enclosure are examined through entropy generation and Bejan heatlines, respectively. The obtained results show that the intensity of circulations of streamlines decrease from 3.9744 to 0.03148 and heatlines from 7 to 4.5 due to increasing couple-stress parameter ( K ) from 0 to 1.5 . It is noted that the heatlines bowls appear due to enhanced buoyancy-driven flow against high Rayleigh number. The reverse relation is noted between the entropy generation and the Hartmann number. The overall heat transfer rate along with the bottom and vertical side walls increase 111.65 % and 75.8297 % , respectively, with increasing the fin height from 0 to 0.25 . Obtained results could help to optimize heat transfer in engineering systems like heat exchangers, cooling processes of devices, chemical reactors, and solar collectors.

Vertical sidewalls in thick epoxy resists – a challenge for laser-based direct write lithography

Straight, almost vertical sidewalls can be achieved in thick negative-tone resist using focused laser beam-based direct write lithography (DWL). This is possible despite beam divergence and Gaussian intensity distribution that cause non-homogeneous illumination over the resist thickness and non-sharp edges between exposed and non-exposed areas. Three write modes with different focal lengths, numerical apertures and resolutions were used in our DWL 66+ pattern generator from Heidelberg Instruments. By variation of dose, vertical adjustment of location of focus, and multipass exposure, up to 88° sidewalls were achieved in 60 μm high and 100 μm wide ridges. The results show the potential of DWL to achieve resist structures with larger height up to 200 μm, higher resolution down to 5 μm, aspect ratio of over 8 and defined sidewall shape.

Anisotropic non-plasma HCl gas etching of a (010) β-Ga2O3 substrate

We demonstrated the effectiveness of plasma-free HCl gas etching on a SiO2-masked (010) β-Ga2O3 substrate. The etching process proceeded anisotropically in the window areas, resulting in the fabrication of holes or trenches that were surrounded by etching-resistant (100)- and (01)-faceted sidewalls. When we etched in the striped windows along [001], we were able to create fins and trenches with flat (100)-faceted vertical sidewalls and slightly rough {310}-faceted inclined bottom corners. The vertical-to-horizontal etching ratio was as high as ∼11–14. Our findings indicate that HCl etching is a promising method for fabricating high-aspect-ratio fins/trenches on (010) substrates without causing plasma damage.