Oxide Layer Research Articles

Study on Oxygen Plasma-Based Copper Etching Process

Abstract A plasma-based, room-temperature copper etch process using the chlorine- or bromine-containing feed gas was reported. This simple process could potentially replace the chemical mechanical polishing method in preparing copper interconnects. However, the chlorine- and bromine-containing gases are corrosive and must be handled with expensive equipment following stringent safety procedures. In this paper, the oxygen plasma-based copper etch process is presented. The copper film was converted into a porous and polycrystalline copper oxide film which was subsequently dissolved in a dilute hydrochloric acid solution. The copper film was expanded when converted into an oxide film. The oxidation precursors, i.e., oxygen radicals and ions, were generated in the plasma phase and then transported through the oxide layer to the underneath copper film where the oxidation reaction proceeded. The oxide growth rate is affected by plasma parameters, such as pressure and power, and the kinetics of the oxidation reaction. This new oxygen plasma-based process is a simple solution for preparing copper interconnects for nano and microelectronic products.

Modelling of Cut-off Frequency of Armchair Graphene Nanoribbon Tunnel Field Effect Transistor Using Transfer Matrix Method

Graphene is considered as a promising two-dimensional material for electronic device applications due to its high charge carrier mobility and it is extremely thin in size. As a material, graphene has great potential for the development of high-speed nano electric devices. Graphene can be used as a channel material in Tunnel Field Effect Transistor (TFET). In this study, the cut-off frequency of the armchair graphene nanoribbon tunnel field effect transistor (AGNR-TFET) device was modelled quantum mechanically. The solution of the Dirac-like Hamiltonian and Poisson equations self-consistently is used to determine the potential profile of device and the transmittance is calculated using the transfer matrix method (TMM). The Landauer formulation with the help of Gauss Legendre Quadrature Method (GLQM) is used to calculate the tunnelling current and the cut-off frequency of AGNR-TFET. The calculation results showed that the cut-off frequency increased as the drain voltage increased, while the increase in channel length and the N-index graphene made the cut-off frequency decreased. Moreover, the thicker the oxide layer could increase the cut-off frequency and the higher the temperature on the device would reduce the cut-off frequency.

Silicon-based integrated passive device stack for III-V/Si monolithic 3D circuits operating on RF band

In this study, we demonstrated a silicon (Si)-based integrated passive device (IPD) stack to support III-V/Si monolithic 3D (M3D) ICs operating on the radio frequency (RF) band. The IPD stack was fabricated based on an 8-inch CMOS process line and integrated via M3D with an InGaAs HEMT layer. A process condition for a trap rich layer and a buried oxide layer in the IPD was established to simultaneously minimizing both the RF loss and wafer bowing. Through the process condition, the RF loss of the coplanar waveguides was −0.631 dB/mm at 30 GHz, lower than that of the CMOS foundry, and the wafer bowing of the stack was as low as −5.5 μm. The maximum quality factor of the inductors showed good values when compared to those of other CMOS foundry process-based inductors operating on the RF bands reported thus far. To obtain a compressive profile for the IPD stack, which is one of the most important requirements in advancing to wafer-to-wafer-level 3D bonding with the III-V active layer, a process method for the final IMD layer of the IPD was developed, resulting in a change from a tensile profile to a compressive profile for the IPD (corresponding wafer bowing value from −12.6 to + 10.7 μm).

Improvement of charge trapping memory performance by modulating band alignment with oxygen plasma

Metal-oxide charge trapping memory (CTM) integration into amorphous and organic flexible devices encounters challenges due to high-temperature treatment. Our approach enhances memory performance via room-temperature oxygen plasma treatment, subtly adjusting surface band alignment without changing the original material structure and surface roughness. Infiltration of oxygen plasma induces band alignment bending, creating a barrier for charge trapping. The device with oxygen plasma treatment exhibits an impressive 19.06 V memory window and a charge trapping density of 3.58 × 1013/cm2. In comparison, the memory window of untreated device only has 5.56 V, demonstrating that oxygen plasma treatment significantly improves memory characteristics. The charge retention rate exhibits outstanding stability, potentially reaching 94% after a decade. It should be noted that careful control during plasma treatment is crucial to maintaining optimal memory effects. This facile, efficient technique, applicable to various oxide layers, offers a way for future advancements in metal-oxide CTM technology.

Field-Free Superconducting Diode Effect and Magnetochiral Anisotropy in FeTe0.7Se0.3 Junctions with the Inherent Asymmetric Barrier.

Nonreciprocal electrical transport, characterized by an asymmetric relationship between the current and voltage, plays a crucial role in modern electronic industries. Recent studies have extended this phenomenon to superconductors, introducing the concept of the superconducting diode effect (SDE). The SDE is characterized by unequal critical supercurrents along opposite directions. Due to the requirement on broken inversion symmetry, the SDE is commonly accompanied by electrical magnetochiral anisotropy (eMCA) in the resistive state. Achieving a magnetic-field-free SDE with field tunability is pivotal for advancements in superconductor devices. Conventionally, field-free SDE has been achieved in Josephson junctions by intentionally intercalating an asymmetric barrier layer. Alternatively, internal magnetism was employed. Both approaches pose challenges in the selection of superconductors and fabrication processes, thereby impeding the development of SDE. Here, we present a field-free SDE in FeTe0.7Se0.3 (FTS) junction with eMCA, a phenomenon absent in FTS single nanosheets. The field-free property is associated with the presence of a gradient oxide layer on the upper surface of each FTS nanosheet, while eMCA is linked to spin splitting arising from the absence of inversion symmetry. Both SDE and eMCA respond to magnetic fields with distinct temperature dependencies. This work presents a versatile and straightforward strategy for advancing superconducting electronics.

Exploring the mechanism of stress-induced passive layer degradation in additively manufactured Ni-Fe-Cr-based alloy 718

This study explores the formation and degradation mechanisms of the passive layer on laser powder bed fusion (L-PBF) processed Ni-Fe-Cr-based alloy 718 using high-resolution submicron analysis and microcapillary electrochemical techniques. The findings provide new insights into passive layer breakdown under tensile loading, revealing the influence of microstructural characteristics, dislocation distribution, and mechanical stresses. Tensile loading caused oxide layer cracking near cell boundaries with higher dislocation density. Detachment of the oxide layer from the matrix created voids, allowing aggressive ions to penetrate, promoting crevice corrosion. Cell boundaries remained mostly intact, as metallic particles within the surface oxide layer.

Evaluation of Elevated Temperature Oxidation of Higher Manganese Ni-Resist Alloy

Nowadays Nickel was used mostly in battery, elevated temperature application and also corrosive environment. The boost of electric and hybrid vehicle had maximized the usage of Nickel as main composition in alloying industry. As such the Nickel price was at peak and become volatile to interest manufacturer. Among affected compound is Ni-Resist alloy. In this study, an alloy known as ductile Ni-resist alloy was modified to minimize its processing cost by decreasing its Nickel weight percentage. The modification was investigated in order to reduce nickel usage in the alloying composition so the alloying process cost can be minimized. More than 12 wt % chromium and manganese were alloyed with 10 wt % nickel during melting stage. Then, the evaluation of properties, oxidation behavior and its microstructure were examined. The results indicated more carbide was formed which later decreased tensile strength at elevated temperature. Oxidation resistance increased with addition of Mn/wt%. After oxidation at 765oC for 25 hours, there are oxide layers visible on the changed alloy.

Threshold Switching and Resistive Switching in SnO2-HfO2 Laminated Ultrathin Films

Polycrystalline SnO2-HfO2 nanolaminated thin films were grown by atomic layer deposition (ALD) on SiO2/Si(100) and TiN substrates at 300 °C. The samples, when evaluated electrically, exhibited bipolar resistive switching. The sample object with a stacked oxide layer structure of SnO2 | HfO2 | SnO2 | HfO2 additionally exhibited bidirectional threshold resistive switching properties. The sample with an oxide layer structure of HfO2 | SnO2 | HfO2 displayed bipolar resistive switching with a ratio of high and low resistance states of three orders of magnitude. Endurance tests revealed distinguishable differences between low and high resistance states after 2500 switching cycles.

The Identification of Microstructural Changes in High-Temperature Superconducting Tapes for Superconducting Fault Current Limiters

HTS 2G tapes used in Superconducting Fault Current Limiters (SFCLs) have properties that allow for the effective limitation of short-circuit currents; however, due to the specificity of the device operation, they should be characterized by the high stability of the parameters when repeatedly leaving the superconducting state. During the operation of SFCLs, a situation may occur in which the parameters of the HTS tapes used will change several times as a result of the action of short-circuit currents that exceed the critical current IC of the superconductor of the tape used. This paper presents the results of microstructural tests of 2G HTS tapes intended for SFCLs, subjected to surge currents corresponding to prospective short-circuit currents with values higher than their critical currents IC and for which IC changes were observed. The HTS tapes were examined using a JEOL 7600F field emission scanning electron microscope (SEM), and their chemical composition was analyzed using Energy-Dispersive X-ray Spectroscopy (EDS). The test results indicate the possibility of micro-damage in the form of cracks in the superconductor layer, as well as the interruption of the buffer layers and the oxidation of the silver layers. The analysis of the chemical composition of the HTS tape layers may indicate the occurrence of diffusion processes.

Unraveling the Subsurface Damage and Material Removal Mechanism of Multi-Principal-Element Alloy FeCrNi Coatings During the Scratching Process

Multi-principal-element alloys (MPEAs) exhibit superior strength and good ductility. However, tribological properties of FeCrNi MPEAs remain unknown at nanoscale and complex environments. Here, we investigate the effects of scratching speed, depth, and temperature on microstructural and tribological characteristics of FeCrNi using molecular dynamics simulations combined with an elevated temperature tribological experiment. The scratching force experiences the increase stage, the undulated stage, and the stable stage due to chip formation. Compared to traditional alloy coatings, low force enhances the useful life. With increased speed, the friction coefficient decreases, agreeing with previous work. High speed impacting includes severe local plastic deformation, from dislocation to amorphization. As the scratching depth increases, the average scratch force and friction coefficient increases owing to material accumulation in front of the abrasive particles. The surface morphology and dislocation behavior are significantly different during the scratching process. In addition, we revealed a temperature-dependent friction mechanism. FeCrNi MPEAs have excellent wear resistance at an intermediate temperature, which is attributed to the high Cr content promoting the formation of the compact oxide layer. This work provides atomic-scale mechanistic insights into the tribological behavior of FeCrNi, and would be applied to the design of MPEAs with high performance.

Oxidation anisotropy of 4H-SiC wafers during chemical-mechanical polishing

4H silicon carbide (4H-SiC) wafers are widely used in high-power, high-temperature, and high-frequency electronics owing to their excellent physical and electrical properties. In the processing of 4H-SiC wafers, chemical-mechanical polishing (CMP) is commonly employed to realize atomic-scale smoothness, damage-free surface, and global planarization. The CMP process is the synergy of wet oxidation and mechanical grinding, whose efficiency significantly relies on the oxidation process. Therefore, understanding the wet oxidation mechanism of Si face and C face of 4H-SiC wafers is critical to high-efficiency double-side CMP. In this work, the anisotropic CMP performance of Si face and C face of 4H-SiC wafers are investigated. It has been found that the material removal rate of the C face is 2–3 times that of the Si face. The thicknesses of the transient oxide layer on the C face and Si face are 8.71 nm and 3.50 nm, respectively. X-ray photoelectron spectroscopy analysis reveals that the oxygen content on the C face is higher than that on the Si face after wet KMnO4 oxidation. This indicates that the C face of 4H-SiC is easier to oxidize, which results in more oxides that that on the Si face of 4H-SiC. Our work shows that accelerating the oxidation of the Si face of 4H-SiC wafers during the simultaneous double-sided CMP process is crucial for the efficient polishing of 4H-SiC wafers.

Synthesis and assessment of the Mo/MoO3/CZTS/Ag diode fabricated by one-pot hydrothermal route: impact of temperature

A facile one-step hydrothermal method was utilized to prepare Cu2ZnSnS4 film employing EDTA as a complexing agent. An effective Molybdenum oxide layer was also formed in the same approach for forming the Cu2ZnSnS4 film. The influence of preparation temperature on structural, morphology, and optical characteristics was studied. The formation of crystalline kesterite phase Cu2ZnSnS4 films with preferred orientation along the (112) plane was confirmed by X-ray diffraction and Raman spectroscopy, and it was also demonstrated that structure property changes with preparation temperatures: kesterite phase Cu2ZnSnS4 is formed at lower preparation temperatures and kesterite phase Cu2ZnSnS4 and Cu2S are formed with increasing preparation temperature. Also, Raman analysis confirmed the formation of a Molybdenum oxide layer on the Mo substrate. Field emission scanning electron microscopy revealed that surface morphology changes from leaves of trees to flake-flowers. According to UV-visible analysis, Cu2ZnSnS4 films exhibited high and wide absorbance spectra in the visible and infrared regions and a band gap between (1.67-1.9) eV. Photoluminescence analysis revealed emission peaks at (1.569, 1.55, and 1.56) eV for samples prepared at (160, 200, and 230)0C, respectively, which is very close to the band's gap of Cu2ZnSnS4. Finally, the electrical study of Mo/MoO3/CZTS/Ag junctions was performed by using current-voltage (I-V) measurement.

Направления совершенствования сероочистки, осушки и переработки природного газа

The results of the work of the staff of the Department of “Chemical Technology of Oil and Gas Refining” of Astrakhan State Technical University in the field of separation of three-phase reservoir mixture, increasing the efficiency of desulfurization, improving the process of drying gas and the production of continuous hydrocarbons – raw materials for petrochemistry. The influence of the quality of raw materials entering processing on the formation of deposits in technological equipment has been studied. Reconstruction of the inlet and three-phase separators of high-pressure reservoir mixture separation plants by installing a vibration damper and a depulsor on the reservoir mixture supply line to the installation, as well as reconstruction of the input of raw materials into the separator of the installation. The use of the KPG-200 defoamer and the KPG-200 AV antifoamer made it possible to reduce the consumption rate of defoaming reagents several times in gas purification plants from acidic components. The influence of various impurities on the foaming of working amine solutions (mechanical impurities, coal dust, products of thermal destruction of amine, thermostable salts, corrosion inhibitors) has been determined. It was revealed that the products of thermal degradation of amine have the greatest effect at concentrations above 3% by weight. A method for reducing the content of mechanical impurities in a solution of diethanolamine in a constant magnetic field has been developed and introduced into an industrial desulfurization plant. The filtration efficiency increases 2.6 times, the foam height is halved, and the foam stability is quadrupled. At the same time, the activity of the defoamer increases by 1.7 times. The mathematical dependence of the height of the protective layer of aluminum oxide in an adsorber with zeolite on impurities of diethanolamine has been experimentally found. The effectiveness of the developed improved distribution ring device is shown, the use of which makes it possible to practically eliminate dead zones in the zeolite layer and thereby increase the efficiency of the adsorption process and increase the inter-regeneration period on the drying unit. Studies of the catalytic pyrolysis of the butane fraction using CVM-type pentasils modified with the introduction of chromium can reduce the process temperature compared with the thermal decomposition of raw materials by more than one hundred degrees 100 °C.

Laser assembly of CeO2 nanobrushes and their resistive switching performance

Memristors in a metal/oxide/metal configuration emerge as an advanced non-volatile information storage technology due to their high operating speed and low power consumption. Understanding the role of the microstructure of the active oxide layer in its resistive switching (RS) performance is scientifically important for revealing the conduction mechanism of oxides, and technically critical for the development of high-performance memristors. Here, self-assembly of vertically aligned CeO2 nanobrushes, a typical RS material, is demonstrated in pulsed laser epitaxy. The growth map of CeO2 is fully explored, and optimized growth conditions for CeO2 nanobrushes are established. Microstructure and crystallinity characterizations reveal the single-crystalline epitaxy nature of CeO2 nanobrushes. A nanobrush memristor exhibits a threshold switching feature with an On/Off ratio of 50, as 16 times high as a thin-film memristor, and excellent endurance of up to 500 cycles and retention time of up to 104 seconds. Theoretical fitting of the I-V curves of the thin-film and nanobrush memristors show interfacial switching in the thin-film memristor and filamentary switching in the nanobrush memristor. The distinct RS mechanisms between thin films and nanobrushes suggest the fundamental role of the structural design of active oxide layers in the RS performance of oxide-based memristors.

Freestanding Germanium Photonic Crystal Waveguide for a Highly Sensitive and Compact Mid-Infrared On-Chip Gas Sensor.

The performance of mid-infrared (MIR) on-chip gas sensors, operating via laser absorption spectroscopy, hinges critically on light-matter interaction dynamics, significantly influenced by external confinement and the effective light path length. Conventional on-chip sensors, however, face challenges in achieving the required limit of detection for highly sensitive applications, primarily due to their intrinsically short effective light path. Furthermore, these sensors are limited in their spectral range coverage within the MIR spectrum by the constraints of standard silicon-based platforms. To overcome these limitations, our research presents a novel approach to fabricate a freestanding germanium (Ge) photonic crystal waveguide (PCW) on a germanium-on-insulator (Ge-OI) platform, utilizing yttrium oxide (Y2O3) as the buried oxide layer. This device leverages the broad transparent windows of Ge and Y2O3, broadening the spectral coverage across the MIR range. The introduction of the PCW and its slow light effect significantly elevate external confinement and light-matter interactions, enabling a notable reduction in waveguide length, which traditionally limits on-chip configurations. The freestanding structure not only expands the sensing region and enhances external confinement but also prevents the emergence of leaky modes within the PCW. As a result, our compact sensor achieves an exceptionally low LoD of 7.56 ppm for carbon dioxide (CO2) sensing at the operational wavelength of 4.23 μm, with a compact waveguide length of only 800 μm.

Tribological and corrosion performance of duplex electrodeposited Ni-P/Ni-W-P coatings

The present research investigates the properties of duplex electrodeposited Ni-P/Ni-W-P coatings consisting of Ni-P and Ni-W-P as inner layers alternately. This study aims to examine how various heat treatment conditions affect the mechanical, tribological, and electrochemical properties of the coatings.The results show that the heat treatment temperature and duration have a profound influence on the coating’s microstructure, which significantly affects its overall performance. Optimal microhardness and lower wear rates are observed at 400 °C temperature for 1 h duration. However, at 800 °C for 4 h, duplex electrodeposited coatings display cracks and increased oxide layers, negatively impacting mechanical, tribological, and corrosion properties. The Ni-W-P outer layer coating exhibited higher hardness and a lower wear rate compared to the Ni-P outer layer coatings. However, the assessment of corrosion behavior shows that Ni-P offers increased corrosion resistance, largely due to its ability to form a passive layer, which is further enhanced after heat treatment. When compared to their individual single-layer coatings, the present duplex coatings demonstrate superior overall performance.

Fabrication of optimized partial-reflection coatings for mid-infrared quantum cascade lasers

This study presents both numerical modeling and experimental fabrication of three different partial-reflection (PR) coatings each optimized for quantum cascade lasers (QCLs) that emit radiation in the mid-infrared range. A novel double-layer PR coating comprising silicon dioxide (SiO2) and silicon nitride (Si3N4) was proposed as a potential solution for compatibility with QCLs fabrication processes. Subsequently, the PR coating was compared with two well-known PR coatings: a single layer of aluminum oxide (Al2O3) and a single layer of yttrium oxide (Y2O3). The coatings were designed to reduce the reflectivity of the front laser mirror from 30% to approximately 13%. The thickness of the dielectric layers was optimized for lasers emitting at 4.4 μm, with applicability in the 2.5–6 μm range. The proposed double-layer coating achieved the desired reflectivity while reducing the total coating thickness by 120 nm. By using the presented coatings it will be possible to increase the optical power of Mid-Infrared QCLs.

The Effect of Shot Blasting Abrasive Particles on the Microstructure of Thermal Barrier Coatings Containing Ni-Based Superalloy

Grit particles remaining on the substrate surface after grit blasting are generally considered to impair the thermal performance of thermal barrier coatings (TBCs). However, the specific mechanisms by which these particles degrade the multilayer structure of TBCs during thermal cycling have not yet been fully elucidated. In this study, the superalloy substrate was grit-blasted using various processing parameters, followed by the deposition of thermal barrier coatings (TBCs) consisting of a metallic bond coat (BC) and a ceramic top coat (TC). After thermal shock tests, local thinning or discontinuities in the thermally grown oxide (TGO) layer were observed in TBCs where large grit particles were embedded at the BC/substrate interface. Moreover, cracks originated at the concave positions of the TGO layer and propagated vertically towards BC; these cracks may be associated with additional stress imposed by the foreign grit particles during thermal cycling. At the BC/substrate interface, crack origins were observed in the vicinity of large grit particles (~50 μm).

Machine learning force field for thermal oxidation of silicon.

Looking back at seven decades of highly extensive application in the semiconductor industry, silicon and its native oxide SiO2 are still at the heart of several technological developments. Recently, the fabrication of ultra-thin oxide layers has become essential for keeping up with trends in the down-scaling of nanoelectronic devices and for the realization of novel device technologies. With this comes a need for better understanding of the atomic configuration at the Si/SiO2 interface. Classical force fields offer flexible application and relatively low computational costs, however, suffer from limited accuracy. Ab initio methods give much better results but are extremely costly. Machine learning force fields (MLFF) offer the possibility to combine the benefits of both worlds. We train a MLFF for the simulation of the dry thermal oxidation process of a Si substrate. The training data are generated by density functional theory calculations. The obtained structures are in line with abinitio simulations and with experimental observations. Compared to a classical force field, the most recent reactive force field, the resulting configurations are vastly improved. Our potential is publicly available in an open-access repository.

On the Surface Property–Oxidation Relationship in Refractory High‐Entropy Alloys

In this study, oxidation behavior in as‐cast polycrystalline HfNbTaTi3, HfNbTaTiZr, HfMoTaTiZr, and NbMoTaTiZr refractory high‐entropy alloys (RHEAs), and the amorphous form of NbMoTaTiZr RHEA, is investigated. Herein, the surfaces of samples undergoing static oxidation experiments at 700, 800, and 900 °C using scanning electron microscopy, energy‐dispersive X‐Ray spectroscopy, X‐Ray photoelectron spectroscopy, and X‐Ray diffraction are explored. In the corresponding findings, the presence of three different oxidation behaviors in the studied RHEAs is shown: formation of a non‐protective scale, powderization and pesting of the sample, and a distinct amorphous oxidation behavior compared to its polycrystalline counterpart. Notably, Nb appears to induce a detrimental effect on the oxidation properties of samples due to the high ratio of volume change between the oxide and the metal. In the current findings, it is also evidenced that Mo can cause catastrophic failure in RHEAs that lack a protective oxide layer. Overall, the results constitute a step forward in enhancing the understanding of oxidation behavior in RHEAs and developing novel oxidation‐resistant RHEAs.