Inline Removal of Oxide Layers From Electronic Components

Effect of pickling process on removal of oxide layer on the surface of ferritic stainless steel

The oxidized layers at the surface of hydrogenated diamond-like carbon (H-DLC) were studied with X-ray photoelectron spectroscopy, near-edge X-ray absorption fine structure, and Raman spectroscopy. The structure of these layers was correlated with the friction and wear behavior observed on H-DLC. H-DLC is well-known for its ultralow friction in inert environments, but the steady superlubricious state is always preceded by a run-in period with a high friction. It was hypothesized that the run-in period is related to the surface oxide layer formed naturally upon exposure of the sample to air. To test this hypothesis, thermal oxide layers were grown, and their structures were analyzed and compared with the native oxide layer on a pristine sample. It was found that the Raman spectra of the surface oxide layers of H-DLC have higher D/G band ratio than the bulk, indicating a larger amount of aromatic clusters compared to the bulk film. Thick oxide layers grown at 300 °C showed a run-in friction behavior that resembled the friction of graphite. The run-in periods were found to become longer when the thickness of the oxide layers increased, indicating that the run-in behavior of H-DLC is attributed to the removal of the surface oxide layers.

The piezoelectric detection of electrode surface processes

The coalescence of aluminum and aluminum alloy drops in molten salt flux was observed in different salt fluxes as a function of time. Salts based on equimolar NaCl–KCl with addition of other metal chlorides or metal fluorides were used. All salts showed the ability to coalesce metal drops into one drop, but time taken for complete coalescence was different for different salts. Metal drops are covered with oxide film, which hinders their ability to coalesce into one metal drop. Thus, the coalescence ability of any salt depends on the efficiency of oxide removal by the salt. Removal of oxide layer from aluminum surface by equimolar NaCl–KCl and equimolar NaCl–KCl containing 5 mass%NaF was observed by interference microscopy. It was found that the oxide layer was not removed by equimolar NaCl–KCl, while it was removed by equimolar NaCl–KCl containing 5 mass%NaF. Coalescence ability of salt is related to weight loss of metal in salt and interfacial tension between metal and salt.

OMOG (opaque MoSi on glass) blank is widely used in advanced masks because of its advantage in high resolution and 3D effect1-2. And the manufacture flow is simple compared to phase shift mask. But the repair of this type mask is a challenge. The OMOG material is sensitive to the etching gas thus the etching rate is much higher than PSM. This article presents a problem, the poor edge roughness after repair in OMOG mask, is also related to the high etching rate. The CD (critical dimension) of advanced masks is very small. If there is some distortion in the features’ edge, the AIMS result is easy out of spec. The poor edge roughness we met usually gets poor AIMS result. To find the reason, we checked the manufacture flow and then focused on three steps: repair process, plasma treated process and short clean. Finally we found the plasma treated process was the main reason, and the clean process also contributed to it. Plasma process makes the mask surface oxidization and the oxide layer is high clean durability. The etching rate of oxide is slower than pure OMOG material, and the oxide layer’s uniformity is not good. The two characteristics lead to different etching ratio in the defect area. This is the reason of the poor edge roughness. If the oxide layer is uniform in the defect area, the problem won’t happen. That’s why not all the masks we repaired met the problem. We also found the removal of the oxide layer by clean process could solve this problem. This is an indirect evidence for explaining the reason.

In the secondary chamber of ducted rocket, there exists a relative speed between boron particles and air stream. Hence, the ignition laws under static conditions cannot be simply applied to represent the actual ignition process of boron particles, and it is required to study the effect of forced convective on the ignition of boron particles. Preheating of boron particles in gas generator makes it possible to utilize the velocity difference between gas and particles in secondary chamber for removal of the liquid oxide layer with the aid of Stoke's forces. An ignition model of boron particles is formulated for the oxide layer removal by considering that it results from a boundary layer stripping mechanism. The shearing action exerted by the high-speed flow causes a boundary layer to be formed in the surface of the liquid oxide layer, and the stripping away of this layer accounts for the accelerated ignition of boron particles. Compared with the King model, as the ignition model of boron particles is formulated for the oxide layer removal by considering that it results from a boundary layer stripping mechanism, the oxide layer thickness thins at all times during the particle ignition and lower the ignition time.

Low-temperature direct bonding technique of semiconductor substrates has been developed to integrate dissimilar materials (e.g. Si, Ge, III-V) regardless of lattice and thermal expansion mismatches. Among the direct bonding techniques, a hydrophilic bonding method, which initiates a dehydration reaction between OH-terminated substrates, is commonly used because wafer-scale bonding can be fabricated under atmospheric conditions. Recently, our research group achieved direct bonding of wide-gap materials, including SiC, GaN, β-Ga2O3, and diamond substrates, by using this bonding method.The hydrophilic bonding of Si wafers has been practically applied for the fabrication of silicon-on-insulator substrates. In the bonding process, the Si substrates are typically irradiated with reactive ion etching using oxygen plasma, which efficiently generates OH groups on the surface. By contacting the substrates under atmospheric conditions, the activated surfaces can adhere to each other by hydrogen bonds across the OH groups. The annealing at ~200 °C causes the dehydration reaction and forms atomic bonds between the substrates, as shown in the following equation.Si-OH + HO-Si → Si-O-Si +H2OThe bonding process generates a sub-10-nm-thick SiOx layer at the bonding interface, which limits thermal and electrical conductance between the bonding substrates.Our research group demonstrated that the diamond substrates can be bonded with other semiconductor substrates (e.g. Si, InP, β-Ga2O3) by the hydrophilic bonding method. The pre-bonding treatment using oxygen plasma is not suitable for the diamond surface because it is easily etched by the strong oxidizing treatment. Meanwhile, the mild oxidizing treatment using H2SO4/H2O2 (i.e. piranha solution) and NH3/H2O2 (i.e. SC1) mixtures enables OH termination of the diamond substrate without a significant increase in the surface roughness. Figure A shows the photograph of the diamond substrate bonded on the Si substrate. At the Si/diamond and InP/diamond bonding interfaces, ~3-nm-thick SiOx and InPOx layers were observed by an electron microscope, respectively, as displayed in Figure B. These oxide layers were formed by the oxidizing treatment at the pre-bonding step.However, when β-Ga2O3 and diamond substrates were bonded, such an oxide intermediate layer was not observed at the bonding interface. This is because diamond never develops the oxide layer and β-Ga2O3 is an oxide material. As shown in Figure C, we achieved the direct bonding of monocrystalline β-Ga2O3 and diamond substrates with an amorphous intermediate layer thinner than 1 nm. As the intermediate layer was atomically thin, efficient electrical and thermal conductance across β-Ga2O3/diamond substrates was possible, as plotted in Figure D.Qiushi Kang et al. demonstrated that the hydrophilic bonding of the SiC substrate is possible by using oxygen plasma. This treatment develops the ~4-nm-thick SiOx layer on the SiC substrate, which possibly became a thermal and electrical barrier at the bonding interface. However, our research group revealed that the SiC substrate dipped into HF acid can form direct bonding with an atomically thin intermediate layer. It is known that the SiC surface is OH terminated after the removal of the native oxide layer by HF acid, unlike the Si substrate. We revealed that the HF-dipped SiC substrate can form direct bonding with the O2-plasma-activated β-Ga2O3 substrate through an intermediate layer as thin as 1 nm. as displayed in Figure E.About the GaN substrate, we have demonstrated that hydrophilic bonding with the Si substrate is possible using oxygen and nitrogen plasma activations. In addition, the GaN substrate dipped into H2SO4/H2O2 and NH3/H2O2 mixtures can also form direct bonding. The thickness of the GaOx layer at the GaN/Si bonding interface was approximately 1 nm.We believe the low-temperature direct bonding technique will contribute to future wide-bandgap semiconductor devices because it is possible to achieve efficient electrical and thermal conduction across dissimilar materials. Figure 1

We describe the natural oxidation of silicon nanocrystals (SiNCs) and the method of etching the natural oxide layer of SiNC with hydrogen fluoride (HF) vapor. Electrical measurements are conducted in order to investigate the influence of the natural oxidation of SiNCs. The wet HF etching process, which is currently used in the semiconductor industry, results in the removal of all SiNCs from the substrate. Therefore, we use HF vapor etching, which can remove only the natural oxide layer without the removal of SiNCs from the substrate. Consequently, the HF vapor process is suitable for SiNC devices. From electrical measurements, it is observed that current increases by four orders of magnitude after the HF vapor etching treatment. In addition, it is revealed that we can control the thickness of the oxide layer of SiNCs by changing the HF vapor etching time.

Bakelite is a thermoset plastic commonly found in electronic and automobile components. CaCO3 is generally found in the polymer as a filler material. Since it cannot be remelted, the disposal of this material has become an environmental issue. The present study investigates a new route to utilize waste bakelite as a source of carbon in EAF steelmaking process. This paper reports the carbon dissolution behaviour of bakelite/coke blends into liquid steel at 1550 °C. The carbon pick up in the liquid steel after reaction with varying blends of bakelite/coke for 30 minutes ranged between 0.13 wt% to 0.17 wt%; these were generally higher than that observed from coke alone (0.1 wt%). The dissolution rate (K) was also found to improve and the observed trend was BK2 (0.045 × 10−3 s−1) > BK3 (0.023 × 10−3 s−1) > BK1 (0.005 × 10−3 s−1) > coke (0.003 × 10−3 s−1). The reaction products formed at the interface after 30 minutes of contact between liquid steel and bakelite/coke blends were observed to be a CaS‐Al2O3 complex. The presence of CaS in the interfacial layer due to the CaO in the ash, lowered melting temperature of the layer, thereby allowing for increased removal of the ash layer and greater carbon pick‐up. The CaO is formed from the decomposition of CaCO3, and its presence was found to have a positive effect on modifying the properties of the coke, and thereby enhancing the carbon dissolution behaviour.

A reliable process to fabricate self-supporting thin Si single crystals has been developed, which fundamentally uses MeV boron implantation followed by a selective etching technique. Several additional steps in the process including post-implantation annealing, fast rough etching, removal of the oxide layer and removal of the implanted layer, are presented in detail. The area of the self-supporting film is about 6 mm diameter supported by a thick Si sheet, and the thickness of the film is 1-5.5 /spl mu/m which is well controlled by an implantation energy of 0.6-MeV. After removal of the implanted layer, the flatness and the crystalline quality of the film is excellent. This can be shown by channeling experiments in transmission geometry using a wide He beam. Several experiments carried out using this material will be presented, as well as other possible application.

Swedish companies team up for PM gears

Oxidation of silicon nitride base reaction sintered material at 1400°C with subsequent removal of the oxide layer makes it possible to increase the strength of the material at 20°C by 20%. On the other hand, short-term strength at 1400°C after such treatment is lower than the strength of nonoxidized specimens, yet it is still greater than the strength of oxidized specimens from whose surface the oxide layer was not removed.

Microstructure and bonding mechanism of Al/Ti bonded joint using Al–10Si–1Mg filler metal

Indium-tin oxide (ITO) is the main material for making transparent electrodes in electronic devices and flat panel displays. Laser direct write technology has been widely used for patterning ITO. Organics-based electronics devices, as OLEDs, impose special requirements on the geometrical and electrical quality of the conductors. High repetition rate lasers with a short, picosecond pulse width offer new possibilities for high efficiency structuring of transparent conductors on glass and other substrates. The results of ablation of the indium-tin oxide (ITO) layer on glass with picosecond lasers at various wavelengths are presented. Laser radiation initiated ablation of the material, forming trenches in ITO. Profile of the trenches was analyzed with a phase contrast optical microscope, a stylus type profiler, SEM and AFM. Clean removal of the ITO layer was achieved with the 266 nm radiation when laser fluence was above the threshold at 0.20 J/cm2, while for the 355 nm radiation the threshold was higher, above 0.46 J/cm2. The glass substrate was damaged in the area where the fluence was higher than 1.55 J/cm2. The 532 nm radiation allowed getting well defined trenches, but a lot of residues in the form of dust were generated on the surface. UV radiation at the 266 nm provided the widest working window for ITO ablation without damage of the substrate. Use of UV laser radiation with fluences close to the ablation threshold made it possible to minimize surface contamination and the recast ridge formation during the process. The latter is specifically important to prevent shortcut formation in OLED devices.Indium-tin oxide (ITO) is the main material for making transparent electrodes in electronic devices and flat panel displays. Laser direct write technology has been widely used for patterning ITO. Organics-based electronics devices, as OLEDs, impose special requirements on the geometrical and electrical quality of the conductors. High repetition rate lasers with a short, picosecond pulse width offer new possibilities for high efficiency structuring of transparent conductors on glass and other substrates. The results of ablation of the indium-tin oxide (ITO) layer on glass with picosecond lasers at various wavelengths are presented. Laser radiation initiated ablation of the material, forming trenches in ITO. Profile of the trenches was analyzed with a phase contrast optical microscope, a stylus type profiler, SEM and AFM. Clean removal of the ITO layer was achieved with the 266 nm radiation when laser fluence was above the threshold at 0.20 J/cm2, while for the 355 nm radiation the threshold was higher, abo...

Copper is utilized in a variety of industrial applications (e.g. heat conductors, electronic components, protective coating), where it is frequently exposed to high temperatures [1]. However, contact with the atmosphere at these high temperatures causes uncontrolled oxidation of the metal. Previous research investigated the oxidation mechanism by oxidizing at specific temperatures and then analyzing the oxide layers with a scanning electron microscope [2].This work presents a new method for the simultaneous investigation of the oxide layer formation by electrochemical impedance spectroscopy and cyclic voltammetry. The high-temperature electrochemical polarization method allows a dynamic adjustment of the oxygen partial pressure on the surface of the copper, leading to oxide layers with different compositions in respect to their thickness and defect density. The common combination of a potentiostat and a frequency response analyzer (FRA) in a three-electrode setup suffers from bandwidth limitations and artifacts [3]. Therefore, a novel method developed by Fafilek in 2009 [3] for a potential controlled electrochemical spectroscopy was adapted to our high-temperature oxidation setup. Thereby the two measuring units, potentiostat and FRA are electrically separated with regard to their grounding. Cyclic voltammograms are obtained as the result of the polarization of a sputtered copper ring versus a reference electrode, while the impedance spectra are recorded between the same copper ring (large contact area) and a copper sphere (small contact area) as shown in Figure 1. The FRA has nearly no internal resistance which ensures that both samples are adopting the same potential during the potential sweep resulting in an equal oxide formation on them. As the copper ring shows a significantly larger area than the copper sphere, the current received by the potential sweep is assumed to stem from the copper ring. Conversely, it is considered that the impedance spectra originate from the copper sphere, since the impedance of the copper ring can be neglected due to its large size. The data obtained from the potential sweep, such as the oxide structure and film thickness, are combined with the electrical properties acquired by impedance spectroscopy. This allows accurate characterization of the oxide layer that forms during electrochemically controlled oxidation.[1] Davis, J.R. ed., 2001. Copper and copper alloys. ASM international.[2] Zhu, Y., Mimura, K. and Isshiki, M., 2002. Oxidation mechanism of copper at 623-1073 K. Materials transactions, 43(9), pp.2173-2176.[3] Fafilek, G., 2009. A novel experimental method for potential controlled electrochemical impedance spectroscopy. Monatshefte für Chemie-Chemical Monthly, 140(9), pp.1121-1127. Figure 1