This study empirically investigates the influences of several parameters on surface morphology and etch rate in a high-aspect-ratio silicon etching process. Two function formulas were obtained, revealing the relationship between the controlled parameters and the etching results. All the experiments were conducted on an inductively coupled plasma system, using a Bosch process. The tested trenches' width ranged from 15 to 1500 mm and their depth ranged from 50 to 500 mm, which covers nearly all the typical sizes of micromechanical devices in practical applications. The controlled parameters are etching chamber pressure, bias power, and gas flow rate. The parameters of surface morphology include sidewall angle, surface roughness, and sidewall condition. We tested how the controlled parameters can influence the surface morphology and etch rate and formulated assumptions to explain those relationships. Meanwhile, we utilized linear regression to obtain experiential function formulas of the relationships among etch depth, structure width, etching time, and passivation time, with a correlation coefficient higher than 0.99. Using these formulas, 12-mm-wide and 377-mm-deep (aspect ratio 31.4) trenches with sidewall angles of 89°were achieved. Additionally, this experience was applied as a critical structure in a gas turbine structure system.

This paper studies the impact of freezing of video on quality as experienced by users. Two types of freezes are investigated. First a freeze where the image pauses, so no frames were lost (frame halt). In the second type of freeze, the image freezes and skips that part of the video (frame drop). Measuring Mean Opinion Score (MOS) was done by subjective tests. Video sequences of 20 seconds were displayed for four types of content, to a total of 23 test subjects. We conclude there is no difference in the perceived quality between frame drops and frame halts. Therefore one model for single freezes was constructed. According to this model the acceptable freezing time (MOS>3.5) is 0.36 seconds.Pastrana -Vidal et al. (2004) suggested a relationship between the probability of detection and the duration of the dropped frames. They also found that it is important to consider not only the duration of the freeze but also the number of freeze occurrences. Using their relationship between the total duration of the freeze and the number of occurrences, we propose a model for multiple freezes, based upon our model for single freeze occurrences. A subjective test was designed to evaluate the performance of the model for multiple freezes. Good performance was found on this data i.e a correlation higher than 0.9.

In this study, the filling process of high aspect ratio through-silicon-vias (TSVs) under dense conditions using the electroplating method was efficiently achieved and optimized. Pulsed power was used as the experimental power source and the electroplating solution was prepared with various additive concentrations. Designed control variable experiments were conducted to determine the optimized method. In the control variable experiments, the relationship of multiple experimental variables, including current density (0.25–2 A/dm2), additive concentration (0.5–2 mL/L), and different shapes of TSVs (circle, oral, and square), were systematically analyzed. Considering the electroplating speed and quality, the influence of different factors on experimental results and the optimized parameters were determined. The results showed that increasing current density improved the electroplating speed but decreased the quality. Additives worked well, whereas their concentrations were controlled within a suitable range. The TSV shape also influenced the electroplating result. When the current density was 1.5 A/dm2 and the additive concentration was 1 mL/L, the TSV filling was relatively better. With the optimized parameters, 500-μm-deep TSVs with a high aspect ratio of 10:1 were fully filled in 20 h, and the via density reached 70/mm2. Finally, optimized parameters were adopted, and the electroplating of 1000-μm-deep TSVs with a diameter of 100 μm was completed in 45 h, which is the deepest and smallest through which a three-dimensional inductor has ever been successfully fabricated.

Clostridium botulinum produces botulinum neurotoxin (BoNT), which is the most toxic known protein and the causative agent of human botulism. BoNTs have similar structures and functions, comprising three functional domains: catalytic domain (L), translocation domain (HN), and receptor-binding domain (Hc). In the present study, BoNT/E was selected as a model toxin to further explore the immunological significance of each domain. The EL-HN fragment (L and HN domains of BoNT/E) retained the enzymatic activity without in vivo neurotoxicity. Extensive investigations showed EL-HN functional fragment had the highest protective efficacy and contained some functional neutralizing epitopes. Further experiments demonstrated the EL-HN provided a superior protective effect compared with the EHc or EHc and EL-HN combination. Thus, the EL-HN played an important role in immune protection against BoNT/E and could provide an excellent platform for the design of botulinum vaccines and neutralizing antibodies. The EL-HN has the potential to replace EHc or toxoid as the optimal immunogen for the botulinum vaccine.

Black silicon fabrication and manipulation have been well reported by institutes around the world and are quite useful for solar absorption and photovoltaic conversion. In this study, silicon micro-nano hybrid structures were fabricated, and the morphologies of the hybrid structures were analyzed. This paper studied nanostructures formed on tips, pits and a flat surface using a dry etching method and a wet etching method. In terms of nanostructure morphology, nanostructures etched by the wet etching method (13 μm) were taller than those etched by the dry etching method (1 μm), but the wet etched morphology was less organized. After the nanostructures were grown, six samples with nano sturctures and three samples with micro sturctures were measured by a photometer for reflectivity testing. The nine samples were compared and analyzed using the integral of reflectivity and solar emissivity at the earth’s surface. The results show that the nanostructures grown on a tip surface using the wet etching method had the minimum reflectivity in the wavelength range of 300 nm–1100 nm, in consideration of the forbidden energy gap of silicon.

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High-precision, low-temperature-sensitive microelectromechanical system (MEMS) capacitive accelerometers are widely used in aerospace, automotive, and navigation systems. An analytical study of the temperature drift of bias (TDB) and temperature drift of scale factor (TDSF) for an asymmetric comb capacitive accelerometer is presented in this paper. A five-layer model is established for the equivalent expansion ratio in the TDB and TDSF formulas, and the results calculated by the weighted average of thickness and elasticity modulus method are closest to the results of the numerical simulation. The analytical formulas of TDB and TDSF for an asymmetric structure are obtained. For an asymmetric structure, TDB is only related to thermal deformation and fabrication error. Additionally, half of the fixed electrode distance is not included in the expressions of Δ d and Δ D for asymmetric structures, thus resulting in the TDSF of the asymmetric structure being smaller compared to a symmetric structure with the same structural parameters. The TDSF of the symmetric structure is [−200.2 ppm/°C, −261.6 ppm/°C], while the results of the asymmetric structure are [−11.004 ppm/°C, −72.404 ppm/°C] under the same set of parameters. The parameters of the optimal asymmetric structure are obtained for fabrication guidance using numerical methods. In the experiment, the TDSF and TDB of the packaged structure and the non-packaged structure are compared, and a significant effect of the package on the signal output is found. The TDB is reduced from 3000 to 60 μg/°C, while the TDSF is reduced from 3000 to 140 ppm/°C.

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