There is growing consensus that exercise improves cognitive functioning, but research is needed to identify exercise interventions that optimize effects on cognition. The objective of this pilot study was to evaluate Taekwondo implemented in public middle school physical education (PE). Two classes were randomly assigned to either: five sessions per week of PE or three sessions of PE and two sessions of Taekwondo. In PE sessions, evidence-based curriculum to address the Presidential Core Fitness Guidelines and California Physical Fitness Tests was implemented. Taekwondo sessions included traditional techniques and forms taught in an environment emphasizing respect and self-control. Sixty students were evaluated at baseline and during the last week of the intervention (nine months later). Differences in mean residualized change scores for parent-rated inhibitory behavioral control yielded a significant, large effect size (d =.95, p =.00), reflecting greater improvement among Taekwondo students. Results from an executive function computer-administered task revealed greater accuracy on the congruent trial (d = 2.00, p = .02) for Taekwondo students. Differences in mean residualized change scores for BMI z scores yielded a moderate, non-significant effect size (d = − .51, p = .16). The majority of Taekwondo students reported positive perceptions of Taekwondo and perceived self-improvement in self-control and physical fitness. Results suggest that Taekwondo is an exercise program that improves cognitive functioning and is both feasible and acceptable to implement in a public school setting.

X-ray photoelectron spectroscopy was used to determine the level of surface fluorination damage of Ge2Sb2Te5 (GST) etched by fluorocarbon gases at different F/C ratios. When blank GST was etched, the gas with a higher F/C ratio produced a thinner C–F polymer on the etched surface but fluorinated Ge, Sb, and Te compounds were observed in the remaining GST. When the sidewall of the etched GST features was investigated, a thicker fluorinated layer was observed on the GST sidewall etched by the higher F/C ratio gas, indicating more fluorination due to the difficulty in preventing F diffusion into the GST through the thinner C–F layer.

No abstract

As the packing density increases in the fabrication of semiconductor chips, the aspect ratio and the critical dimension (CD) of a metal contact are exponentially aggravated in dry etch processing. The aspect ratio dependency of plasma-induced charging damage during the rf precleaning of a metal contact has been evaluated with a two-dimensional Monte Carlo simulation and with related experiments. From the simulation of a metal contact opened on a gate metal, it is found that the potential on a metal contact bottom, which is directly related to plasma-induced charging damage, is saturated near an aspect ratio of 4 after initially linearly increasing with the aspect ratio. However, the linear decrease of CD of a metal contact exponentially increases the potential stress on the gate oxide. These simulation results are confirmed with the two different experiments, an in situ charge-up monitoring and the electrical test of fully fabricated complementary metal–oxide–semiconductor wafers. A phase controlled inductively coupled plasma is newly proposed to suppress the plasma-induced charging damage. With this system, the plasma-induced damage is strongly suppressed when the phase delay of the bias power to the source power is near 180°.

We developed a new method to enhace the photoresist selectivity in SiO2 etching by modulating both the source and bias powers and by controlling the phase difference between the modulation functions. Enhancement of mask selectivity was observed in the pulse plasma, especially in the out-phase condition. To understand the heavy polymerization in the out-phase pulse plasma, we analyzed the ion energy distributions of CF x +(x=1, 2, 3) ions using the energy-spectroscopic quadrupole mass spectrometer (QMS) and measured the waveforms of the bias power with a high-voltage probe which was connected directly to the wafer. Two distinct plasma potential distributions were obtained in the pulse plasma and the dc bias voltage (V DC) was maximum in the out-phase condition. The heavy polymerization in the out-phase condition was explained as a result of high V DC. We also investigated the emission intensity of the C2 (516.5 nm) line, and found that C2 species were precursors of the polymerization and contributed to the heavy polymerization in the out-phase condition.