The time variation of the plasma parameters along with their spatial distributions were measured in pulse-modulated (PM) inductively coupled argon plasma via the phase delay harmonic analysis method (PDHAM). During the initial active-glow, the distributions of both the ion flux and the electron temperature in the plasma bulk have M-shaped profiles due to the antenna geometry. Then, while the plasma is approaching a steady state, the spatial distribution evolves into a profile with a convex shape. The effects of the antenna geometry and the time evolution on the distribution profile are lesser under low gas pressure, and diminish at the wafer level. The diffusion of the charged particles and the nonlocal electron kinetics account for these characteristics. It is observed that the initial distribution of the electron temperature is affected by the electron density distribution of the previous after-glow at the wafer level. The distribution profiles at different pulse frequencies were also measured. At higher pulse frequencies, the distribution profile is more frequently smoothed by diffusion during the after-glow, leading to higher uniformity.
For appling low temperature co-fired ceramics technology on NiZnCu ferrite with Ag electrode, the synthesis of nano-sized NiZnCu ferrite powders using metal nitrates and the fabrication of ferrite thick films by a doctor blade method were carried out. Microstructural analysis confirmed that nano-sized ferrite powders and fully densified thin films were successively fabricated. At a sintering temperature of 950 °C the magnetic properties of the ferrite thick film with 0.2 -0.3 mol Cu were close to those of bulk materials (permeability > 450, coercivity < 3 Oe).
We explore the effect of high-speed blade coating on electrical characteristics of conjugated polymer-based thin-film transistors (TFTs). As the blade-coating speed increased, the thickness of the polymer thin-film was naturally increased while the surface roughness was found to be
unchanged. Polymer TFTs show two remarkable tendencies on the magnitude of field-effect mobility with increasing blade-coating speed. As the blade-coating speed increased up to 2 mm/s, the fieldeffect mobility increased to 4.72 cm2V−1s−1. However,
when the coating speed reached 6 mm/s beyond 2 mm/s, the field-effect mobility rather decreased to 3.18 cm2V−1s−1. The threshold voltage was positively shifted from 2.09 to 8.29 V with respect to increase in blade-coating speed.
Physical and microstructural properties of Pungchon and Maggol limestone were investigated quantitatively during 50 cycles of artificial freezing and thawing test. There were decrease in dry weight and P,S-wave velocity, and increase in absorption rate in both rock types. Porosity, pore volume, equivalent diameter, throat thickness and pore orientation were analyzed using X-ray computed tomography images. Porosity increased, and initiation and expansion of pores were investigated as weathering progresses. Physical and microstructural variation in Maggol limestone was larger than that of Pungchon limestone because Maggol limestone has more pores and microcracks at initial state. As this study analyzes physical and microstructural properties of rock specimens comprehensively, it can be applied to further rock weathering study and can be used as fundamental data of construction and resource development in cold regions.
In cylindrical floating probe measurements, the plasma density and electron temperature are overestimated due to sheath expansion and oscillation. To reduce these sheath effects, a compensation method based on well-developed floating sheath theories is proposed and applied to the floating harmonic method. The iterative calculation of the Allen-Boyd-Reynolds equation can derive the floating sheath thickness, which can be used to calculate the effective ion collection area; in this way, an accurate ion density is obtained. The Child-Langmuir law is used to calculate the ion harmonic currents caused by sheath oscillation of the alternating-voltage-biased probe tip. Accurate plasma parameters can be obtained by subtracting these ion harmonic currents from the total measured harmonic currents. Herein, the measurement principles and compensation method are discussed in detail and an experimental demonstration is presented.
A monitoring device is proposed to investigate the charge accumulation effects in a high-aspect-ratio trench structure. This monitoring device is made of an anodic aluminum oxide (AAO) template, which is a self-organized material with parallel pores, to demonstrate a high aspect ratio trench structure. A top electrode and bottom electrode were formed in the AAO contact structure for measuring electric potentials. These electrodes can be assumed to be electrically floating due to the very high input resistance of the measurement circuit. Therefore, the electric potentials resulting from the charge accumulation can be measured. In this paper, the fabrication process of the proposed device and experimental demonstrations are presented.
The authors propose a noninvasive electrical plasma monitoring method that uses two initially present metal reactor substrates, without the probe insertion. When a small sinusoidal voltage is applied between these two substrates, harmonic currents flow in a closed-loop circuit through the plasma. Assuming that the plasma exhibits nonlocal electron kinetics, the electron temperature and plasma density are determined based on an asymmetric double probe harmonic currents analysis. Experimental demonstrations were conducted in an inductively coupled plasma reactor, in which a grounded substrate and a bias electrode were used as the current-sensing electrodes. The electron temperature and plasma density measured with the proposed method agree well with measurements from a floating-type planar probe. This method can be applied to processing reactors that have no available port for electrical probe installation.
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