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To validate the possibility of the developed microwave plasma source with a novel structure for plasma aerosol deposition, the characteristics of the plasma flow velocity generated from the microwave plasma source were investigated by a Mach probe with pressure variation. Simulation with the turbulent model was introduced to deduce calibration factor of the Mach probe and to compare experimental measurements for analyses of collisional plasma conditions. The results show calibration factor does not seem to be a constant parameter and highly dependent on the collision parameter. The measured plasma flow velocity, which witnessed fluctuations produced by a shock flow, was between 400 and 700 m/s. The optimized conditions for microwave plasma assisted aerosol deposition were derived by the results obtained from analyses of the parameters of microwave plasma jet. Under the optimized conditions, Y2O3 coatings deposited on an aluminum substrate were investigated using scanning electron microscope. The results presented in this study show the microwave plasma assisted aerosol deposition with the developed microwave plasma source is highly feasible for thick films with &gt, 50 μm.

Silicon carbide (SiC) is an emerging material for applications in ultra-precision devices and space optics due to its low thermal expansion characteristics (3.8×10−6/℃) and light density (3g/cm³). However, machining and polishing of SiC are challenging because of its hardness and stiffness. Further, the conventional mechanical processing methods could result in micro-cracks on the surface of SiC, which consequently degrade the lifetime of the device under harsh conditions. We find that very smooth polishing of SiC without any surface damage is possible using plasma atomic layer etching, an emerging technology in the field of semiconductor manufacturing. In the present study, we conducted experiments to identify the mechanism of plasma atomic layer etching for bi-atomic materials and elucidated the optimized processing conditions to minimize the surface roughness of the etched SiC. By using process gases, such as SF6, H2, and O2, the etch rate could be controlled and the increase in the surface roughness could be minimized. We identified three main reasons for the increase in the surface roughness. The first is different etching speed of the silicon and carbon by fluorine active species. The second is the masking effect of C-H-F films produced during process. The last is the selective etching of silicon oxide and the other layers by fluorine active species. Due to the low etching property of silicon oxides, the surface roughness may increase at a faster rate under rich oxygen condition. Conversely, it is possible to minimize the surface roughness by adjusting the ratio of process gases. Under the optimum conditions of SF6 and O2 gas ratio (0.8), the etch rate of 1 layer/cycle and the roughness increment of 0.1 nm were obtained

To deposit copper seed layer on ultra large scale integration devices, a large-area (O 378 mm) electron cyclotron resonance plasma has been generated by using permanent magnets-embedded Lisitano antenna. The plasma source operates in the pressure range of 0.2–1.5 mTorr with microwave power range of 500–2,000 W. By using a Langmuir probe, the electron density and temperature have been measured near the DC sputter target position. Measurements indicate argon plasmas having electron densities of ~5 × 1010/cm and electron temperatures of 5 eV with 750 W microwave power at gas pressures of 0.5 mTorr. Using this plasma source and a DC sputter, we obtained excellent conformal copper seed layer with high aspect ratios of 12:1. This is in contrast with conventional methods using magnetron sputter, which has aspect ratios of 2–3:1. Also, improvements are observed in the smoothness (root mean square roughness of 1.345 nm), uniformity (2.5 % at 300 mm wafer), and sidewall symmetricity (more than 95 %) of the copper seed layer.

Hydrogen was produced from water plasma excited in high frequency (HF) inductively coupled tubular reactor. Mass spectrometry was used to monitor gas phase species at various process conditions, Water dissociation rate depend on the process parameters such as ICP power, flow-rate and process pressure, Water dissociation percent in ICP reactor decrease with increase of chamber pressure, while increase with increase of ICP power and flow rate. The effect of gas addition to a water plasma on the hydrogen production has been studied in a HF ICP tubular reactor. The main roles of additive gas in plasma are to react with 0 radical for forming and CHO and resulting additional production. Furthermore, additives in plasma is to suppress reverse-reaction by scavenging 0 radical. But, process optimization is needed because addition has some negative effects such as cost increase and emission.

Hydrogen is produced by direct dissociation of water vapor, i.e., splitting water molecules by the electrons in water plasma at low pressure (