As one of the many nano-device fabrication techniques employed in the semiconductor industry, neutral beams are being examined using various methods to solve possible charge-related problems that occur during device processing. This review introduces a neutral beam generated by surface neutralization of an ion beam using a low angle forward reflection technique and explains its application to various areas such as surface treatments and etching. The neutralization efficiency of an ion beam using a low angle forward reflection technique was approximately 99.7%. When a metal-oxide-semiconductor device was etched using a reactive neutral beam, it was confirmed that charge-related problems such as aspect-ratio-dependent etching and gate oxide charging could be removed using reactive neutral beam etching instead of conventional reactive ion etching. Neutral beams can be beneficial to other devices such as the III-V device and field emission device.

Copper-catalyzed cross-and carbonylative coupling reactions have been achieved in the reaction of a variety of alkynyliodonium salts with arylboronic acids and organostannanes under the mild reaction conditions in high yield. Our investigation shows that the alkynylidonium tetrafluoroborates are more efficient than those of triflates and tosylates.

A CoFeB thin film composing a magnetic tunneling junction of CoFeB/MgO/CoFeB was etched in an inductively coupled plasma ͑ICP͒ etching system using CO/NH 3 gas mixtures, and its etch characteristics were compared with those of the CoFeB thin film etched using Cl 2 /Ar. When Cl 2 /Ar was used to etch the CoFeB thin film, even though its etch rate was faster than that of the CoFeB thin film etched using CO/NH 3 , a rough CoFeB surface could be observed due to the corrosion of the CoFeB surface during exposure to the air in addition to the significant change of surface composition. On the other hand, no corrosion of the CoFeB thin film was observed after the etching using CO/NH 3. When the ratio of CO/NH 3 was varied, the highest etch rate of 12 nm/min could be observed at the ratio of 1:3 compared to about 4 nm/min for CO or NH 3 at the ICP source power of 700 W, bias power of 300 W, and 5 mTorr of operating pressure. The highest etch rate was related to the formation of volatile metal carbonyls between metal and CO, where NH 3 appeared to assist the easier formation of metal carbonyl by preventing the dissociation of CO into C and CO 2 .

The etch characteristics of magnetic tunneling junction (MTJ) materials and the etch selectivity over W have been investigated using RF pulsebiased conditions in addition to the continuous wave (CW) bias condition with a CO/NH 3 gas combination in an inductively coupled plasma system. By using a time-averaged substrate DC bias voltage condition for the RF pulse biasing, the etch rates of MTJ materials for the RF pulsebiased conditions were generally similar to those etched using the CW RF bias condition even though the etch rates were slightly decreased with decreasing the duty percentage of the RF pulse biasing. However, the use of the RF pulse biasing improved the etch selectivity of the MTJ materials over mask materials such as W. When the surface roughness and the residual thickness remaining on the etched surface of the MTJ material such as CoFeB were investigated by using atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS), respectively, it was clear that the use of the RF pulse biasing instead of CW RF biasing also decreased the residual thickness and the surface roughness. This is believed to be related to the formation of a more uniform chemically reacted layer on the etch CoFeB surface during the RF pulse-biased etching condition.

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.