To minimize radiation damage caused by charge buildup or ultraviolet and x-ray photons during etching, we developed a high-performance neutral-beam etching system. The neutral-beam source consists of an inductively coupled plasma (ICP) source and parallel top and bottom carbon plates. The bottom carbon plate has numerous apertures for extracting neutral beams from the plasma. When a direct current (dc) bias is applied to the top and bottom plates, the generated positive or negative ions are accelerated toward the bottom plate. Most of them are then efficiently converted into neutral atoms, either by neutralization in charge-transfer collisions with gas molecules during ion transport and with the aperture sidewalls in the bottom plate, or by recombination with low-energy electrons near the end of the bottom plate. We found that negative ions are more efficiently converted into neutral atoms than positive ions. The neutralization efficiency of negative ions was almost 100%, and the maximum neutral flux density was equivalent to 4.0 mA/cm2. A neutral beam can thus be efficiently produced from the ICP source and apertures in our new neutral-beam source.

To avoid several kinds of radiation damage caused by charge build-up and by ultraviolet and X-ray photons during etching processes, we have developed a high-performance, neutral-beam etching system. The neutral-beam source consists of an inductively coupled plasma (ICP) source and top and bottom carbon parallel plates. The bottom carbon plate includes numerous apertures for extracting neutral beams from the plasma. By supplying a direct current (DC) bias to the top plate, the generated ions are accelerated towards the bottom plate. Most of them are efficiently converted into neutral atoms, either by neutralization in charge-transfer collisions with gas molecules during the ion transport and with aperture sidewalls in the bottom plate, or by recombination with low-energy electrons near the end of the bottom plate. When the aperture diameter and aperture length were 1 mm and 10 mm, respectively, the neutralization efficiency was almost 100% and the neutral flux density was equivalent to 1.2–2.8 mA/cm2. A neutral beam could thus be produced efficiently from the ICP source and the apertures in the bottom plate.

To prevent several kinds of radiation damage caused by charge build-up and by ultraviolet and X-ray photons during etching processes, we have developed a high-performance, neutral-beam etching system. The neutral-beam source consists of an inductively coupled plasma (ICP) source and top and bottom carbon parallel plates. The bottom carbon plate includes many apertures for extracting neutral beams from the plasma. By supplying a positive or negative direct current (DC) bias to the top and bottom carbon plates in the pulsed SF6 plasma, the generated positive or negative ions are respectively accelerated towards the bottom plate. The negative ions are more efficiently converted into neutral atoms in comparison with the positive ions, either by neutralization in charge-transfer collisions with gas molecules during the ion transport or with aperture sidewalls in the bottom plate. The neutralization efficiency of negative ions was more than 98% and the neutral flux density was equivalent to 4 mA/cm2.

Interface quality of Sc2O3 and Gd2O3 films based metal-insulator-silicon structures using Al, Pt, and Ti gates: Effect of buffer layers and scavenging electrodes J. Vac. Sci. Technol. B 31, 01A106 (2013); 10.1116/1.4768678Damage-free metal-oxide-semiconductor gate electrode patterning on thin HfSiON film using neutral beam etching J.Study of neutral-beam etching conditions for the fabrication of 7-nm-diameter nanocolumn structures using ferritin iron-core masks A 50-nm-width metal-oxide-semiconductor ͑MOS͒ gate etching process was established using a recently-developed neutral-beam etching system by optimizing the gas chemistry and the electrode bias condition. In a comparison with poly-Si gate etching using either SF 6 or Cl 2 gas chemistries, opposite etching characteristics were observed in the pattern profile. Consequently, the use of a mixture of these gases was proposed in order to achieve fine control of the etching profiles. The energy of the neutral beam was increased by applying a 600 kHz rf bias to the bottom electrode. The rf bias was very effective in increasing the etch rate and the anisotropy of the poly-Si gates, with no deterioration of the neutralization efficiency. The oxide leakage current achieved for a MOS capacitor etched by the neutral beam was one order of magnitude lower than that achieved by conventional plasma etching.

Fast atom beam (FAB) etching of multicomponent glass and silica glass was performed using a contact mask (electron beam resist) and two non-contact masks (typically 5-µ m-diameter particles and a copper mesh with a 5 µ m line width and 20 µ m line spacing). FAB etching of a multi component glass substrate with the micro-particle mask successfully fabricated a precisely projected, 1.0-µ m-high outline pattern on the substrate. FAB etching of a silica glass substrate with the copper-mesh mask, which was separated from the substrate by about 100 µ m, successfully produced a projected, 34-nm-high outline pattern on the substrate. A combination of electron beam lithography with FAB etching on silica glass successfully fabricated nano-scale ultrafine patterns whose aspect ratio was higher than 7 (50 nm line width and 360 nm height). In all three fabrications, the side walls and etched surfaces were very smooth and were perpendicular to each other.