Three-Dimensional Nanofabrication Utilizing Selective Etching of Silicon Induced by Focused Ion Beam Irradiation

A simple process of fabricating a three-dimensional nanostructure on a silicon surface was investigated in this study. The silicon surface area irradiated by focused ion beam (FIB) was selectively etched in HF, whereas the non-irradiated area was scarcely etched, and consequently, a concave nanostructure was fabricated on the irradiated area. To control the depth of the nanostructure, the depth dependence on ion irradiation parameters was investigated. As a result, it was found that the depth of the irradiated area can be controlled by changing ion irradiation parameters, such as dose and ion energy. Under a low-dose condition, the irradiated area was scarcely etched, due to the formation of an amorphous layer on the interior of silicon. Subsequently, it was etched in KOH to evaluate the mechanism of this phenomenon. In addition, the surface roughness dependence on ion irradiation parameters was investigated. Finally, three-dimensional nanostructures were fabricated on the basis of these results, suggesting that this method is a novel three-dimensional nanofabrication method

Effect of Acoustic Emission Sensor Location on the Detection of Grinding Wheel Deterioration in Cylindrical Grinding

The acoustic emission (AE) technique is an effective method for monitoring grinding wheels, and numerous studies have been published on applying an AE to monitor grinding wheels. However, there are few studies on the effect of the location of the AE sensor in stably acquiring the AE signals generated during deterioration in cylindrical grinding wheels. In this study, we propose a stable method for detecting the deterioration of a cubic boron nitride (cBN) grinding wheel during cylindrical grinding using AE. We compared the AE signals acquired during grinding from an AE sensor located on the hydrostatic bearing, which supports the grinding wheel shaft, with those from the tailstock spindle. Although positioning the AE sensor on the hydrostatic bearing was found to reduce the AE signal intensity, the AE signal variations were smaller at the same grinding position, and the effect of the grinding position was less than that for the tailstock spindle. Moreover, positioning an AE sensor on the hydrostatic bearing is considered to provide the characteristics of AE signals specifically focused on the changes in cBN on the grinding wheel surface allowing the surface roughness of the workpiece to be estimated during grinding