Development of a Sharp-Tipped L-Shaped Stylus for Measurement of Nanoscale Sidewall Features

This paper presents a system for measuring nanoscale sidewall features using an L-shaped stylus with a sharp tip. By sharpening the tip of the stylus to the nanometer scale, it is possible to measure nanoscale sidewall features. The stylus shaft is deflected when the sharpened stylus tip contacts the measured surface, and this deflection is measured optically. In this study, we develop the fabrication method of an L-shaped sharpened stylus 20 μm in diameter and 4 mm in length by etching, CO2 laser processing, and bonding. Then, the measurement accuracy and repeatability are examined by measuring V-grooves with nanoscale features. The results clarify that the pitch is approximately 0.3 μm, which is almost the same as the value measured using the photographic image, but the depths measured by the styli fabricated by CO2 laser processing and bonding are approximately 0.15 and 0.07 μm, respectively. The depth measured by the stylus fabricated by bonding is smaller than that measured from the image (approximately 0.16 μm), presumably because of the morphological filter. The maximum repeatability errors for 10 measurements using the styli fabricated by CO2 laser processing and bonding are within ±0.056 and ±0.022 μm in scanning mode, respectively. It is also confirmed that the stylus tip exhibits minimal wear even after 500 measurements.