Development of a High-Function Fiber Stylus for Microstructure Measurement with Water-Repellent and Antistatic Coatings

The precise measurement of microstructures and other micron-sized materials has garnered considerable interest in recent years. We have developed a measurement system that uses an etched small diameter optical fiber as a stylus to measure microstructures with low contact force. However, when the diameter of the stylus tip is less than a few tens of micrometers, the surface forces between the measured surface and the stylus tip become larger than the gravity of the stylus tip, causing the stylus tip to stick to the measured surface. This adhesion leads to an increase in measurement time and a decrease in measurement accuracy. In this study, we fabricated a high-function stylus with water-repellent and antistatic coatings applied to the stylus tip to reduce the adhesion between the stylus tip and measured surface due to surface forces, and conducted performance evaluation tests. As a result, the average separation distance was 13.8 µm when a fluorinated resin coating with a contact angle of 105° was used, confirming that the influence of liquid bridge forces could be reduced by approximately 78%. Additionally, when static elimination experiments were conducted by scanning the charged surface at a pitch of 0.5 µm using an antistatic coating stylus with a gold on the stylus surface, the average adsorption distance was 3.6 µm, confirming that the effect of electrostatic force could be reduced by 71%.