Tactile probing system based on micro-fabricated capacitive sensor

With the development of micro systems in recent years, the demands for ultraprecision measurement become more important in the field of dimensional metrology. In this paper, a tactile probing system based on capacitive sensor for precision metrology is presented. The capacitive sensor is fabricated by MEMS technique, and a commercial micro-probe and the capacitive sensor are integrated together to constitute the initial probing system. The signal processing circuit is designed to be based on AD7747 chip which is substantially a high resolution, Σ-Δ capacitance-to-digital converter (CDC). Then the experiment set-up is configured and experimental results indicate that when a 0.3 mm probing head is used, the probing system has a resolution of better than 10 nm along axial direction and better than 25 nm along radial direction. With the low residual nonlinear error, the proposed system can therefore be used for submicron measurement of small structures with dimension larger than 0.3 mm and depth down to 2.3 mm.

► Tactile probing system based on micro capacitive sensor is designed and fabricated by MEMS technique. ► A high precision experimental set-up including piezoelectric nano-positioning stage is configured. ► We design signal processing circuit based on AD7747 capacitance-to-digital converter. ► The probing system is tested and proved to be used for submicron measurement of small structures.