Tactile probing system based on micro-fabricated capacitive sensor

Abstract

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 0.3mm probing head is used, the probing system has a resolution of better than 10nm along axial direction and better than 25nm 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 0.3mm and depth down to 2.3mm.