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, - 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.
© 2013 Elsevier B.V. All rights reserved.
1. Introduction
The increasing demands of micro systems in industry for
ultraprecision measurement has led to the development of the
field of micro and nano dimensional metrology [1–3]. Many measurements
can be performed on coordinate measuring machines
(CMMs) with micro-probes that can access the narrow channels
on workpiece [4,5]. In general, CMM contains a high accuracy
probing system composed of a specific micro-probe and a focus
sensor [6–8]. According to different sensors in probing system,
the methods of probing to achieve high accuracy are diverse,
such as piezoresistive, capacitive, optical and inductive [9–11].
Various institutes have developed prototype micro-probes with
high precision, the typical research work is as follows.
The probe by the Physikalisch-Technische Bundesanstalt
(PTB) consists of a membrane with integrated piezoresistive strain
gauges, a stylus with probe tip is attached to the center of the membrane
using epoxy adhesive. The strain gauges are used to detect
deformations of the membrane and can thus be used to measure a
displacement of the probe tip. However, a membrane suspension
is overdetermined, which may result in internal stresses when
∗ Corresponding