Large area contact resonance spectroscopy mapping system for on-the-machine measurements

A piezo resistive, phase locked loop (PLL) controlled micro tactile measurement system for on-the-machine contact resonance spectroscopy (CRS) mapping of square centimeter sized areas is developed and evaluated. For the CRS-based layer and material analysis, we used a robust, large dimension, piezo resistive silicon cantilever (length × width × thickness of 5 mm × 200 μm × 50 μm) probe. A compact, LabVIEW-controlled, fully automated scanning system using a homemade software PLL circuit for resonance frequency tracking and out-reading was realized. Different layer thicknesses of photo resist (PR) on silicon (from 11 ± 2 nm to 1653 ± 76 nm) and material transitions of different Young's moduli were used to validate the system. For optimization of the sensor sensitivity and efficiency, amplitude and phase were analyzed under different conditions (contact force, excitation amplitudes). Using CRS for on-the-machine analysis of tools and work pieces can be a valuable method for quality assurance and reproducibility of future industrial manufacturing and just-in-time production.