Laser scanning confocal vibration microscopy for simultaneous in-situ detection of topography and vibration

Confocal microscopy (CM) has emerged as a widely adopted technique for the three-dimensional geometric characterization of micro-electromechanical systems (MEMS), owing to its non-contact nature and sub-micrometer resolution. However, the rapid development and widespread adoption of MEMS resonant devices have rendered standalone static topography measurements inadequate to meet evolving characterization requirements. This gap necessitates innovative approaches for synchronous in-situ detection of geometric and dynamic parameters during device operation. To address this challenge, this study proposes a novel laser scanning confocal vibration microscopy (LSCVM) method that enables simultaneous topographical mapping and vibrational parameter acquisition without requiring operational state switching. The LSCVM method utilizes continuous wavelet transform (CWT) to perform time–frequency analysis on vibration-coupled confocal axial response curves, thereby extracting vibrational parameters. Concurrently, linear bilateral fitting of skewed segments is applied to derive topographic parameters. Through this approach, the LSCVM method achieves simultaneous topographic and vibrational detection via a single axial scan, attaining a geometric spatial resolution of 300 nm and an amplitude resolution of 0.4 nm. Experimental validation using a micro-cantilever beam device confirmed the feasibility and advantages of the LSCVM method, demonstrating its potential as a novel approach for the in-situ performance evaluation of operational MEMS devices.