案例:MEMS MicrophoneA MEMS microphone is composed by a diaphragm vibrating between two holed back-plates. Measurement of topography and vibration modes of each of them are challenging :
The diaphragm has a one millimeter diameter and has to be measured through the grid of 7 microns diameter holes of the back-plate.
The 1 micrometer thin back-plate silicon membranes is transparent for visible and near IR illumination. It is a source of measurement artifacts due to multiple reflection through and by the plates.
MEMS microphone : Diaphragm ⌀1mm, lateral resolution 0.5 µm Crop : detail of ⌀7 µm back-plate holes Stitched up measurement in stroboscopic modeStitching algorithms enable to combine multiple individual measurements to produce a high lateral resolution topography map of the microphone over its complete surface. It enables diaphragm characterization through the back-plate holes.
Combining stitching with stroboscopic synchronization acquisition provides a time sequence of both the diaphragm and the back-plates topographies along the excitation period of the microphone. Complete vibration analysis of each of them can be performed.
Movie:
Field of view : 1 x 1 mm
Lateral resolution : 0.5 μm
32 topographies are recorded along the excitation period
10×10 stitching : each topography measurement has a super high resolution of 30 MpxUV laser sourceThe thin silicon back-plate membranes is totally reflective using a DHM® operating with UV light sources. It prevents from any measurement artifact observed using blue, green, red or NIR wavelengths.