The holographic MEMS analyzer solution provides time sequences of the successive 3D topographies of a MEMS along its driving signal. This unique set of data contains an unrivalled wealth of information. In particular, in- and out-of-plane displacements and frequency response can be analyzed at any location within the measurement field of view.
The Lyncée Tec holographic MEMS analyzer includes a complete characterization environment including:
The MEMSTool software enables efficient analysis of 3D topography time-sequences in term of
An international team of researchers from Spain, the Netherlands, and USA have characterized the flexoelectric coefficient of dielectric materials on silicon by measuring the bending radius induced on application of voltage, with the DHM®. Nature publication
The DHM, unlike a vibrometer, directly measures the out of plane displacement induced at each point of a MEMS structure during a vibrational excitation .
Thus, the DHM data lends itself elegantly to harmonic analysis via the application of discrete Fourier transform techniques. The latter is indispensable to distinguish between a response that scales linearly with the applied electric field (for example, piezoelectric strains) and a response that scales quadratically with the applied electric field (for example, electrostictive strains).
German researchers from FHG-IPMS in Dresden, and TU Cottbus Senftenberg have measured the deflection of a revolutionary micro-actuator technology using DHM® (IPMS-FHG press release). Nature publication, Electronic Component News
We can work with any dynamics we want (stroboscopic and continuous measurement) – that makes the DMH unique to alternative tools (WLI and Laser-Doppler-Vibrometer).
It gives the high vertical resolution to precisely characterize the actuator out of plane deflection
A vibrometer measures a velocity using the Doppler effect: tip deflection is calculated by an integration. Consequently, position measurement errors are also integrated, preventing absolute prosition and long term drift measurements.
DHM® doesn’t suffer from this problem as it measures directly a position. Deflection can be measured accurately for any time scale.
The Holographic MEMS Analyzer solution encompasses all the options to provide you with a complete environment for MEMS characterization. The system responds to most users characterization needs, however if something is missing, Lyncée Tec is also pleased to provide you with turnkey customized solutions.
MEMS probing platforms enable direct DHM® characterization of devices without wire-bonding. A heated version enables the investigation of the effects on MEMS responses of temperatures up to 200°C.
Vacuum & thermal chambers enable characterization of devices in real conditions of use, e.g. vacuum, liquids, gas, high and low temperature, down to 196°C, high pressure, etc. Measurements are as simple as in ambient conditions thanks to DHM® unique optical configuration.
Reflection and transmission DHM® with one and two wavelengths are fully compatible with the Holographic MEMS Analyzer solution. They can be configured with any objective, including long working distances, immersion, and glass corrected models, for measuring in presence of probes, in liquid, and through transparent covers respectively.
The stroboscopic unit synchronizes the MEMS excitation with the 3D topography time sequence and electrical response measurements. is recorded to get 3D topographies time sequences along the excitation of the MEMS, vibration and electrical information in a single data set with one system.
The MEMS Analysis Tool software enables movement decomposition in terms of tilt, deformation, in- and out-of-plane displacements. Vibration amplitude, speed and acceleration at any location of the sample can then be calculated. Moreover, this software enables resonance, Fourier, and Bode frequency analysis.
Holographic MEMS Analyzer overcomes limitations of usual MEMS analyzers. It is the only solution able to synchronize MEMS excitation and 3D topography measurement at frequencies up to 25 MHz. Moreover, it is ideal to measure in any environmental condition. Alternative systems are :
The main difference between both systems is that the DHM® retrieves simultaneously data points on each pixel on the entire field of view while LDV scans the surface point by point. Therefore LDV lateral resolution is limited by the spot size (few microns). With DHM® you can select the lateral resolution adapted to your sample by choosing the appropriated objective. LDV has to perform a complex chain of signal processing steps to measure a velocity. Each data point is then converted in term of vibration amplitude. LDV alone does not provide an absolute position and thus no 3D topography. DHM® measures a time sequence of successive 3D topographies what enables direct calculation of absolute position, speed and acceleration. Vibrations amplitude can be determine with high reliability by DHM®.
Features | DHM® | 3D LDV | LDV |
Dynamic topography | |||
3D vibrations (X,Y,Z) | XYZ | XYZ | Z only |
Maximum frequency | 25 MHz | 25 MHz | up to 1.2 GHz |
Full field measurement | with XY scanning | with XY scanning | |
Diffraction limited resolution | limited by laser spot size | limited by laser spot size | |
Objective turret | |||
No need of sample preparation | – diffusive sample required | ||
Measurement of complex structures | |||
Measurement of complex motions (simultaneous in-, out- of plane, tilt, … ) | ++ | – | – |
Measurement of in-plane displacement lager than MEMS structures |
2D stroboscopic microscope is usually combined with LDV to add in-plane displacement measurement capabilities to vibrometer.
Features | DHM® | 2D Stroboscopic Microscopy |
3D topography | ||
3D vibrations (X,Y,Z) | 1 | |
Maximum frequency | 25 MHz | 1 MHz |
Full field measurement |
Some white light interferometers can perform a stroboscopic acquisition to measure MEMS dynamic topography. However, measurements of dynamic sample with a scanning technology are sensitive to environmental noise, i.e. vibrations, and are time consuming. Some systems combine white light interferometer with LDV or 2D stroboscopic acquisition in order to measure a static topography. In this case measurements of topography in environmental chamber face usual limitations of WLI technology.
Features | DHM® | WLI |
Dynamic topography | –1 | |
3D vibrations (X,Y,Z) | –1 | |
Maximum frequency | 25 MHz | 1 MHz |
Stitching measurement | not in stroboscopic mode | |
Measurement in environmental chamber | –2 |
1. WLI are usually used for static topography. Scanning technologies are not adapted to dynamic measurement 2. Limited choice of objective with window (glass) compensation
Optical measurement unit | Reflection DHM® or Transmission DHM® |
MEMS excitation unit | LyncéeTec stroboscopic module |
XYZ stage | Manual or motorized stage |
Software | Koala for acquisition and live analysis MEMS Analysis Tool for advanced post-analysis |
Objective | Turret with 6 positions, magnification from 2.5x to 100x |
In-plane vibration2 | from 10 nm to 5 mm |
Out-of-plane vibrations2 | from 10 pm to 75 μm |
Topography resolution | Vertical : 0.3 nm Lateral1 : from 400nm to 8.5μm |
Excitation frequency | from static to 25 Mhz |
Laser pulse length | down to 7.5 ns |
Max vertical velocity2 | up to 10 m/s |
1. equivalent to vibrometer spot size, objective dependent 2. specification does not depend on excitation frequency
Lyncée Tec Challenge 2022 was successfully launched in May 2022 to call for the best MEMS application which demonstrates the DHM® unique strengths for vibration map measurements. The winner receives a DHM® holographic MEMS analyzer as their prize! After more than 6 months, Silicon Austria Labs SAL won this award for their outstanding and innovative demonstration of measuring dynamic deformations of MEMS mirrors at all scanning angles using DHM’s unique full field vibration mode shape analysis. Congratulations to the winner and to all participants!
For more details, please visit webpage: https://challenge.lynceetec.com/
Among all applications, 5 best measurements are shown below.