Optical characterization of dynamics inside Si-capped MEMS
Dynamic characterization of MEMS devices to measure and visualize mechanical response is important for product development, trouble shooting and FE model validation. The MSA Micro System Analyzers from Polytec provide fast, accurate optical measurements of out-of-plane (OOP) and in-plane motion (IP). Until now, this has been limited to unpacked devices that are optically accessible. Now, the Polytec MSA-650 IRIS Micro System Anlayzer allows even measuring through intact silicon caps on encapsulated microstructres like e.g. intertial sensors, MEMS microphones, pressure sensors and more.
Highlights
- IR capability to measure MEMS dynamics through different layers of Si-capped devices
- Real-time out-of-plane response measurement up to 25 MHz (w/o post-processing)
- Sub-picometer out-of-plane displacement resolution
- Straighforward FE model validation of MEMS in final state
- Superior separation of the individual device layers
- Stroboscopic video microscope to measure in-plane motion up to 2.5 MHz
- Automated system that integrates well for production (probe station compatibility)
Superior separation of the individual device layers
The MSA-650 IRIS turn-key measurement solution comprises a controller, function generator with additional reference channels, powerful optical scanning software suite and optical sensor head with a sophisticated IR-optical design. With its dedicated IR camera and a low-coherence SLD source it is the premier full-field vibration measurement system to capture entire sample layers through silicon caps under operating conditions. This patented interferometer technology delivers excellent data quality due to superior separation of the individual device layers.
Modal testing of silicon encapsulated MEMS
As silicon is transparent in the near infrared spectrum above wavelengths of 1050 nm, the underlying technology of infrared-interferometer-based vibration measurement opens up the possibility for inspecting of encapsulated MEMS for authentic and most representative analysis results. Polytec‘s brand new, patented state-of-the-art interferometer technology now delivers supreme data quality due to superior separation of individual device layers in the si-capped MEMS devices. With a dedicated SWIR camera and a low-coherence SLD source the MSA-650 IRIS is the worldwide first measurement system with this patented technology to visualize the si-encapsulated devices, measure in-plane vibration with down to 30 nm resolution and real-time out-of-plane vibrations up to 25 MHz with picometer resolution and below.
Use the leading technology in vibration analysis
In order to use Laser Doppler vibrometry (LDV) for a look into encapsulated MEMS, it is necessary to study the optical properties of silicon. While silicon is opaque for visible light, it shows a good transmission in the near- infrared range starting at around 1050 nm. A limitation for transmission however, is the high refractive index of around 3.4 at 1550 nm leading to considerable Fresnel reflections at boundary interfaces.
The Poyltec patented approach uses short coherent light to improve accuracy. In contrast to laser light, low coherent light from a superluminescence diode only interferes if the light paths in the interferometer are balanced within the coherence length of the source. Thereby excluding light from outside the focus. This principle is utilized in white- light interferometers or for optical coherence tomography and now for the first time in the Laser Doppler Vibrometry (LDV). Enabling scanning LDV measurements with 25 MHz bandwidth and with an amplitude resolution of 100 fm/√Hz on encapsulated MEMS.
Accessories and components
Tripods, test stands, positioning stages
A-STD-TST-01 Test Stand
Test stand providing ample workspace. With motorized z-axis, travel range 200 mm.
A-STD-BAS-02 Base Stand
Rigid support for the sensor head. Includes manual focus block with 100 mm travel range with coarse and fine drive. Interfaces to commercially available optical tables.
A-STD-F50 Focus Block
Travel Range 50 mm. With coarse and fine drive for manual z-axis adjustment of the sensor head. Interfaces with commercially available wafer probe stations.
Vibration isolation, breadboards
A-TAB-AIR-01 Active Vibration Isolation Table
Air-damped vibration isolation table with active level adjustment. Compatibility: A-STD-TST-01 Test Stand, A-STD-BAS-02 Base Stand.
A-TAB-ELC-01 Active Vibration Isolation Table
Electronically controlled voice coil stabilization for highest isolation performance. Compatibility: A-STD-TST-01 Test Stand, A-STD-BAS-02 Base Stand.
A-BBO-ME02 Breadboard
Breadboard with metric hole pattern. Footprint 900 mm x 600 mm. Compatibility: A-STD-BAS-02 Base Stand.
A-AVI-MELA Active Vibration Isolation Breadboard
Electronically controlled for highest vibration isolation performance. With metric hole pattern. Footprint 600 x 800 mm. Compatibility: A-STD-BAS-02 Base Stand.
Miscellaneous
MSA-A-WPM Wafer Prober Module
Together with the A-PST-200P XY Positioning Stage, the wafer prober module forms a motorized platform for electrical contacting and high-precision measurement of wafers and substrates up to 200 mm in diameter.
Related products
Analyseur de microstructures MSA-600
Système de mesure tout-en-un pour la caractérisation 3D statique et dynamique des MEMS et des microstructures - maintenant jusqu'à 2,5 GHz. Le MSA-600 améliore les processus de développement et de contrôle qualité. Intégré aux stations sous pointes disponibles dans le commerce, il permet des tests au niveau des wafer.
Analyseur de microstructures 3D MSA-100
L'analyseur de microstructures saisit simultanément des composantes vibratoires dans les trois directions spatiales. Il permet l'analyse 3D de vibrations haute résolution avec une résolution d'amplitude de l'ordre du sous-picomètre pour des composantes vibratoires dans le plan et hors plan.
Analyseur de microstructures MSA-050
Le vibromètre sous microscope d’entrée de gamme permet de saisir des vibrations sur l’ensemble de la surface de petits éléments et de microstructures. Il fonctionne parfaitement sans contact et mesure la de petits objets avec une extrême précision.
PSV Software
The PSV Software is the heart of every Polytec full-field vibration measurement system. This comprehensive software package allows the fast and simple acquisition, display and editing of vibration measurement data gathered with all PSV Scanning Vibrometers, the MSA Micro System Analyzer series for microscopic observations or the automated structural test station RoboVib®.