Fully automated MEMS vibration analysis in cleanroom: Polytec Micro System Analyzer now with ISO-3 certification and script automation

(Copyright: Polytec GmbH)

With the Micro System Analyzers (MSA-600, MSA-650 IRIS, MSA-100-3D), Polytec has been addressing contactless characterization of MEMS dynamics and topography for years – from individual dies to wafer-level testing on probe stations. The current expansion combines this optical measurement technology with a certified cleanroom configuration and new automation functions, enabling fully automatic processing of complete wafer maps in externally controlled lab and fab workflows.

Technical innovations for a broader range of applications

- Cleanroom-certified configuration: MSA Micro System Analyzers are available in an ISO 3 cleanroom-certified version, making them suitable for demanding front-end processes.
- Automated wafer map measurement: The goal is fully automatic measurement and evaluation of all devices on a wafer, including resonance frequencies, quality factors, and mode shapes for each component.
- Script and recipe control: In the Polytec PSV software, recipes for automated measurement sequences at the individual die level can be defined, which can be scaled to entire wafer maps via scripts and external controls.
- Integration into fab workflows: Network-based remote control enables integration into fab-managed workflows, e.g., via a PLC/SPS of the production line.
- The setup time, including wafer alignment and script configuration, typically takes only about 20 minutes for new devices or wafers.
- Automated grid alignment via image processing and autofocus ensure precisely reproducible measurement conditions and accurate results for each die and all wafers.

Application context: wafer-level testing of MEMS

The established approach for characterizing the dynamics of MEMS components at the wafer level uses a microscope-based scanning laser Doppler vibrometer system on a (semi-)automatic probe station to contactlessly capture resonances, mode shapes, and process variations. The automated sequence of coarse positioning, focusing, contour recognition, frequency sweep, and mode shape scan can now be implemented as a fully script- and recipe-based measurement cycle for each position on the wafer map with the new MSA automation functions.

Example of an automated workflow

- Transfer of a wafer map (coordinates/devices) from the fab database.
- Automatic XYZ positioning on the next die, autofocus, and grid alignment via image processing.
- Fast single-point measurement for resonance search, followed by fine frequency sweep and optional surface scan of the mode shape.
- Feedback of measurement data for pass/fail classification to the fab MES/PLC system and statistical analysis across the entire wafer.

Increased productivity in MEMS development and manufacturing

- Higher throughput: Fully automated measurement sequences reduce cycle time per die to seconds and enable 100% testing in series production.
- Early rejection of defective devices: Wafer-level tests sort out defective structures before dicing, reducing unit costs and scrap.
- Better model and process control: Denser data sets on resonance frequencies and mode shapes improve correlation with FEM models and process drift monitoring (with special test structures).
- Reliable cleanroom integration: The ISO 3-certified version of the MSA systems facilitates qualification in regulated production environments and reduces validation effort.

About the Micro System Analyzer

The Polytec Micro System Analyzers are optical measurement platforms for static and dynamic 3D characterization of MEMS and microstructures – from laboratory setups to integrated wafer-level measurements on probe stations. They combine laser Doppler vibrometry with high-resolution microscope optics and support frequencies from DC into the MHz or GHz range, including in-plane and out-of-plane vibrations as well as IR transmission measurements on encapsulated structures.