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Semiconductor and biomedical devices

Automating Inspection of Biomedical Wafers

A probing station that images thousands of electrodes and measures test structures, while staying fully usable for R&D.

The problem

A manufacturer of silicon wafers for biomedical devices needed to verify the quality and repeatability of its process. That meant imaging thousands of electrodes for defect analysis, and stepping a probe card through test structures to take electrical measurements.

What we built

Pre-loaded definition files tell the station where every device sits on the wafer. The application moves a Wentworth Pegasus prober through those locations, streams high-resolution images to disk in a structured way, and runs V-I measurements through Keithley instruments and a multiplexer.

That took custom LabVIEW drivers for the prober over GPIB and for the microscope over RS-232, plus changes to the frame grabber’s supplied driver.

The result

The station works as a production test system, and still gives engineers almost full manual control for diagnostics and R&D.

Automated Probe Station main control panel with setup, wafer imaging, and structure testing controls
The main interface coordinates setup, imaging, and electrical testing.
Wafer map showing the current probe position as a red dot
Live position on the wafer during a run.
Electrical measurement results panel with plots and pass or fail indicators
Measurement results with visual pass/fail indicators.