15 cm shiny wafer with multiple membranes vibrating at 38 kHz
The new Optonor system for wafer level vibration testing can do full field testing of shiny and non-shiny wafer surfaces up to 25 cm or more. Such wafers may contain up to several hundred individual MEMS units or membranes, which can be tested at wafer level before cutting and packaging. The Optonor Wafer Tester can do full field recording like shown in the figures within less than 0.2 seconds, where the vibration amplitude and phase of each MEMS or membrane is measured. A full frequency scan, which can take less than 10 seconds, detects the resonance frequency for each individual MEMS or membrane unit. This is used to check the quality of each individual unit, and to detect defect units.
The figure above show higher order vibration modes, while a frequency scan will normally look for the lowest frequency mode, such modes are shown below
Cross section plot of shiny wafer vibrating at 38 kHz
2,5 kHz. This recording takes less than 0,2 seconds to finish
A full frequency scan of a large wafer with up to several hundreds MEMS or membranes takes typically less than 10 seconds