Nondestructive static and dynamic MEMS characterization using supercontinuum scanning white light interferometry

Scanning White Light Interferometry (SWLI) provides high vertical precision for measuring step-like structures in microelectromechanical systems (MEMS). The SWLI performance depends on its light source. A rapidly modulated light source with a broad bandwidth inside the infrared (IR) region is necessary to measure layered MEMS that move. Typical SWLI light sources - light emitting diodes (LEDs) and Halogen (HG) bulbs - fulfill only one of these requirements. To overcome this shortcoming we equipped our SWLI setup with a supercontinuum (SC) light source produced by Fiberware Gmbh (Ilum 100 USB II). We tested our setup by measuring in plane and out of plane oscillating thermal bridges with visible light, as well as top and bottom surfaces of silicon structures using IR light. The wide SC spectrum creates localized interferograms. This allowed us to measure top and bottom surfaces of a thin (4 μm) bridge. The stroboscopically measured profiles of oscillating thermal bridges were comparable to those measured using a white LED. The results of static measurements were similar to those achieved with an HG lamp.