Production metrology for MEMS characterization

Accurate measurements of MEMS geometries and motions are crucial to achieving the desired performance of the devices. The wide variety of MEMS devices in development and production requires very flexible metrology for single-platform characterization. In addition to having greatly varying geometries, devices must also be characterized statically and under actuation. White-light interferometry, fortunately, is a technique flexible enough to meet most MEMS measurement needs. This high-speed, non-contact measurement method allows both large lateral and vertical ranges with nanometer-level vertical resolution and position accuracy. When standard illumination is replaced with strobed light, dynamic measurements of MEMS can also be carried out. This paper presents some of the hardware and software design considerations for producing a single metrology platform with the required flexibility for production MEMS metrology. Several static and dynamic MEMS measurements are presented to illustrate the design requirements.