The ESD Handbook

24MEMs

24.1 Micro-electromechanical (MEM) Devices

Micro-electromechanical (MEM) structures are being developed for a large range of applications from basic electrical components, micro-engines, and micro-mirrors [1–10]. For motors, MEMs are being used as “energy scavengers” converting the energy of mechanical vibration to electrical energy. MEM electrical components include capacitors, inductors, and switches [1–10]. MEMs are also being used as arrays of micro-mirrors [10]. Today, there are a wide range of applications that are being explored from electrical, biomedical, consumer, multi-media, hand-held electronics, energy to military needs. A key issue that is unique and common in all these devices is that the majority of the MEM structures are as follows:

• MEM structures contain air gaps.
• MEM structures contain air cavities or suspended structural elements.
• MEM structures have moveable elements.
• MEM structure mechanical motion is initiated by electrostatic fields (electro-statically actuated).

As a result, the failure mechanisms of MEM structures are a function of both electrical failure, and mechanical failure [1–10]. Mechanical failure can consist of creep, fatigue, wear, and “stiction.” The failure of operation of a MEM structure can be associated with structural damage impeding the motion of the movable elements. Electrical failure can be associated with surface or air gap breakdown. The electrical breakdown can lead to structural melting, electrostatic deflection, or ...