EVALUATION OF MEMS (MICRO-ELECTRO-MECHANICAL SYSTEMS) USING ACOUSTIC MICRO IMAGING

摘要

MEMS (Micro-Electro-Mechanical Systems) are a rapidly growing technology. Presently MEMS are used mostly in automotive and medical applications and increasingly in RF microelectronics and photonic applications. The materials, fabrication and packaging of MEMS share some similarities with IC (Integrated Circuit) packages. MEMS also share some similar package related failure mechanisms to ICs such as delamination. In fact delaminations can be more of a problem in MEMS than in IC systems as there are more varied bonding applications used in MEMS. Acoustic Micro Imaging (AMI) has become an established method to evaluate the quality and reliability of IC packages from the standpoint of package integrity. Ultrasound is sensitive to variations in the elastic properties of materials and is particularly sensitive to locating air gaps (delaminations and voids). Since there are a number of similarities in the packaging of MEMS and IC devices AMI is proving a valuable tool in the non-destructive analysis of MEMS. However the construction and packaging of MEMS is often more complex than typical IC packages which presents certain challenges for AMI inspection. Therefore, the AMI techniques of examining the devices had to evolve to accommodate the changes. This paper will discuss AMI techniques pertinent to MEMS and a survey of applications.