Unified characterization of surfaces and gases in MEMS devices

Chemical and physical materials-aging processes can significantly degrade the long-term performance reliability of dormant microsystems. This degradation results from materials interactions with the evolving microenvironment by changing both bulk and interfacial properties (e.g., mechanical and fatigue strength, interfacial friction and stiction, electrical resistance). Eventually, device function is clearly threatened and as such, these aging processes are considered to have the potential for high (negative) consequences. Sandia National Laboratories is developing analytical characterization methodologies for identifying the chemical constituents of packaged microsystem enviromnents, and test structures for proving these analytical techniques. To accomplish this, we are developing a MEMS test device containing structures expected to exhibit dormancy/analytical challenges, extending the range of detection for a series of analytical techniques, merging data from these separate techniques for greater information return, and developing methods for characterizing the internal atmosphere/gases. Surface analyses and data extraction have been demonstrated on surfaces of various geometries with different SAMS coatings, and gas analyses on devices with internal free volumes of 3 microliters have also been demonstrated.