Ph.D. Dissertation Defense by James F. Nichols
Tuesday, March 30, 2004
( Dr. Thomas Kurfess, Chair)
"Metrology of High Aspect Ratio MEMS"
The current tools for geometric analysis of MEMS are primarily limited to those of the semi-conductor industry. These tools are suited for measuring entities that are two-dimensional in nature such as lines, circles, and planes. Hardware that is capable of collecting three-dimensional data is typically limited by the slope variations in the surfaces of the part, and cannot accurately capture information from steep sidewalls, especially in parts fabricated using the LIGA microfabrication process.
This research develops a methodology to qualify MEMS, by implementing a novel
computer-aided inspection (CAI) software framework. This software platform uses
data acquired from current MEMS inspection hardware, and applies newly developed
analysis algorithms to geometrically characterize a part. This work implements
algorithms for all the procedures typical to a CAI program (e.g., point-to-entity
assignment, registration, and data analysis) in addition to new techniques suited
for inspection of high aspect ratio MEMS. This methodology describes possible
registration errors based on the type of geometries being analyzed and the type
of data acquired. Analyses of multiple point clouds with the use of fiducial
information are shown to provide a critical link between single point cloud
analyses that has heretofore been unrealized.