Surface Micromachined Accelerometers
Dr. Gary Atkinson
The mission of this project is
to fabricate accelerometers
(such as those found in air
bag deployment systems)
using surface micromachining
accelerometers have never
been fabricated in the
Center Cleanroom. The
problem faced with surface micromachining is the stress on the cantilever beams (shown in figure
below) and the adhesive properties of the deposited films. This project focused on obtaining a
process that can successfully fabricate a structure that would experience a sudden acceleration
using surface micromachining techniques.
After intensively researching existing processes for surface micromachined accelerometers and
analyzing the limitations of the VMC cleanroom, a preliminary procedure was developed. This
procedure factored in the adhesive properties of deposited metals, the stress of the metal after
each step, and the proper release of the overall structure.
In theory, the preliminary procedure developed appeared to have no complicated issues. As the
process was carried out, issues arose that required the re-evaluation of the procedure. The majority
of the problems encountered arrived from the adhesion and thicknesses of the deposited layers.
After altering these parameters, successful accelerometers were fabricated and tested.
Considering that the VMC cleanroom has yet to attempt surface micromachining, the success of this
project has the potential to enhance the capabilities of the School of Engineering cleanroom. The
VMC now has a preliminary procedure to fabricate surface micromachined devices. This will allow
future students to improve this process and advance the VMC’s abilities to make more surface
micromachined devices. As the accelerometers experience a force, the constructed structures bend.
Once the force stops acting on it, the accelerometer vibrates until it returns to its original position.
This is similar to how a diving board acts when a person jumps off of it.
Acknowledgements: Josh Starliper, VMC Lab Technician, Will Clavijo, Graduate Student/Former
VMC Intern, and Dr. Michael Cabral, Associate Professor