A Plasma-Therm Deep Reactive Ion Etcher (DRIE) became fully functional Oct. 25, for the Systems Engineering Department Fuze and Initiation Branch, at Naval Surface Warfare Center Indian Head EOD Technology Division (NSWC IHEODTD).
The machines capabilities and efficiency will simplify processes at the Fuze and Initiation Branch. DRIE fulfills a vital role in Microelectromechanical Systems (MEMS) device fabrication. MEMS are microscopic mechanical and electro-mechanical devices.
“MEMS are way smaller than your typical mechanical device but larger than integrated circuits,” said Ezra Chen, a NSWC IHEODTD mechanical engineer in the Fuze and Initiation Systems Branch. “MEMS are used in accelerometers such as air bag-sensors, shock-sensors, pressure sensors, but mostly in car air bags. Other applications of MEMS include Inertial Measurement Units (IMUs), printer heads and video game controllers. We’re leading up to incorporating MEMS into products developed here.”
According to Chen, DRIE is a method of very high aspect ratio etching into silicon using the “Bosch Process” known as pulse etching. NSWC IHEODTD has been working with MEMS since 1995. Historically, NSWC IHEODTD used various contractors to fabricate MEMS devices. Now, with the DRIE on site design cycles between MEMS fabrication runs will be drastically reduced.
“DRIE is a time saver and a cheaper option,” he said. “Previously we had to rely upon outside contractors to etch our designs. We often encountered difficulties fitting into their schedule. With DRIE on station the design cycle gets much shorter.”
Within every weapon system a fuze is used to ensure weapon safety along with providing a detonation for the warhead. Current MEMS technologies are not incorporated into the mechanical systems used for fuzing.
“The problem with current fuzing systems is they’re too big,” Chen said. “We’re trying to shrink fuzing systems in various weapons systems. The traditional mechanical systems can be unreliable; they have a lot of gears and widgets. Because of the complication of their operation and assembly a lot of duds occur. Many fuze systems are old and don’t pass current safety criteria. MEMS will help shrink fuzing mechanisms, and will upgrade the technology to make fuzing mechanisms more safe and reliable.”
DRIE will create the mechanical structures via etching within the MEMS that enable the safety and arming functions.
“The more defined etch the stronger and more safe the safe and arm system becomes,” Chen said. “You can’t shrink explosives indefinitely; but I think we’re close to what the lower limit is. A deeper etch allows more space for explosives to be inserted for a more effective result.”