MEMS

An important research area at Draper is the design, prototyping, and test of microelectromechanical systems (MEMS). We have invested in technologies fundamental to MEMS inertial instrument design, including deep reactive ion etching (DRIE), wafer bonding, resonant sensor design, g-hard mechanical design, and custom vacuum packaging.


The DRIE technology enables both silicon-on-insulator wafer etching and through-wafer etches with sidewall angles approaching 90 degrees. This capability supports design of thicker sensors with increased scale factors, improved signal-to-noise ratios, and less temperature sensitivity. As validated by DoD, Draper has demonstrated the best MEMS gyro performance in an IMU over military specified environments for temperature, shock, and vibration. Draper MEMS accelerometer designs accommodate applications with varying dynamic range and sensitivity requirements. Resonance quality factors in excess of 100,000 enable the Silicon Oscillating Accelerometer to accurately and stably measure micro-g accelerations. These MEMS instruments form the core technology of the most advanced guidance systems being developed for the Navy and the Army.

The breadth of MEMS inertial sensor capability and infrastructure has spawned the growth of new MEMS technologies, devices, and systems. Deep silicon etching has been applied to fabrication of a MEMS mirror and flexure supports for a novel resonance-based, low power LIDAR. Anisotropically etched silicon is used to fabricate molds for polymer scaffolds to support cell growth. Deep silicon etching, coupled with anodic bonding, supports the fabrication of a MEMS ion-mobility spectrometer that, as a reusable gas sensor, outperforms similar systems orders of magnitude larger in size. Draper’s ability to dry-etch glass allows construction of waveguide structures used in the development of a novel integrated optic gyro.

Low-stress thin film deposition is also a critical Draper technology. We have fabricated a directional microphone that relies on a structural frame of thick polysilicon to provide a stiff, lightweight membrane for acoustic sensing. Other thin film capabilities include silicon nitride and oxides. Draper’s experience with piezoelectrically actuated MEMS is being used to develop an RF resonator (100 MHz – 1 GHz) design and a flexural plate-wave based microfluidic pathogen detector. The technology for microfluidic delivery and control of samples to MEMS sensors is a growing area that has many applications outside of sensing. MEMS microfluidics is enabled both by advanced mechanical design and polymer processing techniques. Draper can place metallization on polymers, use lasers for precision micromachining, conduct replica molding, and apply either lamination or spin coating to create polymer layers.

Draper’s microfabricated components are used in areas ranging from environmental monitoring, surveillance, communications, and inertial navigation, to sensors for medical diagnostics, drug delivery and control, and medical prostheses. Our expertise in anisotropic through-wafer etching, wafer bonding, submicron features, and electromechanical design will continue to enable new innovations in applications such as microphones, optical waveguides, and MEMS-based frequency standards.

The future of MEMS technology at Draper will include a heavy emphasis on attaining smaller (nano-scale) features in existing sensors and processes and the development of novel materials such as piezoelectrics and polymers for existing as well as new applications.

Facilities

• Class 100-1000 clean rooms
• Submicron alignment facility
• Metal, dielectric semiconductor thin film deposition equipment
• Deep reactive ion etching and ICP equipment
• Wafer bonding facility
• Optical, SEM, electrical, and mechanical metrology

Applications

• Inertial instruments
• Biomedical sensors
• Environmental monitoring and surveillance
• Communications systems
• Drug delivery and control
• Chip-scale atomic clocks

Technologies / Capabilities

• Dissolved wafer process development
• Polymer process development
• Electro/thermal/mechanical device design/modeling
• Vacuum packaging
• Wafer thick processes
• Piezo, electrostatic, magnetic devices