Inertial Sensors R&TD Group

Inertial Sensors R&TD GROUP

Technical leader: Dr. Said Emre Alper
Group Members (Alphabetical Order):

  • Burak Eminoğlu (M.Sc. student)
  • Erdinç Tatar (M.Sc. student)
  • İlker Ender Ocak (Ph.D. student)
  • Mert Torunbalcı (M.Sc. student)
  • Serdar Tez (Ph.D. student)
  • Soner Sönmezoğlu (undergraduate student)
  • Uğur Sönmez (M.Sc. student)

Alumni

  • Emre Şahin (M.Sc., 2009)
  • Kanber Mithat Silay (M.Sc., 2006)
  • Kıvanç Azgın (M.Sc., 2007)
  • Korhan Şahin (M.Sc., 2008)
  • Mehmet Akif Erişmiş (M.Sc., 2004)
  • Refet Fırat Yazıcıoğlu (M.Sc., 2003)
  • Reha Kepenek (M.Sc., 2008)
  • Yüksel Temiz (M.Sc., 2007)

Research Interests:

  • Design
    • Theoretical design and analysis of MEMS inertial sensors
    • Finite element modeling
    • Analytical modeling of complete inertial sensor systems
  • Fabrication
    • Silicon-on-glass micromachining
    • Dissolved-wafer silicon micromachining
    • Electroforming
    • Wafer-level vacuum packaging
  • Circuit design
    • Low-noise preamplifier design
    • Hybrid and CMOS analog circuit design
    • Closed-loop controller design
  • Packaging
    • Hybrid substrate design for the integration of sensor and electronics
    • Vacuum packaging of integrated inertial sensor systems
    • Compact packaging of MEMS inertial sensor systems
  • Testing
    • Wafer-level testing of fabricated inertial sensors
    • Modular testing of system sub-modules.
    • Performance characterization of the inertial sensor systems

Milestones:
Inertial sensors research has been initiated at METU in 1998.  Over the years, the group has conducted research on various topics with the following milestones:

  • 1998: Development of the concept of a symmetric and decoupled MEMS gyroscope.
  • 1999: Fabrication of the first gyroscope prototypes using polysilicon surface micromachining process offered by MCNC (currently MEMSCAP).  Development of the first preamplifier designs using 0.8mm CMOS process offered by AMS.
  • 2001: Started development of in-house MEMS fabrication processes including dissolved-wafer process and nickel electroforming.  Also started design and development of MEMS accelerometers.
  • 2003: Design and fabrication of MEMS inertial sensors using SOIMUMPS process offered by Cronos Microsystems (currently MEMSCAP).
  • 2005: Started development of silicon-on-glass (SOG) micromachining process using 100mm-thick silicon substrates
  • 2007: Integration of MEMS inertial sensors with hybrid preamplifier and control circuits inside platform packages.
  • 2009: Started development of a new silicon-on-glass micromachining process using SOI wafers.  Also started development of a new dissolved wafer process using silicon wafers with thick epitaxial layers.

Currently, the group has developed MEMS gyroscope and accelerometer prototypes with bias instabilities better than 10deg/hr and 100mg, respectively.

Inertial Sensors R&TD Group has the capability of fabricating silicon MEMS inertial sensors over glass substrates. Fabrication over 4-inch substrates yield more than 150 sensor dies per wafer.

Close-up view of fabricated silicon-on-glass inertial sensors.

Close-up view of an inertial sensor fabricated at METU-MEMS Research Center by dissolved-wafer micromachining process.


Another sensor fabricated with silicon-on-glass micromachining process, occupying an area of less than 25mm2.

Thickness of the fabricated inertial sensors varies in the range 15 to 100mm, depending on the fabrication process.

Electrostatic actuation and capacitive sensing mechanisms contain features as small as 1m.

Fabricated sensors are suspended a few microns over the substrate, with the help of flexible suspensions and anchors.

Performances of the fabricated inertial sensors are closely related with the quality and precision of the fabrication process.

It is possible to seal the sensors inside a cavity under vacuum ambient.

Volume of the wafer-level packaged inertial sensor die is smaller than 0.2cm3.


Fabricated inertial sensors are integrated with electronic control circuits over hybrid substrates.  These substrates are then mounted in a suitable hybrid platform package.

Hybrid platform packages can be welded under vacuum using projection welding.


Fabricated inertial sensor chips are tested with a micromanipulator probe station, before being integrated with electronics.

There is a number of special test equipment located at METU‑MEMS Research Center, including single-axis rate table and vibration table.

 
The performance of the inertial sensors fabricated at METU-MEMS Research Center approaches to the
performances of state-of-the-art MEMS inertial sensors available in the market..