Bistable nanomechanical beams for data storage


  • Contact Researcher: Benoit CHARLOT, Dr.
  • Hosted LIMMS Japanese Laboratory: Hiroshi TOSHIYOSHI Lab --- thematiques

Project Overview

  • Keywords
MEMS, data storage, memory, bistable, microbeam
  • Context :
There is a large research activity nowadays in the development of non-rotating MEMS based data storage devices. These new devices are developed to fit the gap between large disk drives and Flash RAMs. Most of these systems are composed of servo actuators for moving arrays of AFM/STM like probes over a recording media. The information is stored on the media through several mechanisms (magnetic, optical or plastic deformation like the Millipede project at IBM[1]) and read by a local probe which is scanned on the media surface by a MEMS or piezoelectric XY stage. These systems[2] will benefit from smaller size, lower cost, better access time and shock resistance compared to actual rotating disk systems[3] and thus will address the huge portable device market. Beside the development of actuator systems, some recent works were related with the fabrication of MEMS based memory point. In this case the data is store within the mechanical state of a microstructure actuated by an electrostatic force. A research team at Cornell University and the Cavendish kinetics[4] company have both developed such systems. Micro bridges or cantilevers are switched toward pull-in by an electrostatic force and are maintained in this position. The reading is made by measurement of the capacitance of the structure.
  • Objectives :
The goal of this project is to evaluate the possibility to build a mechanical bistable micro / nano structure to be used as a non-volatile memory point for a MEMS data storage device.
  • Methods :
An in plane clamped clamped beam is created from a prestressed material (Silicon dioxyde). When released the beam will relax in an asymetric deformed shaped (Euler beam). Once in that position, the beam can be actuated with the electrostatic force from a static electrode to buckle in the other stable position. The reading of the position of the beam through a capacitive method allows then to read the bit. At this moment of the project, the device has been built with a specific process using electron beam lithography and reactive ion etching to create beams with 200nm width and 10µm length. As can be seen in the SEM picture above, the structures is relaxed in a stable position. Futher works will be devoted to the electrostatic buckling




  1. Vettiger P.; Cross G.; Despont M.: Drechsler U.; Durig U.; Gotsmann B.; Haberle W.; Lantz M.A.; Rothuizen H.E.; Stutz R.; Binnig G.K.; “The millipede - nanotechnology entering data storage”. IEEE Transactions on Nanotechnology, Vol. 1 , Issue 1, March 2002, Pages:39–55.
  2. Carley, R.L.; Ganger, G.R.; Nagel, D.F.; “MEMS-Based Integrated-Circuit Mass-Storage Systems”. Communications of the ACM, November 2000, Vol.43, No.11.
  3. Alfaro J.F.; Fedder G.K.; “Actuation for Probe-Based Mass Data Storage”. Technical Proceedings of the 2002 International Conference on Modeling and Simulation of Microsystems.
  4. Cavendish Kinetics