AVS 53rd International Symposium
    MEMS and NEMS Tuesday Sessions
       Session MN-TuA

Paper MN-TuA7
Molded Electromechanical Shift-Register Memories

Tuesday, November 14, 2006, 4:00 pm, Room 2007

Session: Fabrication and Characterization of MEMS and NEMS
Presenter: G.M. McClelland, IBM Research Division, Almaden Research Center
Authors: G.M. McClelland, IBM Research Division, Almaden Research Center
B. Atmaja, IBM Research Division, Almaden Research Center
Correspondent: Click to Email
Mechanical bistability is a simple well-understood phenomenon that can be used to store information. However, most designs for mechanical memories require individual elements to be addressed, written, and read electrically. We propose a much simpler design in which bistable levers are arranged in a shift register, so that information is accessed by the simple electrostatic interaction of neighboring levers. A shift register containing > 1000 bits can be operated with only two conductors. The shift register can be molded in a single step from a single elastomeric material (e.g PDMS). In one design, the levers are conducting, and a voltage pulse from a single top electrode pulls charge to the levers, inducing repulsion, and shifting information. We have built a working 100-cm-scale memory based on this idea. In another design, which can work in a liquid, the insulating levers are charged with alternating signs to create primary and secondary components of individual memory cells. The problems of coding, initializing the memory, and recovering from errors are analyzed. A "broadcasting" scheme is described, in which the first lever is made unique, so that only it responds to a write pulse from the upper electrode, while the other elements respond to only shift pulses. These memories have been studied using both realistic finite element methods and phenomenological models. An integration scheme is proposed in which a crosspoint array of shift registers is imprinted into a series of optical waveguides. This structure can be read and written by electrical attachment to only one edge, enabling a memory system in which many layers can be "shingled" onto a silicon drive chip. This geometry, combined with simple one-imprint layer manufacturing, could allow solid state storage with the price/bit of disk drives.