SCRATCH DRIVE ACTUATOR WITH MECHANICAL LINKS FOR SELF-ASSEMBLY OF 3-DIMENSIONAL MEMS

The self-assembling of three-dimensional (3-D) MEMS from polysilicon s urface micromachined part is very attractive. To avoid risky external manipulation, the practical use of integrated actuator to perform the assembling task is required. To that goal, this paper presents detaile d characteristics of the electrostatic surface micromachined scratch d rive actuator (SDA). First, from numerous SDA test, it results that th is actuator is able to produce a threshold force of 30 mu N, with a yi eld above 60%. With polysilicon devices consisting of SDA mechanically linked to buckling beam, a horizontal force of 63 mN have been demons trated with +/-112 V pulse, and up to 100 mu N can be obtain with high er voltage. With buckling beams, displacements up to 150 mu m have bee n obtained in the vertical direction. The generation of vertical force of 10 mu N was confirmed with a 100 mu m displacement producing in 1 nJ work in the vertical direction. Finally, SDA proves to overcome the usual sticking of surface machined polysilicon by producing enough ve rtical force to completely release wide polysilicon plate (500 mu m x 50 mu m) without external manipulation. The above characteristic, both in terms of structure releasing and vertical/horizontai forces and di splacements provide the SDA with the capability of self-assembling com plex 3-D polysilicon part, opening new integration capabilities and ne w application held of MEMS.