Dual-axis piezoresistive cantilevers: design, fabrication and characterization

Abstract

In the preceding chapters it was shown how reading and writing in AFM data storage can be accomplished with simple planar cantilevers incorporating the appropriate functionality. To form a complete storage system, however, a data tracking method is required as well. This is because of the inevitable runout that occurs when a data disk is not precisely centered with respect to the spindle axis (see Fig. 5.1). In this situation, the read head needs to be able to move from side to side in order to follow a particular data track on the spinning disk. In addition, there needs to be a mechanism by which the read head senses any deviation from the track. Finally, the deviation signal—usually called the tracking error signal (TES)—needs to be processed by a servo controller that constantly adjusts the position of the read-head actuator in order to maintain tracking.