Present and future developments of SPM systems as mass storage devices

SPM technology offers a great potential to increase storage data density. T he use of magnetic force microscopy (MFM) and scanning capacitance microsco py (SCM) as possible methods for a future ultrahigh-density-storage (UHDS) device has been explored. Two methods to create parallel large areas of nan ometer-settle magnetic dots have been developed. The first technique is bas ed on nanometer latex balls that serve as a mask. For the second method the mask is produced by means of interferometric lithography. The MFM allows t he imaging and manipulation of these magnetic dots with full width at half maximum (FWHM) of 150 nm and smaller. Furthermore we have explored the poss ibility of using a scanning capacitance microscope (SCM) for charge storage . A metallic cantilever was positioned over a nitride-oxide-silicon (NOS) h eterostructure. The SCM measures the capacitance as a function of the bias voltage and can detect the stored charge by the displacement of the CV curv e. This technique allows a data density of more than 180 bit/mu m(2). Besid es a high data density, a high data rate is an important requirement for a mass storage device. To overcome the problem of the low relative velocity b etween tip and sample for all commercial scanning probe microscopy (SPM) de vices, we have developed a high speed SCM prototype which has the potential to reach data rates of Mbit/s.