Present and future developments of SPM systems as mass storage devices

SPM technology offers a great potential to increase storage data density. The use of magnetic force microscopy (MFM) and scanning capacitance microscopy (SCM) as possible methods for a future ultrahigh-density-storage (UHDS) device has been explored. Two methods to create parallel large areas of nanometer-settle magnetic dots have been developed. The first technique is based 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 the imaging and manipulation of these magnetic dots with full width at half maximum (FWHM) of 150 nm and smaller. Furthermore we have explored the possibility of using a scanning capacitance microscope (SCM) for charge storage. A metallic cantilever was positioned over a nitride-oxide-silicon (NOS) heterostructure. The SCM measures the capacitance as a function of the bias voltage and can detect the stored charge by the displacement of the CV curve. This technique allows a data density of more than 180 bit/mu m(2). Besides 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 between tip and sample for all commercial scanning probe microscopy (SPM) devices, we have developed a high speed SCM prototype which has the potential to reach data rates of Mbit/s.