We present a method for data storage in continuous ferroelectric (FE) media, applicable to storage systems based on one or more scanning probes. Written FE domains are read back in a destructive fashion by applying a constant voltage of magnitude greater than the coercive voltage, as is done in FE random access memory (FeRAM). The resulting flow of screening charges through the readback amplifier provides sufficient signal to allow readback of domains of minimum dimension of the order of 10 nm at MHz rates, orders of magnitude faster than previously demonstrated techniques for readback of domains in continuous FE media.

Many advanced microsystems rely on nanometer-resolution in-plane motion between two substrates requiring precise control of gap spacing. Accurately maintained gaps may not only provide desired mechanical response but also enable position-sensing and signal transduction between the substrates. A method of passive gap-spacing control using MEMS-fabricated rigid spacers is proposed. A model to design a low-friction and low-wear interface between the sliding substrates is developed. Prototype parts with hard-coated interfaces and with and without lubrication were fabricated and tested. Sliding friction coefficients of less than 0.1 were achieved on prototype parts with boundary lubrication over a million sliding cycles. Wear life of several million sliding cycles is predicted.

We report a novel MEMS read-write head for probe data storage using ferroelectric (FE) media. In our FE storage approach, the minimum bit length is not dependent on the physical dimension of the writer electrode, which simplifies the writer fabrication. FE media has the advantages of high thermal stability, narrow domain walls, and low-voltage writability compared with magnetic storage. A read-write head based on MEMS technology is presented, along with process details. Preliminary test results on a scan stand show an obtainable areal density approaching 1 Tb/in2 with our prototype head and media.

Applications involving sub-nanometer, relative, in-plane motion between two substrates require precise control of gap-spacing between substrates for, both position-sensing as well as for signal transduction between the substrates. A method of passive gap-spacing control using MEMS-fabricated rigid spacers is proposed. A model to design a low-friction and low-wear interface between the sliding substrates is developed. Prototype parts with hard-coated interfaces and with and without lubrication were fabricated and tested. Sliding friction coefficients of 0.1-0.15 or less and wear life of millions of sliding cycles were achieved on prototype parts. Better results are predicted for MEMS-scale devices.

In this paper, we investigated the conditions at the electrochemical interface for additive adsorption during the pulse current deposition of a CoFeNi alloy. Depending on the magnitude of the pulse currents used, different potentials and the corresponding additive coverage of CoFeNi surface are established affecting the CoFeNi alloy composition, concentration of incorporated C, S, and O inclusions, crystal structure, magnetic properties, and the surface quality of the deposit. The maximum content of S, O, and C in the CoFeNi deposit is found for the pulse current where the electrode potential is in the range where the maximum additive coverage is observed, indicating a close correlation between additive adsorption and additive incorporation phenomena. The anomalous codeposition effect was moderate in the potential range where maximum surface coverage of additives occurs, causing the composition of the CoFeNi films and their crystal structure to have a relatively mild change for a broad range of pulse current densities. The surface quality and the coercivity of the CoFeNi alloy have a strong correlation to the additive coverage during the pulse stage, and practical aspects of these findings are discussed. (c) 2005 The Electrochemical Society. All rights reserved.

A self-organized array of magnetic nanoparticles can be potentially used to increase the storage density in magnetic recording. One challenge in this approach is to obtain long-range order assemblies of the nanoparticles. One method to solve this problem is to pattern a substrate having circumferential patterns, whose dimensions are within the coherent length of the self-organized array. By patterning the disk into topographically confined circumferential patterns with such dimensions, thermally stable magnetic nanoparticles may be used to fabricate magnetic recording disks. The circumferential patterns in this case are formed on the disk substrate with dimensions of 100–500 nm and depths of 5–20 nm, prepared by electron beam lithography and reactive ion etching techniques. The monodispersed FePt nanoparticles were synthesized by thermal decomposition of iron pentacarbonyl and reduction of platinum salt simultaneously in the presence of surfactant molecules, achieving a size distribution of 3.15±0.20 nm. Our initial experimental results showed that the monodispersed FePt nanoparticles were successfully deposited into the circumferential patterns and they self-organized into a superlattice. The self-assembly of the FePt nanoparticles in the circumferential pattern strongly relied on the line edge roughness (LER) of the circumferential pattern. This suggests that we need to fabricate the circumferential pattern with LER at the length scales of approximate an individual nanoparticle size 3–4 nm in order to improve the assembly quality further. This is another challenge for today’s advanced lithography and etching processes.

Understanding the proximity effect is crucial to fabricating repeatable sub-100 nm features for magnetic recording devices. Top down CD-SEM measurements have been used to measure the proximity effect parameters in negative and positive resists at dimensions below 100 nm. The goal of this work is to experimentally determine the values of the parameters alpha, beta and eta and what they depend on.

Thin film delamination can occur when the stored elastic energy per unit area in the film due to the residual stress exceeds the interfacial toughness. Telephone cord morphology is commonly observed in delaminating thin films under compressive stresses. Here, the biaxial film stress is partially relieved by film buckling in the direction perpendicular to the telephone cord propagation, and by “secondary” blister buckling in the direction of telephone cord propagation, which results in the sinusoidal fracture patterns. A superlayer indentation test, in which additional stress is supplied to the crack tip using a nanoindenter, can be used to measure the interfacial toughness. Estimates of the energy release rate for diamond-like carbon (DLC) films on magnetic media were obtained using the superlayer indentation test, as well as the delaminated buckling profiles. The results obtained by these two independent methods are in good agreement with each other. We find the average adhesion energy to be 6 J/m2 for DLC films on magnetic media. Normally telephone cord blisters “run out of steam” and stop once the interfacial toughness exceeds the strain energy release rate. It is possible to make blisters propagate further by either putting mechanical energy into the system, or by introducing liquids at the crack tip, thus reducing the film interfacial toughness. Environmental species can assist cracking and contribute to thin film delamination, which is readily observed in vintage mirrors. Crack propagation rates on the order of microns per minute were measured for DLC films in different fluid environments. We identify how telephone cord buckling delamination can be used as a test vehicle for studying crack propagation rates and environmentally assisted cracking in thin films.