We present a method for growing bit patterned magnetic recording media using directed growth of sputtered granular perpendicular magnetic recording media. The grain nucleation is templated using an epitaxial seed layer, which contains Pt pillars separated by amorphous metal oxide. The scheme enables the creation of both templated data and servo regions suitable for high density hard disk drive operation. We illustrate the importance of using a process that is both topographically and chemically driven to achieve high quality media.

Bit-patterned media (BPM) for magnetic recording provides a route to thermally stable data recording at >1 Tb/in2 and circumvents many of the challenges associated with extending conventional granular media technology. Instead of recording a bit on an ensemble of random grains, BPM comprises a well-ordered array of lithographically patterned isolated magnetic islands, each of which stores 1 bit. Fabrication of BPM is viewed as the greatest challenge for its commercialization. In this paper, we describe a BPM fabrication method that combines rotary-stage e-beam lithography, directed self-assembly of block copolymers, self-aligned double patterning, nanoimprint lithography, and ion milling to generate BPM based on CoCrPt alloy materials at densities up to 1.6 Td/in2. This combination of novel fabrication technologies achieves feature sizes of <;10 nm, which is significantly smaller than what conventional nanofabrication methods used in semiconductor manufacturing can achieve. In contrast to earlier work that used hexagonal arrays of round islands, our latest approach creates BPM with rectangular bit cells, which are advantageous for the integration of BPM with existing hard disk drive technology. The advantages of rectangular bits are analyzed from a theoretical and modeling point of view, and system integration requirements, such as provision of servo patterns, implementation of write synchronization, and providing for a stable head-disk interface, are addressed in the context of experimental results. Optimization of magnetic alloy materials for thermal stability, writeability, and tight switching field distribution is discussed, and a new method for growing BPM islands from a specially patterned underlayer-referred to as templated growth-is presented. New recording results at 1.6 Td/in2 (roughly equivalent to 1.3 Tb/in2) demonstrate a raw error rate <;10-2, which is consistent with the recording system requirements of modern hard drives. Extendibility of BPM to higher densities and its eventual combination with energy-assisted recording are explored.

The goal of the presented work is to develop and demonstrate a fabrication process for thin film encapsulation of MEMS devices with large gaps by modifying an existing technique. The process is being developed for encapsulation of silicon micro machined gyroscope which will be fabricated on SOI (silicon-on-insulator) wafers using Bosch DRIE etching technique. The encapsulation of the device is carried out using epitaxial polysilicon in order to provide a high vacuum inside the device chamber. This technique helps in reducing the die area and the vacuum inside the encapsulation increases the quality factor Q and sensitivity of the device. In this paper we describe a unique method of wafer scale encapsulation of large gaps using sacrificial silicon structures that are completely oxidized.

Experiments were conducted to evaluate a silicon accelerometer as an implantable sound sensor for implantable hearing aids. The main motivation of this study is to find an alternative sound sensor that is implantable inside the body, yet does not suffer from the signal attenuation from the body. The merit of the accelerometer sensor as a sound sensor will be that it will utilize the natural mechanical conduction in the middle ear as a source of the vibration. With this kind of implantable sound sensor, a totally implantable hearing aid is feasible. A piezoresistive silicon accelerometer that is completely encapsulated with a thin silicon film and long flexible flex-circuit electrical cables were used for this study. The sensor is attached on the middle ear ossicles and measures the vibration transmitted from the tympanic membrane due to the sound in the ear canal. In this study, the sensor is fully characterized on a human cadaveric temporal bone preparation.

This paper explores the possibility of using oxidation of sacrificial beams to encapsulate wide gaps. This method of oxidizing silicon beams in order to create diffusion barriers and structural supports has been reported in literatures. The idea is to encapsulate gaps of various widths in a method that is independent of the width of the gaps. In this experiment we try to encapsulate devices and structures with large gaps of the order of 10-20 mum using this technique and observe the results through SEM images.

While micromachined accelerometers are widely available and used in various applications, some biomedical applications require extremely small dimensions (< mm) or mass (< mg) that cannot be fulfilled with commercially available accelerometers. In this work, we present a fully packaged piezoresistive accelerometer that has the smallest dimension (0.034 mm(3)) ever published. We achieve miniaturization by using a film encapsulation technique with a thick epitaxial polysilicon layer. This packaging technique enables the dimensions of the die to be only tens of microns larger than the micromechanical structure. We have fabricated accelerometers as small as 0.034 mm(3) (387 mu m x 387 mu m x 230 mu m) with noise floor of 0.25 mg/root Hz. These ultra-miniature motion sensors have potential opening up new frontiers in biomedical science and engineering.

A Wafer scale encapsulation process has been developed for devices that require wide gaps. In this experiment, we focus on devices that have gaps or trenches 10-20μm wide. This process can also be applied to larger gaps of the order of 50-100μm. The chief focus of the process development is to achieve a wafer scale encapsulation technique, which can avoid deposition of very thick LPVCD oxide. Once the processing and encapsulation is carried out, SEM images are taken to ensure that the device is completely released and no sacrificial material is left behind.

In this paper we present design, fabrication, and characterization results for the smallest published fully-packaged accelerometers. The miniaturization is realized by utilizing an advanced packaging scheme using a thick film epitaxial grown polysilicon encapsulation technique. Using this approach, released, encapsulated MEMS devices can be fabricated with exterior dimensions only 10s of microns larger than the micromechanical element. This advantage enables us to make accelerometers almost 2 orders of magnitude smaller than others. We have fabricated accelerometers as small as 0.034mm(3) (387x387x230 mu m) with noise floor of 0.25mg/sqrt(Hz).