Peter Vettiger

Integrated microheaters for in-situ flying-height control of sliders used in hard-disk drives

Air-bearing sliders in todays hard-disk drives are flying above the spinning magnetic disks at a very low distance. With continuously increasing recording density this distance reduces and will fall below ten nanometers in the near future. This paper discusses the use of thin-film microheaters integrated into the air-bearing surface of such sliders for in-situ flying-height control. The microheaters can be realized with only a few fabrication steps that can be added to the standard slider manufacturing process. The microheaters transfer thermal energy into the sliders leading to nonuniform deformation, of the air-bearing surfaces. As a consequence the balance between the air cushion lift forces and the load forces is shifted and the flying height is varied. A transfer of thermal energy into the air cushion is also discussed. A comparison of experiments and simulations reveals that microheater-induced changes in the waviness of the air-bearing surface are responsible for flying-height actuation with both polarities. Based on this finding actuation schemes with improved efficiency are discussed that offer the possibility of compensating manufacturing tolerances and also of improving the reliability of future hard-disk drives.

VLSI-NEMS chip for AFM data storage

We report the microfabrication of a 32/spl times/32 (1024) 2D cantilever array chip and its electrical testing. It has been designed for ultrahigh-density, high-speed data storage applications using thermomechanical writing and thermal readout in thin polymer film storage media. The fabricated chip is the first VLSI-NEMS (NanoEMS) for nanotechnological applications. For electrical and thermal stability, the levers are made of silicon and the heater/sensor element is defined as a lower doped platform with the tip on top. Freestanding cantilevers are obtained with surface micromachining techniques, which result in better mechanical stability and heat sinking of the chip than with bulk micromachining releasing techniques. Two wiring levels interconnect the cantilevers for a time-multiplexed row/column addressing scheme. Two different versions for the array interconnections have been implemented, one with an additional Schottky diode in series with the lever to reduce crosstalk between levers, and one without diodes to investigate various addressing schemes.

The nanomechanical NOSE

We present a novel chemical sensor based on a microfabricated array of silicon cantilevers. Individual cantilevers are sensitized for the detection of analytes using metal coatings. Analyte molecules chemisorbing or physisorbing on the cantilever coating and chemical reactions produce a change in interfacial stress between analyte molecules and cantilever. This leads to a nanomechanical response of the cantilever, i.e. bending. The bending is read out using a time-multiplexed optical beam-deflection technique. From magnitude and temporal evolution of the bending, quantitative information on analyte species and concentration is derived. Here, we demonstrate the detection of ethene and water vapor with such a nanomechanical nose.

Dual-cantilever AFM probe for combining fast and coarse imaging with high-resolution imaging

This paper presents a new scanning probe concept based on an integrated dual-cantilever device, which has been designed to reduce the tip-wear problem. It consists of two cantilevers, one having a robust blunt tip, the other having a sharp tip. By means of integrated bimorph actuators, such a cantilever can be used to switch between coarse and fast imaging with the blunt tip, and high-resolution imaging with the sharp tip. Hence the delicate sharp tip is used only when high resolution is required, which greatly increases the probes lifetime. A high-sensitivity, constricted piezoresistive strain sensor is used for high-resolution imaging. Imaging with the dual-cantilever probe has been demonstrated successfully.

The Millipede – A Nanotechnology-Based AFM Data-Storage System

The millipede concept presented in this chapter is a new approach to storing data at high speed and ultrahigh density. The interesting part is that millipede stores digital information in a completely different way from magnetic hard disks, optical disks, and transistor-based memory chips. The ultimate locality is provided by a tip, and high data rates are a result of massive parallel operation of such tips. As storage medium, polymer films are being considered, although the use of other media, in particular magnetic materials, has not been ruled out. The current effort is focused on demonstrating the millipede concept with areal densities higher than 1 Tb/inch2 and parallel operation of very large two-dimensional (2-D) (up to 64 × 64) atomic force microscopy (AFM) cantilever arrays with integrated tips and write/read/erase functionality. The fabrication and integration of such a large number of mechanical devices (cantilever beams) will lead to what we envision as the very large-scale integration (VLSI) age of micro- and nanomechanics.

An Electronic Nose Based on A Micromechanical Cantilever Array

We present a novel chemical sensor based on a micromechanical array of silicon cantilevers sensitized for the detection of analytes using cantilever coatings such as metals, self-assembled monolayers, or polymers. Chemical reactions are transduced into a mechanical response and read out using an optical beam-deflection technique. Detection of primary alcohols, natural flavors, and water vapor is demonstrated.