Ultrahigh Density Miniature Disk Drive Technology

Abstract

The Engineering Research Center in Data Storage Systems at Carnegie Mellon University is pursuing disk drive technology with astorage density of 10 Gbit/in2. Such a high storage density will make it possible to store over 1 GByte in sub-one-inch disk drives. At such a size, disk drives will no longer be computer peripherals, but rather components which will be attached onto PC boards, much like RAMchips and microprocessors are today. This small size will make it possible to use them in arrays, even €or personal computer applications. This will enable fastex effective access times, higher data rates and higher reliability through miniaturization and redundancy. To make the above technology possible, advanced low-noise thin film disk media with coercivities in the range of 3000 Oe, high magnetization (1600 emu/cc) magnetic write heads with flat frequency response to 200 MHz, magnetoresistive read heads and novel head-disk interfaces are being developed. Thin films of SmCo/Cr offer coercivities in excess of 3000 Oe. Recording tests indicate excellent low-noise performance and good overwrite characteristics in spite of the high coercivity. Sputtered thin film Ba-femte media have also been made with coercivities in excess of 3000 Oe. Either perpendicular or inplane orientation may be achieved by proper control of sputtering parameters. Athough the remanent magnetization (3 15 emu/ cc) is lower than achievable in metallic media, thin film barium femte media are expected to require no overcoat and therefore will have less spacing loss than metallic thin film media. Thin film inductive recording heads made of FeAlN multilayer materials offer not only high saturation flux density (20,000 Gauss), but excellent frequency response to beyond 200 MHz. Head-disk interfaces involving liquids, probe heads and micromachined miniature sliders are all being pursued as means to achieve head-media spacings of the order of 25 nm. This paper will describe the progress in each of these areas and discuss what maybe expected from future magnetic disk drives.