Ming M. Yang

Ultrathin protective overcoats on magnetic hard disks

Composition, structure and protective properties of 50-100 /spl Aring/ thick hard disk overcoats prepared by DC magnetron sputtering and ion beam deposition were examined. Ion beam coatings were shown to possess superior properties as compared to the sputtered carbon films by nanoscale scratching and electrochemical corrosion techniques.

Process And Characterization Of Nitrogenated Carbon

Nitrogenated carbon films prepared in a DC-magnetron sputtering system were studied. Properties, including deposition rate, nitrogen content, nano-hardness, and thin film stress, were investigated as a function of deposition conditions, i.e. sputter power, substrate bias, substrate temperature, and sputter pressure.

Magnetic hard disk overcoats in the 3–5 nm thickness range

Protective properties of 3–5 nm thick carbon overcoat layers deposited on magnetic hard disks by ion beam deposition (IBD) and plasma-enhanced chemical vapor deposition (PECVD) were investigated. It is found that these overcoats are superior to the sputtered carbon films at thicknesses below 5 nm. Low-stiction performance of 3-nm-thick IBD films without any detectable wear was observed during 50 000 contact start-stop cycles at 55 °C and 10% relative humidity. Surface concentration of cobalt ions is reduced by as much as an order of magnitude as compared to the media with sputtered overcoats. Polarization resistivity values for IBD and PECVD overcoats are by an order of magnitude higher. The results show that thickness of protective carbon overcoats on magnetic hard disks can be reduced to 3–5 nm without compromising media reliability requirements. This reduction is critical for the continuing growth of storage density.

Asymmetric DC-magnetron sputtered carbon-nitrogen thin-film overcoat for rigid-disk applications

An asymmetric DC-magnetron sputtering technique was evaluated to deposit carbon-nitrogen (C:N) overcoats for rigid-disk applications. The tribological characteristics of very thin C:N overcoats (/spl sim/100 /spl Aring/) were investigated by using thin-film flying inductive heads, Tripad-proximity recording heads, and carbon-coated magneto-resistive (MR)-heads in different test environments. Comparison of >20 K contact start-stop (CSS) test cycles showed superior stiction and durability performance for the asymmetric DC-magnetron sputtered (asym-C:N) films compared to standard symmetric DC-magnetron sputtered (sym-C:N) films. After CSS testing, no visible wear marks and/or head-build up were observed. Comparison of stress and hardness data showed a reduction of internal stress without noticeable change in hardness for asym-C:N films. Also, elemental analysis showed higher nitrogen content in asym-C:N films. In addition, Raman spectroscopy data suggest that the asym-C:N films have higher sp/sup 3/ content than that of sym-C:N films, which can contribute to greater durability.

Effects of substrate cooling in hard magnetic disk sputtering process on protective overcoat and magnetic layer properties

Abstract An in-situ substrate cooling procedure has been carried out in a hard magnetic disk sputtering process to reduce the disk temperature prior to a deposition of a protective overcoat. The effects of cooling on the tribological and magnetic performance of the media are examined and directly compared for the amorphous carbon (a-C), amorphous hydrogenated carbon (a-C:H) and amorphous nitrogenated carbon (a-C:N) overcoat compositions. The substrate cooling procedure is shown to promote sp 3 -bonding character and to improve the tribological properties of the overcoats. To achieve the best tribological and magnetic performance of the media, the magnetic layer and the protective overcoat should be optimized as a coupled system.

Wear and corrosion resistance of thin overcoat with different interlayer materials

Several interlayer materials were introduced under a thin nitrogenated carbon film for corrosion and tribology evaluation. It was found that CrTa interlayer showed the best corrosion resistance but the worst wear performance, and amorphous carbon (a-C) and NiSi interlayers demonstrated reasonable wear resistance.

Use of Ni/sub x/Si/sub y/ as an interlayer for wear and corrosion resistance

Sputtered carbon/Ni/sub x/Si/sub y/ overcoats as thin as 50 /spl Aring/ are shown to be effective at providing both wear and corrosion resistance for magnetic hard disks. This paper will explore, through the results of an XPS study of the carbon/Ni/sub x/Si/sub y/ interface, the mechanism of how Ni/sub x/Si/sub y/ provides improved reliability.

Tribology of proximity magnetoresistive head–disk interface for 5 Gb/in.2 recording

Low fly-height magnetoresistive (MR) sliders and low glide-height laser-texture thin film disks were introduced to meet the tribological challenges of proximity MR recording, with which an areal density of 5 Gb/in.2 has been achieved when using the sliders with dual-stripe MR heads and the disks with low-noise media. The 30% pico sliders employed two air-bearing designs with a fly height around 12.5 nm. The thin film disks used superfinish substrates with a glide-avalanche-height falling well below 10.0 nm. In the contact start/stop (CSS) zones, small crater-shape laser texture bumps were generated to meet both low stiction and low glide-height requirements. An 80 A thin amorphous nitrogenated carbon was added over the magnetic layers as a protective overcoat. A layer of perfluoropolyether with an additive of phosphazene compounds was applied on the disk surface to improve the reliability of head–disk interfaces. The near contact head–disk interface survived for 20 k-cycle hot/wet and hot/dry CSS tests wi...

Production and characterization of asymmetric laser-textured bumps for magnetic media

Asymmetric “S-shaped” bumps are formed in the presence of a significant temperature gradient on the disk surface during the laser-texture process. The production of S-shaped bumps is of particular interest for low-glide magnetic media, for which the desired high bump densities require the use of high spindle speeds. The formation of S-shaped bumps as a function of laser-pulse energy (0.1–4.5 μJ), pulse width (350–5000 ns), and rotation speed of the spindle (1184–4737 rpm) was investigated. The results show that within the accessible energy range the peak-to-mean bump height increases with the pulse energy. For a constant pulse energy, larger bump heights are obtained for shorter pulse widths. In addition, higher bumps are also obtained for slower spindle speeds if the pulse width is 2000 ns or longer, but this changes as the pulse width is reduced. The full-width-at-half-maximum diameter of the trailing bump cone monotonically increases with the pulse energy for 350–1000 ns pulse width, but shows a local ...

Improved recording performance and optimized durability of thin film disks with zone carbon overcoats

The idea of zone carbon (ZC) is to use a thicker carbon overcoat in the landing zone and a thinner carbon in the data zone. In this study, we demonstrated the use of a zone carbon scheme to improve recording performance while maintaining the durability of the thin film disk.