AVS1997 Session AS+MR+MI-ThA: Hard Disc Processing Issues: I

Thursday, October 23, 1997 2:00 PM in Room J2

Thursday Afternoon

Start	Invited?	Item
2:00 PM	Invited	AS+MR+MI-ThA-1 The Effect of Pressure Sensitive Adhesive Outgassing on Head/Disk Interface Tribology P.R. Segar, M.A. Jesh (Seagate Technology) Outgassing from disk drive materials can adversely affect head / disk tribological performance. The reliability risk of outgassed contamination continues to rise as storage capacity demands force reductions in head flying heights and disk surface roughness. A tribochemical test method is described which can be used to evaluate the effects of outgassing from disk drive materials or pure chemicals on stiction, durability and head smearing. Tribochemical studies of two head / disk interface designs exposed to outgassing from 17 different pressure sensitive adhesives are described. All pressure sensitive adhesives were found to have a detrimental effect on stiction, and several stressed head smearing. Pressure sensitive adhesive outgassing had an equivalent effect on laser bump landing zone and mechanically textured landing zone disks.
2:40 PM		AS+MR+MI-ThA-3 Hard Disk Drive Analysis Using Time Of Flight Secondary Ion Mass Spectrometry (TOF-SIMS). T.J. Schuerlein, P. Lindley (Charles Evans & Associates); C.A. Evans (Purdue University) Time-of-flight secondary ion mass spectrometry (TOF-SIMS) is a surface analysis technique which has proven to be a useful tool in the analysis of hard disk drive components. TOF-SIMS is an extremely surface sensitive technique which is capable of identifying both atomic and molecular materials with detection limits ca. 2 orders of magnitude better than XPS or AES Identification of molecular contaminants is accomplished using high mass resolution mass spectra. The technique is capable of imaging small features and defects with lateral resolution of better than 0.2 micrometers. TOF-SIMS can be used to analyze both hard disks and heads. Applications investigating lubricants on hard disks that will be shown include: lube identification, identification of contaminants within the lube and segregation of lube additives. Hard disks also may be analyzed to identify and show localization of trace metal contamination and magnetic metals at the disk surface as well as defect or particle analysis and identification. TOF-SIMS has also been successful in the analysis of read-write heads. Specific capabilities that will be shown include: identification and mapping of pole tip debris and metal segregation/corrosion of the poles.
3:00 PM	Invited	AS+MR+MI-ThA-4 Analytical Methods for Determining Root Cause in Media Failure. C.C. Martner, S.F. Misquitta (MaxMedia Division, H.E.A.); C. Fenno (Integral Peripherals Inc.); R.D. O'Rourke, B.D. Hermsmeier (MaxMedia Division, H.E.A.) Determination of root cause in media failure has become an issue of importance due to the aggressive demands of higher magnetic density for hard disks. These demands are met by decreasing the magnetic bit size and the interaction distance between the magnetic head and the disk. The present dimensions for magnetic bits are on the order of 3.0 um by 0.1 um and head disk spacing on the order of tens of nanometers. These dimensions put stringent requirements on disk uniformity and interface contamination. In this paper we provide an overview of root cause determination for failures in a typical disk factory. Five major subjects will be discussed: defect types, defect detection, defect identification, methods of analyses, and trouble shooting. First, we will describe the type of problems that produce defects such as embedded particles, substrates nodules, pits, debris, corrosion, delaminations, mechanical damage and lubricant droplets. Second, we will discuss defect detection and defect identification techniques. Third, we will present a review of analytical techniques used for particular applications (Raman, XPS, TOF-SIMS, etc.). And lastly, we will discuss how the root cause determination is arrived as well as corrective action types of experiments. A pragmatic approach will be emphasized and particular examples given that will touch on impact energies associated with glass substrate defects, embedded particles using Raman Spectroscopy, determination of corrosion products, and glide avalanche studies used in determining surface roughness. Finally, a description of the present and future analytical challenges to failure analysis in the storage industry will be discussed.
3:40 PM		AS+MR+MI-ThA-6 Calibration Standards for Substrate Defect Inspection Systems: The Development of the Indentation Technique S. Jayashankar, S. Munoz, R. Wills (Seagate Recording Media) The ever-increasing demand for increased storage density has resulted in the development of slider designs with decreased head-media spacing and recording track widths. Currently used MR head technology demands tighter tolerances, not only in terms of the media surface finish requirements, but also for defect sizes. Consequently, increasing attention has been focused on improving the substrate surface quality through the reliable detection and elimination of substrate defects such as pits and bumps. Non-contact, optical inspection systems employing interferometry and scatterometry have found increasing use in the detection of surface defects. The optimal performance of such systems requires the proper set up and periodic calibration to detect defects ranging from the sub-visual dimensions to the visual range. The reconciliation of plating and polish process related defect data requires the use of invariant standards, whose radial / angular location and geometric dimensions are well known. The indentation technique has been developed as a powerful, yet simple tool for the generation of calibrated pit standards on substrates. In addition to the ease and simplicity of use, it will be shown that the technique is capable of reproducibly generating defects of controlled vertical and lateral dimensions at predetermined locations. It will be shown that defects ranging in size from the sub-visual to the visual range can be generated by varying the indentation load. Optical and AFM evidence is presented, along with detailed defect map and signal strength data to demonstrate the efficacy of the technique.
4:00 PM		AS+MR+MI-ThA-7 Nanoscale Indentation/Scratching of Ultrathin Protective Overcoats on Hard Magnetic Disks E.V. Anoikin, M.M. Yang, J.L. Chao (HMT Technology Corporation); J.R. Elings (Digital Instruments) Thickness of protective overcoats on hard disk magnetic media is being continuously pushed down to fully extract all the benefits of the reduced head-media spacing for signal recording and read-out. It is currently in the range of 150 - 200 A and is expected to drop to as low as 50 A in the near future. Accordingly, there is a strong need in developing experimental techniques capable of reliable characterization of the overcoat properties on the nanometer and even angstrom thickness scale. This report presents the results of the nanoindentation and nanoscratching measurements on hard magnetic disks with 120-A thick overcoats performed with a Dimension 3000 Atomic Force Microscope. The disks were prepared by DC-magnetron sputtering on AlMg/NiP substrates in an INTEVAC 250 system. Amorphous carbon (a-C), hydrogenated carbon (C:H) and nitrogenated carbon (C:N) overcoat compositions were studied. The results show significant differences in the adhesion of the overcoat to the magnetic layer among the various overcoat compositions. The ability of the technique to perform consistent and reproducible nanoindent/nanoscratch testing on the extremely thin overcoats has been demonstrated.
4:20 PM		AS+MR+MI-ThA-8 Corrosion and Tribology Study of Carbon Overcoat on Magnetic Thin Film Disk C. Wang, W.J. Chia, J. Lee, W. Tang (Western Digital Corporation) Thin carbon protective coatings are deposited on magnetic disks by unbalanced DC-magnetron sputtering. The carbon thickness has to be small enough in order to reduce the spacing loss in the head-disk interface, but the thin carbon overcoat has to be corrosion- and wear-resistant. The effect of carbon composition on the corrosion susceptibility and wear resistance will be presented. Strong corrosion agents are used to attack the underlying metals for the corrosion test and contact start-stop test is used to evaluate the tribology. It will be shown that hydrogenated carbon exhibits superior corrosion resistance, while nitrogenated carbon holds good wear resistance for the lubricated test. A detail mechanism is proposed to explain why the hydrogenated carbon has superior corrosion property than the nitrogenated carbon.
4:40 PM		AS+MR+MI-ThA-9 Chemistry / Orientation of Lubricants on Hard Disk Magnetic Media Substrates Using Near Edge X-ray Absorption Fine Structure B.M. DeKoven (Dow Chemical Company); D.A. Fischer (National Institute of Standards & Technology); G.E. Potter, D.J. Perettie (Dow Chemical Company); C.S. Bhatia (IBM); T.A. Morgan (Dow Chemical Company); S.M. Hsu (National Institute of Standards & Technology) In this study we describe the interactions of a lubricant system with carbon overcoat surface typical of a magnetic hard disk. The lubricants used are cyclophosphasene (X-1P) and Fomblin (ZDOL). The following system parameters were studied: effects of surface burnishing; ZDOL alone, X-1P alone, ZDOL / X-1P mixtures, and carbon overcoats (7.5 nm) with varying hydrogen content (using Ar and Ar / H₂ treatments). Near Edge X-ray Absorption Fine Structure (NEXAFS) was used to probe the reactivity and orientation of applied lubricants on the surface of the various (16) lubricant disk systems combinations. NEXAFS is an ideal non destructive tool for studying the disk lubricant system since it has both elemental and chemical sensitivity, with selectivity in bond type. The technique can also make direct comparisons between the surface and bulk by measuring simultaneous electron yield (5 nm depth sensitivity) and fluorescence yield (200 nm) spectra. In addition, the average orientation of chemical bonds may be measured via the polarization anisotropy of the soft x-ray absorption spectra. NEXAFS spectra above the Co and Ni L edges as well as C, O, F K edges were recorded. Orientation of the lubricants, thickness, and morphology of the carbon hardcoat and magnetic media are discussed in detail for the samples listed above.
5:00 PM		AS+MR+MI-ThA-10 Scanning Auger Microscopy Characterization of Magnetic Hard Disc J Huang, D. Harris (Charles Evans & Associates); D. Neiman (Hewlett Packard) Applications of ZalarTM rotation and field emission Auger (FE-AES) analysis in various magnetic hard disc problems will be presented. These applications include thin layer structure characterization, low concentration contaminant (0.1-0.5 atomic percent) detection at deeper interfaces (greater than 1000Å), and small particle (~1000Å) contaminant identification.