Hard-disk drive films

Figure 20.3. Schematic cross section of a thin-film hard disk. Mobile hard disk drives use glass substrates and smaller diameters (2.5 in. and 1 in.). (From Ref. 1, by permission from Elsevier.)...

Molecularly thin lubricant film is an important application of nanoscale confined polymeric fluids, and is the focus of this chapter. Ultrathin lubricant films are necessary in high-density data storage to increase the reliability and performance of hard-disk drive (HDD) systems [2-4]. Spinoff and intermittent contact between the slider (or head) and the lubricated disk [ultrathin perfluoropolyether (PFPE) films are applied to the disk s carbon-overcoated surface, as shown in Fig. 1.1] cause loss and reflow of the lubricant film. The relevant HDD technology is summarized briefly in the end-of-chapter Appendix Section A.I, which provides an overview of how certain information technology devices are controlled by nanoscale chemistry. 

Considerable interest still exists in the application of fluorine-containing cyclophosphazenes in lubricant technology. Recent advances in the use of N3P3(OC6H4F-4) (OC6H4CF3-3)6-n (n 2 code name X-IP) as lubricant either by itself or as an additive to perfluoropolyethers (PFPE) have been reviewed. Addition of X-IP to PFPE films reduces the critical dewetting thickness on amorphous nitrogenated carbon compared to that of neat PFPE. The influence of X-IP on the stabilization of the PFPE lubricant for the slider/disk interface in hard disk drives has been studied. Micro-phase separation of X-IP... 

The wear and degradation of DLC overcoats on a hard disk is a complex process, dependent not only on the head-to-disk material interface but also the environment in which the disk drive operates. Heat and humidity play an important role. Marchon et al. [19,20] have shown that friction and wear rates of amorphous carbon films are dependent on the at-... 

In a computer hard drive, the data are stored on one or more rigid disks coated with magnetic materials. The magnetic film is coated on a planar NiP substrate. NiP film is typically electroplated on an aluminum disk. Before the coating process, the NiP must be planarized. The planarization process is similar to oxide ILD CMP except that the material is a metal. The slurry chemistry is similar to copper or tungsten CMP except that the end point is to form a perfectly planar substrate. Hydrogen peroxide can be used as an oxidizer in NiP CMP as stated in the patent by Jia and coworkers [14,15]. As shown in Fig. 7.5, the removal rate for NiP film follows the same trend as for copper. At higher concentration, the removal rate decreases because of the formation of a native protective NiO film [12]. 

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