Deposition and properties of tetrahedral amorphous carbon films prepared on magnetic hard disks

Abstract

The areal density of information stored on the hard disk has doubled every two years. This substantial increase in disk storage has resulted from the application of giant magnetoresistance heads, new thin film media, and better electronic recording channels. However, such an increase cannot be easily attained without reducing the separation between the magnetic read-write head and magnetic recording medium surfaces. This can be achieved by using a thinner protective overcoat. In this study, ultrathin tetrahedral amorphous carbon (ta-C) films were deposited on magnetic hard disks (CoCrTa/Cr/NiP/Al–Mg) by a magnetic filtered cathodic arc deposition under different substrate bias voltages. The obtained films exhibited smoother surfaces than the uncoated disks as indicated by the atomic force microscopic measurement. The Raman spectra acquired showed a single asymmetric Lorentzian curve shape. Tetrahedral amorphous carbon coatings were subjected to an accelerated corrosion test in vapors of concentrated hydrochloric acid for 24 h. The corrosion test demonstrated a reduced density of corrosion sites when compared to conventional diamond-like carbon films. Similarly, the scratch resistance of the ta-C coated disks, investigated by a nanoindenter, showed significant improvement in comparison to uncoated disks.

Study of facing target sputtered diamond-like carbon overcoats for hard disk drive media

“…In recent years, there have been explorations on alternative carbon deposition processes [1,2] for thinner media overcoat. For years, there have been studies on filtered cathodic vacuum arc process for media overcoat due to its reportedly high sp 3 content, hardness and density [3][4][5][6]. However, despite its promising properties, this process is plagued by issues such as high particle count, due to its arcing nature, relatively low deposition rate and its incompatibility with current mass manufacturing tools.…”

The Head-Disk Interface Roadmap to an Areal Density of Tbit/in2

“…Head carbon has evolved from sputtered to plasma-enhanced chemical vapor deposition (PE-CVD) to filtered cathodic arc (f-CAC) carbon [36][37][38][39], which increased the density, sp 3 /sp 2 ratio, and hardness [40]. On the disk side, f-CAC technology has not yet been made manufacturable [41,42], mostly because of particle and deposition rate challenges, and most if not all disks shipped today are coated with some sort of PE-CVD deposited amorphous carbon overcoat. It is believed that disk deposition tools will soon need to offer new carbon technologies, able to closely emulate a high sp 3 bonded, f-CAC-type carbon film.…”

Advanced Nanomechanical Test Techniques

“…Table 3 summarizes the key differences between the techniques. Small scale fretting of ta-C films on Si Wear and adhesion limit the practical usability of silicon-based devices and several approaches are being considered to overcome that problem including liquid lubrication [89], solid lubrication with self-assembled monolayers [90] and a variety of thin films [91][92][93]. In [48] small scale fretting of 5, 20 and 80 nm thickness ta-C films deposited on Si(100) was investigated using spherical indenters.…”