Mechanical Properties and Wear Resistance of High Moment Thin Film Head Materials
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been reported in the literature. Recently, Jones et al measured the hardness of Fe(N) films sputtered in an Ar-N 2 mixture by nanoindentation[4]. Katori et al conducted a study of wear and corrosion resistance of Fe-N based micrograin soft magnetic thin films[5]. In this paper, we present our experimental results on the mechanical and tribological properties of FeTaN films deposited by dc magnetron sputtering. Hardness(H) and Young's modulus(E) for FeTaN (2.2 at%Ta, 0 - 4 at%N) sputtered films were determined by nanoindentation, which is a powerful technique for characterization of thin film mechanical properties. Wear resistance of these films was measured with a sphere-on-flat wear tester developed in our laboratory, with which the sputtered thin film head materials were directly rubbed by a commercial MP magnetic tape. EXPERIMENTAL Test Films
The FeTaN thin films used in this study were deposited on 7059 Coming glass substrates by dc magnetron sputtering in an Ar-N2 mixture using a Vac-Tec Model 250 Batch Side Sputtering System. The target used was a Fe-10w/o Ta disk with a 4" diameter. With fixed deposition power, total Ar pressure and deposition time, 6 levels of nitrogen flow rates were used in order to examine the effects of nitrogen. Because of the fixed deposition power and total pressure a nearly constant deposition rate of 10 A/s was achieved, and the average film thickness was -4500 A. The sputtering condition details are listed in Table 1. After deposition the specimens were cut into several small pieces for the characterization of magnetic, structure, 773 Mat. Res. Soc. Symp. Proc. Vol. 356 a 1995 Materials Research Society
mechanical and tribological properties. Magnetic and structural properties of similar FeTaN thin films were reported elsewhere[l]. In this paper, we are focusing on the mechanical and tribological properties of these magnetically soft thin films. Furthermore, in order to examine the thermal stability of the films, a piece of each film specimen was annealed at 200 'C for 30 minutes. Table 1. Sputtering Deposition Conditions for FeTaN Magnetic Thin Films. Deposition power: Total Ar pressure: Deposition time:
220 W 3 mTorr 7.5 min
Nitrogen flow rates: Deposition rate: Film thickness:
0, 5, 7, 10, 12, 15 sccm 9.46 - 10.54 A/s 4256 - 4744 A
Nanoindentation Characterization The characterization of the mechanical properties of these films was performed by using a Nano Indenter® II Mechanical Properties Microprobe which continuously measures load and displacement in the indentation process. Prior to the experiments the indenter tip area calibration was carried out by using the data obtained on a standard fused silica sample provided by Nano Instrument, Inc. In the nanoindentation study of the magnetic head films, 6x6 arrays with 50 .tm spacing were used. A constant displacement loading rate in the load segment and a depth limit control were used. Loading rates were varied from 1 nm/s to 10 nm/s depending on the depth limit. The penetration depth was controlled in the range of 10 - 4
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