1. Field of the Invention
The present invention relates to a thin-film magnetic head which performs magnetic recording operations by perpendicular recording schemes, a method of manufacturing the same, a head gimbal assembly and hard disk drive.
2. Related Background Art
In recent years, the areal density in hard disk drives has been increasing remarkably. Recently, the areal density in hard disk drives has reached 160 to 200 GB/platter in particular, and is about to increase further. Accordingly, thin-film magnetic heads have been required to improve their performances.
In terms of recording schemes, thin-film magnetic heads can roughly be divided into those for longitudinal recording in which information is recorded in a (longitudinal) direction of a recording surface of a hard disk (recording medium) and those for perpendicular recording in which data is recorded while the direction of recording magnetization formed in the hard disk is perpendicular to the recording surface. As compared with the thin-film magnetic heads for longitudinal recording, the thin-film magnetic heads for perpendicular recording have been considered more hopeful, since they can realize a much higher recording density while their recorded hard disks are less susceptible to thermal fluctuations.
Conventional thin-film magnetic heads for perpendicular recording are disclosed, for example, in U.S. Pat. No. 6,504,675, U.S. Pat. No. 4,656,546, U.S. Pat. No. 4,672,493, and Japanese Patent Application Laid-Open No. 2004-94997.
Meanwhile, when thin-film magnetic heads for perpendicular recording record data onto areas in inner and outer peripheries of a hard disk, a magnetic pole end part disposed on the side of a medium-opposing surface (also referred to as air bearing surface, ABS) opposing the recording medium (hard disk) yields a certain skew angle with respect to a data recording track. In perpendicular magnetic recording heads (hereinafter also referred to as “PMR”) having a high writing capability, the skew angle has caused a problem of so-called side fringe in which unnecessary data are recorded between adjacent tracks. The side fringe adversely affects the detection of servo signals and the S/N ratio of reproduced waveforms. Therefore, in conventional PMRs, the magnetic pole end part on the ABS side in the main magnetic pole layer has a bevel form gradually narrowing in width toward one direction (see, for example, Japanese Patent Application Laid-Open Nos. 2003-242607 and 2003-203311 in this regard).
Since it is necessary to move the magnetic head when writing data onto a recording medium, eliminate the above-mentioned problem of side fringe and the problem of erasing data in adjacent tracks, and so forth, the bevel angle (θ shown in FIG. 19) in conventional PMRs has been set within the range of 5 to 12 degrees.
Such a PMR has been formed as follows, for example. A method of manufacturing a conventional PMR will now be explained with reference to FIGS. 18 to 21. First, as shown in FIG. 18, a seed layer 401 is formed on an insulating layer 400 made of alumina or the like. Next, a resist pattern 402 provided with a tapered depression corresponding to a bevel angle is selectively formed, and a magnetic layer 403 is formed by plating with a magnetic material such as FeNi, CoNiFe, or CoFe so as to fill the tapered depression. Subsequently, the resist pattern 402 is removed, and the seed layer 401 is etched by ion beam etching (hereinafter referred to as “IBE”), whereby a main magnetic pole layer having a magnetic pole end part 404 is formed as shown in FIG. 19.