A test system for automated characterization of performance relevant storage media defects

Defects in magnetic hard disk media reduce the performance of hard disk drives. A consequence of the increasing storage density is that submicrometer defects in the magnetic storage media become more relevant. However, finding and visual inspection of these defects under an optical microscope is problematic. Therefore, a spin test stand technique was used to reliably map the performance of relevant storage media defect positions, and a computer controlled technique was developed which positions those defects relative to a local analysis tool within 45 s. The accuracy and repeatability was measured to be ±0.05° in angular (approximately ±30 μm of a circular arc) and ±5 μm in radial direction, respectively. Here, surface analysis of defects has been performed using scanning force microscopy. Defect and disk features with heights < 1 nm have been measured routinely while defect diameters were in the range of 1 μm to 250 nm. In particular, nontopographic defects are visualized by means of magnetic force microscopy.