Study of the process for forming microscopic surface bumps with ultra-fine particles

The flying height of magnetic heads in hard disk drives has been markedly reduced in proportion to an increase in the recording density, resulting in a large head-disk stiction. One of the techniques for overcoming this problem is to use laser texturing. The laser can create bumps with a typical height of 20-30 nm and a diameter of 10 μm, although a small bump diameter is needed to obtain better tribological performance. We therefore studied a precise bump diameter control process with ultra-fine particles (UFPs) of SiO2 and a dry etching process. UFPs of 0.3 μm diameter were coated on a disk surface by dipping or an ink-jet method and the surface was etched by oxygen. After removing the UFPs, the bumps formed were measured to have a height of 10-20 nm and a diameter of 0.21 μm. The diameter was about the same as that of the UFPs.