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

The flying height of magnetic heads in hard disk drives has been markedly r educed in proportion to an increase in the recording density, resulting in a large head-disk stiction. One of the techniques for overcoming this probl em is to use laser texturing. The laser can create bumps with a typical hei ght of 20-30 nm and a diameter of 10 mu m, although a small bump diameter i s needed to obtain better tribological performance. We therefore studied a precise bump diameter control process with ultra-fine particles (UFPs) of S iO2 and a dry etching process. UFPs of 0.3 mu m diameter were coated on a d isk surface by dipping or an ink-jet method and the surface was etched by o xygen. After removing the UFPs, the bumps formed were measured to have a he ight of 10-20 nm and a diameter of 0.21 mu m. The diameter was about the sa me as that of the UFPs.