Sputtering through offset mask for disk acceleration standards

Magnetic data storage hard-disk media and substrate manufacturers are generally required to perform axial acceleration testing. A method has been devised to produce standard patterns on disks to audit and control such testing. The key concept is to sputter metal through a mask-hole which is adequately offset from the media to produce a smooth (triply differentiable) pattern with a bell-shaped peak and with frequency content nearly bounded by the acceleration filter cutoff frequency for mechanical testing. Computer modeling of and sputtering indicates that this shape may be obtained when the mask aperture diameter is about twice the sputter width of the sputtered profile and with offset altitude slightly larger than the desired sputter value