As technology moves toward 600 ～ 1000 Gb/in the mechanical spacing between head-slider and disk media must be further reduced to a level of 3 ～ 4 nm. Such a reduction of the head-disk spacing will be accompanied with a lot new challenges. One severe challenge is how to reduce the flying height modulation caused by the surface waviness with an amplitude even as small as 0.4 ～ 2 nm. Shifting slider size from its current pico form-factor to femto form-factor seems to be a promising approach for the reduction of such flying height modulation. However, discussions on the femto slider are still limited to theoretical analysis and computer modeling/simulation until now. This paper reports authors' efforts in the design and fabrication of the femto sliders plus the comparative study of the dynamic performance between the femto and the pico sliders. Results indicate that the femto sliders are of smaller flying height modulation, compared with the pico sliders, if both the femto and the pico sliders are of similar air-bearing surface layout. Investigations also extend to the study of flying performance sensitivity of the femto slider to its possible parameter offsets caused by the manufacturing and integration processes. Results indicate that, in general, the flying performance of the femto slider is more sensitive to such offsets, compared with the pico sliders. For example, the flying height of the femto sliders is of greatly increased sensitivity to the gram load change, compared with the pico sliders. Such a phenomenon becomes more significant when the gram load is further reduced for the femto slider case.
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