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BPM array consisting of MLs deposited onto Si pillar substrates fabricated via e-beam directed assembly of block copolymer films. SEM micrographs of (a) the block copolymer film after selective removal of the PMMA cylinder cores, (b) Si pillars after Cr lift-off using the template in (a) and subsequent reactive ion etching, and (c) magnetic BPM after depositing a Co/Pd ML thin film onto the pillar structures (left: top view, right: section view at 85° angle). (d) Bright field TEM cross-sectional image through two consecutive rows of bits (into the image plane) that are 180° phase shifted with respect to each other.
Microspot PMOKE hysteresis loops [(a) and (c)] and corresponding island reversal curves [(b) and (d)] [enlarged view of the dashed boxes in (a) and (c)] from BPM arrays fabricated via e-beam directed assembly of block copolymer films. (a) and (b) show results from a (38 nm pitch) array, while (c) and (d) were obtained from a (28 nm pitch) pattern. The insets display a high resolution MFM image of the array after demagnetization (top) and a SEM image of the array after media deposition (bottom), respectively.
Normalized SFD vs density for BPM fabricated by e-beam alone (solid circles) and by directed assembly (open circles).
SEM images of BPM at with various size distributions fabricated by (a) directed block copolymer assembly, , [(b) and (c)], undirected block copolymer assembly, and 19%, respectively, and (d) e-beam lithography alone . (e) PMOKE reversal curves of the same four patterns. (f) Normalized magnetic SFD vs pillar size distribution for the four samples. The line is a guide to the eye.
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