Fabrication of 1 Teradot/in.2 CoCrPt bit patterned media and recording performance with a conventional read/write head
(Color online) Process flow for BPM disk fabrication. (a) Diagram of material stack on disk. (b) Windows etched into the top 6 nm thick Si hard mask. (c) The disk with patterned windows coated with an additional 1–3 nm carbon layer. (d) e-beam patterned dots inside the Si window. (e) Etched carbon hard mask pillars inside the Si window. (f) Etched 6 nm height CoCrPt pillars inside the window with mask present. (g) BPM pattern with hard mask stripped.
(Color online) Etched windows in Si hard mask: (a) Candella image of disk. (b) Tapping mode AFM image of the Si window with step height of 8 nm. The unit of the z-axis is 10 nm.
Data showing HSQ Thickness at different dilutions in methyl isobutyl ketone.
Lithographic performance comparing two thicknesses of HSQ exposed with the same dose on identical disk material stacks. (a) AFM height map of patterned 9.5 nm thick HSQ as developed. (b) SEM micrograph of the HSQ pattern in (a) etched into the carbon hard mask. (c) SEM micrograph of patterned 7.5 nm thick HSQ pattern etched into the carbon hard mask.
AFM height micrograph of etched carbon hard mask, patterned with 8.5 nm thick HSQ, plasma hardened, and etched with a 140 V bias.
(Color online) Etched CoCrPt magnetic media. (a) and (b) Results of Silvaco Monte Carlo model etching process simulation for CoPtCr. Initially, the carbon hard mask was 20 nm thick. (c) and (d) TEM cross sectional micrographs of etched magnetic media. (c) The carbon hard mask was present. (d) The carbon hard mask was removed.
Top–down SEM micrograph of patterned media analyzed in Table I.
(Color online) (a)–(c) SEM micrographs of patterned magnetic islands with increasing e-beam patterning dose. (d) Corresponding magnetic coercivity, magnetic switching field distribution width, and relative magnetic switching field distribution width vs e-beam patterning dose.
(Color online) Diagram of shingled recording on bit patterned media. Head moves from the left to the right to record the data.
Effect of BPM defects on recording performance, left column (a)–(d) shows the write rate vs position of center of head from the target track for a matrix of four doses on one sample. The open circles are the data and the solid lines are the best fit to the data. The right column (e)–(h) shows the corresponding micrographs of the BPM measured in (a)–(d). The doses were: (a) and (e) 5870 μC/cm2; (b) and (f) 6050 μC/cm2; (c) and (g) 6415 μC/cm2; (d) and (h) 6608 μC/cm2.
Analysis of dot placement and size variation in micrograph of Fig. 7.
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