Directed Self-Assembly of Block Copolymer for Bit Patterned Media with Areal Density of 1.5 Teradot/Inch2 and Beyond

AbstractBit patterned media, including media fabricated with a gradient in composition, is being developed as a potential path to higher information storage density. The noise level in such media is significantly impacted by the precision of the ordering of the individual bits and by the narrowness of their size distribution. Block copolymers that phase separate on the appropriate length scale are one method of pattern generation that is receiving considerable attention. For cylinder forming block copolymer phases the ordering and degree of perpendicular alignment is largely determined by the matching of the substrate surface to the block copolymer. If the chemical properties of the substrate surface match the average for the block copolymer, then thin films of the block copolymer align perpendicularly on annealing. Although there are a number of examples where the substrate surface fortuitously matches the block copolymer, in general an orienting layer is necessary to provide the appropriate match. The most popular approach has been to synthesize a random copolymer with the same average composition as the block copolymer. In order to produce suitably thin orienting layers it has been necessary to chemically tether the random copolymer to the substrate. Previously used chemistry has not been suitable for noble metal substrates such as platinum. We have been developing an alternate approach using thiol functional groups which we anticipate will be more suitable for Pt capped substrates.

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Silicon Mold Etching with Hard Mask Stack Using Spherical Structure of Block Copolymer for Bit-Patterned Media with 2.8 Tbit/in.2

Japanese Journal of Applied Physics ◽

10.7567/jjap.52.086201 ◽

2013 ◽

Vol 52 (8R) ◽

pp. 086201

Author(s):

Masaru Kurihara ◽

Makoto Satake ◽

Tetsuya Nishida ◽

Yuko Tsuchiya ◽

Yasuhiko Tada ◽

...

Keyword(s):

Block Copolymer ◽

Silicon Mold ◽

Bit Patterned Media ◽

Patterned Media ◽

Hard Mask ◽

Spherical Structure

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Micromagnetic Simulation of L10-FePt-Based Exchange-Coupled-Composite-Bit-Patterned Media with Microwave-Assisted Magnetic Recording at Ultrahigh Areal Density

Micromachines ◽

10.3390/mi12101264 ◽

2021 ◽

Vol 12 (10) ◽

pp. 1264

Author(s):

Pirat Khunkitti ◽

Naruemon Wannawong ◽

Chavakon Jongjaihan ◽

Apirat Siritaratiwat ◽

Anan Kruesubthaworn ◽

...

Keyword(s):

Magnetic Recording ◽

Magnetic Domain ◽

Hysteresis Loops ◽

Areal Density ◽

Bit Patterned Media ◽

Patterned Media ◽

Microwave Assisted ◽

The Media ◽

5 Ghz ◽

Exchange Coupled Composite

In this work, we propose exchange-coupled-composite-bit-patterned media (ECC-BPM) with microwave-assisted magnetic recording (MAMR) to improve the writability of the magnetic media at a 4 Tb/in2 recording density. The suitable values of the applied microwave field’s frequency and the exchange coupling between magnetic dots, Adot, of the proposed media were evaluated. It was found that the magnitude of the switching field, Hsw, of the bilayer ECC-BPM is significantly lower than that of a conventional BPM. Additionally, using the MAMR enables further reduction of Hsw of the ECC-BPM. The suitable frequency of the applied microwave field for the proposed media is 5 GHz. The dependence of Adot on the Hsw was additionally examined, showing that the Adot of 0.14 pJ/m is the most suitable value for the proposed bilayer ECC-BPM. The physical explanation of the Hsw of the media under a variation of MAMR and Adot was given. Hysteresis loops and the magnetic domain of the media were characterized to provide further details on the results. The lowest Hsw found in our proposed media is 12.2 kOe, achieved by the bilayer ECC-BPM with an Adot of 0.14 pJ/m using a 5 GHz MAMR.

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Impact of Touchdown Detection on Bit Patterned Media Robustness

ASME 2013 Conference on Information Storage and Processing Systems ◽

10.1115/isps2013-2871 ◽

2013 ◽

Author(s):

Jia-Yang Juang ◽

Kuan-Te Lin

Keyword(s):

Areal Density ◽

Flying Height ◽

Head Disk Interface ◽

Bit Patterned Media ◽

Patterned Media ◽

Disk Interface ◽

Recording Process ◽

Friction Temperature ◽

The Media ◽

The Impact

Bit patterned media (BPM) is considered as a revolutionary technology to enable further increase of areal density of magnetic recording beyond 1 Tbits/in2 [1]. Implementing BPM technology, however, significantly increases the complexity of the recording process, but also poses tremendous tribological challenges on the head-disk interface (HDI) [2]. One of the major challenges facing BPM is touchdown detection by thermal flying-height control (TFC), in which a minute heater located near the read/write transducers is used to thermally protrude a small portion of the slider into contact with the disk, and the contact is then detected by directly or indirectly measuring the friction, temperature rise or vibration caused by the contact [3]–[7]. Most recording heads rely on touchdown detection to achieve a desired flying height (FH), which approaches sub-1-nm regime for many of today’s commercial drives. As a result sensitive and accurate touchdown detection is of critical importance for a reliable head-disk interface by reducing contact duration and unnecessary interaction between the slider and the disk. However, the impact of touchdown on the mechanical robustness of the media has not been properly studied.

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