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Magnetic Bit Patterned Media Fabrication Using Block Copolymer Directed Assembly By Rotary Stage Ebeam Lithography


  Gabriel Zeltzer [1]  ,  Ricardo Ruiz [1]  ,  Lei Wan [1]  ,  Elizabeth Dobisz [1]  ,  Hiroshi Yoshida  ,  Y. Tada [2]  ,  K.C. Patel [1]  ,  Jeffrey Lille [1]  ,  H. Gao [1]  ,  Tsai Wei Wu [1]  ,  Olav Hellwig [1]  ,  Dan Kercher [1]  ,  Michael Grobis [1]  ,  Thomas R. Albrecht [1]  
 Hitachi Global Storage Technologies, San Jose Research Center, San Jose,CA USA
Hitachi Ltd., Hitachi Research Laboratories, Hitachi City Japan

Magnetic Bit Patterned Media Fabrication Using Block Copolymer Directed Assembly By Rotary Stage Lithography

R. Ruiz1, L. Wan1, E. Dobisz1, G. Zeltzer1, H. Yoshida2, Y. Tada2,  K.C. Patel1, J. Lille1, H. Gao1, T-W. Wu1, O. Hellwig1, D. Kercher1, M. Grobis1, T. R. Albrecht1

 

Perpendicular magnetic recording media in excess of 2Tbit/in2 faces thermal stability and/or writeability challenges that are currently driving intense research in alternative technologies. Bit patterned media (BPM), in which magnetic bits are lithographically patterned as individual islands, stands as a promising technology for thermally stable, writable media. One of the main challenges of BPM lies in its lithographic specifications which push dimensions beyond those established for the conventional semiconductor industry roadmap. A potential solution to the lithographic challenge can be found in directed self assembly of block copolymer films which has recently evolved as a viable lithographic technique to achieve large-area, high-density patterns in time for BPM technology.

 

The challenges faced in the fabrication of templates for BPM using block copolymer self assembly have spurred a set of important innovations in nanofabrication techniques such as the formation of geometries that deviate from the typical shapes naturally formed by block copolymers, as well as advances in high-fidelity pattern transfer and progress in scalability towards higher feature densities. In this presentation, we discuss some of these innovations. We demonstrate a process that combines rotary stage ebeam lithography directed self assembly with nanoimprint lithography to achieve rectangular patterns mounted on circular tracks. We will also discuss recent advances in our understanding of the internal structure of block copolymer films and its consequences during pattern transfer. We also explore viable materials for densities above 2Tdot/in2. Lastly, we will also discuss the impact of the nanofabrication process on the magnetic performance of the magnetic islands and the outlook for BPM technology.