Scaling of the bit size in conventional magnetic recording media is becoming increasingly difficult due to the superparamagnetic limit. Innovations in magnetic recording technology are emerging to enable the continued growth in bit areal density. Thermal stability problems of conventional granular media can be greatly helped by patterning single domain magnetic islands for each magnetic bit. Fabrication of patterned media requires application of nanoimprint lithography for high-volume production of patterned media disks and high-resolution electron beam lithography for fabrication of the nanoimprint masters. We discuss the approaches and the many challenges to the implementation of patterned media disks.

Research at the US Naval Research Laboratory (NRL) in the lithography, patterning, and fabrication of structures of nanometer scale dimensions is reviewed. Electron-beam (e-beam) lithography at high (50 keV) and low (5 eV) energies on resist systems developed at NRL is described. The low energy lithography takes advantage of the spatially confined e-beam available in a scanning tunneling microscope type probe. This instrument allows an in situ exposure and characterization of an e-beam sensitive material. A novel approach for implementing dose correction for proximity effects in e-beam lithography is presented using an error measure based on the physical realities of lithography. The compositional disordering of GaAs-Ga/sub x/Al/sub 1-x/As heterostructures as a technique for pattern replication is described. Introducing silicon into the heterostructure (by implantation or diffusion) enhances the aluminum and gallium interdiffusion which can be used for patterning. A complete bibliography of recently published results is included.>