Seminar Abstract:
Block copolymer directed self assembly continues to make advances that place this technology as a potential candidate for sub-20nm lithography. The naturally periodic features found in block copolymer films display superior size uniformity at ultra-high densities, making them ideal lithographic masks to define the highly periodic data bits in the data sectors of hard disk drives for bit patterned media (BPM) technology at densities beyond 1Tbit/in^2.
Nanofabrication challenges towards bit patterned media, however, reach far beyond pattern formation at small length scales. We explore two potential architectures amenable to directed self assembly: arrays of hexagonal close packed (hcp) circular dots and arrays of rectangular bits with a high aspect ratio. On the one hand, hcp patterns maximize feature density for a given lithographic dimension while, on the other hand, rectangular patterns support wider write head poles in order to achieve the high write fields needed to write high-coercivity media. In both cases a combination of e-beam lithography with block copolymer self assembly ensures the small dimensions required for high density media together with the flexibility to achieve accurate translational placement over circular tracks with constant angular pitch. We review the benefits and implications of using block copolymer thin films as lithographic masks. We will show that, even though it represents a major departure from the semiconductor lithography roadmap, a combination of e-beam lithography with block copolymer assembly stands as one of the most viable candidates to nanoimprint templates for BPM technology.