eLearning

Soojin Park,
Dong Hyun Lee,
Ji Xu,
Bokyung Kim,
Sung Woo Hong,
Unyong Jeong,
Ting Xu,
Thomas P. Russell

Generating laterally ordered, ultradense, macroscopic arrays of nanoscopic elements will
revolutionize the microelectronic and storage industries. We used faceted surfaces of commercially
available sapphire wafers to guide the self-assembly of block copolymer microdomains into
oriented arrays with quasi–long-range crystalline order over arbitrarily large wafer surfaces.
Ordered arrays of cylindrical microdomains 3 nanometers in diameter, with areal densities in
excess of 10 terabits per square inch, were produced. The sawtoothed substrate topography
provides directional guidance to the self-assembly of the block copolymer, which is tolerant of
surface defects, such as dislocations. The lateral ordering and lattice orientation of the single-grain
arrays of microdomains are maintained over the entire surface. The approach described is parallel,
applicable to different substrates and block copolymers, and opens a versatile route toward
ultrahigh-density systems.

Producing a surface with an ultradense ar-
ray of addressable nanoscopic elements that
is perfectly ordered over macroscopic length
scales is a formidable challenge. The self-assembly
of block copolymers (BCPs), two chemically dis-
similar polymers joined together, is emerging
as a promising route to generate templates and
scaffolds for the fabrication of nanostructured
materials and offers a potential solution to this
challenge (1–3). Despite the substantial advances
that have been made to enhance the lateral or-
dering of the BCP microdomains in thin films,
achieving perfect order over macroscopic length
scales has not been possible (4–7). In thin films,
BCPs self-assemble into grains, tens of microns
in size, of laterally ordered nanoscopic micro-
domains. Electron beam (e-beam) lithography
is a serial writing process, and although slow,
has been successfully used to produce nano-
scopic chemical or topographic surface patterns
that can be used to guide the self-assembly of