Enabling Chemistry for Fabrication of Semiconducting Graphene Using Block Copolymer Lithography

초록

Block copolymer (BCP) thin films with perpendicular orientation of microdomains are of considerable interest as one of the microdomains can be easily removed, resulting in a patterned structure. Directing the orientation of the microdomains can be achieved by surface modification to tune the interfacial energies. Random copolymer can be used as a platform to modify surface, where the surface modifying copolymer has a distribution of a third polar monomer which is capable of multi-point anchoring via side groups to an oxide surface or crosslinking with itself. We will discuss the relationship between the composition of the copolymer, the composition of the overlying BCP equilibrated on these surfaces and the resulting morphology. This chemistry is further extended to nanopattern transfer to graphene. Scientific and technological interest in graphene has rapidly grown due to its outstanding physical and electronic properties. To fully realize its technological potential, it is crucial to understand how to create a band gap as graphene is a semimetal and therefore it does not have a technologically relevant band gap. It has been shown that sub-20 nm patterning can be used to open up a band gap in graphene through the quantum confinement effect. We will discuss approaches for creating semiconducting nanoperforated graphene and graphene nanoribbons using block copolymer lithography, which addresses all of the following challenges simultaneously: (i) scalability, (ii) compatibility with the current manufacturing processes, (iii) high resolution, and (iv) pattern fidelity. By developing the materials and processes for the fabrication of sub-10 nm features over large areas, we study the structure-property relationships in nanopatterned graphene as a function of constriction width. We will further discuss the limitations of top-down etching based fabrication methods, highlighting the importance of edge structure engineering in combination with patterning techniques to attain