(253c) Defect Probability In Block Copolymer Directed Assembly

Block copolymers (BCP) find applications in a wide variety of technologies, ranging from adhesives to nanolithography.  Device fabrication relies on the ability to create precisely ordered nanoscale structures. Recent works from our group and others have shown that BCPs can be used to create such structures. A central challenge in the nano-fabrication area is to determine the origin and frequency of defects. Although these defects are thermodynamically unstable, they are formed when BCP’s are trapped kinetically due to their low mobility.  Our research uses Theoretically Informed Monte Carlo (MC) simulations to study some of the more commonly occurring defects in BCPs. In particular, precise calculations of free energy enable concrete predictions of the probability of forming distinct defects over large surface areas. In our work, we observe that the defect occurrence becomes less probable when the strength of the pattern on the bottom surface is increased. When the defects occur on the top surface (rather than through the film); their occurrence is more probable when the pattern is stretched or compressed in comparison to pattern at its natural periodicity.