Predicting process windows for pattern density multiplication using block copolymer directed self-assembly in conjunction with chemoepitaxial guiding layers

Pattern density multiplication using directed self-assembly (DSA) of block copolymers (BCPs) is a technique capable of producing patterns with small pitches utilizing guiding template patterns printed as larger feature sizes and pitches. One method for achieving this density multiplication is to utilize chemoepitaxy based on a guiding underlayer that is nominally topographically flat but which is composed of a pinning region, or stripe if referring to lamellae, which will chemically prefer one microphase of the BCP, as well as a second region that is often referred to as neutral to both phases of the BCP. In most conceptions of such a chemoepitaxial approach for alignment of lamellae patterns, the pinning stripe is typically the width of a single lamellae of the phase separated BCP, while the neutral stripe is some odd number of lamellae widths. In this work, detailed simulation studies have been performed to elucidate the effects of variables such as guiding stripe size, chemical composition of the neutral stripes, and small topography on the process window of DSA pitch sub-division patterning processes. A simple but novel technique has been developed and utilized to quantify the level of alignment of a simulated BCP film to an underlying guiding pattern. Such process windows and lithographic parameters have been studied for different pitch sub-division conditions including 1:3 and 1:5 pinning stripe:neutral stripe width ratios. It is found that the center of the processing window occurs at a composition of the neutral stripe such that it is slightly to somewhat strongly preferential to the type of polymer of opposite type to that attracted by the pinning stripe, and that this ideal neutral stripe composition becomes more neutral as the density multiplication increases.