Directed Assembly of Block Copolymers on Lithographically-Defined Chemically Nanopatterned Substrates

Block copolymer materials spontaneously form structures at the length scale of 5 to 50 nm. Unfortunately self-assembled patterns derived from these materials are riddled with defects and non-uniform features which preclude their use in many applications at the nanoscale. On the other hand, top-down processes offer exceptional precision and perfection in patterning features with dimensions as small as 30 nm, but may become prohibitively expensive, or reach technological roadblocks as tools and materials are pushed to reach 20 nm features and below. Over the past decade we have conceived of and demonstrated an approach to integrate block copolymers into the lithographic process. The principal concept of the approach is to use the most advanced lithographic materials and tools to create patterned surfaces with regions of different chemical functionality, and to use the patterns to direct the assembly of overlying block copolymer films. The intrinsic properties of self-assembling block copolymers lend themselves to precise control over the shape, size, and dimensional uniformity of patterned features, and to improved resolution. Directed assembly in this context is intended to enhance or augment the capabilities of the lithographic process, not replace it.