Directed self-assembly of block copolymers for nanocircuitry fabrication

This paper is a perspective on progress that has been made in the use of block copolymers as potential, non-UV lithographically formed, on-chip etch masks for the fabrication of ultra-small circuit elements. Rather than focus on a comprehensive review of the fundamentals of the self-assembly process, the article will provide a personal, retrospective appraisal of what has been done and what needs to be done using published and unpublished material. It is hoped it will provide a summary of the field to as wide an audience as possible. The science of the self-assembly of these systems will be briefly reviewed. We will provide a brief overview how block copolymers can produce ordered nanopatterns, how they can be ‘directed’ to provide long-range order and how the patterns formed can be transferred to a substrate. In the article we will review key developments over the last 10 years or so that have moved these materials from the laboratory to a point where they are close to use in integrated circuit (IC) manufacturing. We will centre on challenges that remain in the chemistry and processing of block copolymer films that if successfully met would allow their insertion into current IC manufacturing. In particular we will explore issues such as: definition of pattern alignment and orientation, defectivity in the as formed systems and development of reliable process flows. During the article, we will examine emerging challenges such as the need to develop systems that can reach feature sizes of sub 10 nm, techniques such as solvent-annealing that can be used to generate patterns in short times and polymers that can be designed or modified to give high etch contrast during pattern transfer. We also will look at the future of these systems and where they may add value to the production of nanowires, nanodots etc. for application in micro- and nanoelectronics.