Abstract:

In this thesis we examine the feasibility of self-assembled systems as tools for nanofabrication. The principal objective of the thesis is to guide self-assembled processes in such a manner so as to produce lithographic templates appropriate for subsequent device development.

The thesis is divided into eight chapters. Chapter 1 provides the motivation of the thesis and introduces alternative patterning approaches to those studied in this work. The relative advantages and disadvantages of each technique are discussed as a way of understanding the need for self-assembled processes. The main body of the thesis concerns itself with three self-assembly systems. Chapters 2-5 deal with lithographically induced self-assembly (LISA). Chapter 2 provides background theory on this process. Chapter 3 presents the first real time observations of this pattern formation phenomenon in which we detail the ordered manner of pattern development. Chapter 4 addresses a new pattern morphology for LISA: concentric rings. The procedure for creating such patterns is detailed. In addition, a comparison with prevailing models is presented. In Chapter 5, the issue of scaling is addressed. Using an external electric field to drive the LISA process, 50 nm features have been achieved. In addition, experiments are presented in which LISA formation has been demonstrated in bilayer polymer systems.

In Chapter 6, a new pattern formation phenomenon is presented in which a thin homopolymer film fractures into periodic grating lines when confined between silicon substrates. The smallest period achieved in this work is 200 nm. An overview of the experiments is presented along with possible mechanisms for such pattern formation.

Chapter 7 concerns itself with self-assembled patterns in block copolymer thin films. Using a shear force, alignment of cylinders in a polystyrene-b-polyisoprene film is demonstrated. The patterns are then used to develop molds for nanoimprint lithography. In this work we show a successful imprint of 30 nm period gratings over an area spanning 1 cm x 1 cm. The imprint process takes only a few minutes which is unachievable using other patterning techniques.

Finally, Chapter 8 provides a brief summary of the work and possible directions for the future.