Directed Self-Assembly of Block Copolymers with Density Multiplication and Its Integration with Lithographic Processes

This dissertation centers about a novel approach for chemical pattern fabrication and the directed self-assembly (DSA) of block copolymer thin films on such chemical patterns. Each chapter can be read as a stand-alone story, while read together, they constitute the stairway that leads toward the implementation of DSA in the lithography technology. Important literatures and the rationale for studying the DSA are briefly discussed in Chapter 1. The studies of this dissertation begin with the fabrication method of a well-defined chemical pattern demonstrated in Chapter 2. The precise control of the chemical pattern, in terms of geometry and chemistry, is illustrated through the DSA with density multiplication, NEXAFS spectroscopy, and Au nano-particle adsorption. Because of the precise control provided by this fabrication method, we are able to further explore the chemistry effect of the chemical pattern on the DSA. In Chapter 3, we observe that the optimum brush composition for the DSA on chemical patterns with density multiplication is different from that for homogeneous surfaces. These counter-intuitive experimental observations are found to be well supported by free energy analysis and molecular simulations.;Because one of the important potential applications for DSA is the extension of the existing lithography tools, we illustrate that how simple it would be to integrate the proposed method with the state-of-the-art 193 nm immersion lithography in Chapter 4. Moreover, a fabrication process of nanowire field-effect transistor in which the critical layer was patterned by DSA density multiplication is demonstrated in Chapter 5 to showcase the DSA as an advanced patterning technique. In addition, a detailed calculation method of order parameter can be found in Appendix A. The calculation results prove that the pattern quality can be improved by the DSA and will be retained after pattern transfer.;The main purpose of this dissertation is to pursue fundamental understandings about the DSA of block copolymers on chemical patterns. At the same time, this dissertation also reinforces the idea that the DSA can provide improved pattern quality at reduced process complexity, which makes it a promising candidate as an extension of the existing lithography technologies.