Patterning of Nanostructures by Block Copolymer Self-Assembly

• Author / Creator

  Zhang, Xiaojiang

• Fabrication of nanofeatures with precisely defined size and ordering is essential for a broad range of technologically important applications, including integrated circuit production. Self-organizing block copolymers are capable of patterning substrates with nanoscale precision. This thesis describes patterning of nanostructures by block copolymer self-assembly.
  Rapid block copolymer self-assembly was realized with an innovative microwave-based method that used a scientific microwave reactor to anneal block copolymer films inside a sealed container in the presence of an appropriate solvent. Simple transformation of the as-annealed poly(styrene)-block-poly(2-vinylpyridine) (PS-b-P2VP) block copolymer films into metallic nanostructures led to better visualization of the self-assembled pattern in SEM. A study was made of a number of different parameters affecting the polymer assembly speed and the pattern defect density, such as solvent, annealing time, annealing temperature, and substrate resistivity. The approach was also applied to the commonly used poly(styrene)-block-poly(methyl methacrylate) block copolymers. Highly ordered linear patterns were obtained both on un-prepatterned substrates and e-beam lithography defined substrates in less than 3 minutes.
  
  On adapting the microwave annealing technique to a conventional household microwave oven, highly ordered linear structures of self-assembled BCPs were obtained in 60 seconds. Using binary PS-b-P2VP block copolymer blends, linear feature spacing was readily controlled with nanometer scale precision. To show the high level of control over feature spacing, 12 to 19 metallic nanolines were fabricated between 500-nm-wide topographic wall-like silica features on a silicon surfaces with an annealing time of less than 2 minutes. In addition, PS-b-P2VP/PS-b-P4VP binary blends were used to produce hybrid dot and line nanostructures. Although this study is still in an early stage, the concept of using self-assembled PS-b-P2VP/PS-b-P4VP mixture to template hybrid metallic nanostructures was successfully demonstrated.
  PS-b-P4VP block copolymer films were employed as templates to pattern silicon surfaces with pseudo-hexagonal arrays of nanoscale etched pits, using a simple etching in HF(aq). The etched pit interiors were terminated by Si-Hx while the top unetched silicon surface remains capped by the native silicon oxide. The potential utility of this interface was demonstrated by selective patterning of a nanostructured metal oxide and metal features within these pits on the silicon top face.

• Subjects / Keywords

  • Integrated circuits--Materials
  • Nanotechnology
  • Nanostructures
  • Block copolymers

• Graduation date

  Spring 2012

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R3NW8R

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.