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A Developer-free Approach to Conventional Electron Beam Lithography

  • Author / Creator
    Zheng, Ai Zhi
  • In order to achieve the best results possible by electron beam lithography (EBL), many aspects of the different stages of EBL have to be carefully optimized. In the exposure stage, dose, energy, aperture size, step size and working distance have to be carefully set. In the development stage, an appropriate developer formula corresponding to the resist has to be chosen, as well as development temperature, duration, rinsing and drying method. There are many challenges present in the co-optimization of the conditions mentioned above. Particularly in the development stage, resist swelling, line edge roughness (LER) and pattern collapse are the major obstacles to achieving the ultimate in resolution. What is noteworthy is that all three of these development problems are related to the liquid environment. Therefore, if there is a way to avoid liquid developers, all problems associated with the liquid behaviour will be eliminated. This thesis presents an approach that has the potential to fabricate dense structures without using liquid developers. The work was mainly conducted in the low exposure energy regimes from 1 keV to 5 keV. Two kinds of electron beam resist, 950k PMMA and ZEP 520A, were studied for their properties and behaviours throughout various processes such as optimized exposure, thermal development and reactive ion etching (RIE). So far, 70 nm half-pitch gratings have been successfully patterned on both 950k PMMA and ZEP 520A without liquid development. This validates a concept that may ultimately lead to widespread use of dry processing of EBL structures.

  • Subjects / Keywords
  • Graduation date
    2012-06
  • Type of Item
    Thesis
  • Degree
    Master of Science
  • DOI
    https://doi.org/10.7939/R3M374
  • 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.
  • Language
    English
  • Institution
    University of Alberta
  • Degree level
    Master's
  • Department
    • Department of Electrical and Computer Engineering
  • Specialization
    • Microsystems and Nanodevices
  • Supervisor / co-supervisor and their department(s)
    • Dew, Steven (Electrical and Computer Engineering) and Stepanova, Maria (National Institute for Nanotechnology - NRC)
  • Examining committee members and their departments
    • Decorby, Raymond (Electrical and Computer Engineering)
    • Mitra, Sushanta (Mechanical Engineering)
    • Stepanova, Maria (National Institute for Nanotechnology - NRC)
    • Dew, Steven (Electrical and Computer Engineering)