Abstract
For soft lithography, the conventional negative tone resists, such as SU-8, that are used to create the mold have a number of drawbacks. PMMA, which is normally used as a positive tone resist, can be used as a negative resist by using high-fluence irradiation conditions. In this report, we outline optimization of the irradiation conditions for PMMA thin films using 2 MeV H + ions to exploit their ability to work as a negative tone resist at ion fluences above 1.0 × 10 15 ions cm -2. The main aim was to induce cross-linking while maintaining the exposed regions free of blisters and maintaining short irradiation times. We found that by using a two-step process with a low-flux irradiation, followed by a high-flux irradiation, the exposure time could be shortened by ∼50%. We also found that ion fluences greater than 5.0 × 10 15 ions cm -2 minimized the distortion in stitched regions.
Original language | English |
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Pages (from-to) | 18-21 |
Number of pages | 4 |
Journal | Microelectronic Engineering |
Volume | 102 |
DOIs | |
Publication status | Published - 2013 Feb |
Externally published | Yes |
Keywords
- Blisters
- Contraction
- Cross-linking
- H ion irradiation
- Negative resists
- PMMA
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Atomic and Molecular Physics, and Optics
- Condensed Matter Physics
- Surfaces, Coatings and Films
- Electrical and Electronic Engineering