Abstract
We have systematically studied the interaction of ultrapure, de-ionized water droplets with chemically amplified, deep-ultraviolet photoresist layers during evaporation by means of experiments. The contact lines of the evaporating droplets undergo two pinning events. The footprint diameters during pinning D1,2 scale with the initial droplet diameter D0 approximately as D1,2∼D0 4/3. Evaporated droplets leave a residue behind, generally in the form of an ultrathin layer (order 1–10 nm) with a sub-micron thick mound in the center. We have systematically characterized the residue dimensions as a function of the initial droplet size, the photoresist composition and process conditions. Post-evaporation rinsing steps were found to be unable to completely remove a deposit, depending on how long after droplet evaporation they were performed. Our results indicate that the occurrence of so-called watermark defects might be related to deliquescence induced by ionic residues.
Original language | English |
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Article number | 123912 |
Number of pages | 8 |
Journal | Colloids and Surfaces A: Physicochemical and Engineering Aspects |
Volume | 583 |
DOIs | |
Publication status | Published - 20 Dec 2019 |
Funding
This research is part of the research program Towards zero defectivity with project number 13919, which is (partly) financed by the Netherlands Organisation for Scientific Research (NWO). We are grateful to Wim Schollaert of JSR Micro for providing the photoresist samples. Appendix A
Keywords
- Deliquescence
- Droplet evaporation
- Evaporation
- Evaporation residues