11 March 2002 Evaluation of reticle cleaning performance with different drying methods for high-grade photomasks
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Reticle cleaning is one of the most important processes in photomask making, because the smallest particles on reticle are supposed to be printable on wafer. Moreover, the requirement for reticle cleaning is stricter, because reticle should be zero-defect and there is no killer factor on it. It is facing difficult challenges as it enters new era of 100 nm pattern, introducing DUV lithography and phase shift materials. As defect sizes are decreasing to be controlled in cleaning process, the cleaning performance depends on not only conventional chemical treatment and megasonics but also a new IPA drying method such as direct- displacement IPA vapor dry. So we investigated the cleaning performance with different IPA drying methods by using quartz, chrome, MoSiON mask blanks and several test plates with 70 percent and 30 percent quartz area in main pattern field , such as conventional IPA dry and direct-displace IPA vapor dry , catgorized particle sizes and analyzed residual elements composition after cleaning of two systems. Effectiveness of cleaning with different drying methods on HT PSMs has been also investigated by controlling phase and transmittance of KrF half-tone phase shift mask(HT PSM), within +/- 3 degrees and +/- 0.3 percent respectively. Finally, direct-displacement IPA vapor dry method with traditional chemical treatment presents better removal rate of particles than conventional IPA dry when it comes to remove the smallest particles on quartz and chrome. It is found that direct-displacement IPA vapor dry for reticle cleaning would be considered to be the alternative dry method to control the smallest particles for the high-grade photomasks.
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Woo-Gun Jeong, Woo-Gun Jeong, Si-Woo Lee, Si-Woo Lee, Dae-Hong Kim, Dae-Hong Kim, Young Jin Yoon, Young Jin Yoon, Dong-Heok Lee, Dong-Heok Lee, Boo Yeon Choi, Boo Yeon Choi, Sang-Soo Choi, Sang-Soo Choi, Sung-Mo Jung, Sung-Mo Jung, Soo-Hong Jeong, Soo-Hong Jeong, } "Evaluation of reticle cleaning performance with different drying methods for high-grade photomasks", Proc. SPIE 4562, 21st Annual BACUS Symposium on Photomask Technology, (11 March 2002); doi: 10.1117/12.458260; https://doi.org/10.1117/12.458260

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