11 May 2009 In situ selectivity monitor for dry etch of photomasks
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Proceedings Volume 7379, Photomask and Next-Generation Lithography Mask Technology XVI; 73791T (2009) https://doi.org/10.1117/12.824305
Event: Photomask and NGL Mask Technology XVI, 2009, Yokohama, Japan
Abstract
A method is described to monitor etch selectivity real time in Applied Materials' advanced TetraTM mask etcher module. With the built-in Transmission Endpoint (TEP) capability, the transmission information for a wide range of spectra is collected. As resist thickness continues to be reduced during photomask etching process, interference fringes can be observed at selected wavelengths on the TEP spectrum. Based on known value from n & k simulation, the peak/valley positions of interference fringes can be defined. With the help from an algorithm developed to determine the corresponding time for each peak/valley position, the average resist etch rate can be obtained. In addition, the starting and ending resist thickness on the plate being etched can be calculated, so the incoming resist quality can be verified and being monitored. Combined with Cr etch rate derived from the endpoint time with plasma emission spectra, the Cr to photoresist etch selectivity can be monitored for each production plate automatically.
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Tiecheng Zhou, Jeff Chen, Michael Grimbergen, Madhavi Chandrachood, Ibrahim Ibrahim, Ajay Kumar, "In situ selectivity monitor for dry etch of photomasks", Proc. SPIE 7379, Photomask and Next-Generation Lithography Mask Technology XVI, 73791T (11 May 2009); doi: 10.1117/12.824305; https://doi.org/10.1117/12.824305
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