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Proceedings Paper

SiO2 buffer-etch processes with a TaN absorber for EUV mask fabrication
Author(s): Florian Letzkus; Joerg Butschke; Corinna Koepernik; Christian Holfeld; Josef Mathuni; Lutz Aschke; Frank Sobel
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Paper Abstract

Extreme Ultraviolet Lithography (EUVL) is the favourite next generation lithography candidate for IC device manufacturing with feature sizes beyond 32nm. The SiO2 buffer dry etching is a crucial step in the manufacture of the EUV mask due to stringent CD and reflectance requirements. In contrast to conventional chromium absorber layers new absorber materials e.g. TaN require an adjustment of the SiO2 buffer etch chemistry and process parameters to avoid a strong influence on the initial absorber profile and thickness. We have developed a SiO2 buffer dry etch process that uses the structured TaN absorber as masking layer. A laser reflectometer was used during the SiO2 dry etch process for process control and endpoint detection. Different dry etch processes with SF6/He, CF4 and CHF3/O2 etch chemistry have been evaluated and compared with regard to TaN- and SiO2- etch rate, TaN- and SiO2 etch profile and Si capping layer selectivity. We focused our work on minimum feature sizes and simultaneous etching of different line (e.g. dense- and isolated lines) and hole patterns. Line and contact hole structures with feature sizes down to 100nm have been realized and characterized in a SEM LEO 1560. The whole mask patterning process was executed on an advanced tool set comprising of a Leica SB 350 variable shaped e-beam writer, a blank coater Steag HamaTech ASR5000, a developer Steag HamaTech ASP5000 and a two chamber UNAXIS mask etcher III.

Paper Details

Date Published: 6 December 2004
PDF: 10 pages
Proc. SPIE 5567, 24th Annual BACUS Symposium on Photomask Technology, (6 December 2004); doi: 10.1117/12.569265
Show Author Affiliations
Florian Letzkus, IMS Chips (Germany)
Joerg Butschke, IMS Chips (Germany)
Corinna Koepernik, IMS Chips (Germany)
Christian Holfeld, Advanced Mask Technology Ctr. GmbH & Co. (Germany)
Josef Mathuni, Infineon Technologies AG (Germany)
Lutz Aschke, Schott Lithotec AG (Germany)
Frank Sobel, Schott Lithotec AG (Germany)

Published in SPIE Proceedings Vol. 5567:
24th Annual BACUS Symposium on Photomask Technology
Wolfgang Staud; J. Tracy Weed, Editor(s)

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