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Proceedings Paper

Evaluation of attenuated PSM photomask blanks with TF11 chrome and FEP-171 resist on a 248 nm DUV laser pattern generator
Author(s): Kezhao Xing; Charles Björnborg; Henrik Karlsson; Adisa Paulsson; Anna Rosendahl; Peter Beiming; Jukka Vedenpää; Jonathan Walford; Tom Newman
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Paper Abstract

Tighter requirements on mask resolution, CD and image positioning accuracy at and beyond the 45 nm technology node push the development of improved photomask blanks. One such blank for attenuated phase-shift masks (att-PSM) provides a thinner chrome film, named TF11, with higher chrome etch rate compared to the previous generation Att- PSM blank (NTAR5 chrome film) from the same supplier. Reduced stress in the chrome film also results in less image placement error induced by the material. FEP-171 is the positive chemically amplified resist (PCAR) that is most commonly used in advanced mask manufacturing with both 50 keV variable shaped e-beam (VSB) and DUV laser pattern generators. TF11 allows an FEP-171 resist film down to about 2000 Å thickness with sufficient etch resistance, while the standard resist thickness for NTAR5 is around 3000 Å. This work has experimentally evaluated the use of TF11 chrome and FEP-171 resist together with a 248 nm DUV laser pattern generator, the Sigma7500. First, patterning performance in resist with thicknesses from 2000 Å to 2600 Å, in steps of 100 Å, was tested with respect to swing curve and basic lithographic parameters including resolution, CD linearity, CD iso-dense bias and dose sensitivity. Patterning results on mask showed a swing minimum at around 2200 Å and a swing maximum at around 2500 Å, which correspond to reflectivity measurements for 248 nm wavelength performed by the blank supplier. It was concluded that the overall patterning performance was best close to the swing maximum. Thereafter the patterning performance using TF11 at two resist thicknesses, 2000 Å and 2550 Å, was studied in more detail and compared to performance using NTAR5 with 3200 Å resist. The evaluation showed that the Sigma7500-II offers good compatibility with TF11, especially using the optimized FEP-171 resist thickness of 2550 Å. It also showed that the patterning capability of the Sigma7500-II using TF11 and 2550 Å resist is improved compared to using NTAR5 and 3200 Å resist.

Paper Details

Date Published: 1 November 2007
PDF: 8 pages
Proc. SPIE 6730, Photomask Technology 2007, 67303Z (1 November 2007); doi: 10.1117/12.746855
Show Author Affiliations
Kezhao Xing, Micronic Laser Systems AB (Sweden)
Charles Björnborg, Micronic Laser Systems AB (Sweden)
Henrik Karlsson, Micronic Laser Systems AB (Sweden)
Adisa Paulsson, Micronic Laser Systems AB (Sweden)
Anna Rosendahl, Micronic Laser Systems AB (Sweden)
Peter Beiming, Micronic Laser Systems AB (Sweden)
Jukka Vedenpää, Micronic Laser Systems AB (Sweden)
Jonathan Walford, Micronic Laser Systems AB (Sweden)
Tom Newman, Micronic Laser Systems AB (Sweden)

Published in SPIE Proceedings Vol. 6730:
Photomask Technology 2007
Robert J. Naber; Hiroichi Kawahira, Editor(s)

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