Share Email Print

Proceedings Paper

Error analysis of overlay compensation methodologies and proposed functional tolerances for EUV photomask flatness
Author(s): Katherine Ballman; Christopher Lee; Thomas Dunn; Alexander Bean
Format Member Price Non-Member Price
PDF $17.00 $21.00

Paper Abstract

Due to the impact on image placement and overlay errors inherent in all reflective lithography systems, EUV reticles will need to adhere to flatness specifications below 10nm for 2018 production. These single value metrics are near impossible to meet using current tooling infrastructure (current state of the art reticles report P-V flatness ~60nm). In order to focus innovation on areas which lack capability for flatness compensation or correction, this paper redefines flatness metrics as being “correctable” vs. “non-correctable” based on the surface topography’s contributions to the final IP budget at wafer, as well as whether data driven corrections (write compensation or at scanner) are available for the reticle’s specific shape. To better understand and define the limitations of write compensation and scanner corrections, an error budget for processes contributing to these two methods is presented. Photomask flatness measurement tools are now targeting 6σ reproducibility <1nm (previous 3σ reproducibility ~3nm) in order to drive down error contributions and provide more accurate data for correction techniques. Taking advantage of the high order measurement capabilities of improved metrology tooling, as well as computational capabilities which enable fast measurements and analysis of sophisticated shapes, we propose a methodology for the industry to create functional tolerances focused on the flatness errors that are not correctable with compensation.

Paper Details

Date Published: 10 May 2016
PDF: 12 pages
Proc. SPIE 9984, Photomask Japan 2016: XXIII Symposium on Photomask and Next-Generation Lithography Mask Technology, 99840S (10 May 2016); doi: 10.1117/12.2242282
Show Author Affiliations
Katherine Ballman, Corning Tropel (United States)
Christopher Lee, Corning Tropel (United States)
Thomas Dunn, Corning Tropel (United States)
Alexander Bean, Corning Tropel (United States)

Published in SPIE Proceedings Vol. 9984:
Photomask Japan 2016: XXIII Symposium on Photomask and Next-Generation Lithography Mask Technology
Nobuyuki Yoshioka, Editor(s)

© SPIE. Terms of Use
Back to Top
Sign in to read the full article
Create a free SPIE account to get access to
premium articles and original research
Forgot your username?