Although sulfate free cleaning has reduced number of residual ions on mask surface drastically, the lifetime of photomask has improved marginally. New haze generation mechanism in sulfate free cleaning has been studied and evaluated based on surface properties of photomask thin film materials. It was found that haze generation is co-related with substrate surface properties as well as ionic re-combination under ArF illumination. Based on the haze generation study, the surface modification treatment has been studied and investigated in the view of surface energy. The surface modification treatment increases storage lifetime as well as cumulative haze threshold energy in wafer shops.

Date Published: 23 March 2009
PDF: 9 pages
Proc. SPIE 7272, Metrology, Inspection, and Process Control for Microlithography XXIII, 72721X (23 March 2009); doi: 10.1117/12.816350

Published in SPIE Proceedings Vol. 7272:
Metrology, Inspection, and Process Control for Microlithography XXIII
John A. Allgair; Christopher J. Raymond, Editor(s)