We have investigated and compared a variety of technologies for patterning reflective masks for use with X=13 nm soft x-ray illumination. These patterning methods include: absorbing layers deposited on top of multilayer reflectors; reflective coating removal by reactive ion etching; and ion damage of multilayer regions to form a planar mask structure. Large area samples were prepared by each method and reflectivity measurements made to estimate the expected reflectance contrast for mask features. The reflectivity data were compared with simulation for the absorber overlayer and the etched multilayer measurements and found to be in good agreement. Our measured results indicate that reflectivity changes ranging from 5 to over 300 were effected by the various techniques. Fine patterning tests showed that mask features as fine as 0.1 pm can be achieved with each technology. We have also obtained resist images using several different types of x-ray reflection masks. The developed resist images of 0.1 pm lines and spaces obtained using reflection masks in a 20:1 Schwarzschild projection camera compared favorably with transmission mask results obtained using the same optical system.

Date Published: 1 January 1992
PDF: 14 pages
Proc. SPIE 1604, 11th Annual BACUS Symposium on Photomask Technology, (1 January 1992); doi: 10.1117/12.56938

Published in SPIE Proceedings Vol. 1604:
11th Annual BACUS Symposium on Photomask Technology
Kevin C. McGinnis, Editor(s)