Printed resist images of pattern and probe-based aberration monitors at 248 nm wavelength on an AIMS tool and a projection printer at several NA's will be presented. The results will demonstrate the measurement operation of these monitors compared to their performance as designed through simulation. Initial experiments indicate that the focus monitor has sufficient sensitivity to see systematic focus trends across the die. The focus monitor is estimated to measure focus to 25nm accuracy of 1/8 of the Rayleigh depth of focus, indicating a 2-8x improvement over determination of best focus via the point spread function. This work also shows that the optimum conditions for reading the targets is when the intensity of the probe is just at the exposure threshold of the resist. The target designed to detect coma abberation did not work as expected and this is likely due to the electromagnetic performance of the mask and high-NA vector imaging effects.

Date Published: 17 December 2003
PDF: 9 pages
Proc. SPIE 5256, 23rd Annual BACUS Symposium on Photomask Technology, (17 December 2003); doi: 10.1117/12.518603

Published in SPIE Proceedings Vol. 5256:
23rd Annual BACUS Symposium on Photomask Technology
Kurt R. Kimmel; Wolfgang Staud, Editor(s)