Technique for rapid at-wavelength inspection of extreme ultraviolet mask blanks
- Brookhaven National Laboratory, Upton, New York 11973 (United States)
- Bell Laboratories, Lucent Technologies, Murray Hill, New Jersey 07974 (United States)
- Bell Laboratories, Lucent Technologies, Holmdel, New Jersey 07733 (United States)
We have developed two new methods for at-wavelength inspection of mask blanks for extreme-ultraviolet (EUV) lithography. In one method an EUV photoresist is applied directly to a mask blank which is then flood exposed with EUV light and partially developed. In the second method, the photoresist is applied to an EUV transparent membrane that is placed in close proximity to the mask and then exposed and developed. Both reflectivity defects and phase defects alter the exposure of the resist, resulting in mounds of resist at defect sites that can then be located by visual inspection. In the direct application method, a higher contrast resist was shown to increase the height of the mounds, thereby improving the sensitivity of the technique. In the membrane method, a holographic technique was used to reconstruct an image of the mask, revealing the presence of very small defects, approximately 0.2 {mu}m in size. The demonstrated clean transfer of phase and amplitude defects to resist features on a membrane will be important when flagging defects in an automatic inspection tool. (c) 1999 American Vacuum Society.
- OSTI ID:
- 20217901
- Journal Information:
- Journal of Vacuum Science and Technology. B, Microelectronics Processing and Phenomena, Vol. 17, Issue 6; Other Information: PBD: Nov 1999; ISSN 0734-211X
- Country of Publication:
- United States
- Language:
- English
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