Title :
Focus monitoring utilizing an aperture in Cr film on backside of photo mask
Author :
Nakao, S. ; Maejima, S. ; Ueno, A. ; Yamashita, S. ; Miyazaki, J. ; Kozawa, H. ; Tokui, A. ; Tsujita, Katsuyoshi
Author_Institution :
ULSI Dev. Center, Mitsubishi Electr. Corp., Hyogo, Japan
Abstract :
A simple and high sensitive focus monitoring has been developed utilizing an aperture formed in Cr film on backside of photo mask. A special mask for focus monitoring is developed such that two mark patterns are irradiated by different illuminations which are generated by an aperture on the backside of the mask so as to make two complementally half parts of usually used illumination. Printing mark patterns with overlaying each other, focus deviation is detected as a mutual displacement of mark patterns. Very high focus sensitivity (/spl Delta/x//spl Delta/z) of /spl sim/0.9 is observed for NA=0.68 optics.
Keywords :
chromium; masks; metallic thin films; optical focusing; photolithography; photoresists; proximity effect (lithography); Cr; Cr film; aperture; backside; focus monitoring; photo mask; printing mark patterns; very high focus sensitivity; Apertures; Chromium; Focusing; Lighting; Monitoring; Optical films; Optical imaging; Optical sensors; Printing; Wavelength measurement;
Conference_Titel :
Microprocesses and Nanotechnology Conference, 2002. Digest of Papers. Microprocesses and Nanotechnology 2002. 2002 International
Conference_Location :
Tokyo, Japan
Print_ISBN :
4-89114-031-3
DOI :
10.1109/IMNC.2002.1178662
