Title :
Imaging characteristics of 0.12 /spl mu/m DRAM pattern by KrF lithography
Author :
Nakao, Shuji ; Tsujita, Kouichirou ; Arimoto, Ichirou ; Wakamiya, Wataru
Author_Institution :
ULSI Dev. Centre, Mitsubishi Electr. Corp., Hyogo, Japan
Abstract :
Feasibility of 0.12 /spl mu/m DRAM pattern formation by KrF lithography is investigated by optical image calculations. Using modified illumination optimized for the specific pattern and attenuating phase shift mask (PSM), depth of focus (DOF) can be achieved up to /spl sim/0.8 /spl mu/m under high numerical aperture (NA) of 0.75. However, the image quality is significantly degraded by lens aberration. Accordingly, the development of low aberration lens is inevitable to realize 0.12 /spl mu/m DRAM by KrF lithography.
Keywords :
DRAM chips; aberrations; integrated circuit technology; optical images; phase shifting masks; ultraviolet lithography; 0.12 micron; DRAM; KrF; KrF lithography; attenuating phase shift mask; depth of focus; lens aberration; modified illumination; numerical aperture; optical imaging; pattern formation; Apertures; Focusing; Image quality; Lenses; Lighting; Lithography; Optical attenuators; Optical imaging; Pattern formation; Random access memory;
Conference_Titel :
Microprocesses and Nanotechnology Conference, 1999. Digest of Papers. Microprocesses and Nanotechnology '99. 1999 International
Conference_Location :
Yokohama, Japan
Print_ISBN :
4-930813-97-2
DOI :
10.1109/IMNC.1999.797494
