Application of KrF Excimer Laser Lithography to 256 MbDRAM Fabrication

Sin-ichi FUKUZAWA  Hiroshi YOSHINO  Shinji ISHIDA  Kenji KONDOH  Tsuyoshi YOSHII  Naoaki AIZAKI  

IEICE TRANSACTIONS on Electronics   Vol.E76-C   No.11   pp.1665-1669
Publication Date: 1993/11/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section LETTER (Special Issue on LSI Memories)
Category: Application Specific Memory
DRAM,  KrF excimer laser,  lithography double-layer resist,  triple-layer resist,  

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256 MbDRAM chips have been fabricated by mix-and-match method using high NA KrF excimer laser stepper and i-line stepper. In the case of KrF stepper, the negative siloxane resist is used for rectangular and wiring patterns and the positive novolak-resin resist is used for hole patterns. Both of these two kinds of resist produce accurate pattern shape, allow-able pattern profile, satisfactory depth of focus and sufficient overlay accuracy for device fabrication in 0.25 µm design rule.