Title :
Novel annular illumination using controlled phase and transparency
Author :
Sugihara, T. ; Mori, S. ; Fukushima, T. ; Takagi, J.
Author_Institution :
Central Res. Labs., Sharp Corp., Nara, Japan
Abstract :
An off axis illumination is valid to enlarge resolution limit and depth of focus (DOF) for narrow pitch patterns. While in wide pitch patterns, the DOF is remarkably inferior to conventional illumination. A novel annular illumination has been achieved by amplitude superposition of off axis and on axis illuminations which are controlled inverse phases with appropriate transmittance. It has been confirmed, using a new optical filter, that this method can improve the DOF over wide range of pattern pitches maintaining resolution capability of under 0.25 /spl mu/m.<>
Keywords :
DRAM chips; integrated circuit technology; large scale integration; optical filters; optical resolving power; photolithography; 0.25 mum; DRAM chips; KrF excimer laser lithography; LSI circuit fabrication; amplitude superposition; annular illumination; controlled phase; depth of focus; inverse phases; narrow pitch patterns; off axis illumination; on axis illumination; optical filter; resolution capability; resolution limit; transmittance; transparency; wide pitch patterns; Chemical lasers; Chromium; Delay; Lighting; Linearity; Lithography; Optical filters; Paper technology; Resists; Stability;
Conference_Titel :
VLSI Technology, 1994. Digest of Technical Papers. 1994 Symposium on
Conference_Location :
Honolulu, HI, USA
Print_ISBN :
0-7803-1921-4
DOI :
10.1109/VLSIT.1994.324438
