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Proceedings Paper

Improving the backend focus budget for 0.5 um lithography
Author(s): Satyendra S. Sethi; Alex Flores; P. McHale; R. Booth; Steve W. Graca; S. Frezon; C. Fruga
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Paper Abstract

One of the biggest challenges for printing 0.6 micrometers metal lines (1.3 micrometers pitch) over 1.1 micrometers of topography is the shallow depth of focus. Total random errors, or, Built In Focus Errors (BIFE) for the class of steppers used in this study was determined to be 0.48 micrometers . When topography, and field curvature/astigmatism, are factored in, the required depth of focus to print the metal lines is approximately 2.18 micrometers . However, the 'Available' DOF (as determined from PROLITH simulations) is only 1.8 micrometers . The deficit between available DOF and required DOF grows bigger when there are multiple steppers. To overcome this deficiency, various techniques have been studied. Topography reduction by 0.4 micrometers was achieved by the use of Reverse Well technology. Effect of different resist chemistries, off-axis illumination, variation in numerical aperture and partial coherence, on the focus latitude are shown.

Paper Details

Date Published: 26 May 1995
PDF: 10 pages
Proc. SPIE 2440, Optical/Laser Microlithography VIII, (26 May 1995); doi: 10.1117/12.209290
Show Author Affiliations
Satyendra S. Sethi, Motorola (United States)
Alex Flores, Motorola (United States)
P. McHale, Motorola (United States)
R. Booth, Motorola (United States)
Steve W. Graca, Motorola (United States)
S. Frezon, Motorola (United States)
C. Fruga, Motorola (United States)


Published in SPIE Proceedings Vol. 2440:
Optical/Laser Microlithography VIII
Timothy A. Brunner, Editor(s)

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