9 September 1994 Effects of tungsten deposition on site focal plane deviation
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Increased numerical aperture lenses necessary for imaging smaller features have the trade off of reducing the usable depth of focus (DOF) for larger linewidths in a photolithographic process. Large site focal plane deviations (SFPD) can easily consume the available DOF and severely affect the ability to resolve features. The use of a plasma backside etch of the wafer to remove tungsten residue after tungsten deposition will greatly increase SFPD. This paper demonstrates that a simple hardware retrofit in the CVD tungsten reactor can substantially improve the SFPD and via image quality otherwise degraded by backside etch. This retrofit has improved the imaging of both four metal layer 0.8 micrometers and two metal layer 0.65 micrometers interconnect metallization processes that had experienced localized SFPD problems. This hardware retrofit is easily extendible to greater than four metal layers with no significant effect on SFPD and qualitative post resist develop inspection.
© (1994) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
John Coniff, John Coniff, Stephen Dellarochetta, Stephen Dellarochetta, Terry L. Von Salza Brown, Terry L. Von Salza Brown, } "Effects of tungsten deposition on site focal plane deviation", Proc. SPIE 2335, Microelectronics Technology and Process Integration, (9 September 1994); doi: 10.1117/12.186050; https://doi.org/10.1117/12.186050

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