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Proceedings Paper

Recharacterization of a tungsten etch back process with special emphasis on PFC emission reduction and throughput optimization
Author(s): Gerhard Spitzlsperger; Andreas Rupp; Heike Lorenz
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Paper Abstract

Environment friendly processing becomes more and more important in the semiconductor industry. One of the main targets is PFC emission reduction where, at the 0.5 to 0.25 micrometers technology node one of the main generators, beside CVD chamber cleans, is tungsten etch back using SF6 based chemistries. This process was re characterized by a detailed three level design of experiment with special emphasis on SF6 consumption reduction. Within the experiment, plasma power and SF6 flow were identified as the key parameters to double that utilization, indicating that the process is dominated by dissociation of SF6. Additionally a lower pressure process turned out to remove tungsten very effective during over etch, decreasing gas consumption further. The main issue with the new process was the formation of tungsten residues, which are attributed to micro masking by material sputtered from the upper electrode. The tungsten residue problem could be overcome by adjusting Ar/SF6 ratio. The new process revealed not only lower SF6 consumption by a factor of two, but also higher throughput. This means sometimes environmental protection can be also combined with economic benefits. Actually the new process is ramped up in mass production.

Paper Details

Date Published: 20 April 2001
PDF: 8 pages
Proc. SPIE 4405, Process and Equipment Control in Microelectronic Manufacturing II, (20 April 2001); doi: 10.1117/12.425247
Show Author Affiliations
Gerhard Spitzlsperger, Hitachi Semiconductor GmbH (Germany)
Andreas Rupp, Hitachi Semiconductor GmbH (Germany)
Heike Lorenz, Hitachi Semiconductor GmbH (Germany)

Published in SPIE Proceedings Vol. 4405:
Process and Equipment Control in Microelectronic Manufacturing II
Martin Fallon, Editor(s)

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