Recharacterization of a tungsten etch back process with special emphasis on PFC emission reduction and throughput optimization

Gerhard Spitzlsperger; Andreas Rupp; Heike Lorenz

doi:10.1117/12.425247

20 April 2001 Recharacterization of a Tungsten etch back process with special emphasis on PFC emission reduction and throughput optimization

Gerhard Spitzlsperger, Andreas Rupp, Heike Lorenz

Author Affiliations +

Proceedings Volume 4405, Process and Equipment Control in Microelectronic Manufacturing II; (2001) https://doi.org/10.1117/12.425247
Event: Microelectronic and MEMS Technologies, 2001, Edinburgh, United Kingdom

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.

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Gerhard Spitzlsperger, Andreas Rupp, and Heike Lorenz "Recharacterization of a Tungsten etch back process with special emphasis on PFC emission reduction and throughput optimization", Proc. SPIE 4405, Process and Equipment Control in Microelectronic Manufacturing II, (20 April 2001); https://doi.org/10.1117/12.425247

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