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Proceedings Paper

Integration of a W-plug in an Al-based metallization scheme for 0.25-um IC technology
Author(s): Samit S. Sengupta; Subhas Bothra
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Paper Abstract

Tight interconnect design rules associated with 0.25 micrometer technology and below introduces a number of challenges in backend integration in the course of developing an appropriate process architecture. In this paper, the effect of the underlying metallization on via electrical performance and the attendant integration issues are discussed. For a Ti/TiN/Al-based metal stack, increasing the TiN cap thickness was found to significantly reduce via resistance. Since high density plasma CVD is commonly used to deposit gap-fill oxide after metal patterning, the effect on via resistance of oxygen plasma exposure of the underlying metal stack was also evaluated. A layer of Ti sandwiched between Al and cap TiN was found to give consistently low via resistance values due to reduction of the interfacial resistance contribution from the via/bottom metal interface. In some cases, where W remained exposed after dry etching of the subsequent metal level, complete corrosion of W was observed during solvent strip, for certain structures. Based on these results, various via integration options for current and future multilevel metal interconnect architecture are considered.

Paper Details

Date Published: 4 September 1998
PDF: 12 pages
Proc. SPIE 3508, Multilevel Interconnect Technology II, (4 September 1998); doi: 10.1117/12.324042
Show Author Affiliations
Samit S. Sengupta, VLSI Technology, Inc. (United States)
Subhas Bothra, VLSI Technology, Inc. (United States)

Published in SPIE Proceedings Vol. 3508:
Multilevel Interconnect Technology II
Mart Graef; Divyesh N. Patel, Editor(s)

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