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Proceedings Paper

Etching of TiN local interconnects using HBr in a triode reactor with magnetic confinement
Author(s): Gerfried Zwicker; Christjan Ursic; Detlef Friedrich
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Paper Abstract

In CMOS technology for highly integrated circuits, TiN serves as a diffusion barrier layer between the Si substrate and the Al metallization. Structuring the TiN is a challenge as the selectivities of the etching process have not only to be high against resist and SiO2 but also against the gate and S/D materials. For quarter micron devices with shallow p/n junctions this material can be a salicide, e.g., CoSi2 or TiSi2. To address the described requirements, a TiN etch process employing HBr chemistry has been developed in a triode system with magnetic confinement. The reactor concept leads to relatively high ion densities, which allows anisotropic etching at low pressures (5 m Torr) with reasonable TiN etchrates of about 150 nm/min. Selectivities to SiO2 of 5:1 could be obtained. In comparison to Cl2 chemistry the selectivities to photoresist are with 1.5:1 twice as high and allow longer over-etch. Using experimental design software, an optimization with respect to underlying CoSi2 resulted in a selectivity of nearly 10:1 with the drawback of a reduced TiN etchrate. Using the optimized recipe sub-half micrometers TiN structures over high topography have been patterned. The problem of residue removal after resist stripping is discussed.

Paper Details

Date Published: 16 April 1993
PDF: 10 pages
Proc. SPIE 1803, Advanced Techniques for Integrated Circuit Processing II, (16 April 1993); doi: 10.1117/12.142907
Show Author Affiliations
Gerfried Zwicker, Fraunhofer-Institut fuer Mikrostrukturtechnik (Germany)
Christjan Ursic, Fraunhofer-Institut fuer Mikrostrukturtechnik (Germany)
Detlef Friedrich, Fraunhofer-Institut fuer Mikrostrukturtechnik (Germany)

Published in SPIE Proceedings Vol. 1803:
Advanced Techniques for Integrated Circuit Processing II
James A. Bondur; Gary Castleman; Lloyd R. Harriott; Terry R. Turner, Editor(s)

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