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Optimizing Sputtered Tin ARC Film Properties for Lithography of Sub-0.25μm Interconnect

Published online by Cambridge University Press:  10 February 2011

S. S. Sengupta ,
D. Baker ,
S. Sethi  and
S. Bothra
S. S. Sengupta
Affiliation:
VLSI Technology, Inc., 1109 McKay Drive, M/S 02, San Jose, CA 95131 samit.sengupta@sanjose.vlsi.com
D. Baker
Affiliation:
VLSI Technology, Inc., 1109 McKay Drive, M/S 02, San Jose, CA 95131 samit.sengupta@sanjose.vlsi.com
S. Sethi
Affiliation:
VLSI Technology, Inc., 1109 McKay Drive, M/S 02, San Jose, CA 95131 samit.sengupta@sanjose.vlsi.com
S. Bothra
Affiliation:
VLSI Technology, Inc., 1109 McKay Drive, M/S 02, San Jose, CA 95131 samit.sengupta@sanjose.vlsi.com
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Abstract

Advanced interconnect fabrication may require alternative TiITiN processes, such as an ionized metal plasma (IMP) sputtering technique to deposit Ti/TiN liner for sufficient step coverage in high aspect ratio contacts/vias. Since TiN is also widely used as an anti-reflective coating on top of multilayer metal films, the optical properties of the TiN film are extremely important.

In this paper, both IMP and standard PVD TiN films deposited on an aluminum layer are compared with respect to their lithography performance at exposure wavelengths of 365 nm (i-line) and 248 un (deep ultraviolet, or DUV). The measured optical constants of the two films were found to be very similar. The linewidth response of these two films at 365 nm was comparable; however, with DUV patterning, resist footing was observed on both films; but was especially severe with standard TiN. Differences in resist profile are explained in terms of the surface structure and density of the TiN film. By varying the conditions for deposition of IMP TiN (such as, RF bias, chamber pressure, etc.), the optical properties of the films may be varied. The impact of these varying film properties on DUV lithography is evaluated. Experimentally obtained linewidth response is compared with optical lithography simulations.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 514: Symposium I – Advanced Interconnects & Contact Materials & Processes for… , 1998 , 539
Copyright
Copyright © Materials Research Society 1998

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References

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