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On the Mechanical Integrity of Ultra Low Dielectric Constant Materials for Use in Ulsi Beol Structures

Published online by Cambridge University Press:  17 March 2011

E. O. Shaffer II ,
K. E. Howard ,
M. E. Mills  and
P.H. Townsend III
E. O. Shaffer II
Affiliation:
The Dow Chemical Company, Advanced Electronic Materials, Midland, MI 48674
K. E. Howard
Affiliation:
The Dow Chemical Company, Advanced Electronic Materials, Midland, MI 48674
M. E. Mills
Affiliation:
The Dow Chemical Company, Advanced Electronic Materials, Midland, MI 48674
P.H. Townsend III
Affiliation:
The Dow Chemical Company, Advanced Electronic Materials, Midland, MI 48674
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Abstract

Adherence to the prescript of Moore's law continues to drive materials development for new and lower dielectric constant materials for use as back-end-of-line (BEOL) interlayer dielectric in advanced logic IC's. As is the case for the current generation of low-K materials (<3.0), these ultra-low K materials (<2.2) will need to meet the variety of integration and reliability requirements for successful product development. Excluding the incorporation of fluorine to lower the material polarity, further reductions of dielectric constant can only be achieved by reduced density. Based upon the industry's experience with the current class of full density dielectrics, process integration may be challenging for ultra-low K materials. This anticipated difficulty derives from the profound differences in material properties, e.g. mechanical integrity, as one lowers the material density, which in turn confounds existing manufacturing processes that have evolved over 35 years based on silicon dioxide.

Minimizing these material and processing differences by extending leveraged learning from previous technology nodes is essential for timely and cost-efficient development cycles. As a result, material selection of a full density low-K is somewhat influenced by the ability of that material to be extended into future generations. Understanding how the material properties will change as its density is lowered is vital to this selection process. In this paper, we present a summary of models for calculating effective properties as a function of density and apply these to current low-K materials with emphasis on mechanical integrity. We will also review experimental methods for measuring the mechanical integrity of ultra-low K materials and compare the results to the various models described herein.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 612: Symposium D – Materials, Technology & Reliability for Advanced Interconnects.. , 2000 , D1.1.1
Copyright
Copyright © Materials Research Society 2000

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