[UCI-CalIT2] Presents Guest Speaker on Structural Characterization of Porous Inter-level Dielectric Films

Shellie Nazarenus SNAZ at uci.edu
Tue Sep 7 13:31:58 PDT 2004


Cal-(IT)2 @ UCI Guest Presentation

 

Title:  Structural Characterization of Porous Inter-level Dielectric
Films

Speaker:  Christopher L. Soles, National Institute of Standards and
Technology (NIST), Gaithersburg, MD

 

Date: Monday, Sept. 13, 2004

Time: 10:00 am

Location: 3161 Engineering Gateway, UC Irvine

 

Abstract: With continued miniaturization or rescaling of the integrated
chip (IC), interconnects have become a potential bottleneck in chip
integration and performance. Line resistance and interline capacitance
control interconnect performance in terms of device speed, power
consumption, and signal-to-noise ratio. The noise issue is expected to
become more of a concern in the near future as the chip voltage declines
from 5 to 3.5 to 1.2. To lower the interline capacitance at nodes beyond
65 nm, and especially by the 45 nm node, the consensus among experts is
that porous inter-level dielectrics (ILD) are needed to replace CVD
organosilicates used in current 90 nm node.  Inducing porosity into the
ILD is very effective at reducing the dielectric constant, and hence the
interline capacitance. However, this weakens the mechanical strength of
the film and makes integration a formidable task. Complications often
arise in the subsequent plasma etch, ashing, and barrier layer
construction processes.  In general, the porous structure tends to
collapse or densify upon expose to the etching plasma, with concomitant
changes in the chemical composition. To fabricate porous ILD materials
into sub-100 nm features with acceptable yield and the ability to
withstand the harsh integration processes, one must have exacting
control over the porous film structure. The first step toward achieving
this control, before addressing material concerns, is to develop
metrologies that quantitatively characterize the pore structure with
accuracy in terms of porosity, average pore size, pore size
distribution, and so on. 

 

In this lecture, we present two state-of-the-art metrologies for
characterizing porous structures in relevant porous ILD films.  The
first is a form of porosimetry based on X-ray reflectivity (XRR) that
utilizes capillary condensation of an organic vapor inside the pores.
XRR is a very sensitive probe of film density and upon gradually
increasing the partial press of a gas or vapor, condensation occurs in
progressively larger pores.  This condensation results in an appreciable
increase in the film density that is easily perceived by XRR.  By
knowing the amount of vapor uptake as a function of the partial pressure
(the so-called adsorption/desorption isotherms), the film density, wall
density between the pores, porosity, and pore size distributions can be
obtained.  The second form porosimetry to be discussed is complimentary
in that it also utilizes capillary condensations, but different in that
small angle neutron scattering (SANS) is used to probe the length scales
of the pores being filled by the condensate.  Compared to the XRR
methodology, SANS has the distinct advantage that the scattering length
density of the organic condensate vapor can be "tuned" to exactly match
the porous matrix.  The match condition leads to zero scattering from a
pore once it is filled by the condensate.  By changing the partial
pressure of this contrast matched fluid, SANS porosimetry can be used to
map out the distribution of pores sizes, independent of adsorption
models that relate the partial pressure to a pore size radius.  Examples
from both techniques, on wide range of porous ILD films, will be
discussed and compared in this presentation.

Bio:  Christopher Soles earned his Ph.D. and Bachelor of Science degrees
in Materials Science and Engineering and Mechanical Engineering from the
University of Michigan.  Soles studied under Professor Albert F. Yee,
completing his thesis, "Fundamental Molecular Mechanisms of Moisture
Transport in Epoxy Resin."  He was awarded a NIST National Research
Council Fellowship and continued his training under Dr. Wen-li Wu in the
NIST Polymers Division studying inelastic neutron scattering techniques.
Soles now holds the permanent position of staff scientist in the NIST
Polymers Division where he is currently the Nanoimprint Lithography
project leader in the Electronic Materials Group.

Soles' research interests include fundamental polymer science issues in
patterning and lithography; nanoporous low-k dielectric materials &
characterization techniques; stabilization of biological activity in
proteins & enzymes; and neutron scattering and glass dynamics,
especially under confinement.

 

************************************************************************
************************************************************************
**********

 

 

Shellie Nazarenus

Communications Mgr.

Cal-(IT)2 UC Irvine division 

416 Engineering Tower

Irvine, CA 92697-2800

office: (949) 824-9622 cell: (949) 533-2564 fax: (949) 824-8197

www.calit2.net

 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://maillists.uci.edu/mailman/public/uci-calit2/attachments/20040907/1354b034/attachment.html


More information about the UCI-CalIT2 mailing list