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ELECTRONIC DEVICE FAILURE ANALYSIS | VOLUME 18 NO. 4
56
“WHAT STARTS HERE CHANGES THE WORLD:”
RESEARCH HIGHLIGHTS FROM THE UNIVERSITY OF
TEXAS AT AUSTIN, DEPARTMENT OF PHYSICS
Michael R. Bruce, Consultant
If you’ve seen the ads, mainly during football games,
then you may have heard the motto of the University
of Texas at Austin: “What Starts Here Changes the
World.” Indeed, the University of Texas is one of the
leading research universities in the country, with annual
expenditures exceeding $600 million (average for the
last four years).[1] Some of the research that may be of
interest to the failure analysis community is highlighted
in this issue, which emphasizes research from the depart-
ment of physics. In a future issue, research from the
Microelectronics Research Center will be discussed.
In the physics department, Professor Mike Downer’s
group focuses on femtosecond laser spectroscopy in
condensed matter and plasmas, which includes the
study of kinetic processes and defect structures in
semiconductors. [2] His group has developed scanning
second-harmonic-generation (SHG) microscopy,[3] which
has found applications in the semiconductor industry.
Demonstrated applications of SHG to semiconductor
materials include:
• Hot carrier injection in silicon-on-insulator materials
can be measured without the need for a fabricated
device.
• SHG, combinedwith internal photoemission, is used to
determine bandoffsets anddefects inhigh-k dielectrics
(e.g., HfO2 ).
• SHG has been used to identify antiphase-boundary
defects in epi-GaAs-grown films on silicon substrates.
• SHG is much faster than conventional Raman micros-
copy for measuring strain in through-silicon vias.[4]
Professor Manfred Fink’s group is developing an
intense positron source.[5] Positrons are useful for non-
destructive analysis of lattice defects in semiconductors;
they are particularly effective for identification of lattice
vacancy defects. However, the lack of intense sources
UNIVERSITY HIGHLIGHT
has kept positron annihilation spectroscopy from being
morewidely adopted in the industry. In addition, Dr. Fink’s
group, along with Professor Jacek Borysow at Michigan
Technological University, has developedoneof theworld’s
most sensitive Raman spectrometers. For example, it
has been used to identify trace contamination, such as
ammonium nitrate, on silicon surfaces, with detection
limits below1 nmol. It is expected thatmany other organic
and inorganic trace contaminants could be detectedwith
similar or better sensitivity.[6]
Professor John Keto’s group,[7] the lab where I used
to work, also has extensive experience with Raman
techniques and other nonlinear optical phenomena that
have been applied in industry for contamination, stress,
and thermal analysis. Additionally, an optical third-
harmonic-generation microscopy technique developed
withDr. Downer shows promise for super-resolution (sub-
Rayleigh) analysis of thin films at dielectric interfaces.[8]
Professor Keji Lai’s team has developed a novel
near-field microwave impedance microscope.[9,10] Using
microwave (gigahertz) frequencies, the probe is unusually
qualified to nondestructively determine local dielectric
(capacitive) and conductivity (resistive) properties of
materials (simultaneously) down to 10 nmresolution; fur-
thermore, it can be easily integrated into an atomic force
microscope (AFM). In one application, the researchers
were able to showan unexpected implant layer in a SRAM
that scanning capacitance microscopy failed to detect. [11]
Other research groups involved with near-field scan-
ning techniques are those of Professor Alex De Lozanne
and Professor Chih-Kang “Ken” Shih. Both are some of
the earliest practitioners of near-field scanning probe
technology. Professor De Lozanne’s group[12] uses scanning
tunneling microscopy (STM), magnetic force micros-
copy, and AFM to study nanostructures, thin-filmdevices,