L. Bischoff, B. Schmidt, C. Akhmadaliev, and L.
Röntzsch, Forschungszentrum Rossendorf, Dresden, Germany
Nano structures, like wires or pearl chains play an increasing role in areas as plasmonics, nano-optics or nano-electronics as well as in the implementation of optical components in microelectronic devices. CoSi2 is a promising materials candidate due to its metallic behaviour with low resistivity and the compatibility to the microelectronics technology. Two methods to fabricate CoSi2-nano-wires using FIB technique in terms of ion beam synthesis (IBS) are investigated. An oxide layer, structured by use of a high resolution Ga beam, acting as an implantation mask for a broad beam Co doping and subsequent annealing was investigated and discussed. Secondly, a mass separated FIB of cobalt is applied for a direct writing IBS process. Therefore different alloys as source materials were tested and applied in the FIB column (Canion 31Mplus, Orsay Physics). The use of the doubly charged ions emitted from the Co source allows to increase the implantation energy up to 60 keV, important to obtain buried structures of high quality.
Philipp M. Nellen, Rolf Brönnimann, Joachim C. Reiner, Stephan Meier,
Pascal Jud, Andreas Beu, EMPA, Swiss Federal Laboratories for Materials Testing
and Research, Dübendorf, Switzerland.
This
presentation shows investigations in direct FIB writing of arbitrary
three-dimensional microstructures. Structure writing uses the fact that focused
high energy ions sputter away material in an efficient way. However, the amount
of sputtered material depends on various parameters in a nonlinear way. The
presentation also discusses competing effects, which influence the accuracy of
microstructuring. These effects are redeposition of the sputtered material,
amorphization in a thin surface layer, swelling of the material, and Ga
precipitation. Emphasis will be on redeposition effects. Examples will cover
basic experiments to understand these mechanisms and tests on machined
three-dimensional structures.
By improving the predictability of microstructuring FIB many new applications may
emerge, e.g., MEMS device fabrication and modification, scanning probe
microscope tips, micromedical device, and sensor structuring, micro- and
nano-print master fabrication (e.g. diffractive optical elements), and others.
G.C. Gazzadi and S.
Frabboni, Università di Modena, MODENA, Italy
Fabrication
of structures probing the electrical properties of nanosized objects is a key
issue for nanotechnology. Using a FIB-SEM Dual Beam workstation, we have
explored three different approaches. (1) By electron-beam Pt deposition,
FIB-patterned Au pads were bridged by 120nm-gap pillar-electrodes, grown with
opposite tilt angles. Further SEM scanning onto the pillars tips, under
precursor gas flow, allowed to reduce the gap size down to 5 nm under visual
control. (2) Always exploiting e-beam Pt deposition, in-plane electrodes were
grown within the pads gap, reaching 7 nm gap size. (3) By FIB direct
lithography, i.e. opening the gap in Au wires by FIB milling, gap sizes of the
order of 15-20 nm were obtained. These results are comparable to state of the
art nanogap fabrication by means of Electron Beam Lithography and put Dual Beam
workstations among the best facilities for nanoscale device prototyping, with a
major advantage of quick and completely in-situ processing on the bare sample.
Hans W.P. Koops, Klaus Edinger, Volker Boegli, NaWoTec GmbH, Rossdorf,
Germany
The characteristics of ion- and electron-beams, and of beam induced reactions and processes is presented, as well as the method of 3 dimensional structurization. Pro‘s and Con‘s for ions versus electrons are given. As an example the repair of photomasks shows advantages of the electron-beam over the ion-beam. Only e-beam based mask repair tools meet the requirements of damage free defect review and repair for advanced mask technologies. Focused ion beam local deposition and etching leaves quartz stained, as measured by AIMS system in transmission. Computer controlled 3-D beam induced structurization and rapid prototyping is described and examples for 3-D structurization and repair are given. Processing capabilities of FIB versus E-Beam are reviewed and compared.
A. Lugstein, M. Weil and E. Bertagnolli , Technical University Vienna, Vienna, Austria
We present a new approach for the generation of nanopattern, which in contrast to conventional bottom up or top down processes is based on a subtractive self organization process relying on material decomposition induced by FIB exposure. First, we study the evolution of the InAs, GaAs, GaP, GaSb surface due to FIB exposure by in-situ FIB-SEM combined with XRD, AFM and high resolution AES. Two dimensional ordered arrays of embedded as well as freestanding metallic dots were fabricated by a site control technique relying on preformed craters and an irradiation mediated migration and agglomeration. We completed these many-facetted experimental study with the morphological study of the FIB exposed surface subjected to RTA by optical microscopy, AFM and electrical measurements. In summary, the surface topography resulting from FIB bombardment is being investigated for possible use in nano-technology applications.
Christian Boit, Berlin University of Technology, Germany.
Valery Ray, Particle Beam Systems &
Technology, Methuen, Massachusetts, USA.
Development of efficient GAE recipes is a critical factor contributing to technically successful and cost-effective utilization of the FIB equipment in industrial environment. Current state of the GAE theory provides insight into dynamics of the FIB GAE process and allows making starting point recommendations for development of FIB GAE recipes in both surface micromachining and High Aspect Ratio (HAR) via milling applications.
John F. Walker and Awla Alibhai-Sanghrajka,
SiVenture, Maidenhead, UK.
Ted Lundquist, Tahir Malak, Rajesh Jain, Credence Systems Corporation.
As devices continue to shrink transistor densities increase and thus access to M1 metallization becomes more difficult. (With the number of metallization levels increasing as process nodes decrease, front side access is even more difficult.) However, by no means does this make through silicon circuit edit impossible. We shall examine several devices and discuss the transparency for editing past the active diffusions to M2 and M3 metallizations as well as to M1. We shall review the specific edit challenges that must be addressed to be successful. Besides the increased density with its reduction of edit-space, 90nm means copper and low-k dielectric interconnects. Further we shall emphasize the value in assisting designers to design for FIBability both in terms of turn-around-time and success rates moving forward.
Copper has become the
material of choice of interconnect in high speed IC’s and is proliferating fast
in the IC world as the process becomes robust and economies of scale are
realized. However, FIB systems until recently could only deposit conductors
with a resistivity orders of magnitude higher than the fabricated copper.
We present a process
whereby copper is deposited in an FIB system. Using a copper pre-cursor,
resistivity of 60 micro-Ohm cm can achieved (about ¼ of the resistivity of
tungsten) yet the deposition rate is similar to that of tungsten. This now
allows for edits that can be tested at much higher speed than previously and
the relationship of resistivity to deposition rate allows for a wide range of
time to resistance applications.
Klaus Reischle, Dr. Klaus Burger, ATMEL,
Germany.
Due the efficient ExB-filter and the energy-filter in the TTL detector (through the
lens) of modern CFESEM (cold field emission SEM) in using the BSE-signal (back
scattered electrons) it is possible without further preparation to get numerous
geometric and material information's out of FIB x-sections of semiconductor
structures.
The fast exchange between FIB and SEM the sample handling has been optimized by
mounting the device with conductive carbon cement on a standard specimen stub
and using a modified stub converter in the SEM. Examples will be presented
demonstrating the successful combination of optical microscopy, emission
microscopy, focused ion beam x-sectioning, field emission scanning electron
microscopy and energy dispersive x-ray spectroscopy in the daily work of
physical failure analysis.
Ruediger Rosenkranz, Infineon Technologies
Dresden, Germany.
FIB
VC is of growing importance in semiconductor failure analysis because it can
grant access to failure locations where electrical failure analysis does not. A
systematic overview over the different phenomena of VC generation is presented
and possibilities and limitations are discussed. Several case studies are shown
and an outlook to the opportunities of active voltage contrast by micro-probing
is given.
Stephan Kleindiek, Kleindiek Nanotechnik, Reutlingen, Germany.
Safe and fast micro- and nano manipulation becomes more and more
important in SEM and FIB systems. Handling and transportation of small
particles like TEM lamellae, dust particles to be investigated by TEM or even
cutting of micro- and nanostructures are tasks that have to be fulfilled with
high efficiency and speed inside the vacuum chambers of SEM and FIB.
A finger sized manipulator is introduced that requires so little space
that there is plenty of room for other items of equipment in the vacuum
chamber. Adaptations to most SEM and FIB offer installation within minutes.
Intuitive and precise control by means of miniature joystick or a cube with
three dials gives the user a high degree of control even at the highest
magnification of the microscope.
Application examples will be presented in the fields of TEM sample and CNT
manipulation, electrical probing, microinjection of liquids, cutting,
lithography, micro-welding, nanoindentation, gripping and force measurement.
H. Bender, O. Richard, A. Benedetti, P. Van Marcke, C. Drijbooms, IMEC, Leuven, Belgium.
The
ion beam milling in the FIB results in a non-passivated Cu surface, which is
potentially susceptible to corrosion effects during air exposure. The nature of
the corrosion layer on ion beam scanned Cu layers is investigated with Auger
electron spectroscopy. Sometimes, corrosion is spread over the TEM lamellae in
a variety of morphologies. The effect is not related to I2 in the
FIB system [1]. The conditions leading to the corrosion effects are not always
clear. The presence of the corrosion shows no direct correlation with the time
that the specimens are stored in air.
In certain cases a relationship to poor barrier quality is found.
Electron beam irradiation during an initial TEM investigation stimulates
corrosion during subsequent air exposure.
Hélène Jousset and Paul-Henri Albarede, Altis Semiconductor, Corbeil-Essonnes, France, in collaboration with FEI.
As device geometries continue
to shrink, smaller features need to be examined, and transmission electron
microscopy takes precedence of conventional scanning electron microscopy.
Therefore, it becomes necessary to make more and more thin-film samples for
process development, process monitoring and defect characterization. Most of
these specimens need to be very precisely positioned, and with some materials,
tripod polishing cannot be used. For these reasons, in the semi-conductor
industry, FIB is extensively used to prepare thin lamellas. Therefore, FEI has
developed a dedicated dual beam tool: the Strata DB-STEM 237. It is equipped
with an annular STEM detector and a FlipStage sample handling allows the
specimen to be positioned for ion beam thinning and for STEM imaging. The STEM technique
can be used to evaluate sample integrity, or also for final imaging of the
sample. After the description of the TEM lamella preparation (mechanical pre
thinning, and FIB thinning with Auto TEM), the paper will report the capability
of the annular STEM detector to do diffraction contrast. We will thus discuss
the potential and limitations of the technique.
D. Vogel, A. Gollhardt, J. Keller, B. Michel,
Micro Materials Center Berlin,Germany.
fibDAC is a new method for
deformation measurements based on load state images captured in a FIB cross
beam equipment. Objects are loaded mechanically and/or thermally inside the
microscope. Comparison of different load states is performed by means of locally
applied digital image correlation (DIC) algorithms. As a result incremental
displacement and strain fields over the object surface are determined. The
advantage of the fibDAC approach occurs in the incorporation of specimen
preparation (ion milling, ion beam surface polishing and DIC patterning),
specimen loading options by ion milling and DIC deformation measurement in a
single equipment. The authors apply the fibDAC tool with regard to reliability
studies on electronics, MEMS, photonics packaging components. They present
respective test results with particular focus on measurements of residual
stresses.
In
the study of many historic paintings the characterization of the build-up of
the various paint layers plays an important role. Elemental mapping in scanning
or transmission electron microscopy is a most important instrument for a full
and detailed physical and chemical understanding of layered systems. Such
knowledge is of interest in authenticity questions, as later additions or
restorations need to be recognized as such.
Due to the heterogeneous composition of art samples and different physical
behaviour of various layers conventional mechanical cutting usually crushes the
sample. In this contribution we used a Dual-Beam FIB in the study of
cross-sections of 17th-century paintings. The identification of the pigments
and other particles in works by Vermeer and Jan Steen solved historic puzzles
related to these paintings.
Simultaneous operation with
ion and electron beams in a Dual-Beam technique, suggests the possibility of
cutting a cross section and looking into the orthogonal direction of the
sample, or of some machining at micro/nano scale. Another feature of an ion
column, not so “popular” as the above mentioned one, is the capability to
produce a signal (by using ions as primary beam and the emitted secondary
electrons as reading tool) from the very few nanometer near the surface. This
provides a pure morphology information
of the surface without the interference of inner layers.
This property has been used
to read a Soft X-Ray Micrography, made from PMMA resist. Comparing these images
with those collected in the conventional way (AFM scan) or by means of a SEM column, we can see that this technique provides much better results in terms of
the quality of images (therefore a better interpretation), a larger amount of
information and a significant compression of the operation time. This evolution
in the read out process gives a significant contribution towards the expansion
of the SXCM (Soft X-Ray Contact Microscopy) technique.
Three-dimensional (3D) data
represent the basis for reliable quantification of complex microstructures.
Therefore, the development of high-resolution tomography techniques is of major
importance for many materials science disciplines. In a recent paper (Holzer
et al., in press.), we present a novel serial
sectioning procedure for 3D analysis using a dual-beam FIB (focused ion beam).
A very narrow and reproducible spacing between the individual imaging planes is
achieved by using drift correction algorithms in the automated slicing
procedure. The spacing between the planes is nearly of the same magnitude as
the pixel resolution on the SEM-images. Consequently, the acquired stack of
images can be transformed directly into a 3D data volume with a voxel
resolution of 6*7*17 nm.
To demonstrate the
capabilities of FIB nanotomography, a BaTiO3 ceramic with a high
volume fraction of fine porosity was investigated using the method as a basis
for computational microstructure analysis and the results compared with
conventional physical measurements. Significant differences between the
particle size distributions as measured by nanotomography and laser
granulometry indicate that the latter analysis is skewed by particle
agglomeration/aggregation in the raw powder and by uncertainties related to
calculation assumptions. Significant differences are also observed between the
results from mercury intrusion porosimetry (MIP) and 3D pore space analysis.
There is strong evidence that the ink-bottle effect leads to an overestimation
of the frequency of small pores in MIP.
FIB nanotomography thus reveals quantitative information of structural
features smaller than 100 nm in size, which cannot be acquired easily by other
methods.
