8th European FIB Users Group Meeting (EFUG2004)
Programme, abstracts and presentations
Monday 4 October 2004, EMPA Akademie, Dübendorf, Switserland

print EFUG2004 preliminary programme

Review lecture

Oral presentations


Micro and nano structuring

Circuit Edit

Failure Analysis Applications

(S)TEM sample preparation Other FIB applications



The EFUG2004 meeting and dinner were sponsored by Credence, FEI, JEOL and Zeiss.

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CoSi2 nano – wires synthesized by FIB processing.

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.

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Focused Ion Beam Microstructuring.

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.

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Dual Beam approach to fabrication of sub-20nm gap nanoelectrodes

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.

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Comparison of ion and electron beam induced deposition and etching techniques.

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.

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Advanced nanopattern formation by a subtractive self organization process with Focused Ion Beams

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.

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FIB backside circuit edit

Christian Boit, Berlin University of Technology, Germany.

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Recipe Development Considerations for Focused Ion Beam Gas Assisted Etching (FIB GAE).

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.

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Using FIB to hack security chips.

John F. Walker and Awla Alibhai-Sanghrajka, SiVenture, Maidenhead, UK.

The role of FIB in device edit is usually seen as a benefit to the chip designer or manufacturer in that design errors can be modified to make the chip operate successfully. However, if the same techniques are applied to smart card chips, they may lead to vulnerabilities compromising the security of the information stored on the chip. We discuss how security chips might be attacked by FIB directly. We also looking at how FIB makes possible indirect attacks on the chip, by disabling defence circuits and allowing cryptographic and fault attacks. We also discuss how security chips are defended against these attacks with different types of shield, and how these shields can be defeated. Finally, we look at future defences and attacks in this micro- arms race, specifically looking at how advances in FIB must be countered to successfully defend the chip.

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Backside Circuit Edit at the 90nm Process Node.

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. 

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FIB based copper deposition

Nicholas Antoniou, Tom Gannon, FEI Company.

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.

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Fast images of FIB x-sections using a CFESEM with BSE-TTL-detection

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.

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FIB Voltage Contrast for Failure Localisation on CMOS Circuits.

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.

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Secure and fast micromanipulation in SEM/FIB.

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.

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Some observations on the corrosion of Cu after FIB preparation

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.

1. On the Corrosion of Cu Metallization in the Focused Ion Beam System due to a low I2 Background, H. Bender, S. Jin, I. Vervoort and Y. Lantasov, in : Proceedings 25th International Symposium for Testing and Failure Analysis, (ASM International, Materials Park, Ohio) p. 135-140 (1999).

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Dual Beam FIB/SEM-STEM : the missing link between SEM and TEM.

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.

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FIBDAC Deformation Measurements.

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.

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Dual-Beam Focused Ion Beam in the Study of Artworks.

V. Sivel, P. Alkemade, J. Dik, R. de Visser, Delft University of Technology.

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.

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FIB assisted Soft X-Ray Microradiography Readout

M. Milani, D. Drobne, F. Tatti, I. DallaCosta and D. Batani, University of Milano-Bicocca, Italy

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.

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Three dimensional analysis of porous materials using FIB nanotomography.

L. Holzer, Ph. Gasser, EMPA, Dübendorf, Switzerland.

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.

Holzer, L., Indutnyi, F., Gasser, P., Münch, B. & Wegmann, M., 2004. 3D analysis of porous BaTiO3 ceramics using FIB nanotomography. Journal of Microscopy (in press. Issue October 2004).

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