9th European FIB Users Group Meeting (EFUG2005)
Programme, abstracts and presentations
Monday 10 October 2005, Arcachon (near Bordeaux), France

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Abstracts

Review lecture

Oral presentations

Equipment development

Circuit Edit

(S)TEM sample preparation

Failure Analysis Applications

Other FIB applications

Posters

Sponsoring

The EFUG2005 meeting and dinner were sponsored by Credence, FEI, JEOL, SII NanoTechnology and Carl Zeiss.

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Abstracts

Triple Beam for TEM sample preparation.

Toshiaki Fujii, Haruo Takahashi, SII NanoTechnology Inc., Japan.

An Ar ion beam column was installed on a double beam tool which has FIB column and SEM column. All of columns look to one point at the surface of a specimen. This equipment is labeled as “Triple Beam”. Triple Beam has several advantages. Machine concept and experimental results will be reported .

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A new wrist Rotation Manipulator.

Stephan Kleindiek, Kleindiek Nanotechnik, Reutlingen, Germany.

A new wrist rotation manipulator is introduced. The new manipulator consists of the approved 3-axis manipulator MM3A and an additional wrist rotation axis. New applications like true lathe-like FIB milling, eucentric rotation for tomography, STEM are now possible with a simple retrofit. Results from semiconductor industry about reprocessing and re-thinning of ex-situ lamellas for EELS analysis, EFTEM mapping, high resolution imaging, 3D information, and planar sample preparation will be presented.

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Milling High Aspect Ratio (HAR) Holes in Dielectrics.

VV Makarov, RK Jain and TR Lundquist,Credence Systems Corp., Milpitas CA.

Milling HAR holes is important in circuit edit to contact buried traces. Metallization levels increase with transistor density, making HAR hole milling and end-pointing more difficult-often requiring aspect ratios >20 for box sizes <300nm. Assisting chemistries are required to increase milling and reduce material redeposition. For optimal efficiency, the floor surface of milled holes must be sufficiently covered with assisting molecules. However, the arrival rate of these molecules strongly depends on hole aspect ratio. This significantly limits the hole depth that can be reached for a given geometry and local pressure. Dynamics of milling HAR holes in SiO2 using XeF2 was studied, using variable dwell and frame times. The reachable hole depth for a given aspect ratio increases with frame times. This dependence on frame time is explained within a model considering the rate of accumulation of assisting molecules at the hole bottom. Successful milling of HAR holes with aspect ratios <30 and reliable end point is demonstrated.

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High-Throughput Via Milling with Concentrated Gas Delivery.

Valery Ray, Particle Beam Systems and Technology, Methuen, MA, USA.

Milling deep High Aspect Ratio (HAR) vias for probe-point access is a common and time-consuming task, carried out in a FIB during design debug of Integrated Circuits (ICs). An increase of the milling rates could have direct economic benefits to FIB users. With the use of efficient gas-enhanced recipes, milling rates are limited by concentration of precursor gas to the process zone without the excessive raise of the pressure in a main chamber of the FIB system. Concept of via milling with a gas concentrator, theoretically proposed in the past, was experimentally tested on Vectra 986 system and results showing throughput improvement and chamber pressure reduction will be presented.

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In-line TEM sample preparation and wafer return strategy for rapid yield learning.

P.Guyader 1,N.Bicaïs-Lépinay 1, F.André 1, S.Decorne 1, C.Trouiller 1, L.F.Tz.Kwakman 2, E.Sicurani 3 , D.Verkleij 4, R.Schampers 4. 1 STMicroelectronics, Crolles, France,2 Philips Semiconductors, Crolles, France,3 CEA-Leti,Grenoble, France,4 FEI Company, Acht, the Netherlands, STMicroelectronics, 850 rue Jean Monnet, F38926 Crolles, France.

In semiconductor industry, defect analysis and in-line process control are becoming more challenging as a result of the ever shrinking feature sizes. At the same time, fabs are trying to improve time to data and to reduce wafer costs. A few years ago, in-line FEI dual beam systems have been introduced into the 200 and 300 mm fabs at Crolles. These full wafer systems are integrating SEM, FIB columns and defect review capabilities and offer the possibility to keep wafers in-fab for rapid and multiple SEM cross-sectional views of defects. More recently, a unit to extract TEM samples has been added. With this additional system feature, TEM samples can be prepared in the fab and transferred to the lab for atomic resolution TEM imaging if SEM resolution is insufficient. Since the SEM inspection and TEM sample extraction are non-destructive at wafer level, wafers can be reintroduced in the fab for further processing steps. However, this wafer return strategy is only possible if wafers are not severely contaminated and do not contaminate other process tools or other wafers in the lot. To evaluate these contamination risks, an intensive study has been performed to quantify particle generation, FIB induced Gallium contamination and re-deposition of sputtered material. The overall impact on wafer yield has been verified on several device wafers. The full process offered by the in-line dual beam system with TEM sample preparation capability will be described and the results of the study on the process induced contamination will be presented.

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New TEM sample prep using a moving box software.

Geoffroy Auvert, STMicroelectronics 850 Rue Jean Monnet 38926 Crolles France, and CEA-LETI-SCPIO 17 Avenue des Martyrs 38054 Grenoble France.

Existing FIB etching procedures of silicon use a fixed form: point, line or rectangle. These procedures have some undesirable secondary effects as re-deposition and uncontrolled sidewall. In order to improve the quality of the etching of silicon in microelectronic and using a FIB, a moving box software has to be used. The main application of this software is to prepare a sample for TEM observation. This sample has two flat and parallel surfaces improving the quality of the TEM analysis.

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Descrambling techniques for EEPROM and Flash memories: EMMI, EBT and FIB.

Christophe De Nardi, Romain Desplats and Philippe Perdu, CNES, Félix Beaudouin and Vanessa Chazal, Thales, Jean Luc Gauffier, INSA, Toulouse, France.

For Failure analysis on memory devices, we need to localize the data information. “Descrambling” must be done to link electrical byte addresses with their physical locations in the IC. Indeed, failure analysis engineers seldom have access to memory table organization at byte and bit levels, which is usually confidential manufacturer data. In this presentation, three different techniques of descrambling are presented: Electron Beam Testing (EBT), Emission Microscopy (EMMI) and Focused Ion Beam (FIB). This quick overview and results will demonstrate the advantage of each approach. We will show that FIB is the most appropriate method for certain flash memories where EMMI and EBT fail because of block (or page) erase mode.

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Fabrication and Investigation of High Quality Single Crystal Nano-Capacitors Cut Using FIB for Non-Volatile Ferroelectric Random Access Memory (NVFeRAM) Applications.

*Mohamed Saad1, Paul Baxter1, Alina Schilling1, Tim Adams1, Robert Bowman1, Marty Gregg1, Finaly Morrison2 & J.F. Scott2 1 Nanostructure Media & Ferroelectric Group, International Research centre for Experimental Physic, Queen’s University Belfast, BT7 1NN, Belfast, UK 2 Symetric Centre for Ferroelectric, Department of Earth Sciences, University of Cambridge, Cambridge CB2 3EQ, UK.

Ferroelectric materials are obvious candidates for non-volatile random access memories (NVRAMs). The FIB has been used to fabricate high quality parallel-plate capacitor nanostructures from ferroelectric single crystals (BaTiO3 & SrTiO3) in which the thickness of lamellae was varied between 660nm and 75nm.The novelty and adventure in this project is that this is the first time that the behaviour of thin film ferroelectric systems is investigated at reduced dimensions without the large number of extrinsic factors that occur in normally deposited thin film systems. In other words, the significant changes in the dielectric properties that occur in moving from bulk single crystal material to heteroepitaxial deposited thin film is not related to any intrinsic effect of reduced dimension.

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Propulsion of Ripples on Glass by Ga+ Bombardment.

P. Alkemade, National Center of High-Resolution Electron Microscopy and Kavli Institute of Nanoscience Delft University of Technology, Delft The Netherlands.

Apart from milling and beam-assisted deposition, ion bombardment of solids can lead to the formation of topographical surface structures. A well-known example is the formation of ripples on an ion-bombarded surface. In this work the growth and propagation of ripples on SiO2 by a 30 keV Ga+ beam were investigated by alternated FIB milling and SEM imaging in a dual-beam FIB instrument. We observed that the ripples propagate across the bombarded surface. However, the speed and direction of propagation contradict existing models for ion sputtering and ion-beam enhanced viscous flow. We introduce a new model, which includes spatial variations in the deposition of the energy of the ion beam. This work shows that one can use secondary effects in ion beam milling (or deposition) to prepare special surface structures.

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