Effects of Ion Beam Milling on Surface Topography

Author(s):  
P.G. Pawar ◽  
P. Duhamel ◽  
G.W. Monk

A beam of ions of mass greater than a few atomic mass units and with sufficient energy can remove atoms from the surface of a solid material at a useful rate. A system used to achieve this purpose under controlled atmospheres is called an ion miliing machine. An ion milling apparatus presently available as IMMI-III with a IMMIAC was used in this investigation. Unless otherwise stated, all the micro milling operations were done with Ar+ at 6kv using a beam current of 100 μA for each of the two guns, with a specimen tilt of 15° from the horizontal plane.It is fairly well established that ion bombardment of the surface of homogeneous materials can produce surface topography which resembles geological erosional features.

Author(s):  
M. Herráez ◽  
A. Fernández ◽  
C. S. Lopes ◽  
C. González

The characterization of the strength and fracture toughness of three common structural fibres, E-glass, AS4 carbon and Kevlar KM2, is presented in this work. The notched specimens were prepared by means of selective carving of individual fibres by means of the focused ion beam. A straight-fronted edge notch was introduced in a plane perpendicular to the fibre axis, with the relative notch depth being a 0 / D ≈0.1 and the notch radius at the tip approximately 50 nm. The selection of the appropriate beam current during milling operations was performed to avoid to as much as possible any microstructural changes owing to ion impingement. Both notched and un-notched fibres were submitted to uniaxial tensile tests up to failure. The strength of the un-notched fibres was characterized in terms of the Weibull statistics, whereas the residual strength of the notched fibres was used to determine their apparent toughness. To this end, the stress intensity factor of a fronted edge crack was computed by means of the finite-element method for different crack lengths. The experimental results agreed with those reported in the literature for polyacrylonitrile-based carbon fibres obtained by using similar techniques. After mechanical testing, the fracture surface of the fibres was analysed to ascertain the failure mechanisms. It was found that AS4 carbon and E-glass fibres presented the lower toughness with fracture surfaces perpendicular to the fibre axis, emanating from the notch tip. The fractured region of Kevlar KM2 fibres extended along the fibre and showed large permanent deformation, which explains their higher degree of toughness when compared with carbon and glass fibres. This article is part of the themed issue ‘Multiscale modelling of the structural integrity of composite materials’.


Author(s):  
J. R. Reed ◽  
D. J. Michel ◽  
P. R. Howell

Recent studies have shown that the T2 (Al6CuLi3) phase particles in dilute Al-Li-Cu alloys transform to microcrystalline aggregates during TEM examination, during ion-beam thinning, or during in- situ heating in the TEM. Other studies, however, have noted that the T2 phase particles exhibit an ‘apparent’ five-fold symmetry suggesting that microcrystalline or twinned regions, rather than ‘single crystal’ regions, were responsible for the five-fold diffraction patterns. As a consequence, additional work was considered necessary to investigate further the stability of the T2 phase in dilute Al-Li-Cu alloys.The 3-mm diameter TEM disc specimens were prepared from a specially melted Al-2.5%Li-2.5%Cu alloy produced by conventional procedures. The TEM specimen thermal treatment and electropolishing procedures were previously reported. The electropolished disc specimens were examined in a JEOL 200CX microscope operated at 200 kV. Selected disc specimens containing the T2 phase were then subjected to ion beam thinning in a Gatan precision ion-milling system, operated with an argon ion beam, at accelerating voltage of 6 kV and a beam current of lμA.


1998 ◽  
Vol 523 ◽  
Author(s):  
N. I. Kato ◽  
K. Tsujimoto ◽  
N. Miura

AbstractIn focused ion beam (FIB) fabrication of cross-sectional transmission electron microscopy (X-TEM) specimens, highly accelerated ion beams sometimes cause serious damage. The damage can be induced in both the specimen surface and in the side walls. We used X-TEM observations to investigate the side-wall damage induced by FIB fabrication in crystalline silicon. The damaged layer was found to be about 20 nm thick in the case of 30-keV FIB etching. We tried to reduce the damage by several methods, such as gas-assisted etching (GAE) with iodine, broad argon ion milling and wet etching. The damaged layer was 19 nm for GAE and 12 nm for argon ion milling with a beam current of 70 mA and the tilt angle between the beam and the specimen of 15 degrees. Wet etching using a mixture of nitric and hydrofluoric acid removes most of the damaged layer.


Author(s):  
J.P. Benedict ◽  
Ron Anderson ◽  
S. J. Klepeis

Traditional specimen preparation procedures for non-biological samples, especially cross section preparation procedures, involves subjecting the specimen to ion milling for times ranging from minutes to tens of hours. Long ion milling time produces surface alteration, atomic number and rough-surface topography artifacts, and high temperatures. The introduction of new tools and methods in this laboratory improved our ability to mechanically thin specimens to a point where ion milling time was reduced to one to ten minutes. Very short ion milling times meant that ion milling was more of a cleaning operation than a thinning operation. The preferential thinning and the surface topography that still existed in briefly ion milled samples made the study of interfaces between materials such as platinum silicide and silicon difficult. These two problems can be eliminated by completely eliminating the ion milling step and mechanically polishing the sample to TEM transparency with the procedure outlined in this communication. Previous successful efforts leading to mechanically thinned specimens have shown that problems center on tool tilt control, removal of polishing damage, and specimen cleanliness.


2018 ◽  
Author(s):  
C.S. Bonifacio ◽  
P. Nowakowski ◽  
M.J. Campin ◽  
M.L. Ray ◽  
P.E. Fischione

Abstract Transmission electron microscopy (TEM) specimens are typically prepared using the focused ion beam (FIB) due to its site specificity, and fast and accurate thinning capabilities. However, TEM and high-resolution TEM (HRTEM) analysis may be limited due to the resulting FIB-induced artifacts. This work identifies FIB artifacts and presents the use of argon ion milling for the removal of FIB-induced damage for reproducible TEM specimen preparation of current and future fin field effect transistor (FinFET) technologies. Subsequently, high-quality and electron-transparent TEM specimens of less than 20 nm are obtained.


Author(s):  
B. Domengès ◽  
P. Poirier

Abstract In this study, the resistance of FIB prepared vias was characterized by the Kelvin probe technique and their physical characteristics studied using cross-sectional analysis. Two domains of resistivity were isolated in relation to the ion beam current used for the deposition of the via metal (Pt). Also submicrometer vias were investigated on 4.2 µm deep metal lines of a BiCMOS aluminum based design and a CMOS 090 copper based one. It is shown that the controlling parameter is the shape and volume of the contact, and that the contact formation is favored by the amount of over-mill of the via into the metal line it will contact.


Author(s):  
Thomas M. Moore

Abstract The availability of the focused ion beam (FIB) microscope with its excellent imaging resolution, depth of focus and ion milling capability has made it an appealing platform for materials characterization at the sub-micron, or "nano" level. This article focuses on nanomechanical characterization in the FIB, which is an extension of the FIB capabilities into the realm of nano-technology. It presents examples that demonstrate the power and flexibility of nanomechanical testing in the FIB or scanning electron microscope with a probe shaft that includes a built-in strain gauge. Loads that range from grams to micrograms are achievable. Calibration is limited only by the availability of calibrated load cells in the smallest load ranges. Deflections in the range of a few nanometers range can be accurately applied. Simultaneous electrical, mechanical, and visual data can be combined to provide a revealing study of physical behavior of complex and dynamic nanostructures.


Author(s):  
Gunnar Zimmermann ◽  
Richard Chapman

Abstract Dual beam FIBSEM systems invite the use of innovative techniques to localize IC fails both electrically and physically. For electrical localization, we present a quick and reliable in-situ FIBSEM technique to deposit probe pads with very low parasitic leakage (Ipara < 4E-11A at 3V). The probe pads were Pt, deposited with ion beam assistance, on top of highly insulating SiOx, deposited with electron beam assistance. The buried plate (n-Band), p-well, wordline and bitline of a failing and a good 0.2 μm technology DRAM single cell were contacted. Both cells shared the same wordline for direct comparison of cell characteristics. Through this technique we electrically isolated the fail to a single cell by detecting leakage between the polysilicon wordline gate and the cell diffusion. For physical localization, we present a completely in-situ FIBSEM technique that combines ion milling, XeF2 staining and SEM imaging. With this technique, the electrically isolated fail was found to be a hole in the gate oxide at the bad cell.


Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3970
Author(s):  
Wojciech J. Nowak

An electron backscattered diffraction (EBSD) method provides information about the crystallographic structure of materials. However, a surface subjected to analysis needs to be well-prepared. This usually requires following a time-consuming procedure of mechanical polishing. The alternative methods of surface preparation for EBSD are performed via electropolishing or focus ion beam (FIB). In the present study, plasma etching using a glow discharge optical emission spectrometer (GD-OES) was applied for surface preparation for EBSD analysis. The obtained results revealed that plasma etching through GD-OES can be successfully used for surface preparation for EBSD analysis. However, it was also found that the plasma etching is sensitive for the alloy microstructure, i.e., the presence of intermetallic phases and precipitates such as carbides possess a different sputtering rate, resulting in non-uniform plasma etching. Preparation of the cross-section of oxidized CM247 revealed a similar problem with non-uniformity of plasma etching. The carbides and oxide scale possess a lower sputtering rate than the metallic matrix, which caused formation of relief. Based on obtained results, possible resolutions to suppress the effect of different sputtering rates are proposed.


1998 ◽  
Vol 523 ◽  
Author(s):  
John Mardinly ◽  
David W. Susnitzky

AbstractThe demand for increasingly higher performance semiconductor products has stimulated the semiconductor industry to respond by producing devices with increasingly complex circuitry, more transistors in less space, more layers of metal, dielectric and interconnects, more interfaces, and a manufacturing process with nearly 1,000 steps. As all device features are shrunk in the quest for higher performance, the role of Transmission Electron Microscopy as a characterization tool takes on a continually increasing importance over older, lower-resolution characterization tools, such as SEM. The Ångstrom scale imaging resolution and nanometer scale chemical analysis and diffraction resolution provided by modem TEM's are particularly well suited for solving materials problems encountered during research, development, production engineering, reliability testing, and failure analysis. A critical enabling technology for the application of TEM to semiconductor based products as the feature size shrinks below a quarter micron is advances in specimen preparation. The traditional 1,000Å thick specimen will be unsatisfactory in a growing number of applications. It can be shown using a simple geometrical model, that the thickness of TEM specimens must shrink as the square root of the feature size reduction. Moreover, the center-targeting of these specimens must improve so that the centertargeting error shrinks linearly with the feature size reduction. To meet these challenges, control of the specimen preparation process will require a new generation of polishing and ion milling tools that make use of high resolution imaging to control the ion milling process. In addition, as the TEM specimen thickness shrinks, the thickness of surface amorphization produced must also be reduced. Gallium focused ion beam systems can produce hundreds of Ångstroms of amorphised surface silicon, an amount which can consume an entire thin specimen. This limitation to FIB milling requires a method of removal of amorphised material that leaves no artifact in the remaining material.


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