Focused ion beam

Focused ion beam

Focused ion beam, also known as FIB, is a technique used particularly in the semiconductor and materials science fields for site-specific analysis, deposition, and ablation of materials.

The FIB is a scientific instrument that resembles a scanning electron microscope. However, while the SEM uses a focused beam of electrons to image the sample in the chamber, a FIB instead uses a focused beam of gallium ions. Gallium is chosen because it is easy to build a gallium liquid metal ion source (LMIS). In a Gallium LMIS, gallium metal is placed in contact with a tungsten needle and heated. Gallium wets the tungsten, and a huge electric field (greater than 108 volts per centimeter) causes ionization and field emission of the gallium atoms. The FIB can also be incorporated in a system with both electron and ion beam columns, allowing the same feature to be investigated using either of the beams [ [ FEI DualBeam systems] ] [ [ Carl Zeiss CrossBeam series] ] .

These ions are then accelerated to an energy of 5-50 keV (kiloelectronvolts), and then focused onto the sample by electrostatic lenses. A modern FIB can deliver tens of nanoamps of current to a sample, or can image the sample with a spot size on the order of a few nanometers.

Unlike an electron microscope, the FIB is inherently destructive to the specimen. When the high-energy gallium ions strike the sample, they will sputter atoms from the surface. Gallium atoms will also be implanted into the top few nanometers of the surface, and the surface will be made amorphous.

Because of the sputtering capability, the FIB is used as a micro-machining tool, to modify or machine materials at the micro- and nanoscale. FIB micro machining has become a broad field of its own, but nano machining with FIB is a field that still needs developing. The common smallest beam size is 4-6 nm.FIB tools are designed to etch or machine surfaces, an ideal FIB might machine away one atom layer without any disruption of the atoms in the next layer, or any residual disruptions above the surface. Yet currently because of the sputter the machining typically roughens surfaces at the submicrometre length scales] .

A FIB can also be used to deposit material via ion beam induced deposition. FIB-assisted chemical vapor deposition occurs when a gas, such as tungsten carbonyl (W(CO)6) is introduced to the vacuum chamber and allowed to chemisorb onto the sample. By scanning an area with the beam, the precursor gas will be decomposed into volatile and non-volatile components; the non-volatile component, such as tungsten, remains on the surface as a deposition. This is useful, as the deposited metal can be used as a sacrificial layer, to protect the underlying sample from the destructive sputtering of the beam. Other materials such as platinum can also be deposited.

FIB is often used in the semiconductor industry to patch or modify an existing semiconductor device. For example, in an integrated circuit, the gallium beam could be used to cut unwanted electrical connections, or to deposit conductive material in order to make a connection.

The FIB is also commonly used to prepare samples for the transmission electron microscope. The TEM requires very thin samples, typically ~100 nanometers. Other techniques, such as ion milling or electropolishing can be used to prepare such thin samples. However, the nanometer-scale resolution of the FIB allows the exact thin region to be chosen. This is vital, for example, in integrated circuit failure analysis. If a particular transistor out of several million on a chip is bad, the only tool capable of preparing an electron microscope sample of that single transistor is the FIB.

The drawback to FIB sample preparation is the above-mentioned surface damage and implantation, which produces noticeable effects when using techniques such as high-resolution "lattice imaging" TEM or electron energy loss spectroscopy. This damaged layer can be removed by further milling with a low voltage argon ion beam after completion of the FIB process [ [ A Three Beam Approach to TEM Preparation Using In-situ Low Voltage Argon Ion Final Milling in a FIB-SEM Instrument] E L Principe, P Gnauck and P Hoffrogge, Microscopy and Microanalysis (2005), 11: 830-831 Cambridge University Press doi:10.1017/S1431927605502460] [ [ "Triple-Beam" Focussed-Ion-Beam Microscope] EPSRC grant EP/F019564/1] .

FIB preparation can also be used with cryogenically frozen samples in a suitably equipped instrument, allowing cross sectional analysis of samples containing liquids or fats, such as biological samples, pharmaceuticals, foams, inks, and food products [ [ Unique Imaging of Soft Materials Using Cryo-SDB] ]

Future FIBs will be much faster than the current FIBs that have a ~100ns dwell time, making them too slow for direction competition in device fabrication. Nanostructures 10 nm in diameter grown serially across a single 12-in. wafer would require more than two years, not including the time to get the FIB from one nanostructure to the next . Also the cut and paste type of work the FIB can perform will make it more and more viable.


External links

* [ Orsay Physics]
* [ Triple Beam Focused Ion Beam with SEM and EDX]
* [ Technology and Examples of FIB] at S3, INFM, Italy

Wikimedia Foundation. 2010.

См. также в других словарях:

  • Focused Ion Beam — Foto eines FIB Arbeitsplatzes Ein Focused Ion Beam (Abk.: FIB; englisch für „fokussierter Ionenstrahl“, deutsch auch Ionenfeinstrahlanlage) ist ein Gerät zur Oberflächenanalyse und bearbeitung. Steht der Materialabtrag im Vordergrund, heißt das… …   Deutsch Wikipedia

  • Focused-Ion-Beam-Mikroskop — Foto eines FIB Arbeitsplatzes Ein Focused Ion Beam (Abk.: FIB; englisch für „fokussierter Ionenstrahl“) ist ein Gerät zur Oberflächenanalyse und bearbeitung. Steht der Materialabtrag im Vordergrund, heißt das Verfahren auch Ionendünnung. Wenn die …   Deutsch Wikipedia

  • focused ion-beam lithography — fokusuojamoji jonpluoštė litografija statusas T sritis radioelektronika atitikmenys: angl. focused ion beam lithography vok. Lithografie mittels fokussierter Ionenstrahlen, f rus. литография с фокусируемым ионным пучком, f pranc. lithographie par …   Radioelektronikos terminų žodynas

  • Ion-beam sculpting — Ion Beam scultping is a term used to describe a two step process to make solid state nanopores. The term itself was coined by Golovchenko and co workers at Harvard in the paper Ion beam sculpting at nanometer length scales [J. Li, D. Stein, C.… …   Wikipedia

  • Ion beam — An ion beam is a type of particle beam consisting of ions. Ion beams have many uses in electronics manufacturing (principally ion implantation) and other industries. Today s ion beam sources are typically derived from the mercury vapor thrusters… …   Wikipedia

  • Ion beam lithography — By analogy to E beam lithography, focused ion beam lithography scans an ion beam across a surface to form a pattern. The ion beam may be used for directly sputtering the surface, or may induce chemical reactions in the exposed top layer (resist) …   Wikipedia

  • Ion beam deposition — (IBD) is a process of applying materials to a target through the application of an ion beam.In an ion source source materials gases or evaporated solids are ionized using electron ionization or by application of high electric fields (Penning ion… …   Wikipedia

  • Gas cluster ion beam — Gas Cluster Ion Beams (GCIB) is a new technology for nano scale modification of surfaces. It can smooth a wide variety of surface material types to within an angstrom of roughness without subsurface damage. It is also used to chemically alter… …   Wikipedia

  • Ion thruster — An ion thruster is a form of electric propulsion used for spacecraft propulsion that creates thrust by accelerating ions. Ion thrusters are characterized by how they accelerate the ions, using either electrostatic or electromagnetic force.… …   Wikipedia

  • Electron beam induced deposition — (EBID) is a process of decomposing gaseous molecules by electron beam leading to deposition of non volatile fragments onto a nearby substrate. Process Focused electron beam of scanning electron microscope (SEM) or scanning transmission electron… …   Wikipedia

Поделиться ссылкой на выделенное

Прямая ссылка:
Нажмите правой клавишей мыши и выберите «Копировать ссылку»