Gas cluster ion beam
Encyclopedia
Gas Cluster Ion Beams 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 surfaces through infusion or deposition.
ion
s. The clusters are formed when a high pressure gas (approximately 10 atmospheres
pressure) expands into a vacuum
(1e-5 atmospheres). The gas expands adiabatically
and cools then condenses
into clusters. The cluster
s are nano sized bits of crystalline matter with unique properties intermediate between the realms of atomic physics and those of solid state physics. The expansion takes place inside of a nozzle that shapes the gas flow and facilitates the formation of a jet of clusters. The jet of clusters passes through differential pumping apertures into a region of high vacuum (1e-8 atmospheres) where the clusters are ionized by collisions with energetic electron
s. The ionized clusters are accelerated electrostatically to very high velocities, and are focused into a tight beam.
The GCIB beam is then used to treat a surface -- typically the treated substrate is mechanically scanned in the beam to allow uniform irradiation of the surface. Argon
is a commonly used gas in GCIB treatments because it is chemically inert and inexpensive. Argon forms clusters readily, the atoms in the cluster are bound together with Van der Waals forces. Typical parameters for a high energy Argon GCIB are: average cluster size 10,000 atoms, average cluster charge +3, average cluster energy 65 keV
, average cluster velocity 6.5 km/s
, with a total electrical current of 200 µA
or more. When an Argon cluster with these parameters strikes a surface, a shallow crater is formed with a diameter of approximately 20 nm and a depth of 10 nm. When imaged using Atomic Force Microscopy
(AFM) the craters have an appearance much like craters on planetary bodies. A typical GCIB surface treatment allows every point on the surface to be struck by many cluster ions, resulting in smoothing of surface irregularities.
Lower energy GCIB treatments can be used to further smooth the surface, and GCIB can be used to produce an atomic level smoothness on both planar and nonplanar surfaces. Almost any gas can be used for GCIB, and there are many more uses for chemically reactive clusters such as for doping
semiconductor
s (using B2H6 gas), cleaning and etching (using NF3 gas), and for depositing chemical layers.
s, optical thin films, trimming SAW
and FBAR
filter deviceshttp://www.veeco.com/pdfs.php/243, fixed disk memory systems and for other uses. GCIB smoothing of high voltage electrodes has been shown to reduce field electron emission, and GCIB treated RF cavities are being studied for use in future high energy particle accelerator
s.
Now a wide flux of fullerites making, so as fullerens is in progress. And in this case the carbon GCIB is very perspective.
Ångström
The angstrom or ångström, is a unit of length equal to 1/10,000,000,000 of a meter . Its symbol is the Swedish letter Å....
of roughness without subsurface damage. It is also used to chemically alter surfaces through infusion or deposition.
Process
Using GCIB a surface is bombarded by a beam of high energy nanoscale clusterCluster (physics)
In physics, the term clusters denotes small, multiatom particles. As a rule of thumb, any particle of somewhere between 3 and 3x107 atoms is considered a cluster. Two-atom particles are sometimes considered clusters as well....
ion
Ion
An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. The name was given by physicist Michael Faraday for the substances that allow a current to pass between electrodes in a...
s. The clusters are formed when a high pressure gas (approximately 10 atmospheres
Atmosphere (unit)
The standard atmosphere is an international reference pressure defined as 101325 Pa and formerly used as unit of pressure. For practical purposes it has been replaced by the bar which is 105 Pa...
pressure) expands into a vacuum
Vacuum
In everyday usage, vacuum is a volume of space that is essentially empty of matter, such that its gaseous pressure is much less than atmospheric pressure. The word comes from the Latin term for "empty". A perfect vacuum would be one with no particles in it at all, which is impossible to achieve in...
(1e-5 atmospheres). The gas expands adiabatically
Adiabatic process
In thermodynamics, an adiabatic process or an isocaloric process is a thermodynamic process in which the net heat transfer to or from the working fluid is zero. Such a process can occur if the container of the system has thermally-insulated walls or the process happens in an extremely short time,...
and cools then condenses
Condensation
Condensation is the change of the physical state of matter from gaseous phase into liquid phase, and is the reverse of vaporization. When the transition happens from the gaseous phase into the solid phase directly, the change is called deposition....
into clusters. The cluster
Cluster (physics)
In physics, the term clusters denotes small, multiatom particles. As a rule of thumb, any particle of somewhere between 3 and 3x107 atoms is considered a cluster. Two-atom particles are sometimes considered clusters as well....
s are nano sized bits of crystalline matter with unique properties intermediate between the realms of atomic physics and those of solid state physics. The expansion takes place inside of a nozzle that shapes the gas flow and facilitates the formation of a jet of clusters. The jet of clusters passes through differential pumping apertures into a region of high vacuum (1e-8 atmospheres) where the clusters are ionized by collisions with energetic electron
Electron
The electron is a subatomic particle with a negative elementary electric charge. It has no known components or substructure; in other words, it is generally thought to be an elementary particle. An electron has a mass that is approximately 1/1836 that of the proton...
s. The ionized clusters are accelerated electrostatically to very high velocities, and are focused into a tight beam.
The GCIB beam is then used to treat a surface -- typically the treated substrate is mechanically scanned in the beam to allow uniform irradiation of the surface. Argon
Argon
Argon is a chemical element represented by the symbol Ar. Argon has atomic number 18 and is the third element in group 18 of the periodic table . Argon is the third most common gas in the Earth's atmosphere, at 0.93%, making it more common than carbon dioxide...
is a commonly used gas in GCIB treatments because it is chemically inert and inexpensive. Argon forms clusters readily, the atoms in the cluster are bound together with Van der Waals forces. Typical parameters for a high energy Argon GCIB are: average cluster size 10,000 atoms, average cluster charge +3, average cluster energy 65 keV
Electronvolt
In physics, the electron volt is a unit of energy equal to approximately joule . By definition, it is equal to the amount of kinetic energy gained by a single unbound electron when it accelerates through an electric potential difference of one volt...
, average cluster velocity 6.5 km/s
Metre per second
Metre per second is an SI derived unit of both speed and velocity , defined by distance in metres divided by time in seconds....
, with a total electrical current of 200 µA
Ampere
The ampere , often shortened to amp, is the SI unit of electric current and is one of the seven SI base units. It is named after André-Marie Ampère , French mathematician and physicist, considered the father of electrodynamics...
or more. When an Argon cluster with these parameters strikes a surface, a shallow crater is formed with a diameter of approximately 20 nm and a depth of 10 nm. When imaged using Atomic Force Microscopy
Atomic force microscope
Atomic force microscopy or scanning force microscopy is a very high-resolution type of scanning probe microscopy, with demonstrated resolution on the order of fractions of a nanometer, more than 1000 times better than the optical diffraction limit...
(AFM) the craters have an appearance much like craters on planetary bodies. A typical GCIB surface treatment allows every point on the surface to be struck by many cluster ions, resulting in smoothing of surface irregularities.
Lower energy GCIB treatments can be used to further smooth the surface, and GCIB can be used to produce an atomic level smoothness on both planar and nonplanar surfaces. Almost any gas can be used for GCIB, and there are many more uses for chemically reactive clusters such as for doping
Doping (semiconductor)
In semiconductor production, doping intentionally introduces impurities into an extremely pure semiconductor for the purpose of modulating its electrical properties. The impurities are dependent upon the type of semiconductor. Lightly and moderately doped semiconductors are referred to as extrinsic...
semiconductor
Semiconductor
A semiconductor is a material with electrical conductivity due to electron flow intermediate in magnitude between that of a conductor and an insulator. This means a conductivity roughly in the range of 103 to 10−8 siemens per centimeter...
s (using B2H6 gas), cleaning and etching (using NF3 gas), and for depositing chemical layers.
Industrial applications
In industry, GCIB has been used for the manufacture of semiconductor deviceSemiconductor device
Semiconductor devices are electronic components that exploit the electronic properties of semiconductor materials, principally silicon, germanium, and gallium arsenide, as well as organic semiconductors. Semiconductor devices have replaced thermionic devices in most applications...
s, optical thin films, trimming SAW
Surface acoustic wave
]A surface acoustic wave is an acoustic wave traveling along the surface of a material exhibiting elasticity, with an amplitude that typically decays exponentially with depth into the substrate.-Discovery:...
and FBAR
Thin film bulk acoustic resonator
Thin Film Bulk Acoustic Resonator is a device consisting of a piezoelectric material sandwiched between two electrodes and acoustically isolated from the surrounding medium. FBAR devices using piezoelectric films with thicknesses ranging from several micrometres down to tenth of micrometres...
filter deviceshttp://www.veeco.com/pdfs.php/243, fixed disk memory systems and for other uses. GCIB smoothing of high voltage electrodes has been shown to reduce field electron emission, and GCIB treated RF cavities are being studied for use in future high energy particle accelerator
Particle accelerator
A particle accelerator is a device that uses electromagnetic fields to propel charged particles to high speeds and to contain them in well-defined beams. An ordinary CRT television set is a simple form of accelerator. There are two basic types: electrostatic and oscillating field accelerators.In...
s.
Now a wide flux of fullerites making, so as fullerens is in progress. And in this case the carbon GCIB is very perspective.