High purity sputter coater targets High purity sputter coater targets Sputter coating is a widely used technique for depositing thin layers of conductive metal onto non-conducting or semiconducting specimens or surfaces prior to observation with a scanning electron microscope SEM. Sputter coating is also used in a diverse range of thin film applicatons. Sputter coater targets are available in a wide range of metals. Some sputtering targets can be relatively expensive due to the high purity of the precious metals which require multiple refining steps. For most sputter coater metals a purity of
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Uses[ edit ] One of the earliest widespread commercial applications of sputter deposition, which is still one of its most important applications, is in the production of computer hard disks. Sputtering is used extensively in the semiconductor industry to deposit thin films of various materials in integrated circuit processing. Thin antireflection coatings on glass for optical applications are also deposited by sputtering. Because of the low substrate temperatures used, sputtering is an ideal method to deposit contact metals for thin-film transistors.
Another familiar application of sputtering is low- emissivity coatings on glass , used in double-pane window assemblies. The coating is a multilayer containing silver and metal oxides such as zinc oxide , tin oxide , or titanium dioxide. A large industry has developed around tool bit coating using sputtered nitrides, such as titanium nitride , creating the familiar gold colored hard coat.
Sputtering is also used as the process to deposit the metal e. Hard disk surfaces use sputtered CrOx and other sputtered materials. Sputtering is one of the main processes of manufacturing optical waveguides and is another way for making efficient photovoltaic solar cells.
Sputter-coated ant specimen Aulacopone relicta for SEM examination. A conductive coating is needed to prevent charging of a specimen with an electron beam in conventional SEM mode high vacuum, high voltage. While metal coatings are also useful for increasing signal to noise ratio heavy metals are good secondary electron emitters , they are of inferior quality when X-ray spectroscopy is employed.
For this reason when using X-ray spectroscopy a carbon coating is preferred. An important advantage of sputter deposition is that even materials with very high melting points are easily sputtered while evaporation of these materials in a resistance evaporator or Knudsen cell is problematic or impossible.
Sputter deposited films have a composition close to that of the source material. The difference is due to different elements spreading differently because of their different mass light elements are deflected more easily by the gas but this difference is constant.
Sputtered films typically have a better adhesion on the substrate than evaporated films. A target contains a large amount of material and is maintenance free making the technique suited for ultrahigh vacuum applications. Sputtering sources contain no hot parts to avoid heating they are typically water cooled and are compatible with reactive gases such as oxygen.
Sputtering can be performed top-down while evaporation must be performed bottom-up. Advanced processes such as epitaxial growth are possible. Some disadvantages of the sputtering process are that the process is more difficult to combine with a lift-off for structuring the film.
This is because the diffuse transport, characteristic of sputtering, makes a full shadow impossible. Thus, one cannot fully restrict where the atoms go, which can lead to contamination problems.
Also, active control for layer-by-layer growth is difficult compared to pulsed laser deposition and inert sputtering gases are built into the growing film as impurities. Pulsed laser deposition is a variant of the sputtering deposition technique in which a laser beam is used for sputtering.
Role of the sputtered and resputtered ions and the background gas is fully investigated during the pulsed laser deposition process. In a magnetic field, electrons follow helical paths around magnetic field lines, undergoing more ionizing collisions with gaseous neutrals near the target surface than would otherwise occur. As the target material is depleted, a "racetrack" erosion profile may appear on the surface of the target.
The sputter gas is typically an inert gas such as argon. The extra argon ions created as a result of these collisions lead to a higher deposition rate. The plasma can also be sustained at a lower pressure this way. The sputtered atoms are neutrally charged and so are unaffected by the magnetic trap. Charge build-up on insulating targets can be avoided with the use of RF sputtering where the sign of the anode-cathode bias is varied at a high rate commonly Stray magnetic fields leaking from ferromagnetic targets also disturb the sputtering process.
Specially designed sputter guns with unusually strong permanent magnets must often be used in compensation. Ion-beam sputtering[ edit ] A magnetron sputter gun showing the target-mounting surface, the vacuum feedthrough, the power connector and the water lines.
This design uses a disc target as opposed to the ring geometry illustrated above. Ion-beam sputtering IBS is a method in which the target is external to the ion source. A source can work without any magnetic field like in a hot filament ionization gauge. In a Kaufman source ions are generated by collisions with electrons that are confined by a magnetic field as in a magnetron.
They are then accelerated by the electric field emanating from a grid toward a target. As the ions leave the source they are neutralized by electrons from a second external filament. IBS has an advantage in that the energy and flux of ions can be controlled independently. Since the flux that strikes the target is composed of neutral atoms, either insulating or conducting targets can be sputtered. IBS has found application in the manufacture of thin-film heads for disk drives.
A pressure gradient between the ion source and the sample chamber is generated by placing the gas inlet at the source and shooting through a tube into the sample chamber.
This saves gas and reduces contamination in UHV applications. The principal drawback of IBS is the large amount of maintenance required to keep the ion source operating.
The deposited film is therefore different from the target material. The chemical reaction that the particles undergo is with a reactive gas introduced into the sputtering chamber such as oxygen or nitrogen; oxide and nitride films are often fabricated using reactive sputtering.
The composition of the film can be controlled by varying the relative pressures of the inert and reactive gases. Film stoichiometry is an important parameter for optimizing functional properties like the stress in SiNx and the index of refraction of SiOx. Ion-assisted deposition[ edit ] In ion-assisted deposition IAD , the substrate is exposed to a secondary ion beam operating at a lower power than the sputter gun.
Usually a Kaufman source, like that used in IBS, supplies the secondary beam. IAD can be used to deposit carbon in diamond-like form on a substrate.
Any carbon atoms landing on the substrate which fail to bond properly in the diamond crystal lattice will be knocked off by the secondary beam. NASA used this technique to experiment with depositing diamond films on turbine blades in the s. IAD is used in other important industrial applications such as creating tetrahedral amorphous carbon surface coatings on hard disk platters and hard transition metal nitride coatings on medical implants.
The plasma is generated in a side chamber opening into the main process chamber, containing the target and the substrate to be coated. As the plasma is generated remotely, and not from the target itself as in conventional magnetron sputtering , the ion current to the target is independent of the voltage applied to the target.
Gas flow sputtering[ edit ] Gas flow sputtering makes use of the hollow cathode effect , the same effect by which hollow cathode lamps operate. In gas flow sputtering a working gas like argon is led through an opening in a metal subjected to a negative electrical potential.
This causes a high flux of ions on the surrounding surfaces and a large sputter effect. Thornton applied the structure zone model for the description of thin film morphologies to sputter deposition. In a study on metallic layers prepared by DC sputtering,  he extended the structure zone concept initially introduced by Movchan and Demchishin for evaporated films. The most important point of this extension was to emphasize the pressure p as a decisive process parameter.
In particular, if hyperthermal techniques like sputtering etc. Next to the deposition temperature Td the chamber pressure or mean free path should thus always be specified when considering a deposition process. Since sputter deposition belongs to the group of plasma-assisted processes, next to neutral atoms also charged species like argon ions hit the surface of the growing film, and this component may exert a large effect.
It has been shown recently  that textures and residual stresses may arise in gas-flow sputtered Ti layers that compare to those obtained in macroscopic Ti work pieces subjected to a severe plastic deformation by shot peening.
Zulumi Optical lens cleaning tissue. Separate, dedicated coaters avoid any contamination issues and deliver high quality, high purity sample coatings. The Cressington series sputter coaters are designed to quickly coat non-conductive SEM samples with a thin conductive coating of precious metal. The target shutter allows cleaning of non-precious targets. Micro to Nano V.
High purity sputter coater targets