- Ion beam
An ion beam is a type of
particle beamconsisting 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 developed by NASAin the 1960s.
Ion beam etching or Sputtering
One type of ion beam source is the
duoplasmatron. Ion beams can be used for sputteringor ion beam etching and for ion beam analysis.
Ion beam etching, or
sputtering, is a technique conceptually similar to sandblasting, but using individual atoms in an ion beam to ablatea target. Reactive ion etchingis an important extension that uses chemical reactivity to enhance the physical sputtering effect.
In a typical use in semiconductor manufacturing, a
maskis used to selectively expose a layer of photoresiston a substrate such as a silicon dioxideor gallium arsenide wafer. The wafer is developed, and for a positive photoresist, the exposed portions are removed in a chemical process. The result is a pattern left on the surface areas of the wafer that had been masked from exposure. The wafer is then placed in a vacuum chamber, and exposed to the ion beam. The impact of the ions erodes the target, abrading away the areas not covered by the photoresist. This method is frequently enhanced by bleeding a reactive gas into the vacuum system, which is known as reactive ion etching.
Focused Ion Beam (FIB) instruments are also used in the design verification and/or
failure analysisof semiconductor devices. Engineering prototype devices may be modified using the ion beam in order to rewire the electrical circuit. The technique may be effectively used to avoid performing a new mask run for the purpose of testing design changes. A device edit (FIB milling operation) is accomplished by focusing the ion beam on selected regions of the device in order to mill through metal or polysilicon structures. In addition to milling, it is also possible to use the ion beam to force the deposit of new conductive lines on the surface of the device. This is accomplished by injecting chemicals into the ion stream near the device surface. The interaction between the ions and the chemicals result in chemical deposition on the surface. This process is typically referred to as a FIB deposit operation.
Sputtering is also used in materials science to thin samples or specific regions of samples for
transmission electron microscopeanalysis, or for extending surface analytical techniques such as secondary ion mass spectrometryor electron spectroscopy (XPS, AES) so that they can depth profile them.
High energy ion beams
High energy ion beams produced by
particle accelerators are used in atomic physics, nuclear physicsand particle physics.
The use of ion beams as a
particle beam weaponis theoretically possible, but has not been demonstrated. See particle beam weaponfor more information on this type of weapon.
science fiction, weaponised ion beam generators are usually dubbed ion cannons.
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