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Sputtering is a process whereby atoms are ejected from a solid target material due to bombardment of the target by energetic particles.[1] It only happens when the kinetic energy of the incoming particles is much higher than conventional thermal energies ( 1 eV). This process can lead, during prolonged ion or plasma bombardment of a material, to significant erosion of materials, and can thus be harmful. On the other hand, it is commonly utilized for thin-film deposition, etching and analytical techniques.

A commercial sputtering system at Cornell NanoScale Science and Technology Facility.

Physics of sputtering[edit]

Physical sputtering is driven by momentum exchange between the ions and atoms in the materials, due to collisions.[1][2][3]


The incident ions set off collision cascades in the target. When such cascades recoil and reach the target surface with an energy greater than the surface binding energy, an atom would be ejected, known as sputtering. If the target is thin on an atomic scale the collision cascade can reach the back side of the target and atoms can escape the surface binding energy "in transmission". The average number of atoms ejected from the target per incident ion is called the sputter yield and depends on the ion incident angle, the energy of the ion, the masses of the ion and target atoms, and the surface binding energy of atoms in the target. For a crystalline target the orientation of the crystal axes with respect to the target surface is relevant.




Physical sputtering has a well-defined minimum energy threshold equal to or larger than the ion energy at which the maximum energy transfer of the ion to a sample atom equals the binding energy of a surface atom. This threshold typically is somewhere in the range 10–100 eV.


Electronic sputtering[edit]


Potential sputtering[edit]

A commercial sputtering system


Etching and chemical sputtering[edit]

Removing atoms by sputtering with an inert gas is called "ion milling" or "ion etching".



Applications and phenomena[edit]

Film deposition[edit]

Main article: Sputter deposition

Sputter deposition is a method of depositing thin films by sputtering that involves eroding material from a "target" source onto a "substrate" e.g. a silicon wafer. Resputtering, in contrast, involves re-emission of the deposited material, e.g. SiO2 during the deposition also by ion bombardment.




For analysis[edit]


In space[edit]



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