Sputtering

[6] An algorithm that simulates sputtering based on a quantum mechanical treatment including electrons stripping at high energy is implemented in the program TRIM.

That is to say, it can only happen when an ion is capable of transferring more energy into the target than is required for an atom to break free from its surface.

At elevated temperatures, chemical sputtering of carbon can be understood to be due to the incoming ions weakening bonds in the sample, which then desorb by thermal activation.

In 1955 Farnsworth, Schlier, George, and Burger reported using sputter cleaning in an ultra-high-vacuum system to prepare ultra-clean surfaces for low-energy electron-diffraction (LEED) studies.

Sputtered atoms are ejected into the gas phase but are not in their thermodynamic equilibrium state, and tend to deposit on all surfaces in the vacuum chamber.

Sputter damage is usually defined during transparent electrode deposition on optoelectronic devices, which is usually originated from the substrate's bombardment by highly energetic species.

The main species involved in the process and the representative energies can be listed as (values taken from[23]): As seen in the list above, negative ions (e.g., O− and In− for ITO sputtering) formed at the target surface and accelerated toward the substrate acquire the largest energy, which is determined by the potential between target and plasma potentials.

Although the flux of the energetic particles is an important parameter, high-energy negative O− ions are additionally the most abundant species in plasma in case of reactive deposition of oxides.

However, energies of other ions/atoms (e.g., Ar+, Ar0, or In0) in the discharge may already be sufficient to dissociate surface bonds or etch soft layers in certain device technologies.

In addition, the momentum transfer of high-energy particles from the plasma (Ar, oxygen ions) or sputtered from the target might impinge or even increase the substrate temperature sufficiently to trigger physical (e.g., etching) or thermal degradation of sensitive substrate layers (e.g. thin film metal halide perovskites).

This can affect the functional properties of underlying charge transport and passivation layers and photoactive absorbers or emitters, eroding device performance.

For instance, due to sputter damage, there may be inevitable interfacial consequences such as pinning of the Fermi level, caused by damage-related interface gap states, resulting in the formation of Schottky-barrier impeding carrier transport.

One such example occurs in secondary ion mass spectrometry (SIMS), where the target sample is sputtered at a constant rate.

Sputtering is one of the forms of space weathering, a process that changes the physical and chemical properties of airless bodies, such as asteroids and the Moon.

On icy moons, especially Europa, sputtering of photolyzed water from the surface leads to net loss of hydrogen and accumulation of oxygen-rich materials that may be important for life.

Sputtering is also one of the possible ways that Mars has lost most of its atmosphere and that Mercury continually replenishes its tenuous surface-bounded exosphere.

Due to its adaptability with a wide range of materials, Sputtering is used to create various types of coatings that enhance the performance of optical components.