Views: 0 Author: Site Editor Publish Time: 2023-05-11 Origin: Site
Sputtering is a phenomenon in which microscopic particles of a solid material are ejected from its surface after the material itself has been bombarded by energetic particles of a plasma or gas.It occurs naturally in outer space and can be an unwelcome source of wear in precision components. However, the fact that it can act on extremely fine material layers is exploited in science and industry where it is used to perform precise etching, perform analytical techniques, and deposit thin-film layers in the manufacture of optical coatings, semiconductor devices and nanotechnology products.It is a physical vapor deposition technique.
The term electron sputtering can denote sputtering caused by energetic electrons (such as in a transmission electron microscope), or sputtering caused by very high energy or highly charged heavy ions that lose energy to solids mainly by electron blocking power.The electron excitation causes sputtering.Electron sputtering produces high sputtering rates from insulators because the electron excitations that cause sputtering are not immediately extinguished as they are in conductors.An example of this is Jupiter's snow-covered moon Europa, where MeV sulfur ions in Jupiter's magnetosphere can eject as many as 10,000 H2O molecules.
In the case of multiple charged projectile ions, a special form of electron sputtering, called potential sputtering, can occur.In these cases, when the ions recombine during impact on the solid surface (the formation of hollow atoms), the potential energy stored in the multiply charged ion (i.e., the ion from which the neutral atom generates that charge state) required energy) is released.This sputtering process is characterized by the strong dependence of the observed sputtering yield on the charge state of the impinging ions and can already occur at ion impact energies well below the physical sputtering threshold.Potential sputtering is only observed for certain target species and requires a minimum potential.
Etching and chemical sputtering
Removing atoms by sputtering with an inert gas is called ion milling or ion etching.Sputtering can also play a role in reactive ion etching (RIE), a plasma process using chemically active ions and free radicals, which can significantly increase sputtering yields compared to purely physical sputtering.Reactive ions are often used in secondary ion mass spectrometry (SIMS) equipment to increase sputtering rates.The mechanisms leading to sputtering enhancement are not always clear, although the case of fluorine etching of Si has been theoretically well modeled.Sputtering observed to occur below the threshold energy of physical sputtering is also commonly referred to as chemical sputtering.The mechanism behind this sputtering is not always clear and can be difficult to distinguish from chemical etching.At high temperatures, chemical sputtering of carbon can be understood as the weakening of bonds in the sample by incoming ions, which are then desorbed by thermal activation.The observed hydrogen-induced sputtering of carbon-based materials at low temperatures has been explained as the entry of H ions between C-C bonds and thus breaking them, a mechanism known as fast chemical sputtering.
This category is empty.