Definition of sputtering

Sputtering is a process whereby particles are ejected from a solid target material due to bombardment of the target by energetic particles. It only happens when the kinetic energy of the incoming particles is much higher than conventional thermal energies. 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.

Film 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.

Sputtered atoms ejected into the gas phase are not in their thermodynamic equilibrium state, and tend to deposit on all surfaces in the vacuum chamber. A substrate (such as a wafer) placed in the chamber will be coated with a thin film. Sputtering usually uses an argon plasma.

Etching

In the semiconductor industry sputtering is used to etch the target. Sputter etching is chosen in cases where a high degree of etching anisotropy is needed and selectivity is not a concern. One major drawback of this technique is wafer damage.