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 (see below).

Source: Wikipedia