Sputtering is a process whereby atom

Atom

The atom is a basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons. The atomic nucleus contains a mix of positively charged protons and electrically neutral neutrons...

s are ejected from a solid target material due to bombardment of the target by energetic particle

Particle

A particle is, generally, a small localized object to which can be ascribed physical properties. It may also refer to:In chemistry:* Colloidal particle, part of a one-phase system of two or more components where the particles aren't individually visible.In physics:* Subatomic particle, which may be...

s. It is commonly used for thin-film deposition, etching and analytical techniques (see below).

Physical sputtering is driven by momentum exchange between the ions and atoms in the materials, due to collisions.
The incident ions set off collision cascade

Collision cascade

A collision cascade is a set of nearby adjacent energetic collisions of atoms induced by an energetic particle in a solid or liquid....

s in the target.