**2. Sputtering deposition**

Sputtering is a physical vapor deposition process (PVD) and was firstly coined by M. Blocher. This process is initiated by the bombardment of positive ions, usually Ar + gas

**Figure 1.** *Historical flowchart.*

is used due to its low cost, chemical inertness and high sputtering yield provider ability. It is the process of directing high-energy ions to a target in a vacuum and remove target atoms**.** The deposition of these emitted atoms on the surface of substrate is called Sputter deposition.

Sputter deposition takes place in an evacuated chamber with a low pressure of a rare gas such as argon backfilled in, as shown in **Figure 2**. The film is then formed on a substrate with a dc voltage applied between a metal target (the source of the film atoms) and substrate upon which the film is deposited. The voltage causes the gas to break down into Ar + ions and electrons, forming a glow discharge. Positively charged

**Figure 2.** *Sputtering tube.*

#### *Sputtering Deposition DOI: http://dx.doi.org/10.5772/intechopen.107353*

ions are accelerated and collide with the target, to sputter the target atom through momentum transfer. Some of it deposits on the substrate or sample [1].

There are some requirements for sputtering deposition as given below:


In order to maintain clean surfaces and prevent contamination from residual gas molecules, especially on the substrate, a good vacuum is required (< 10−5 Torr).

Sputtering can also be induced by electronegative elements like oxygen and fluorine as negative ions. Reflection of high-energy ions from a sputtered surface produce high-energy neutrals [2, 3].

The energy of incident ions influences the sputtering effect. With energy less than 10 eV, the ions can also adsorb to the surface and provide that energy to phonon. At energies over around 10 keV, the ion enters the substance, passes through multiple atomic layers, transmitting the majority of its energy in the form of heat deeply into the material and altering the target materials' configuration [4].

The **Figure 3** predicts a series of collisions that occur when an ion hits the surface of a target. When the surface is bombarded with the high energy ions, emitted electrons from the metal surface are known as secondary electron. Under this ionic interaction between atoms of the substrate, ions might be neutralized or reflected.
