CHEM02200704003 Nilamadhab Pandhy - Homi Bhabha National ...

Chapter 3
various industrial applications because of, (a) its simplicity and reliability, (b) capability for
operating in different physical conditions, (3) sputtering sources can be designed up to industrial
scale, and (4) as an alternative to meet the functional and economical industrial requirements
compared to the traditional process. Moreover, the process limitations in conventional sputtering
process, such as low deposition rate, low ionisation efficiency in plasma, and substrate heating
effect is not encountered in magnetron sputtering. Today, magnetron sputtering technology is
largely used in different applications such as (a) decorative coating on items in everyday life such
as jewellery and glasses (b) in semi-conductor industries for application in Si integrated circuits,
and (c) to improve the surface properties of base material particularly wear, load bearing and
corrosion resistance etc [58-60]. The driving force for the fast development of magnetron
sputtering technology is due to the requirement of advanced thin films with prescribed physical
and functional properties in many diverse technological applications.
The basic sputtering process has been known for many years. In the basic sputtering
process, a target (cathode) is bombarded by energetic ions generated in a glow discharge plasma
situated in front of the plasma. The bombardment process causes the removal i.e. sputtering of the
target atoms, which may then condense as a thin film on the substrate. However, secondary
electrons are also generated from the target surface as a result of ion bombardment and these
electrons do not significantly contribute in maintaining the plasma and cause unnecessary heating
of the substrate.
Magnetrons make use of the fact that a magnetic field configured parallel to the target
surface can constrain secondary electron motion to the vicinity of the target [61,62]. The
schematic of magnetron sputtering is shown in Fig. 3.2 [62]. The magnets are arranged in such a
way that one pole is placed at the central axis of the target and the second pole is formed by a ring
of magnets arranged around the outer edge of the target.