The size of the sputter target is given by the type of sputter coater used. Foil targets are sputter targets without a backing plate of different material. The coater model / design defines if targets with or without backing plate can be used.

The thickness of a target defines the amount of material that can be sputtered during the target life cycle. If a target gets very thin in some areas or even gets holes it has reached its end of live and needs to be exchanged.