When the target is bombarded by high-energy particle, the atoms absorb enough energy to eject and eventually deposited as the thin film grown on the substrate. In the magnetron sputtering process, electrons collide with argon molecule and produce argon ions. Argon ions accelerated by the electric field hit the target and result in sputtering, which lead that the secondary electrons carry out circular motion in the form of cycloid under the electric and magnetic fields on the target surface. Bound electrons have a longer trajectory, thereby increasing the probability of electron ionization of argon gas.