Magnetron sputtering sputtering technology "DC sputtering method"
The direct current sputtering method requires the target material to be able to transfer the positive charge obtained from the ion bombardment process to the cathode in close contact with it, so this method can only sputter conductive materials and is not suitable for insulating materials. Because when bombarding the insulating target, the ion charge on the surface cannot be neutralized, which will cause the potential of the target surface to rise, and almost all the external voltage is applied to the target, the chance of ion acceleration and ionization between the two poles will be reduced, or even ionization will not be possible. As a result, continuous discharging is impossible or even discharging stops, and sputtering stops. Therefore, for insulating targets or non-metallic targets with poor conductivity, radio frequency sputtering (RF) must be used.
The sputtering process involves a complex scattering process and a variety of energy transfer processes: the incident particles collide elastically with the target atoms, and part of the kinetic energy of the incident particles will be transferred to the target atoms; the kinetic energy of some target atoms exceeds that of its surroundings. The potential barrier formed by other existing atoms (5-10 eV for metals), which are collided from the lattice lattice to produce off-site atoms; these off-site atoms further collide with nearby atoms repeatedly, causing collisions Cascade: When this collision cascade reaches the target surface, if the kinetic energy of the atoms close to the target surface is greater than the surface binding energy (for metals, it is 1-6 eV), these atoms will break away from the target surface and enter the vacuum.