Radio Frequency Magnetron Sputtering
  Magnetrons are a class of cold cathode discharge devices used generally in a diode mode. The plasma is initiated between the cathode and the anode at pressures in the mTorr range by the application of a high voltage that can be either DC or RF.The plasma is sustained by the ionization caused by secondary electrons emitted from the cathode due to ion bombardment which are accelerated into the plasma across the cathode sheath. What differentiates a magnetron cathode from a conventional diode cathode is the presence of a magnetic field. The magnetic filed in the magnetron is oriented parallel to the cathode surface. The local polarity of magnetic field is oriented
such that E〜B drift of the emitted secondary electrons forms a closed loop. Due to the increased confinement of the secondary electrons in this E〜B drift loop compared to a DC diode device, the plasma density will be much higher, often by an order of magnitude or more, than a conventional DC diode system.
  Magnetron sputtering is a low-cost and easy control
method for film growth, especially suitable for large-scale
film deposition.
   rf magnetron sputtering also can be used to sputter electrically insulating materials besides metal and alloy.