RF sputtering Advantages | RF sputtering Disadvantages
This page covers advantages and disadvantages of RF sputtering technique. It mentions RF sputtering advantages and RF sputtering disadvantages.
The figure-1 below depicts RF sputtering system.
Silent features of the system are as follows.
• RF Source frequency : 13.56 MHz
• RF peak to peak voltage : 1000 V
• Electron densities : 109 to 1011 Cm-3
• Chamber pressure : 0.5 to 10 mTorr
There are two processes (in positive and negative cycles) involved in RF sputtering technique. In positive cycle, electrons are attracted to cathode which creates negative bias. In negative cycle, ion bombardment continues. Here ion buildup is prevented for insulating targets by avoiding constant negative voltage on the cathode. Refer What is RF sputtering >> for more information.
RF sputtering Advantages
Following are the RF sputtering advantages:
➨It produces better film quality and step coverage compare to evaporation.
➨It helps in deposition of wide variety of insulators, metals, alloys, composites etc. It Works well for insulating targets.
➨Charge-up effects are avoided and arcing is reduced due to use of AC RF source of frequency 13.56 MHz. This is due to the fact that electric field sign at every surface inside plasma chamber changes with RF.
➨It can operate at low pressures ( 1 to 15 mTorr) while sustaining plasma. Hence RF sputtering offers higher efficiency.
➨This sputtering technique is used to sputter any type of film.
➨Recently developed RF diode sputtering technique works better compare to normal RF sputtering.
RF sputtering Disadvantages
Following are the RF sputtering disadvantages:
➨Deposition rates are very low for some materials in RF sputtering technique.
➨Application of RF power is not simple. It requires expensive power supply and additional impedance matching circuitry.
➨Stray magnetic fields leakage from ferromagnetic target disturbs the undergoing sputtering process. To avoid this leakage, sputter guns with strong permanent magnets should be used, which will increase cost of the system.
➨Most of the incident energy on the target becomes heat energy. This needs to be removed.
➨It is difficult to deposit uniformly on complex structures e.g. turbine blades.
➨It is hard to produce high performance thick coatings due to higher internal residual stress levels.