Increasing the sputter voltage increases the sputter yield and typically voltages are from -2 to -5 kV. The deposition rate is increased by means of sputter yield and is found decreased with increasing Ar pressure. Usually a substrate bias voltage is applied to avoid electrons hitting the substrate while neutral atoms being deposited independently. Substrate temperature increases with increasing sputter voltage and decreases with increasing substrate bias. The deposition rate also usually decreases with increasing substrate bias.

RF Sputter Deposition

In DC systems, positive charge builds up on the cathode (target) and typically one requires 10¹² volts to sputter insulators. To avoid this charge build up, an RF potential is used and can be used for depositing insulating materials. Sputter deposition occurs when target is negative. The schematic diagram of an RF plasma system is shown in Fig. 3.31. The substrate and chamber make a very large electrode and so not much sputtering of substrate occurs.