ABSTRACT

Radio-Frequency (rf) plasma is sustained by the rf electromagnetic field radiated from an rf current coil. This is named the inductively coupled plasma (ICP) or transformer coupled plasma (TCP) based on the difference of the current coil arrangement, as shown in Figure 10.1 [1]. Usually ICP is initiated locally by the capacitive coupling between both terminals of the current coil with increasing the voltage amplitude between terminals of the coil (E-mode). A locally sustained low-density plasma diffuses into gas, and an abrupt change occurs from a capacitive coupling between the terminals (E-mode) to an inductive coupling between the plasma and coil (H-mode) when the power (or coil current) is further increased. The phase transition is known as an E-H transition in ICP with a hysteresis loop between a rise and fall in the power. ICP and TCP in Figure 10.1 are examples of the electrodeless plasma. The pressure range of ICP in plasma etching is between a few mTorr to some tens of mTorr, whereas for thin film deposition the feed gas pressure is usually distributed over 100 mTorr and 10 Torr.