Inductively Coupled Plasma Etching (ICP)

Inductively coupled plasma etchers produce higher plasma density and are hence called HDP, High Density Plasma, systems. These have two sources of plasma power. The first, a non-capacitive coupled source, such as inductively coupled (ICP) or ECR coupled, where power is transferred or coupled to the plasma with minimal voltage difference between the plasma and the wafer (about 50 V or less). The inductively coupled plasma referred to as the source power, controls the plasma density (number of ions per cc) and thus controls the ions flux (ions per sq cm per sec) bombarding the wafer. The second power source is the bias power and is connected through the wafer chuck/electrode and is capacitively coupled (CCP). The bias power is used to control the voltage between the wafer and the plasma. This voltage between wafer and plasma is important, as it controls the energy and directionality of the ions bombarding the wafer surface. Thus, with high density plasmas we have the ability to control both ion flux and ion energy independently.