Inductively Coupled Plasma is an etching technique where the gases are introduced above an Inductive coil, placed around a ceramic tube. RF is applied to both the coil, and chuck to create a plasma.
The substrate is placed on the RF powered chuck, and similar to RIE, the wafer takes on potential which accelerates etching species extracted from plasma toward the etched surface. Introducing different gases can create a chemical reaction. With this technique, etch profiles are typically anisotropic.
A DC bias measurement can be taken from the chuck which can give a good indication of the amount of etching that is occurring.
This technique is used for Deep Silicon etching, and is also known as a High Density Plasma source.
Inductively Coupled Plasma (ICP) Source
“In conventional RIE the plasma density is limited by the method of coupling RF energy into the plasma. This limits the rates at which certain materials can be etched or deposited. This problem becomes particularly acute at reduced pressures where, with the efficiency of an RIE, the plasma density can become prohibitively low…”