I understand that inductively coupled plasma (ICP) means inductively coupled plasma, which has coils around the dielectric wall, and reactive ion etching (RIE) uses combination of chemical and physical etching. I am trying to understand different etching techniques and I have some confusion.
Does the term ICP and CCP (capacitively couple plasma) refer to the structure of the hardware where as RIE refers to the etching mechanism? So for example, could RIE be done with both ICP and CCP (ICP-RIE or CCP-RIE)? Or Could RIE be done with only ICP?
The ICP etcher I have access to has two RF sources. So I can set RF power 1 and RF power 2 on the recipe. What are the two different RF power sources?
Please let me know if there is a good resource I can use to learn more about etching. I am having hard time finding a good resource.
Thanks!
Dear Seohong Park,
Kindly go through the following useful literature:
-> Article Plasma Etching: Comparing PE, RIE and ICP-RIE
-> https://purdue.edu/discoverypark/birck/files/Plasma_RIE_Etching_Fundamentals_and_Applications.pdf
Reactive-ion etching (RIE) is an etching technology used in microfabrication. RIE is a type of dry etching which has different characteristics than wet etching. RIE uses chemically reactive plasma to remove material deposited on wafers. The plasma is generated under low pressure (vacuum) by an electromagnetic field. High-energy ions from the plasma attack the wafer surface and react with it producing anisotropic etching preferable in the direction of the ions.
Different types of RIE systems exist, including inductively coupled plasma (ICP) RIE. In this type of system, the plasma is generated with a radio frequency (RF) powered magnetic field. Very high plasma densities can be achieved, though etch profiles tend to be more isotropic.
A combination of parallel plate and inductively coupled plasma RIE is also possible. In this system, the ICP is employed as a high density source of ions which increases the etch rate, whereas a separate RF bias is applied to the substrate (silicon wafer) to create directional electric fields near the substrate to achieve even more anisotropic etch profiles.
An inductively coupled plasma (ICP) or transformer coupled plasma (TCP) is a type of plasma source in which the energy is supplied by electric currents which are produced by electromagnetic induction, that is, by time-varying magnetic fields. So it is a part of the RIE system.
Hope this helps. Best regards.
RIE is the name of the process. In normal sputtering process we physically remove atoms from the substrate surface by bombarding them by using energetic ions. But, if we choose the gas chemistry in such a way that these ions are also capable of reacting chemically with the substrate (and form volatile etch products) then the rate of etching can be increased drastically. This is RIE. RIE reaction chambers can be made in several geometries (cylindrical, parallel plate) but the parallel plate reactor is most common. In a parallel plate reactor the upper electrode is grounded, and the lower electrode is connected to a RF generator. This is the basic CCP configuration common in old systems. The plasma is created due to the large potential between the two electrodes and the oscillating field. Please read the wikipedia page for more details on how plasma is struck. However, in this setup, both the density of plasma (ions/area) and the kinetic energy of the ions are dependent on the power supplied to the lower electrode and cannot be changed independently. The solution to this is the ICP setup, where a seperate coil is attached above the upper eletrode and a seperate RF power is applied to the coil. This way the gas is first intoduced to this ICP coil and plasma is struck there, so that we can control the plasma density by changing the power supplied to the ICP coil. Then the ions are introduced into the chamber and acclerated towards the lower electrode due to the biasing voltage acheived by applying power to the lower electrode. This bias voltage controls the kinetic energy of the ions.
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