Plasma Etching

The process of etching a polymer, organic substance or hydrocarbon based solid works well with an oxygen based plasma process.  This oxygen based plasma etchs these materials by combining the carbon and hydrogen in the molecular structure with oxygen from the plasma.  This produces CO and HO in combination with short molecular chains that remain in a gas state and are easily pumped out of the chamber as a gas.

The process of plasma etching to reduce an oxide on the surface of a metal or in a bulk oxide state is etched with a hydrogen based gas or gas mixture.  Similarly, this plasma etching process uses the hydrogen to combine with the oxygen on the surface and produce HO and other variants of the bulk molecular structure into a gas that is pumped out of the vacuum system.

The process of plasma etching a surface using argon is a physical etching method versus the chemical etching method described above. In this method of plasma etching the energy of the heavy argon atom in the plasma is very high.  This high level of energy enables the individual argon atom to deliver more energy to the surface of the part breaking the molecular bonds of the surface material.  The result is, these surface material atoms or short molecular components, are etched or ejected into the plasma for removal. 

The process of plasma etching a material with a robust molecular structure or complex composition like metals and chemically stable polymers is done with a corrosive gas based component.  This corrosive gas of choice often focuses on a fluorine based chemistry like CF4, SF6, or other similar gases. The addition of these kinds of corrosive components provide a method of converting additional chemistries into a gas state providing a method of plasma etching.

Reactive ion etching (RIE) is a plasma etching process that adds a charge to the part being etched which induces a directional component to the etching process.  This directionality of the etch enables significantly smaller etch feature sizes which is commonly used in the semiconductor industry.