Ion etching

Also designated "physical etching" because its effect is only based on the kinetic energy of ions, not on chemical reactions. Therefore usually inert gases are used for ion etching.

Inert gases are elementary gases, therefore no radicals can exist in their plasma, but only stimulated atoms, ions (cations) and electrons.

The etching function is based on the bombardement of ions which are accelerated onto the substrate attracted by the negatively charged substrate. A special electrode installation is used for ion etching which uses planar electrodes and an electric installation which allows for self-bias of the substrate. RF-generators are used for generating the plasma. The substrate is located next to the planar electrode which is charged negative by the BIAS effect. So the inert gas ions will be accelerated onto the substrate.

The kinetic energy of the ions is essential to strike atoms, molecules and ions out from the substrate. Etching is only effective in direction of the ion acceleration. Therefore the effect ist highly anisotropic. The method therefore is preferably applicable to produce geometrial structures. 

The etching velocity is low compared to chemical dry etching or liquid etching.

The process gas preferably used is Argon. Ions of this inert gas are relatively heavy, so that the a good etching effect is provided. Also the gas is very common and cheap because almost 1 % of the global atmosphere is Argon.

The kinetic is comparable to sandblasting reduced to much smaller dimensions. Therefore it is also designated for Micro Sandblasting. Even if etching rates are small there may be a rapid emprovement of surface addition because of the cleaning and surface increasing effect.

Ion Etching
Ion etching is effective almost on all substrate materials (non selective) and anisotrope.