Question

Explain why the term ion-assisted etching is a more apt description of dry etching processes which
rely on both chemical and physical etching effects, than is the term reactive ion etching

Answer 1

How the reactive ion etching system works?

In reactive ion etching process, a gas mixture including several gases and plasma will introduce above the substrate to be etched . Function of plasma is to break gas molecules into ions. Those ions having sufficient energy to replace atoms in the surface of substrate will move towards substrate and bombard with atoms and replace the same. The replacement of atoms with ions will be physical process and it will be anisotropic.

Why ion-assisted etching term is better than the term reactive ion etching?

In this process upto breaking of gaseous molecules in to ions, the process is chemical. but after that bombardment of ions on the surface of substrate is physical. Hence in the reactive ion etching process, the ions are only assisting in the process. The are actually not reactive. We are not introducing reactive ions directly to substrate for etching process. As the name indicates , if we are introducing reactive ions the physical part of the reaction will be more isotropic(means substrate atom replacement with ions wiill be equally distributed). But here it is anisotropic.