Dry etching and sputtering.

Dry etching is an important process for micro- and nanofabrication. Sputtering effects can arise in two contexts within a dry-etch process. Incoming ions cause removal of volatile products that arise from the interaction between the dry-etch plasma and the surface to be etched. Also, the momentum transfer of an incoming ion can cause direct removal of the material to be etched, which is undesirable as it can cause electrical or optical damage to the underlying material. This is largely avoided in dry-etch processes by use of reactive chemistries, although in some processes this component of the etching can be significant. Etch processes, both machine type and possible etch chemistries, are reviewed. Methods of characterizing the electrical and optical damage related to ion impact at the substrate are described. The use of highly reactive chemistries and molecular constituents within the plasma is best for reducing the effects of damage.