Process in which material is removed from a surface, in general by a chemical reaction. However, physical processes are also described as etching (physical etching, ion etching).the substrates to remove contaminations. The following are typical etching processes:
- Cleaning of surfaces by removing oxide or passive layers
- Surface structuring for optical reasons (matting) or for improving the gluing properties by enlarging the surface
- Creation of geometrical structures by covering the surface in parts by a mask, restricting the etching process to the freely accessible areas.
Etching processes are carried out either by immersion in acidic or alkaline solutions or by plasma treatment ("plasma etching") in a suitable process gas . Plasma etching processes are used for example in the following applications: Silicon, SiO2 and Si4N3 in micro-electronics, metal with surface oxide, and plastics with poor adhesive properties such as PTFE.