Plasma Physics

Plasma is referred to as being the 4th state of mater. It is an ionized gas for which the percentage of charged particles can vary between 1 to 100 %. For products of modern life, plasma processes are absolutely vital. Many process steps for the production of semiconductor devices like microcontrollers and thin film coating applications are performed with the help of plasma processes. The need for vacuum is derived by the necessities of having a sufficient mean free path of atoms or molecules as well as high purity in an experimental environment. The actual plasma sputter process in most application takes place in the medium to high vacuum regime: p = 10-2 Pa to 1 Pa ( p= 10-4 to 10-2 mbar) . In order to maintain high purity before introducing a sputter gas like argon, the process chamber often need to be evacuated to ultra high vacuum (UHV): p < 10-5 Pa ( p < 10-7 mbar).