What is the difference between chemical and physical plasma processes?
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photons generated from the application of electromagnetic radiation to
a gas volume at low pressure.
The highly energized nonequilibrium plasma is capable of surface
cleaning and surface activation through physical, chemical, and
physical/chemical mechanisms.
In a physical process, ions such as those generated in an argon plasma
bombard the surface with sufficient energy to sputter contamination
from the surface.
Chemical processes use the plasma generated gas phase radicals to
chemically react with the compounds on the sample surface to produce
gas phase byproducts that are subsequently pumped from the plasma
system.
Organic contamination is effectively removed with an oxygen plasma
where the oxygen radicals react with contamination producing carbon
dioxide, carbon monoxide, and water.
Gas mixtures and plasma conditions that produce both physically and
chemically active plasma are often used to enhance the surface
activation and/or surface cleaning process.
The degree of selectivity, anisotropy, uniformity and cleaning rates
are a function of whether the process is physical, chemical or a
combination of these mechanisms.