Plasma Technology for Advanced Devices Reactive and Condensable
Species Neutral species that arrive at the wafer surface can
stick to the surface and react. Depending on the sticking
coefficients and reaction probabilities, reactive and
condensable species can be distinguished among the species in
the feed gas and the reaction products (slide 1). The balance
between reaction and condensation influences the etch profile.
Reactive species: React chemically with surfaces. Reactions are
not very temperature sensitive because of low activation
energies for the reactions. Surface coverage is typically
saturated at a few monolayers. Condensable species: Form liquid
or solid films on surfaces. Surface coverage dependents strongly
on the substrate temperature. Slide 2 shows reactive and
condensable species for the example of tungsten Etching with
Cl2/O2.