Reactive ion etching is the interaction of reactive plasmas with surfaces. For a

detailed understanding, significant properties of reactive composite low pressure

plasmas driven by electron cyclotron resonance were investigated and compared with

the radial uniformity of the etch rate. The determination of electronic properties

of chlorine and hydrogen containing plasmas enabled the understanding of the

pressure dependent resonance behavior and gave a better insight into the

electronic parameters of reactive etch gases. With electrical evaluation of

I(V) characteristics obtained with a Langmuir probe, differently composed

plasmas were investigated and the most important methods of analyzing the I(V)

characteristics were compared. A mathematical model to reduce noise sensitivity

was used and compared to the standard method of Druyvesteyn to derive the electron

energy distribution functions. Special attention was payed to the power of the

energy dependence in the exponent. Especially for plasmas which are generated by

electron cyclotron resonance with EM modes, the existence of Maxwellian

distribution functions are not to be taken as a self-evident fact, but it was

proven for Ar- and Kr-stabilized plasmas. Aside from the electron temperature,

which could be derived within a certainty of ten percent using the discussed

methods, the global uniform discharge model of Lieberman has been shown to be

useful to calculate the neutral gas temperature. To what extent the invasive

method of using a Langmuir probe could be replaced with the non-invasive

optical method of emission spectroscopy, especially actinometry, was

investigated and the resulting data showed the same relative behavior as

Langmuir data.