Basic Mechanisms in Plasma Etching

A summary is given on the temperature dependence and basic processes in dry etching. The basic processes as Physical and Chemical Sputtering and Surface Film Etching completed by ion or electron stimulation of gas-surface reactions and combined with adsorption and desorption are used in modelling different types of etch characteristics. Of special interest are non-monotoneous characteristics. For some typical examples a comparison between measured and calculated curves is given which permit the determination of some kinetic parameters as activation energies and residence times.     

Synthesis and characterization of polycarbonyl compounds via their BF2-adducts

A cobalt-catalyzed 1,4-hydrovinylation reaction is the key step in the synthesis of 1,3-dicarbonyl and higher tri- and tetracarbonyl compounds after ozonolysis of the 1,4-diene intermediates. For the isolation and characterization of the products, the 1,3-dicarbonyl subunits were complexed with a BF(2)- or a BR(2)-fragment eliminating the keto-enol tautomerisation. Other 2,3-disubstituted 1,3-butadienes can be generated by a Grubbs enyne metathesis of a symmetrical internal alkyne with ethene. After hydrovinylation and ozonolysis, other 1,3-diketones are accessible.     

Determination of sheath parameters by test particles upon local electrode bias and plasma switching

Equilibrating gravitation by electric forces, microparticles can be confined in the plasma sheath above suitably biased local electrodes. Their position depends on the detailed structure of the plasma sheath and on the charge that the particles acquire in the surrounding plasma, that is by the electron and ion currents towards it. Bias switching experiments reveal how the charge and equilibrium position of the microparticle change upon altered sheath conditions. Above a critical bias, the particle is subject to an additional downward acceleration that cannot be explained solely by gravity and ion drag. This acceleration can be attributed to a positive charging of the particle induced by extreme out-of-equilibrium conditions of the plasma sheath in its surroundings: locally the plasma sheath can be completely deprived of electrons by means of the bias. We observe similar particle behaviors also in the afterglow of the discharge for a persisting bias voltage on the electrode: damped oscillation into a new equilibrium or (accelerated) fall according to the bias. The observed particle dynamics in locally tailored plasma sheath environments directly monitors changes in electric field structures and plasma density profiles.