Peter Awakowicz

Innovative plasma diagnostics and control of process in reactive low-temperature plasmas

Abstract By means of two independent diagnostic methods, the plasma parameters in a RIE system (ALCATEL GIR 300) were measured. Density and collision rate of electrons and the power dissipated in the plasma body in He, Ar, O2, CF4, and SF6 were determined. The first completely new diagnostic method is the self-excited electron plasma resonance spectroscopy (SEERS), which is based on the occurrence of harmonics in the discharge current due to the non-linearity of the sheath at the powered electrode. Owing to the inductive behaviour of the plasma body (bulk, ∈ The second method is a completely automatic Langmuir probe (LP). The compensation of the rf signal was achieved by means of a triaxial setup. The measurement time of one I–V pair takes only 19.5 μs. Retracting the probe tip pneumatically prevents undesirable coating. The I–V curve is smoothed by several FIR-filters to support the automatic calculation of the plasma parameters. Both methods have shown an agreement concerning the electron density and the possibility of advanced process control by innovative plasma diagnostics.

Diamond deposition and plasma diagnostics in a 27 MHz inductive coupled reactor (ICP)

Abstract An inductive coupled planar radio frequency (rf) reactor (ICP) with separately mounted concentric coils was used to deposit diamond films onto silicon and boron nitride. A grounded Faraday polarizer was mounted on top of the reactor below the rf-coil to prevent capacitive coupling. The electrically heated substrates were immersed in the most intense plasma region shaped like a torus. Mainly two different argon-hydrogen-methane mixtures were used, namely Ar/H2/CH4—250/25/0.5 sccm (mixture #I) and Ar/H2/CH4—50/50/0.5 sccm (mixture #II). With the conditions of mixture #I, deposition of good quality diamond with relatively high growth rates (0.6–1 μm h−1) has been obtained. During diamond growth, the plasma was investigated by means of a Langmuir probe system (LP), providing radial distributions of several plasma parameters. The energy distributions of the most often occurring ions were analysed by an energy and mass spectrometer (EMS). Correlations between the measured parameters and the grown coatings will be given.

Deposition of a-C:H films with an ECWR-reactor at 27 MHz: plasma diagnostics and film properties

Abstract For the first time, an electron–cyclotron-wave resonance (ECWR) source was used to deposit thin amorphous hydrocarbon (a-C:H) films. The deposition experiments have been supported by intensive plasma diagnostics with Langmuir probe (LP) measurements and energy mass spectrometry (EMS). The LP-investigations yielded a set of external parameters for homogeneously grown hard films at deposition rates of approximately 1.5 μm/h. By calibrating the EMS-system for particle number densities of stabile hydrocarbons and by using an appropriate fit-formula to evaluate absolute ion flux densities, the growth rates were in good agreement with predictions of the ‘thermally activated re-etching’-model (TR-model).

Continuous calibration of a vacuum ultraviolet system from 65 to 125 nm by a cascade arc and comparison with the calibrated line radiation of a hollow cathode

A high-power stationary helium cascade arc has been developed as a standard source for continuum radiation in the VUV spectral range from 65 to 125 nm. The calibration of the VUV system response was based on the calculated and measured continuum radiation of a 2-mmphi pure He arc. Diagnostics of the arc plasma in partial thermal equilibrium yielded the electron density and the temperature that were inserted in the calculations of the continuous radiation. The results were compared with the helium, argon, and krypton radiation lines of a high-current hollow cathode lamp. This lamp was built according to the construction drawings of a hollow cathode, which was calibrated by means of the electron synchrotron radiation at the Physikalisch Technische Bundesanstalt Berlin.

Energy-mass spectrometry and automatic Langmuir probe measurements in reactive ICP plasmas for diamond deposition

Abstract Two different argon-hydrogen-methane gas mixtures Ar/H2/CH4 250/25/0.5 sccm (mixture 1) and Ar/H2/CH4 50/50/0.5 sccm (mixture 2) were used in an inductive coupled planar radio frequency (rf) reactor (ICP). By means of separately mounted concentric coils and a grounded Faraday polarizer on top of the reactor, diamond films were grown on to silicon. The electrically heated substrates were immersed in the most intense plasma region shaped as a torus. The selected plasma conditions (4 mbar, 1.2 kW) in combination with mixture 1 resulted in fair quality diamond with relatively high growth rates (0.6–1 µmmh−1). In the course of diamond growth, the plasma was investigated by means of a Langmuir probe system (LP) and an energy and mass spectrometer (EMS).