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A combination of steered arc process and modified pulsed arc process was investigated in order to determine the effects on the plasma and on the coating qualities during deposition. Titanium, titanium–aluminium and chromium were used as target materials. The work pressure was 1 Pa with nitrogen as work gas. The usage of a pulsed arc current instead of a continuous arc current leads to an accelerated spot movement during the pulse period. The pulse phase also causes the division of the formerly single spot into multiple spots. Those multiple spots move on average on the circular trace that can be observed also without pulsed arc currents. Therefore the spot traces and their velocity leave vary only locally while the pulse current is applied. Another trait of the process combination is the attenuation of the plasma focussing compared with the pure modified pulsed arc process. This weakening influences the film thickness uniformity.

The modified pulsed arc process was studied by optical emission spectroscopy and ion current measurement during TiN deposition discharge. We recorded spectra of the titanium nitride deposition plasma and identified species (for example: Ti ++ , TiN, N 2 + , N + ). We found a dependence of the normalized intensities and of the mean ion current density with increase of pulse current. Further, a higher direct current led to an increase of the normalized intensities, but the mean ion current density was not affected by this variation. These results were discussed in this paper with the aim to get a better understanding of the process.

As shown in previous publications concerning cathodic arc deposition, the vacuum arc as a technological tool can be very complexly influenced by variation of the electrical arc parameters. The pulsed arc current and the resulting ion current influence the formation of the coating. To determine optimised parameters for the deposition process, the dependence on the frequency, on the rate of current rise and on the maximum pulse current in particular were investigated. Using the variation of the output parameters of a pulsed arc power supply, the ion current was steered in its shape and its absolute values. Therefore, the shape of arc current pulses was varied, especially in the phase of rise and fall (triangle, sine, rectangle). Among other things, it was noted that at the beginning of the pulse an excessive increase in ion current is measurable. In order to use this increase for a more effective coating process, experiments were carried out using pulses with controlled slopes and current levels or double pulses of rectangular shape. The examinations have shown that an increase in the ion current ratio in the arc current can be reached by a suitable choice of the electrical parameters. The plasma can be controlled by the electrical parameters of the current source.

The deposition rate and the film thickness uniformity in a vacuum arc deposition process were investigated with respect to dependence on static and dynamic arc current parameters. Measurements were based on the ion current density. The known relations between the investigated process parameters were verified for the d.c. arc process and served as a reference. In the modified pulsed arc process a considerably increased ion current density was measured (up to 1.2 mA A -1 cm -2 during a 500-A pulse). The angular distribution changed in dependence on maximum pulse current especially and could be measured to be cos 3 φ for I p = 150 A to cos 7 φ for I p = 500 A. This results in very high deposition rates in the central region of the substrate and in changes of the film thickness uniformity. A maximum increase of the deposition rate by a factor 3 (perpendicular to the cathode) was measured. Only in a smaller sector the distribution of the film thickness can be approximated by a cosine function (with exponent n up to 27).

The interaction of the substrate temperature and the deposition rate in a vacuum arc deposition process were investigated with regards to dependence on static and dynamic arc current parameters. Two different deposition systems both for industry as well as for laboratory application distinguished in shape and volume of the recipient were used for the experiments. In reference to the d.c. process one can achieve the same deposition rate at a noticeably lower substrate temperature when using the modified pulsed arc process. Furthermore, it is obvious without a detailed analysis that the quality of the coatings deposited by the pulsed arc is fairly higher. In order to control the substrate temperature via the pulse parameters the r.m.s. ion current has to be changed (at a constant average current). Using a theoretical model a decreased substrate temperature at higher ion energy was found.