ICMCTF2010 Session G7: Advances in Industrial PVD & CVD Deposition Equipment

In the field of decorative coatings the technique of magnetron sputtering plays an important role: Since a couple of years a lot of different products like watches, jewelery, door latches and pens are color coated. For these coatings materials like ZrC_xN_y,TiAlCN or TiZrN were used.

Due to the fact that with these coatings the selection of different colors is limited, it is an interesting alternative to use interference based effects to generate a broad range of different, very strong colors. Interference based colors occur when thin layers of optically transparent materials are involved (e.g. oil drop on water, soap bubble,…).

With magnetron sputtering the controlled deposition of thin films with appropriate optical properties leads to brilliant colors. Nearly every color within the optical spectrum can be produced with this method.

Due to the fact that such Interference coatings consist of very thin layers their mechanical or chemical properties are very poor.

But for the most applications in the field of surface enhancement a good quality of the coatings is absolutely necessary. A solution for this could be the covering of the interference stack with a thick transparent protective topcoat. But with increasing thickness of the topcoat the brilliance of the interference color decrease.

In this work a new technology is presented – called “Aradierung^©” – which enables the production of brilliant Color Coatings with enhanced mechanical, chemical or thermal properties.

These brilliant color coatings consist of an adhesive layer, the color generating stack (2-4 thin layers) and the protective topcoat. The materials of the color coatings vary – depending on the desired color and the specific requirements. The topcoat can show good corrosion behaviour or wear resistance – or other features like an “Anti-Fingerprint” effect. This effect is based on the reduction of the contrast between the fingerprint and the surrounding area and make the fingerprint invisible.

The color coatings can be applied on metals, ceramics, glass and plastics. To reach the best results, the adaption and optimisation of the color coating stack on the given substrate is necessary.

In this paper different fields of applications are presented, examples are shown and their properties are discussed.

For the verification of optical properties Reflection Spectrometry and Ellipsometry is used; morphology and mechanical properties were analysed with SEM, XRD and Nanoindentation.

Flexible coating systems will only be integrated into proprietary production processes when they provide pre- and post-treatment of cutting edges and surfaces, stripping, cleaning, quality control systems and the system enables the deposition of conventional, e.g. TiN and AlTiN as well as high performance coatings, e.g. nanocomposites, oxides and DLC together with dedicated coatings for specific applications. We will give a short presentation of the turn-key Platit in-house coating systems.

We will introduce the new flexible PVD coating unit from Platit, the Pi111. It will be described in detail with emphasis on the upgradeability for DLC and Oxide/Oxynitride coatings and we will show our new coatings produced in this unit, the triple coatings, in particular DLC, oxynitride/oxide coatings and general triple coatings, a combination of nanocomposites and conventional hardcoatings in one.

As general triple coatings, we will focus on nACRo³ and show results on drilling and reaming of cast iron and steels.

Finally we will talk about the new TiXCo coatings for hard milling and drilling including an example on dry hard finishing in steel 1.2080 with a hardness of 61HRC.

Plasmas of CHF₃/Ar, SF₆, and O₂ are characterized with the floating harmonic method, using a Wise probe system, under a variety of etching conditions in a commercial etcher made by Plasma-Therm. The floating harmonic method is a novel measurement technique for electron temperature and ion flux. The current of a 50 kHz sinusoidal voltage applied to the probe is measured continuously. These data then undergo a spectral analysis, and the ratio of first and second harmonics is calculated. From this ratio the plasma parameters can be calculated. Since the measurement technique relies only on high frequency currents, it is insensitive to contamination of the probe tip, providing a major advantage over the conventional Langmuir probe.

Characterization was performed under bias powers of 10-100 W and source powers of 200-900 W. Measurements were conducted at two different distances of samples to plasma source: 4 cm and 14 cm. Real time measurements of electron temperature and ion flux were recorded with dummy wafers and under actual etching of SiO,₂, Si_xN_y, and photoresist. Plasma parameters in the inductively coupled plasmas are largely independent of bias power, as would be expected. At very low source powers the plasma undergoes a transition to capacitive coupling. In the capacitively coupled plasma high electron temperatures combined with low ion fluxes are observed, and an increase in the effect of bias power can also be seen. Although more ions are generated in the bulk plasma at higher pressures, the ion flux to the substrate at higher pressure is reduced, due to the shorter mean free path of ions, which causes slower diffusion.

The effect of the distance of samples to the plasma source was investigated at distances of 4 cm and 14 cm. Ion fluxes at longer distance were much lower, due to longer diffusion distance to the sample surface. The transition from ICP to CCP also occurred at higher powers than at shorter distance. This results in many of the plasma conditions studied producing relatively unstable plasmas with large fluctuations in electron temperature.

When etching through SiO₂ and Si_xN_y films, the electron temperature and ion flux showed measurable changes dependent on the substrate material. This opens the possibility of using the Wise probe system for endpoint detection in certain etching processes. An increase in electron temperature over the course of oxygen cleaning can also be observed, which may also prove useful for the purpose of maintaining chamber conditions more efficiently.

Thin film tungsten carbide coatings are widely used in different applications to reduce wear and friction of components in sliding or rolling contact. In many cases these films are deposited by a PVD sputter process of tungsten carbide targets in a carbon gas containing atmosphere.

In this presentation the results of a statistical design of experiments for the performance optimization of a tungsten carbide layer will be presented. The influence of gas composition, target power and bias voltage on layer hardness, wear behavior, and coefficient of friction was examined. The measurement methods used are micro indentation, calo grinding and pin on disc test. In addition, the coatings have been analyzed by XRD and EDX measurements.

The experiments were carried out on the new coating machine RS50. The vacuum chamber of the RS50 allows a carousel diameter of 950mm and a loading height of 650mm. Its new flange concept gives a high flexibility and easily allows the implementation of new technologies. The RS50 coating machine will be presented also.

High ionization plasma for advanced coatings (HIPAC) is a new adaptation of the high power pulsed magnetron sputtering technique, especially fitted for industrial applications. HIPAC is characterized by its highly ionized plasma including that of the sputtering gas. It is known that by using ions for bombardment of the substrate during the deposition process, coating properties such as density, surface smoothness, phase composition and structure can be altered even at low bias voltages. The use of a highly ionized sputter gas can, in addition, further decrease the substrate bias voltage, and minimize in such a way, the risk for arcing on the substrate. In the present work, high aluminum containing AlTiN coatings are deposited on steel substrates at a bias voltage of ~ 20 V. The mechanical properties and the structure of the coatings are investigated showing that the AlTiN coatings exhibit a high hardness and a low elastic modulus. Furthermore, the crystalline structure of the coatings is examined showing that for the same average power and depending on the target peak current, a number of crystalline structures and morphologies are possible. It is concluded that the HIPAC deposition technique can provide a new means to better control these properties and help, in such a manner, to design coatings for well-specified cutting and milling applications.