PDCs – coating methods
The “Precursor-Derived Ceramics” working group has two different coating systems available: pilot-scale PECVD system for the deposition from gas phase and spin-coating system for thin-films from liquid precursors, solutions or suspensions.
Plasma enhanced chemical vapor deposition (PECVD)
Thin films can be deposited on substrate surfaces by plasma enhanced decomposition of gaseous precursors. This process is characterized by low temperatures as compared to classical thermal CVD processes. In this way, not only deposition of crystalline thin films is possible, but also amorphous silicon films can be created (transparent, conductive oxide films ).
Liquid precursors can be used by vaporization of liquids in the so-called bubbler. This method is suited to create thin-film solar cells (photovoltaics).
Spin coating is a method to produce thin films using solutions, suspensions or liquid precursors (chemical preliminary stage). Preferentially, it is applied for expensive or minor amounts of source solution. A solution is applied on a rotating substrate and nearly completely removed by spinning, so that only a thin film remains (see schematic view below).
Additionally, the majority of the eliminated solution can be collected and led back. Depending on the desired properties of the film the viscosity, the wetting behavior and, if necessary, the solids content will be modified.
- Film made of different materials such as silicon, carbides, oxynitrides, oxides etc.
- Adjusting of film thickness depending on the desired material class in the nanometer and micrometer range
- Characterization of films (e.g. ellipsometry for thickness measurement)
- PECVD system: substrate size 480x480 mm²; temperature up to 450°C; variation of gas composition, pressure and power
- Spin coater: temperature up to 1000°C; spinning velocity up to 7000 rpm; working under inert atmosphere is possible
- Hotplate: temperature up to 900°C with max. heating rate of 70 K/min; working under inert atmosphere is possible