PECVD and plasma etching at atmospheric pressure by means of a linearly-extended DC arc plasma source

Plasma processes are applied for a variety of surface modifications. Examples of this are coatings to achieve improved corrosion and scratch protection, or surface cleaning and texturing. However, since these processes usually take place in a vacuum, they are unfortunately not applicable for industrial use on a large scale. Plasma-enhanced CVD processes at atmospheric pressure enable the deposition of functional coatings on components and semi-finished parts within a continuous air- to-air process without the use of expensive vacuum systems. Their integration into in-line production processes definitely reduces substrate handling and coating costs. A thermal plasma source, based on a linearly-extended DC arc discharge at atmospheric pressure, has been tested for the deposition of silicon nitride at substrate temperatures below 300 deg C in a continuous PECVD process. Furthermore, this source has been tested for plasma-chemical etching and texturing of silicon as well. The costs of solar cell production play a decisive role in the competitiveness of the currently market-leading photovoltaic based on crystalline silicon. Opportunities to reduce costs exist with regard to the materials used, recognizable by the trend towards thinner and larger solar wafers, as well as in the introduction of cost-effective in-line production processes. As the first step in a future in-line solar cell production, continuous plasma etching processes at atmospheric pressure are being developed.