Cleaning with water or light?

In order to meet the highest functional requirements, different cleaning processes can be used according to the requirements. Normally, wet chemical processes are used. The easiest method is to rinse with water, but methods like “Single-Wafer Spin Cleaning (SCROD) with repetitive use of ozonated water and dilute HF” also exist. In this method, ozonated water and dilute hydrofluoric acid are used in a cyclic way. Metallic contamination and organic contamination is removed from the wafer surface extremely efficiently. Such wet chemical methods are proven and effective. Problems only arise with fine structures, due to the surface tension. During cleaning of ultrafine 45 µm patterns, the liquid medium can damage the surface. This problem isn’t relevant for plating but for the production of semiconductor chips.

Rougher methods are used to clean the surfaces of building materials. But there are roof tiles which have a photoactive surface to transform air pollutants by catalytic effects. Titanium dioxide (TiO2) acts as photocatalyst in this case. Previously, the Fraunhofer Institute for Building Physics tested the “Frankfurter Pfanne” (type of roof tile) Titano/x in a laboratory examination and determined good conversion rates. The photocatalytic coating of solar modules is also being tested in order to improve the efficiency.

Both methods seem possible: The classic cleaning with water – but also with light. We look forward to seeing the innovations which will be put on the market this year.