PECVD (Plasma Enhanced Chemical Vapor Deposition)

• Subject Area: Systems Engineering
• Term: Funded in 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 569152579

In plasma-enhanced chemical vapor deposition (PECVD) processes, plasma is used to activate gaseous chemical precursors and trigger chemical reactions on the substrate surface. The plasma is typically generated by high-frequency energy, which ionizes the gaseous molecules and breaks them down into reactive species such as radicals and ions. These are deposited on the substrate and form the desired layer via a chemical reaction. By using a plasma, coating processes can be carried out at lower temperatures compared to other CVD processes. This makes the PECVD process particularly suitable for coating temperature-sensitive substrates. A PECVD system consists of a process chamber into which substrates can be inserted either directly or via a handler. This process chamber must be evacuated for coating, i.e., the chamber pressure must be reduced by several orders of magnitude compared to the ambient pressure (“vacuum”). The chamber contains a substrate heater and inlets for various process gases. The plasma is generated via a parallel plate condenser or a coil in an evacuated chamber. Typical gases that are fed into the process chamber, depending on the layer to be produced, are silane (SiH₄), ammonia (NH₃), oxygen (O₂) or methane (CH₄). PECVD enables the production of a variety of materials, including silicon dioxide (SiO₂), silicon nitride (Si₃N₄), amorphous silicon (a-Si) and carbon compounds such as diamond-like carbon (DLC) and silicon carbide (SiC). Due to the variety of coatings that can be produced, PECVD coatings have numerous applications in microtechnology. They are used, for example, as passivation to protect underlying layers from liquids, gases or electrical currents, as hard masks for dry etching processes or as adhesion promoters for subsequent layers. The PECVD process is therefore a key technology that is required in numerous different fields of research. PECVD processes can be used to coat a wide variety of substrates at relatively low temperatures. This makes the technology interesting for the coating of polyimide-based biomedical microsystems that are not stable at high temperatures. This includes, for example, deep brain probes, optical cochlear implants, optical systems for cardiology and the development of tools for neuroscience and neurotechnology to electrically and optically stimulate structures in the peripheral and central nervous system with high spatial resolution or to record electrical signals. The proposed PECVD system represents a core technology in the university's research profile fields “Brain & Intelligence” in the area of “Signals of Life” as well as in “Pathways to Sustainability” and in the area of “Intelligent Technologies”.

• DFG Programme: Major Research Instrumentation
• Major Instrumentation: PECVD-Beschichtungsanlage
• Instrumentation Group: 0920 Atom- und Molekularstrahl-Apparaturen
• Applicant Institution: Albert-Ludwigs-Universität Freiburg
• Leader: Professor Dr.-Ing. Thomas Stieglitz