Acronyms abound for vacuum deposition processes. That’s mainly because the names tend to be descriptive and, therefore, very long. Still, a fair amount of confusion exists even when names are fully spelled out. PECVD is one such case. So, what is PECVD, and how do PECVD systems work?

Plasma Enhanced Chemical Vapor Deposition (PECVD) is a vacuum thin film deposition process that uses vapors or gases as precursors to create a coating, i.e., the source gas dissociates and condenses on the surface of the substrate. That differs from physical vapor deposition (PVD), where a large portion of the coating material comes from a solid source, or “target.”

How do plasma-enhanced chemical vapor deposition systems create coatings?

PECVD is a variation of chemical vapor deposition (CVD) that uses plasma instead of heat to activate the source gas or vapor. Since high temperatures can be avoided, the range of possible substrates expands to low melting point materials – even plastics in some cases. Moreover, the range of coating materials that can be deposited also grows.

Plasma in vapor deposition processes is typically generated by applying a voltage to electrodes embedded in a gas at low pressures. PECVD systems can generate plasma by different means, e.g., radio frequency (RF) to mid-frequencies (MF) to pulsed or straight DC power. Whichever frequency range is used, the objective remains the same: the energy supplied by the power source activates the gas or vapor, forming electrons, ions, and neutral radicals.

These energetic species are then prime to react and condense on the surface of the substrate. For example, DLC (diamond-like carbon), a popular performance coating, is created when a hydrocarbon gas like methane is dissociated in a plasma, and carbon and hydrogen recombine on the surface of the substrate, forming the finish. Apart from the film’s initial nucleation, the coating’s growth rate is relatively constant, so its thickness is proportional to the deposition time.

PECVD equipment, hybrid PVD/PECVD systems

At a high level, the PECVD equipment is similar to that used for PVD processes. Both include a chamber, vacuum pump(s), and a gas distribution system. Differences in the system configuration of the two processes are generally related to the power source (type and how it’s applied), gas type and flow levels, type and range of pressure sensors, and overall design of the parts racking. Hybrid systems (capable of performing both PVD and PECVD) offer the best of both worlds. However, while PVD is generally a line-of-sight process, PECVD will produce coatings that tend to coat all surfaces in the chamber. Therefore, the utilization and maintenance of such systems will vary depending on the usage rate of each process.

As previously mentioned, PECVD is extensively used to produce diamond-like carbon (DLC) for mechanical performance and decorative coating applications, but the process is also heavily employed in the semiconductor industry, where it’s used to produce the building blocks (SiNx, SiO2, a-Si:H, etc.) used to make thin-film transistors (TFTs), solar cells and other types of electronic and optoelectronic devices.

Vapor Technologies Inc. (VaporTech®) is a leading PECVD system manufacturer.

Headquartered in Colorado, VaporTech is a global PVD and PECVD system manufacturer. Our PVD/PECVD coating equipment deposits DLC coatings and traditional PVD coatings. Don’t hesitate to contact us today for more information about how our PECVD systems can meet your needs.

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