PECVD

Plasma Enhanced Chemical Vapor Deposition (PECVD) is a thin-film deposition technique in which chemical reactions of volatile precursors are driven by an in-situ plasma. The plasma generates reactive species that enable film formation at lower temperatures than conventional chemical vapor deposition, making PECVD suitable for temperature-sensitive substrates.

In PECVD, the substrate is typically heated to moderate temperatures (often around 100–400 °C). A radio frequency or microwave plasma is used to activate the gas-phase precursors, which can include silane (SiH4), ammonia (NH3), nitrous oxide (N2O), oxygen (O2), and tetraethyl orthosilicate (TEOS), among others. The reactive species decompose at the substrate surface to form the desired solid film, while byproducts are pumped away. Process conditions such as gas flow, chamber pressure (ranging from tens of millitorrs to a few Torr), plasma power, and temperature determine the film’s composition, density, and microstructure.

PECVD offers several advantages, including deposition at relatively low temperatures, enabling coatings on polymer substrates and flexible electronics. It also provides good conformality over complex topographies and allows tuning of mechanical, optical, and electrical properties through plasma parameters and hydrogen incorporation.

Disadvantages can include plasma-induced damage, incorporation of hydrogen or other impurities, higher film stress, and equipment complexity. Uniformity over large areas may require careful reactor design.

Applications span semiconductor device fabrication, including gate dielectrics, passivation layers, and diffusion barriers; thin-film transistors for displays; solar cell coatings and antireflection layers; and protective or optical coatings. Variants such as remote PECVD and low-temperature PECVD expand the range of compatible materials and substrates.