Plasma Enhanced Chemical Vapor Deposition (PECVD) is a low-temperature deposition process performed inside a vacuum reaction chamber. Process gases, typically silane (SiH₄) together with nitrous oxide (N₂O) or oxygen (O₂), are introduced into the chamber. Radio-frequency power generates a low-pressure plasma that dissociates the precursor gases into highly reactive radicals and ions. PECVD process chamber. The plasma supplies the activation energy instead of furnace heat, so oxide deposits at only 200 to 400 °C. The chuck shields the backside, making PECVD a front-side process. These activated species migrate to the wafer surface where they recombine to form a deposited silicon dioxide film. Because the plasma supplies the activation energy, deposition occurs at only 200 to 400 °C without consuming the substrate. This allows oxide to be deposited after temperature-sensitive materials, aluminum interconnects, and completed MEMS structures are already present on the wafer. PECVD deposits oxide onto silicon, metals, dielectric films, quartz, sapphire, glass, and silicon-on-insulator (SOI) wafers. The deposited film contains small amounts of bonded hydrogen and is slightly less dense than thermal oxide, but it offers outstanding flexibility for late-stage integration. Because the wafer rests on a temperature-controlled chuck or electrode that shields the backside from the plasma, deposition is typically limited to the front side of the wafer. Thickness at RVM: Up to 5µm Typical process sequence: Mid-stage to late-stage fabrication Typical applications: Passivation, ILD, encapsulation, optical overcladding Typical Applications - Passivation - Interlayer dielectric (ILD) - Device encapsulation - Optical overcladding - Low-temperature insulation Choose PECVD oxide when thermal budget is the limiting factor, when oxide must be deposited over metals or completed device structures, or when the substrate is something other than silicon.
