Deposition - Plas-Enhanced Chemical Vapor Deposition (PECVD)

Superior film density and purity.

As device fabrication thermal budgets have decreased, process flows using PECVD have become critical. Using plasma is a way to circumvent high substrate temperatures and provide quality films at temperatures much lower than with furnace-driven processes. Plasma-Therm’s PECVD configuration consists of a parallel-plate reactor with a powered upper electrode to generate a plasma. In the plasma, the precursor and reactant gases are dissociated as part of the deposition mechanism. Film uniformity, one of many key requirements, is achieved using a carefully fabricated showerhead to evenly distribute the gases. Being able to deliver highly uniform stoichiometric films, with low stress, and at temperatures <400C, makes PECVD very attractive.

Films

Films typically deposited by PECVD include silicon oxide, silicon nitride, silicon carbide, diamond-like carbon (DLC), and amorphous silicon.

Applications

PECVD films are found in nearly every device, serving as encapsulants, passivation layers, hard masks, and insulators. Plasma-Therm’s many other applications range from optical coatings and RF filter tuning to sacrificial layers in MEMS devices.

Property Tuning

Film properties such as stoichiometry, refractive index, and stress can be tuned over a wide range, depending on the application. With the addition of other reactant gases, the range of film properties can be expanded and films such as fluorinated silicon dioxide (SiOF) and silicon oxycarbide (SiOC) are possible.

Operating Regime

Typically, PECVD operates in the 1 to 2 Torr range and at temperatures between 200C and 400C. However, lower- and higher-temperature processes are possible.