What gases can be used in plasma enhanced PECVD tube furnaces?

Reactive gases:
Silane (SiH ₄): Used for depositing silicon-based thin films, such as amorphous silicon, microcrystalline silicon, silicon nitride (Si ∝ N ₄), and silicon oxide (SiO ₂).
Ammonia gas (NH3): often used in conjunction with silane to deposit silicon nitride films and provide a nitrogen source.
Nitrogen (N ₂): can be used as a carrier gas or diluent gas, and can also participate in the deposition reaction of thin films such as silicon nitride.
Nitrous oxide (N ₂ O) or oxygen (O ₂): used to deposit silicon oxide films and provide an oxygen source.
Methane (CH ₄) or other hydrocarbons: used for depositing carbon based films, such as diamond-like carbon (DLC) films.

Inert gas (carrier gas/diluent gas):
Argon (Ar): commonly used as a carrier gas or diluent gas to help stabilize the plasma and regulate the partial pressure of the reaction gas.
Helium (He): It can also be used as a carrier gas and has high thermal conductivity, which helps to control the reaction temperature.

Doping gas:
Phosphine (PH ∝): used for n-type doping to prepare n-type semiconductor thin films.
Borane (B ₂ H ₆): used for p-type doping and preparation of p-type semiconductor thin films.
Boron trifluoride (BF ∝): can also be used as a p-type doping source.

Other special gases:
Hydrogen (H ₂): commonly used in reduction reactions or in combination with silane to regulate the deposition rate and properties of thin films.
Sulfur hexafluoride (SF ₆): Used in certain special processes for etching or surface treatment.

Factors influencing gas selection:
Film type: Select the corresponding reactive gas based on the required deposited film material (such as SiO ₂, Si ∝ N ₄, DLC, etc.).
Doping requirements: To prepare p-type or n-type semiconductor thin films, corresponding doping gases need to be introduced.
Process conditions: Parameters such as gas flow rate, proportion, and pressure can affect the deposition rate, quality, and performance of thin films.
Safety: Certain gases, such as silane and phosphine, are flammable, explosive, or toxic and require strict adherence to safety operating procedures.

Practical application example:
Deposition of silicon nitride thin film: Typically, silane (SiH ₄) and ammonia (NH3) are introduced, and sometimes nitrogen (N ₂) or argon (Ar) is added as a carrier gas.
Deposition of Silicon Oxide Thin Films: Typically, silane (SiH ₄) and nitrous oxide (N ₂ O) or oxygen (O ₂) are introduced.
Deposition of DLC film: Typically, methane (CH ₄) and hydrogen (H ₂) are introduced, and sometimes argon (Ar) is added as a carrier gas.