Thermal Nitridation System

Thermal nitridation grows a silicon nitride or oxynitride layer by exposing silicon or an existing oxide to a nitrogen-bearing gas — ammonia or nitrous oxide, typically — at high furnace temperature, with no plasma involved at all. It's the older, gentler counterpart to plasma nitridation, trading the plasma method's speed and lower-temperature operation for a simpler process with less risk of plasma-induced damage to sensitive underlying structures.

Silicon or oxide surface exposed to nitrogen source gas
Ammonia (NH3) or nitrous oxide (N2O), furnace or RTP ambient
Thermal nitridation reaction
High-temperature gas-surface reaction
No plasma — purely thermal activation drives nitrogen incorporation
Nitrogen incorporates into film
Forms SiN or oxynitride, improves barrier/dielectric properties
Nitrided film
Boron-penetration barrier, or improved gate dielectric properties

Thermal nitridation's biggest practical application is blocking boron penetration through thin gate oxides — a problem nitrogen incorporation solves directly. Boron dopant from a heavily doped polysilicon gate can diffuse straight through a very thin gate oxide during subsequent high-temperature steps, shifting the transistor's threshold voltage in an uncontrolled way; incorporating nitrogen into that oxide — forming an oxynitride — creates a diffusion barrier that measurably slows boron's penetration, which is why nitrided gate oxides became standard once oxide thicknesses shrank to the point where boron penetration became a real threshold-voltage reliability concern.

Thermal Nitridation — Nitrogen as a Diffusion Barrier no plasma, just heat and a nitrogen-bearing gas Gate oxide — boron penetration silicon substrate gate oxide — unnitrided: boron passes through boron-doped polysilicon gate oxynitride — nitrided boron blocked nitrogen incorporation slows boron diffusion enough to stabilize threshold voltage

Thermal nitridation's lack of plasma is the whole reason it remains the safer choice wherever plasma-induced damage is a concern, even though plasma nitridation can run faster and at lower temperature. A plasma process exposes the film to energetic ions and UV photons that can introduce charge trapping or interface damage in sensitive gate structures; purely thermal nitridation avoids that risk entirely by relying only on thermal energy to drive the nitrogen-incorporation reaction, accepting a slower process and higher temperature requirement in exchange for a damage profile that's easier to characterize and control.

Thermal nitridation remains the simpler, gentler sibling to plasma nitridation, chosen specifically when a process can afford the higher temperature and longer time a pure thermal reaction needs, in exchange for avoiding the plasma-damage risk that comes with the faster, lower-temperature plasma alternative.

Take thermal nitridation system further

Ask the copilot about this term, or have our engineers assess it against your process.

Ask CFSGPT about this → Request a technical assessment → Open the CFS app