Nitridation incorporates nitrogen atoms into gate oxide or dielectric films to improve reliability, reduce boron penetration, and increase dielectric constant. Methods: Plasma nitridation: Expose oxide to nitrogen plasma (N2 or NH3). Nitrogen incorporates at surface and interface. Most common method. Thermal nitridation: Anneal in NH3 or N2O ambient at high temperature. Nitrogen incorporation at Si/SiO2 interface. NO/N2O oxynitridation: Grow oxide in NO or N2O ambient. Controlled nitrogen at interface. Benefits: Boron penetration barrier: Nitrogen in gate oxide blocks boron diffusion from p+ poly gate through oxide into channel. Critical for PMOS. Reliability improvement: Nitrogen at Si/SiO2 interface reduces hot-carrier degradation and NBTI susceptibility. Dielectric constant increase: SiON has k ~4-7 vs 3.9 for SiO2. Slightly higher capacitance for same physical thickness. Nitrogen profile: Amount and location of nitrogen critically affect device performance. Too much nitrogen at interface increases interface states. Concentration: Typically 5-20 atomic percent nitrogen depending on application. High-k integration: Nitrogen incorporated into HfO2 (HfSiON) for improved thermal stability and reliability. Plasma nitridation process: Decoupled plasma nitridation (DPN) controls nitrogen dose and profile independently from oxide growth. Measurement: XPS or angle-resolved XPS measures nitrogen concentration and depth profile.