sion interfacial layer

**SiON Interfacial Layer** is a **nitrogen-enriched variant of the SiO₂ interfacial layer** — where nitrogen incorporation into the thin IL provides better resistance to boron penetration, slightly higher $kappa$, and improved reliability while maintaining good interface quality. **What Is SiON IL?** - **Formation**: Grow thin SiO₂ by chemical/thermal oxidation, then nitridize using plasma nitridation (decoupled plasma nitridation, DPN) or NH₃ anneal. - **N Content**: ~10-30 atomic % nitrogen at the surface, graded toward pure SiO₂ at the Si interface. - **$kappa$**: ~4.5-5.5 (slightly higher than SiO₂'s 3.9, reducing EOT contribution). **Why It Matters** - **Boron Blocking**: Nitrogen blocks boron diffusion from P+ poly gates (critical for PMOS, pre-HKMG era). - **EOT Reduction**: Higher $kappa$ of SiON vs. SiO₂ allows a physically thicker IL for the same EOT. - **Reliability**: Nitrogen improves NBTI (Negative Bias Temperature Instability) resistance. **SiON IL** is **the reinforced interface** — adding nitrogen to the oxide bridge for better blocking, higher capacitance, and improved long-term reliability.