tan barrier

**TaN Barrier** (Tantalum Nitride) is the **primary diffusion barrier used in copper damascene interconnects** — an amorphous, chemically stable film that effectively blocks copper diffusion while providing a foundation for the subsequent Ta adhesion layer and Cu seed. **What Is TaN?** - **Properties**: Amorphous (no grain boundaries for Cu to diffuse through), $ ho approx 200-400$ $muOmega$·cm. - **Deposition**: PVD (ionized sputtering, iPVD) or ALD (PDMAT + NH₃ plasma). - **Thickness**: 1-3 nm at advanced nodes. - **Stack**: TaN (barrier) + Ta (liner/adhesion) + Cu seed -> Cu ECP fill. **Why It Matters** - **Industry Standard**: The TaN/Ta bilayer has been the copper barrier of choice since the introduction of Cu damascene at 130nm. - **Scaling Limit**: At sub-20nm pitches, even 2 nm of TaN+Ta consumes significant wire cross-section, increasing line resistance. - **Alternatives**: Ru-based barriers and liner-free approaches are being explored to reclaim area. **TaN** is **the invisible wall protecting copper interconnects** — an ultra-thin amorphous barrier that keeps copper atoms confined within their designated channels.