self-aligned via (sav)

**Self-Aligned Via (SAV)** is an **advanced BEOL patterning technique where the via is automatically aligned to the metal trench below** — eliminating the overlay error between via and metal layers that causes reliability failures at tight pitches. **What Is SAV?** - **Problem**: At metal pitches below ~36 nm, conventional via-to-metal overlay error can cause the via to land partially on the barrier or miss the metal entirely. - **Solution**: Use a selective etch or metallic hardmask that inherently constrains the via to land on the metal line. - **Implementation**: TiN hardmask on top of the metal trench acts as a self-aligning template. **Why It Matters** - **Yield**: Eliminates via-to-metal misalignment, a major yield limiter at 7nm and below. - **Reliability**: Ensures full via-to-metal contact area, preventing resistance increase and electromigration. - **Scaling**: Enables continued metal pitch reduction below 30 nm. **Self-Aligned Via** is **auto-aim for interconnects** — removing human alignment error from the equation by using the physics of the process itself to guarantee perfect via placement.