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.