seed layer for electroplating

**Seed Layer** is a **thin, continuous copper film deposited by PVD over the barrier/liner** — providing the conductive surface needed to initiate the electrochemical plating (ECP) process that fills trenches and vias with copper. **What Is the Cu Seed Layer?** - **Material**: Pure copper (Cu), typically 10-50 nm thick. - **Deposition**: PVD (ionized sputtering, iPVD) for conformal coverage in high-aspect-ratio features. - **Requirements**: Continuous (no gaps), uniform, good step coverage on trench sidewalls and via bottoms. - **Challenge**: At narrow pitches (< 20 nm), seed overhang at the trench opening can pinch off and cause voids. **Why It Matters** - **ECP Prerequisite**: Electroplating requires a conductive surface to carry current. No seed = no plating. - **Fill Quality**: Seed uniformity directly determines whether the copper fill is void-free. - **Scaling**: Ultra-thin seeds (< 10 nm) at advanced nodes risk discontinuity and poor nucleation. **Seed Layer** is **the electrical runway for copper plating** — the thin conductive coating that enables the electrochemical bath to build up the bulk copper fill.