ionized pvd (ipvd)

Ionized PVD (IPVD) ionizes sputtered atoms using secondary plasma, enabling directional deposition into high-aspect-ratio features with improved bottom and sidewall coverage. **Principle**: Sputtered atoms pass through dense secondary plasma (RF coil or capacitive) where they are ionized. Electric field at wafer (bias) accelerates ions directionally toward wafer surface. **Advantage over conventional PVD**: Neutral sputtered atoms travel line-of-sight (poor step coverage). Ions can be directed into features by wafer bias. **Bottom coverage**: IPVD achieves 30-60%+ bottom coverage vs 5-15% for conventional sputtering in high-AR features. **Ionization fraction**: 50-90% of sputtered atoms ionized. Higher ionization = more directional deposition. **Wafer bias**: RF or DC bias on wafer chuck attracts ions. Bias level controls directionality and resputtering balance. **Resputtering**: Ion bombardment redistributes deposited material from bottom to sidewalls, improving conformality. **Applications**: Cu seed layers in via/trench, TaN/Ta barrier layers, Ti/TiN liners for W contacts. Essential for features with AR > 3:1. **Equipment**: Long-throw sputtering, hollow cathode magnetron, self-ionized plasma (SIP) are IPVD variants. **Trade-offs**: Higher complexity, lower deposition rate than conventional PVD. Substrate heating from ion bombardment.