pvd

Physical Vapor Deposition (PVD) encompasses techniques that deposit thin conductor and barrier films by physical transfer of material from source to wafer in vacuum. **Primary method**: Magnetron sputtering dominates semiconductor PVD. **Materials deposited**: Aluminum and Al alloys, copper seed layers, titanium, titanium nitride (TiN), tantalum, tantalum nitride (TaN), tungsten, cobalt, ruthenium. **Barrier/liner**: PVD TaN/Ta or TiN/Ti as copper diffusion barrier and adhesion layers in damascene interconnects. **Seed layer**: PVD Cu seed for subsequent electrochemical copper plating. Must be continuous even in high-AR features. **Aluminum**: PVD Al alloy was traditional interconnect metal. Still used in upper metal layers and pads. **Process sequence**: Typical damascene: etch trench/via, PVD barrier, PVD seed, electroplate Cu, CMP. **Chamber**: Ultra-high vacuum (<10^-8 Torr base pressure) to minimize contamination. Cluster tools with multiple chambers. **Temperature**: Generally room temperature to 400 C. Lower thermal budget than CVD. **Ionized PVD**: Modern tools ionize sputtered atoms for improved bottom coverage in high-AR features. **Film properties**: Dense, pure, good adhesion. Stress controllable via power and pressure. **Throughput**: Single-wafer processing. Moderate throughput. Multiple chambers in parallel on cluster tool.