PVD Systems

PVD System Design

A PVD sputtering system consists of:

• Target assembly: A disk of source material (TaN, Ta, Cu, Ti, etc.) backed by a magnetron assembly with permanent magnets. The target is water-cooled to prevent melting.
• Magnetron: Magnets behind the target create a magnetic field that confines the plasma near the target surface, increasing ionization efficiency and sputter rate.
• Process kit: Shields and collimators that contain the sputtered material and prevent chamber contamination.
• Wafer chuck: May include RF bias to accelerate ions toward the wafer for better step coverage.

Advanced PVD techniques:

• Ionized PVD (iPVD): An additional RF coil ionizes the sputtered atoms after they leave the target. Ionized atoms can be directed by wafer bias for excellent bottom coverage in high-aspect-ratio features.
• Long-throw PVD: Increased target-to-wafer distance improves directionality through collimation.

Major PVD Tools and Vendors

Most production PVD in modern fabs runs on three platforms:

An Endura mainframe is a classic example of cluster integration: a single vacuum-coupled platform hosts a degas chamber, a pre-clean, and 4–6 PVD process modules. A typical Cu damascene sequence runs:

1. Degas (200–400 °C) to drive off moisture
2. Ar+ pre-clean to remove native oxide from via bottoms
3. PVD TaN barrier (~1–2 nm)
4. PVD Ta liner (~1 nm)
5. PVD Cu seed (~10–20 nm) — moves to ECD tool for fill