DUV Systems

DUV System Components

A DUV (Deep Ultraviolet) immersion scanner consists of several major subsystems:

• ArF excimer laser: Generates 193 nm light by exciting argon fluoride gas. Modern lasers produce 90W+ at 6 kHz repetition rate with extremely narrow bandwidth (<0.35 pm).
• Illuminator: Shapes the laser beam into the desired angular distribution (conventional, annular, dipole, quadrupole) to optimize imaging for different pattern types.
• Projection optics: 30+ fused silica and CaF₂ lens elements, polished to sub-atomic surface roughness. Total weight: several tons. The last lens element sits just above the water puddle.
• Immersion system: Delivers and recovers ultra-pure water between the final lens and wafer, maintaining a stable meniscus at high scan speeds.
• Alignment system: Multiple sensors measure wafer position, tilt, and height at each die location before exposure.

ArF immersion scanners from ASML (TWINSCAN NXT:2000) achieve 295 wafers/hour and cost approximately $80–100 million.