Laser-produced tin-plasma EUV light source

Fifty times per second, a molten tin droplet twenty-five microns across is fired across a vacuum chamber at seventy metres per second, flattened by one laser pulse, then vaporised by a second into a plasma heated to nearly 220,000 °C — roughly forty times hotter than the surface of the sun. That plasma emits a narrow band of light at 13.5 nanometres, the wavelength that lets the world print transistors at 5 nanometres and below. As of 2026, one company on Earth sells the machine that does this: ASML of the Netherlands. India has no documented programme to build the light source at its heart.

The difficulty is not incidental; it is the whole story. The tin must arrive at up to 100,000 droplets per second, each struck on the fly by a sequence of laser pulses culminating in a high-power CO₂ main pulse. The collector mirror that captures the resulting EUV absorbs 96% of it and degrades roughly 0.1–0.3% per billion pulses — about 10% of its reflectivity lost in two weeks — while tin ions and debris erode it further. For high-volume manufacturing at 100-plus wafers an hour, 350W of EUV power was already required in 2012. Every subsystem sits at the edge of physics.

India's honest status here is a blank. There is no Indian entity attempting development, and the full technology is imported through ASML's monopoly. What exists is the layer beneath: several of the foundational capabilities the source depends on are assessed as competitive — high-power CO₂ laser amplification, precision tin-droplet ejection, multi-layer mirror collector optics, ultrahigh-vacuum chamber technology — while plasma debris mitigation and real-time diagnostics sit at demonstrated. The components are within reach in isolation; the integrated machine is not.

The gap persists because integration, not any single part, is the moat. ASML absorbed the source-maker Cymer and spent €6 billion over 17 years, weaving proprietary technology through relationships with its suppliers. Experts judge that catching up could take any other company decades. China's route is instructive: rather than replicate laser-produced plasma, it has pursued a laser-induced discharge plasma design, reported as simpler and more cost-effective, and by December 2025 had a prototype EUV system.

What it would take is a deliberate assembly of the competitive pieces into a coherent programme — pairing the CO₂ laser, droplet generator, collector optics and vacuum systems with the debris-mitigation and diagnostics work already demonstrated. The parts exist in India's grasp. Nobody has yet been asked to combine them.