Tin droplet generator and delivery system

Fifty thousand times a second, a machine fires a droplet of molten tin — about 25 micrometres across — into a vacuum chamber at 70 metres per second, then hits each one twice with a carbon dioxide laser. India cannot build any part of this system.

The tin droplet generator is a critical subsystem of the light source at the heart of extreme ultraviolet (EUV) lithography, the process needed to print sub-7nm chips. It works by turning tin into plasma. A low-power pre-pulse flattens each droplet into a pancake; a high-power main pulse — around 15 megawatts, roughly 250 millijoules — then ionises it into a plasma that shines at exactly 13.5 nanometres, the wavelength that patterns the finest features on a chip.

The difficulty is in the tolerances. The generator must dispense molten tin continuously and reliably, tens of thousands of times per second, while a tracking system aligns each laser pulse to a moving target firing at 50 kHz. The tin must be extraordinarily pure — 99.999% and beyond — because contamination at the parts-per-million level forms particles that clog the nozzle and fail the system. When it all works, the source sustains in-band EUV output above 250 watts and throughput exceeding 125 wafers per hour.

No single company builds the whole thing alone. TRUMPF makes the high-power CO2 laser; ZEISS makes the collector mirrors; ASML integrates the components — including the droplet generator — into the complete light source. And ASML of the Netherlands is the only company on Earth that manufactures and sells EUV systems for chip production. As of 2026, the world is served by exactly one supplier nation for this capability.

India stands far below this. There is no indigenous tin droplet generator, no EUV light source subsystem, no known builder attempting it. The country operates at the DUV level — 193nm deep ultraviolet — where even the photoresists used at the Semiconductor Laboratory in Mohali are entirely imported, because no Indian company manufactures them.

The gap persists because EUV sits atop a stack of foundational capabilities India does not yet hold: 30-plus-kilowatt pulsed CO2 lasers, precision nozzles, ultra-high-purity tin, multilayer-coated collector mirrors, and the synchronisation software binding them. Despite the India Semiconductor Mission, the equipment for manufacturing continues to be sourced abroad; entry points into fabrication exist, but upstream depth remains external.

Closing the gap would mean building those component capabilities first — the laser, the nozzle, the tin, the optics — before the integration that ASML alone has mastered becomes conceivable.