Neon Ne · 10

A noble gas so unreactive it forms no compounds at all, separated out of ordinary air in tiny quantities.

なぜ重要なのか

Neon is the light source in the excimer lasers that print chip patterns. A shortage of it stops advanced lithography, which is why its supply became a strategic question in 2022.

Where it is in the Earth

Neon is not found in rocks. It is a noble gas — a family of elements so chemically inert that they bond with nothing and therefore never become part of a mineral, an ore body, or any solid material at all. The only place neon accumulates in quantity is the atmosphere, where it sits as a trace constituent of ordinary air, far behind nitrogen and oxygen and even argon. It arrived there partly through outgassing from the Earth's interior over geological time and partly as a primordial inheritance from the solar nebula from which the planet formed. Because neon is lighter than most atmospheric gases yet heavier than hydrogen and helium, it neither drifts away into space nor gets locked into the ground, and so the atmosphere acts as a permanent, if very dilute, reservoir.

There is no geological prospecting for neon in the conventional sense. No map of favourable rock types, no grade measurements of ore bodies, no exploration drilling. The resource is simply the atmosphere above wherever you happen to be standing. What determines whether it is economic to recover is not geology but proximity to industrial infrastructure — specifically, to large air-separation plants already built to supply oxygen and nitrogen to steelmakers, chemical manufacturers, and hospitals. The concentration of neon in air is fixed by atmospheric chemistry and is the same everywhere on Earth. What varies is the scale of the industrial operation sitting beside the resource, and that is an economic and geographic fact, not a geological one.

Getting it out

Neon is not mined. It is recovered as a by-product of air separation, an industrial process that was developed to produce oxygen and nitrogen in large volumes and happens, incidentally, to yield small quantities of noble gases including neon, krypton, and xenon. The process works by cooling air until it liquefies and then allowing the different components to boil off at their own characteristic temperatures — a technique called cryogenic fractional distillation. Neon, because it has a very low boiling point, concentrates in the fraction that separates earliest in this sequence.

The important practical point is that neon production is entirely dependent on the scale and operating rate of air-separation units built for other purposes. A plant that slows or stops its oxygen and nitrogen production — because nearby steel mills are idle, for example — produces no neon regardless of demand for neon itself. This gives the supply of neon a structural inflexibility that has no parallel in conventional mining, where output can in principle be adjusted by changing how many tonnes of rock are moved. With neon, the lever does not exist independently. Global production figures are reported in millions of litres of gas rather than in tonnes, reflecting the fact that what is being measured is a gas at standard conditions, not a solid material extracted from the ground.

Because the source material is air and the separation step is integrated into plants whose primary economics depend on other products, there is no meaningful concept of ore grade or waste-to-product ratio in the usual sense. The "grade" is the atmospheric concentration of neon, which is effectively constant. What matters economically is the efficiency of the separation train, the running hours of the air-separation unit, and whether the operator has invested in the additional cold-end equipment needed to capture the noble-gas fraction rather than venting it.

What pulls on it

The dominant use of purified neon is in excimer lasers, which are the light sources at the heart of photolithography — the process by which circuit patterns are transferred onto silicon wafers. An excimer laser works by electrically exciting a mixture of gases, one of which is neon, to produce ultraviolet light at a precise wavelength. The wavelength determines how fine a feature can be printed, and at the most advanced nodes of chip manufacturing the tolerances on gas purity and laser performance are correspondingly tight. Every wafer that goes through a modern chip fab passes under an excimer laser, and those lasers consume neon continuously. Because chip manufacturing runs around the clock and the gas mix degrades with use, demand from this sector is steady and not easily deferred.

Neon also has older, smaller applications in lighting — the gas-discharge tubes that give neon signs their characteristic glow — and in high-voltage indicator lamps and certain scientific instruments. These uses are individually modest and have been broadly flat or declining as solid-state lighting has displaced gas-discharge technology in many settings. The growth story for neon is entirely in semiconductors, and specifically in the continued expansion of advanced chip fabrication capacity globally. If the number of leading-edge fabs increases, neon demand increases with it; if chip manufacturers find a way to reduce gas consumption per laser shot, or to extend the period between gas changes, the demand intensity per wafer falls even as total wafer production grows.

A sharp change in demand would require either a major shift in lithography technology — moving to a light source that does not use neon, such as extreme ultraviolet lithography, which uses a plasma rather than a gas laser — or a prolonged contraction in global semiconductor production. Extreme ultraviolet tools are already in use at the most advanced fabs, but excimer laser tools remain the workhorses for the large majority of chip layers and for less advanced nodes, so any transition is gradual and does not eliminate neon demand in the near term.