Finding a short term solution to the neon gas shortage problem will be challenging.

BY HITOMI FUKUDA, Gigaphoton, Inc., Oyama, Japan

When many people think of neon, they think of brightly lighted signs used in restaurants and other retail environments. The element neon (Ne) gives a distinct reddish-orange glow when used in either low-voltage neon glow lamps or in high-voltage discharge tubes or neon advertising signs. The red emission line from neon is also responsible for the well known red light of helium–neon lasers. Neon is commercially extracted by the fractional distillation of liquid air. It is considerably more expensive than helium, since air is its only source.

What those outside the chip industry likely don’t know is that neon has been employed for semiconductor manufacturing for more than a decade, since deep ultraviolet (DUV) lithography came into widespread use starting with 248nm exposure systems. Why is neon important in lithography? Excimer lasers use gases like krypton fluoride (KrF) and argon fluoride (ArF) to generate light, and those gases are regularly changed out during use. However, a charge of excimer laser gas is actually about 98 percent neon, making this carrier gas essential to the laser’s operation. Three main steps are involved in producing gas suitable for excimer laser use: (1) bulk neon production, (2) purification, and (3) final mix.

Today, the semiconductor industry is experiencing severe neon shortages, leading to price increases that are impacting end-users’ bottom line. As a result, fab owners are rushing to secure enough neon to keep their facilities in operation, including buying the critical gas on the cash market and then having it purified and mixed to allow them to put it into use as quickly as possible.

Neon is a byproduct of steel production, but because it is a rare component of the waste gases, it must be recovered at very large steel plants. The former Soviet Union manufactured all of its oxygen plants for steel mills with neon, krypton and xenon capabilities and formerly worked on high-powered lasers as weapons, giving rise to significant neon capacity. Ukraine and Russia still operate the old-style massive manufacturing plants that have long since disappeared from Western countries, and have thus historically enabled the gas to be in over-supply.

From 1990 to 2012, many of these eastern European plants simply sent the crude neon into the atmosphere as no one would buy it. This over-supply began to tighten in 2014, as many old oxygen plants in Eastern Europe were either replaced by newer units without neon capability or shutdown altogether, especially with the contraction of the steel industry.

Why the shortage?

The neon crisis was triggered in part by conflict in the Ukraine, resulting in slowed production and escalating costs on the part of gas suppliers. Because neon is used for the majority of lithography light sources, the shortage caused many chip factories to face potential slowdown or even shutdown. In addition to gas prices increasing as much as 10 times over previous rates, chipmakers faced the prospect of a 15-percent or greater reduction in available supply of neon gas.

In China, old oxygen plants are being privatized or de-activated, or are being replaced by newer plants that lack the additional rare gas recovery investment. Even though there is a strong market for rare gases, the new plants are being put in without the rare gas capability due to a minimal ROI impact. Thus, while China has increased its market share in neon gas, the country’s purification facilities are few and far between, so the country currently lacks production capacity for high-grade purification of neon gas. Regional specialty gas suppliers have also reported diminished supplies, all of which has had severe implications for the future of lithography and global chip manufacturing.

Between 2012 and 2014, the net effect of the neon supply shortage was around 125 million liters of lost annual production. In 2015, neon production, at 400 million liters, was falling short of demand by roughly 75 million liters.

A deeper look at the problem

Semiconductor-related lithography accounts for about 70 percent of worldwide neon demand. As mentioned earlier, an excimer laser uses a multi-gas mixture. The term “excimer” refers to the rare gas / halide molecule. Each fill is dedicated to the generation of a single wavelength. Four wavelengths can be generated from fluorine laser gas mixtures: 157 nm (F2), 193 nm (ArF), 248 nm (KrF) and 351 nm (XeF).

According to some reports, the price of neon gas skyrocketed in 2014, from roughly $1,000 for a 6,000-liter bottle of the gas, to approximately $6,000 for the same quantity as of late 2015. This is evident as seen in FIGURE 1, where the different colors represent the various global chipmakers. Neon gas, minerals, and the industry workhorse—silicon — are among the critical materials vital to semiconductor industry operations. The industry has had to deal with shortages in helium and rare earths in recent years, but was able to find at least temporary solutions.

Neon gas, on the other hand, appears to be a shortage for which finding a solution in the short term will be far more challenging. This problem is expected to continue for several years until a) sufficient new capacity comes on line, b) recycling can be implemented, or c) reprogramming of lasers can be accomplished, in order to allow for more efficient usage. In all likelihood, it will be a combination of all three of these factors that will alleviate the industry’s neon supply challenges, although getting prices back down to a more affordable level is likely to take longer.

Neon conservation

In the meantime, the industry is looking at ways to conserve neon gas to help stretch its usage until such as time as the larger issues begin to be addressed in a more long-term fashion. Important developments in neon conservation include recent excimer laser gas usage optimization efforts that have been put in place by lithographic tool and laser equipment vendors to help end-customers reduce consumption. Optimization can be achieved via software updates for current systems and may result in up to 40 percent more efficient neon usage. In addition, recovery and recycling of neon may be relatively straight-forward with few technical challenges, so several suppliers are proposing recycling and recovery plans.

With that said, the potential impact of these conservation efforts should be carefully considered, as some have the potential to put on hold, or even cancel, capital investment plans to produce more neon. This could mean the neon shortage would become exacerbated or prolonged beyond its current, already critical level.

To combat this crisis, Gigaphoton developed its unique Neon Gas Rescue Program, which expands on its previously announced program offering its eTGM technology for all new and existing GT series ArF immersion lasers.

The new program provides a more comprehensive package that includes the following:

1. A program for rapid qualification of new gas suppliers requested by customers. Previously, testing and qualification of a new gas supplier required anywhere from six to 12 months, but the new program will enable customers to begin using new gas suppliers much more quickly – cutting the qualification time down to as little as one month.

2. A limited, free-of-charge offer of the company’s eTGM technology will also be extended to the G41K series KrF lasers and GT40A series ArF lasers. This extended offer will commence in November 2015. By introducing eTGM, customers can reduce the laser’s neon usage by 25 percent on KrF and ArF lasers, and up to 50 percent on ArF immersion lasers.

3. The accelerated introduction of Gigaphoton’s newest gas recycling technology, hTGM, which can be applied to all types of lasers. hTGM is expected to begin roll-out later this year. By implementing the hTGM technology, customers will be able to recycle up to 50 percent of their gas consumption.

Conclusion

While the semiconductor industry is facing a unique challenge with the current neon gas supply shortage, it has history on its side in terms of innovative solutions. The lithography sector, in particular, has repeatedly found ways to extend and revitalize technology applications.