Background

The process of manufacturing integrated circuits is complex and requires over 30 different gasses during production, one of the broadest in any industry. While mixtures for laser light sources are the most common gas-related processes in lithography, there are many other gases used in the semiconductor manufacturing process. Our latest insight provides an overview of the different gases used during the manufacturing of semiconductors and highlights the recent concerns around the supply of Neon.
 

The Use of Gases in Semiconductor Lithography

Lithography is a critical process step during semiconductor manufacturing. Smaller feature sizes (fewer nm nodes) require a finer optical resolution. Over time, illuminating systems with increasingly smaller wavelengths were developed. The current lowest available wavelengths for high-volume manufacturing are 248nm and 193nm. These wavelengths are used in combination with Deep Ultraviolet Lithography (DUV).

In DUV lithography, we know of two types of lasers used for nodes equal to and larger than 10nm, Argon-Fluorine lasers generate 193nm Krypton-Fluorine-based lasers that emit light at 248nm. Neon gas takes the majority portion of 95% in the mix of gas in these lasers. Extreme Ultraviolet (EUV): This type of lithography is used to produce process nodes measuring 7nm or smaller. In this method, the generation of light occurs by aiming a CO₂ beam at a droplet of tin. EUV is different from DUV in that no direct light source is used, and there is an absence of Neon gas in this method.

Gas Types Used Elsewhere

While laser sources are probably the most recognized gas-related process, there are several other gases used throughout the semiconductor manufacturing process.
 

Nitrogen(N): The most used inert (non-reactive) gas. Nitrogen is commonly used to keep tools, space, and tubing free from potential moisture, chemical contaminants, and particles. Due to its commonality in the manufacturing process, most fabs have Nitrogen on site. The use of this gas requires a multiple-step purification process.

Oxygen (O): Used as an oxidizing agent, it is essential for creating deposition reactions. Oxygen is used to grow silicon oxide layers used for various elements within the manufacturing process. Oxygen also helps neutralize reactive gases through oxidation and is used similarly to Nitrogen in the control of contamination.
 

Argon (Ar): The gas is used mainly during the deposition and etching process within the DUV lithography lasers and supports the production of the smaller patterns on the semiconductor chips. Additionally, liquid Argon is used with tools to clean the smallest and most fragile chips.

Helium (He): Helium is extracted from natural gas sources around the globe and is used for cooling optical lenses in lithography. This gas has limited resources and some organizations have developed solutions for Helium recovery.
 

Carbon Dioxide (CO₂): Used in the EUV process (along with non-Neon gases for the smallest nodes (<7nm). Food-grade CO₂ is used to carbonate water, soft drinks, and alcoholic drinks, among other uses. Purity standards for Carbon Dioxide in lithography are more stringent than the standards set for domestic use.

Hydrogen (H): Hydrogen gas is used to prevent tin droplets from being disposed of on reflecting optics in EUV equipment and reduce light power.  It is also used to form volatile tin particles which can be pumped away and prevent a reduction in the number of photons available for illumination in the EUV process. Hydrogen is also used for epitaxial deposition of silicon and silicon germanium as well as to prepare the surface through an annealing process. Additionally, as the gases that are used at the doping stage process are extremely toxic, hydrogen can be used to control decomposition.

Krypton (K) and Xenon (Xe) are used in etching, annealing and lasers for lithography. Krypton and Xenon are commonly used in conjunction with halocarbon etchants for deep trench etch used for 3D NAND SSD devices.
 

Neon (Ne): While commonly associated with glowing signage, Neon and other gases can be extracted from the air by large Air Separation Plants. These multi-million-dollar facilities are designed to supply pure Oxygen to metallurgical facilities. As Oxygen is separated from the other gases that compose air, mixtures of Neon and Helium also accumulate. Lithography is the leading consumer of Neon gas, reporting 70% of global Neon production.

Concerns Around Neon Production and Supply

Ukraine supplies 70% of the global availability of Neon gas, 40% of Krypton gas, and 30% of Xenon gas. Unsurprisingly, more than 90% of Neon gas usage for semiconductor manufacturing in the United States originates in Ukraine. Though the absolute use of these gases is low, the ongoing Russian invasion of Ukraine has only increased concerns about potential supply disruptions.
 

Neon gas is a byproduct of Russia's steel manufacturing industry, reliant on Ukrainian companies in the Crimea region for purification. In other major steel-producing companies – including China, India, Japan, and the United States - adjacent gas production is not a key activity and can take months to develop. China has achieved breakthroughs in the purification technology of these rare gases. To a certain degree, China is able to support its domestic demand for neon gases. Due to current geopolitical tensions, accessing Chinese suppliers is challenging, at best, for western semiconductor manufacturers.

The countries that are in the highest risk category include Japan, South Korea, and the United States.

• Japan can only produce a very small amount of rare gas domestically, with the remaining amount imported from Ukraine or China.
• South Korea used to import all neon gas and relied on foreign technology; however, they nationalized production of about 20% of total usage in early 2022.
• For the United States, the supply of rare gases such as neon is likely to become another sensitive area of negotiations with the Kremlin
   

There are also independent gas companies such as Air Products and Linde that can produce neon. So while it may take some months to scale up new production sources, there are currently sufficient inventory positions of neon to keep the industry running.

Can We Reduce the Use of Neon?

As outlined, Neon is only used in DUV equipment and NOT in the state-of-the-art extreme ultraviolet (EUV)equipment used to manufacture the most advanced semiconductors, <7nm. Even with the advances in manufacturing, end-market products still require parts produced in mature technology nodes built using DUV lithography. As a result, the uncertainty of Neon supply remains concerning to the overall market.  

Alternatives for Neon
Neon can be replaced by Helium and other noble gases; however, these gases are less effective and are available at a substantially higher cost. Can we reduce the usage of Neon? Yes, but Neon needs to be replaced every few weeks because of degradation. In the short term, less gas-intensive lasers have been promoted that provide 50% Neon gas savings. Stretching the intervals between refreshes and injections will reduce Neon usage by a further 30 to 50% without compromising performance.

A longer-term solution is to introduce Neon recycling technologies. The process works with around 85% efficiency, does not affect laser performance and can be done within the fab itself. However, because Neon gas is a relatively cheap commodity, fabs aren't incentivized to change their current Neon gas usage.

Conclusion

In general, semiconductor companies have become more aware of this circular economy. When considering materials that are rare or sourced from challenging regions, organizations that have invested in equipment and processes to re-use neon are not in immediate danger of short supply and are more resilient in the long term. Smaller semiconductor facilities that are using DUV machines run a higher risk should Neon gas shortages occur in the future.

Unless the lack of supply from Ukraine can be made up by facilities elsewhere, an extended Neon shortage could cause supply issues. The 2014 Russian annexation of the Crimea region represented a wake-up call to secure alternative sources of Neon gas.  

Currently, there are no major issues with the neon supply. However, due to the larger environment surrounding major producers, that may change. Jabil will continue to monitor developments closely and will communicate frequently with manufacturers who use Neon gas in the production of semiconductors to determine if a shortage is imminent. 

Please do not hesitate to contact me (rudi_palmans@jabil.com) with any questions or for more information.