In the semiconductor manufacturing field, the continuous miniaturization of devices has directly driven the reliance on advanced lithography technologies. As process nodes shrink to ever smaller dimensions, the number of patterning steps required increases significantly, leading to a corresponding rise in the consumption of excimer laser gases. As the next-generation lithography technology, extreme ultraviolet (EUV) lithography is being developed with the aim of further breaking through physical limitations. This technology indirectly involves the use of carbon dioxide and hydrogen and complements existing deep-ultraviolet (DUV) lithography rather than replacing it in the foreseeable future.

I. Excimer Laser Gases: The Cornerstone of DUV Lithography

The operating principle of an excimer laser is based on stimulated emission from excited-state complex molecules—known as “excimers.” A specific mixture of rare gases (such as argon, krypton, and xenon) combined with halogen gases (such as fluorine and chlorine) can form a short-lived excimer state when subjected to electrical excitation. As these excimers decay back to their ground state, they emit deep-ultraviolet laser light at a specific wavelength.

Core gas mixtures: In semiconductor lithography, the two most common mixtures are:

1. ArF (argon-fluorine) gas mixture: This mixture generates a 193-nanometer wavelength laser and is currently the primary light source for advanced DUV lithography (such as immersion lithography).

2. KrF (krypton-fluorine) mixed gas: Generates a 248-nanometer wavelength laser and is widely used in current domestic process nodes.

Gas Composition and Function: In these mixtures, the rare gas (neon) serves as a buffer gas, occupying the vast majority of the volume—approximately 96% to 97.5%. Its primary roles include optimizing discharge characteristics, facilitating energy transfer, and ensuring the stability of laser output. The halogen gases—such as fluorine—which constitute an extremely small fraction of the mixture, are the key reactants responsible for generating exciplex molecules and determining the output wavelength.

II. Extreme Ultraviolet Lithography Technology: Principles and Gas Applications

EUV lithography uses extreme ultraviolet light with a wavelength of only 13.5 nanometers, which can significantly reduce the number of patterning layers required for complex integrated circuits.

Mechanism of light source generation: EUV light is obtained through plasma radiation generated by irradiating a liquid tin target with high-power CO₂ laser pulses. The application of gases in this process is reflected in two stages:

1. CO₂ laser: The main laser that generates the bombardment of tin droplets; its active medium is a mixed gas composed of high-purity carbon dioxide, nitrogen, and helium.

2. Chamber Cleaning: Debris generated by the tin target can contaminate the EUV optical system. Therefore, hydrogen gas must be continuously introduced for in-situ cleaning to maintain the intensity and stability of the light source.

III. Supply Chain Challenges for Key Gases

Rare gases (such as neon, krypton, and xenon) are present in the air at extremely low concentrations—ranging from parts per million to parts per billion—and their extraction and purification are highly technology-intensive processes.

• Air separation and purification: These gases are typically obtained as byproducts from large-scale air separation plants. For example, neon and helium—having boiling points lower than those of the main components, nitrogen and oxygen—are enriched at the top of the low-pressure column; in contrast, krypton and xenon, with higher boiling points, are concentrated in the liquid oxygen fraction and then undergo multi-stage purification to achieve the high purity required by the semiconductor industry (usually ≥99.999%).

• Halogen Gas Handling: Halogen gases such as fluorine are highly reactive and corrosive, requiring special materials and processing techniques for safe production, purification, and transportation.

IV. Market Drivers and Outlook

The continuous expansion of global semiconductor production capacity—characterized by a stable annual compound growth rate—and the widespread adoption of multi-patterning techniques at advanced process nodes are the key drivers behind the growing demand for laser gas markets. Ensuring the stability and quality of these critical gas supplies is essential for safeguarding the global semiconductor supply chain.

Leading specialty gas suppliers provide foundational material support for the continuous innovation in semiconductor manufacturing through their advanced purification technologies, precise blending processes, and global supply-chain capabilities.

Key technological threshold:

1. Excimer laser gases are composed of a specific mixture of rare gases and halogen gases; the precision of this mixture determines the stability of the product.

2. The extraction of rare gases is relatively difficult and only becomes economically viable when large-scale air separation units are employed.

3. Kaimite’s laser-mixed gas raw materials are entirely self-sufficiently produced.

4. Kemite’s blending technology and analytical capabilities are at the forefront of the global market.