In the field of semiconductor manufacturing, 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 has increased 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 to further push beyond physical limitations. While this technology indirectly involves the use of carbon dioxide and hydrogen, it complements existing deep ultraviolet (DUV) lithography rather than replacing it in the foreseeable future.

1. Excimer Laser Gases: The Cornerstone of DUV Lithography

The operating mechanism of excimer lasers 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 like fluorine and chlorine, can form transient excimer states when subjected to electrical excitation. As these states decay back to the ground state, they emit deep ultraviolet laser light at a characteristic wavelength.

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

1. ArF (argon–fluorine) gas mixture: Generates a 193-nanometer wavelength laser and serves as the primary light source for advanced DUV lithography, such as immersion lithography.

2. KrF (Krypton Fluoride) Mixture: Generates a 248 nm wavelength laser and is widely used in current process nodes domestically.

Gas Composition and Function: In these mixtures, rare gases (such as neon) serve as buffer gases, accounting for the vast majority of the volume (approximately 96%–97.5%). Their primary roles are to optimize discharge characteristics, facilitate energy transfer, and ensure the stability of laser output. Halogen gases—though present in extremely small proportions (such as fluorine)—are the key reactants responsible for generating excimer molecules and determining the output wavelength.

2. Extreme Ultraviolet Lithography: 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.

Light Source Generation Mechanism: EUV light is generated through plasma radiation produced when a high‑power CO₂ laser pulse strikes a liquid tin target. The application of gases in this process is reflected in two stages:

1. CO₂ Laser: The primary laser that generates the bombardment of tin droplets, with a working medium consisting of a high‑purity mixture of carbon dioxide, nitrogen, and helium gas.

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

III. Supply Chain Challenges for Critical 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 of large-scale air separation plants. For example, neon and helium, with boiling points lower than those of the main components nitrogen and oxygen, become enriched at the top of the low-pressure column; in contrast, krypton and xenon, which have higher boiling points, are concentrated in the liquid oxygen distillate 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 specialized materials and processing techniques for safe production, purification, and transportation.

IV. Market Drivers and Outlook

The continuous expansion of global semiconductor production capacity—driven by a steady annual compound growth rate—and the widespread adoption of multi-patterning techniques at advanced process nodes are the core factors propelling the growth in demand for laser gases. Ensuring the stability and quality of these critical gas supplies is essential for safeguarding the security of the global semiconductor industry chain.

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

Key technological barriers:

1. Excimer laser gases are produced by mixing specific rare gases with halogen gases, and the precision of this mixture determines the stability of the product.

2. Extracting 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 produced using self‑sufficient raw material supply.

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