The Gases That Define What a Chip Can Do
Plasma etching is the semiconductor manufacturing process that transfers the circuit pattern from the photoresist mask to the underlying semiconductor, dielectric, or metal film, using a plasma of reactive gas ions and radicals to remove material with the nanometre-level precision that advanced node semiconductor manufacturing requires. The chemistry of the plasma, determined by the composition of the process gas mixture introduced into the etch reactor, defines the etch selectivity between the materials being etched and those that must be protected, the anisotropy of the etch profile whose vertical sidewall geometry determines whether the etched features conform to the photomask dimensions, and the etch rate whose uniformity across the wafer surface determines the dimensional control of the etched features across the tens of millions of transistors on a single chip. The process gases used in plasma etching are fluorine-containing compounds, primarily fluorocarbons including octafluorocyclobutane, hexafluorobutadiene, and difluoromethane, nitrogen trifluoride for chamber cleaning, hydrogen bromide for silicon etch selectivity, and the chlorine-containing gases used in metal etch applications. These are not commodity industrial gases: they are specialty electronic grade chemicals whose purity specifications, measured in parts per billion of specific metallic and molecular impurities, are among the most stringent in any industrial application, and whose synthesis, purification, analysis, and delivery require the technical capability and quality systems that the handful of specialty gas companies serving the semiconductor industry have developed over decades.
The commercial sensitivity of plasma etching gases reflects several overlapping factors that make this market strategically significant well beyond its volume, which is modest compared with commodity industrial gases. The quality of etch process gases directly affects the yield of semiconductor manufacturing, whose value per wafer at advanced nodes can exceed tens of thousands of dollars, creating the commercial consequence of gas quality failure that makes semiconductor manufacturers extremely conservative about gas supplier qualification and extremely reluctant to change qualified suppliers or supply sources. The geographic concentration of plasma etching gas production in a small number of facilities, several of which are located in East Asia, creates the supply chain vulnerability that the semiconductor industry's experience with supply disruptions during COVID-19 and from geopolitical developments has elevated to a strategic risk management priority. And the high global warming potential of fluorinated etch gases, whose GWP values range from hundreds to thousands of times CO2, creates the regulatory pressure for replacement with lower-GWP alternatives that the semiconductor industry's sustainability commitments and emerging F-gas regulations are creating commercial demand for.
NF3 and Chamber Cleaning Chemistry
Nitrogen trifluoride is the fluorine source gas used for remote plasma cleaning of chemical vapour deposition reactor chambers, generating fluorine radicals in a remote plasma that is introduced into the reactor chamber to etch away the deposited film residues from chamber walls and hardware. NF3 replaced perfluorocarbon gases including tetrafluoromethane and perfluorocyclobutane for chamber cleaning in the early 2000s because its decomposition in the remote plasma is more complete, reducing the perfluorocarbon emissions from chamber cleaning operations whose atmospheric lifetime and global warming potential create the greenhouse gas regulatory exposure that semiconductor manufacturers are seeking to reduce. The NF3 market's geographic concentration in South Korea, where SK Materials is the dominant supplier, and in China, where several producers supply the Chinese domestic semiconductor market, creates the supply chain geographic concentration whose resilience the semiconductor industry has been seeking to improve by qualifying additional suppliers in geographically diverse locations. Air Products, Linde, and Mitsui Chemicals are the global industrial gas companies whose NF3 production capabilities outside South Korea create the geographic supply diversity that semiconductor manufacturers have been seeking as part of their critical materials supply chain resilience strategies.
The transition to advanced node manufacturing at three nanometre and below creates new etch chemistry requirements whose process gas compositions differ from those used at older nodes, because the etch process challenges of extreme ultraviolet lithography patterning, whose multiple patterning and self-aligned patterning schemes create more complex etch sequences than earlier single-exposure lithography nodes, require new etch gas chemistries whose performance in these new process contexts has not been fully validated at production scale. The development of new etch process gases, validated through the extensive process qualification that semiconductor manufacturers require before introducing new materials into production fabs, is the technical and commercial activity that specialty gas companies and academic research groups are conducting in collaboration with the semiconductor equipment companies whose etch reactors run the processes that consume the gases.
Geopolitical Risk and the Supply Chain Response
Japan's 2023 export restrictions on twenty-three categories of semiconductor manufacturing equipment and the subsequent tightening of export controls on semiconductor chemicals and materials by Japan, the Netherlands, and the United States have elevated the supply chain security of plasma etching gases to a strategic policy issue whose commercial consequences for both semiconductor manufacturers and specialty gas suppliers are substantial. The fluorine-containing etching gases whose production capabilities in Japan include those of Resonac, Showa Denko, and other Japanese specialty chemical companies create the supply dependency that export control restrictions directly threaten for semiconductor fabs outside Japan that have relied on Japanese sources for qualified etch gas supply.
Top 10 Companies in Semiconductor Plasma Etching Gases Globally
- Air Products: US industrial gas company with electronic specialty gas production for NF3, fluorocarbon etch gases, and semiconductor process gases; its global production network and its semiconductor fab gas supply infrastructure create the most geographically diversified semiconductor specialty gas business whose supply chain resilience differentiates it from more geographically concentrated specialty gas producers.
- Linde: German-US industrial gas company with semiconductor specialty gas production and on-site gas supply systems for semiconductor fabs; its ALOHA on-site generation and its global gas supply network create the semiconductor process gas infrastructure whose scale and geographic reach serve the global semiconductor manufacturing footprint across Taiwan, South Korea, the United States, and Europe.
- SK Materials: South Korean NF3 manufacturer whose dominant position in NF3 production reflects South Korea's Samsung and SK Hynix semiconductor manufacturing concentration; its NF3 production scale and its proximity to the world's largest DRAM and NAND manufacturing operations create the commercial semiconductor gas position whose geographic concentration creates the supply chain risk that global semiconductor manufacturers are seeking to supplement with qualified alternative sources.
- Resonac (Showa Denko): Japanese specialty chemical company with octafluorocyclobutane, hexafluorobutadiene, and other fluorocarbon etch gases for advanced semiconductor manufacturing; its Japanese chemical synthesis capability and its long-term supply relationships with Japanese and international semiconductor manufacturers create the specialty etch gas commercial position whose export control regulatory exposure is the commercial risk whose management is a strategic priority.
- Kanto Denka Kogyo: Japanese specialty gas manufacturer with fluorine gas, nitrogen trifluoride, and specialty fluorocarbon gases for semiconductor applications; its fluorine chemistry expertise and its precision analysis capability for parts-per-billion purity verification create the Japanese specialty gas supplier position in the highest-purity etch gas applications.
- Matheson Gas (Nippon Sanso): US subsidiary of Japanese industrial gas company with semiconductor specialty gas supply and gas handling systems; its integration within Nippon Sanso's global industrial gas business and its US semiconductor fab supply relationships create the specialty gas company whose combination of Japanese production heritage and US market presence serves the geographic supply diversification objective.
- Mitsui Chemicals: Japanese chemical company with NF3 and specialty fluorine chemical production for semiconductor applications; its fluorine chemistry heritage and its semiconductor material supply relationships create the chemical company's semiconductor process gas commercial position in the Japanese and Asian semiconductor manufacturing markets.
- Merck KGaA: German chemical company with semiconductor process materials including specialty gases and precursors; its Electronic specialty gas portfolio and its semiconductor material product breadth spanning etch gases, deposition precursors, and photoresists create the chemical company that positions itself as a comprehensive semiconductor materials supplier beyond any single material category.
- Entegris (Versum Materials): US specialty materials company with gas purification, delivery systems, and specialty chemicals for semiconductor manufacturing following its Versum Materials acquisition; its gas handling and purification systems that maintain the parts-per-billion purity specifications that etch process gases require from cylinder to chamber create the gas delivery infrastructure whose quality is as commercially important as the gas production chemistry itself.
- Central Glass: Japanese chemical company with difluoromethane, hexafluoroethane, and other fluorocarbon gases for semiconductor etch and CVD cleaning; its fluorocarbon chemistry capability and its Japanese semiconductor market relationships create the specialty fluorocarbon gas supplier whose product range complements the NF3 and octafluorocyclobutane that larger gas companies produce.