Helium is one of the most critical specialty gases in semiconductor manufacturing. Due to its excellent thermal conductivity, chemical inertness and low molecular weight, high-purity helium is widely used in wafer cooling, EUV lithography, vacuum leak detection and advanced chip fabrication processes. As semiconductor nodes move toward 3nm and beyond, semiconductor fabs require stable 5N-6N helium supply to maintain process accuracy and improve production yield.
High-purity helium is an inert rare gas that has undergone multi-stage precision purification. Helium with purity ≥99.995% is generally defined as high-purity helium in the industry, which is often referred to as 5N grade. The ultra-high purity helium dedicated to advanced semiconductor processes needs to reach 99.999% and above, up to 99.9999%, fully meeting the needs of nano-precision production.
Helium has unique properties unmatched by all other gases, which is also the core reason why it is irreplaceable in the semiconductor field. It is colorless, odorless, chemically stable inert gas, non-flammable, non-explosive, non-chemical reaction with silicon, metal, coating materials.
At the same time, helium has the lowest boiling point in nature (-268.9℃), it will not solidify in absolute zero environment under normal pressure, and the thermal conductivity of gas far exceeds that of conventional process gases such as nitrogen and argon, and the atomic particle size is very small, which is suitable for semiconductor ultra-precision, ultra-low temperature and high vacuum production environment.
Many wafer foundries hold a misconception: that helium is merely an auxiliary consumable, and the impact of purity differences is negligible. However, in actual production, helium purity is a core variable determining the yield of nanometer-scale processes, and the production gap caused by grade differences is extremely significant.
5.0N/5.5N semiconductor-grade helium can meet the needs of mature processes and mid-range chip production, with controllable defect rates and stable yields, but it is not suitable for EUV lithography and advanced 3nm/5nm nodes.
6.0N ultra-high purity helium can achieve ppb-level impurity control, completely avoiding process defects caused by trace contamination, keeping the yield of advanced processes stable at a high level, and significantly reducing batch process fluctuations.
From a cost perspective, helium consumables only account for 0.5%–1% of the total production cost of a wafer foundry, a very small percentage. However, the cascading losses caused by substandard purity can multiply production costs.
First, there is the cost of wafer scrapping, with losses per batch reaching tens to hundreds of thousands of yuan. Secondly, there are equipment maintenance costs. Impurities and contamination can lead to cavity buildup, increasing the frequency of downtime for cleaning and reducing equipment uptime.
Furthermore, unstable processes can result in poor batch consistency, increasing the defect rate and directly raising the production cost per qualified chip.
Helium is divided into multiple grades according to different purity levels.
Balloon grade helium (97.5%-99%): The lowest purity, extremely high impurity content, only used for balloon inflation, celebration floating and other civilian scenes, no industrial precision application value, strictly prohibited for semiconductor production.
Industrial high purity helium 4.5 – 4.8N (99.995%-99.998%): conventional industrial grade gas source, suitable for welding protection, common equipment leak detection, industrial pressurization and other general scenarios. Due to excessive oxygen, water vapor and hydrocarbon impurities, it cannot be used for chip precision manufacturing.
Semiconductor general grade 5.0N (99.999%): special gas source for basic chip process, strictly control oxygen, water vapor impurities ≤1ppm. It is mainly used for ion implantation, conventional chamber purging, and basic protection scenarios for general wafer processing.
Advanced process 5.5N (99.9995%): medium and advanced semiconductor process adaptation level, core impurity content ≤0.5ppm. Widely used in DUV deep ultraviolet lithography, CVD/ALD film deposition, mid-end wafer cooling and other precision processes.
Ultra-high purity 6.0N (99.9999%): advanced process core gas source, oxygen, water vapor, hydrocarbon impurities ≤0.1ppm. It is an essential level for advanced nodes of 5nm, 3nm and below, EUV lithography, plasma etching and precision temperature control.
Scientific research grade 7.0N+(99.9999%+): top-level ultra-high purity gas source, impurity control accuracy of less than 0.05ppm, currently mainly used in quantum chip research and development, next generation advanced process exploration and other scientific research scenarios, has not been large-scale mass production application. Higher helium purity helps semiconductor manufacturers reduce contamination risks and improve process stability, especially in advanced nodes where even trace impurities may affect wafer yield.
Helium has become an irreplaceable core process gas in semiconductor manufacturing due to its four unique advantages: chemical inertness, extreme thermal conductivity, extremely small atomic particle size and low viscosity. From wafer pretreatment to chip formation, the six key processes are highly dependent on the stability of high-purity helium.
Core semiconductor processes such as plasma etching, thin film deposition, and ion implantation are all high-temperature and high-energy processes, and the wafer surface will instantly generate a large amount of heat. If the temperature can not be quickly and evenly dispersed, it will directly cause wafer deformation and process deviation. During production, ultra-high purity helium is continuously introduced between the wafer and the electrostatic chuck, acting as an efficient heat transfer medium. It can quickly remove heat from the wafer surface and control the process temperature fluctuation within ±0.01 ° C to meet the extreme temperature control requirements of advanced nano-nodes.
Lithography is the core process of chip pattern formation, especially EUV lithography equipment, which is the core equipment of 3nm and 5nm advanced process. The annual helium consumption of a single equipment can reach tens of thousands of cubic meters, and the purity of helium is required to reach the extreme. High purity helium plays two key roles in lithography system. First, the equipment is cooled, continuously taking away the high temperature generated by the work of high-power laser and optical mirror, avoiding the thermal deformation of optical devices and ensuring the stability of lithography accuracy. Second, the light path is purged and protected. EUV light is easily absorbed by air, water vapor and impurity gases. Ultra-high purity helium can evacuate impurities in the optical path cavity, create a pure transparent environment, ensure stable transmission of 13.5nm extreme ultraviolet light, and achieve nano-level accurate pattern reproduction.
Chemical vapor deposition (CVD) and atomic layer deposition (ALD) are the key processes in chip film preparation, which directly determine the molding quality of chip insulating layer and conductive layer, and have high requirements for cavity cleanliness. Before and after production, high-purity helium continuously purges the process chamber to completely replace residual oxygen, water vapor, waste precursors and trace impurities. Maintain oxygen-free, water-free and impurity-free inert vacuum environment throughout the process to eliminate problems such as film oxidation, doping abnormalities, surface defects, etc. At the same time, helium can be used as an auxiliary carrier gas to accurately transport coating precursor raw materials, stabilize plasma density, ensure uniform and dense film growth, and improve the stability and reliability of chip circuit layers. Ion implantation and plasma process stability control Ion implantation process is used to dope and modify the silicon substrate of the chip and accurately control the conductivity of the semiconductor. It is the core process of chip electrical performance molding. This process has zero tolerance for environmental stability and impurity control. High-purity helium is used as diluent gas and carrier gas, which can accurately control the transport rate and concentration of dopant ions and ensure doping uniformity. At the same time, the plasma working state is stabilized, and the cavity oxidation and impurity doping abnormalities are avoided in the high-energy reaction process. Stable ultra-high purity helium supply can effectively reduce ion implantation deviation, avoid quality problems such as chip electrical performance failure and poor batch consistency, and ensure stable chip performance.
All precision semiconductor processes are completed in high vacuum chambers, and small leaks in the chamber will introduce external impurities, destroy the process environment, and lead to batch wafer scrap. Helium leak detection is currently the only accurate microleak detection solution in the semiconductor industry. Helium atom particle size is very small, permeability is very strong, can penetrate the equipment micron, nanometer small leakage point. With helium mass spectrometer, it can accurately detect micro leakage hazards as low as 10 atm-cc/sec. Through regular helium leak detection, the wafer fab can check the leakage problems of cavities, pipelines and valves in advance, maintain the stability of vacuum system, eliminate the risk of batch pollution, and ensure the continuous and stable operation of production lines.
Helium is a scarce strategic resource, naturally existing in natural gas deposits, conventional natural gas helium content is only 0.1%-7%. Ultra-high purity helium for semiconductors requires multiple precision purification processes to extract and refine from natural gas in order to achieve mass production standards.
Step 1: raw gas pretreatment.
The natural gas raw material after exploitation contains impurities such as moisture, carbon dioxide, hydrogen sulfide, heavy hydrocarbon and mercury. Through amine absorption, molecular sieve adsorption, ethylene glycol dehydration and other processes, harmful impurities are completely removed to avoid subsequent low-temperature equipment clogging and corrosion.
Step 2: natural gas liquefaction enrichment.
After pretreatment, the clean natural gas enters the cryogenic liquefaction equipment and is liquefied in the ultra-low temperature environment. Methane, heavy hydrocarbon and other components are liquefied and separated, helium boiling point is extremely low, gas is always maintained, preliminary enrichment is realized, and crude helium raw materials are obtained.
Step 3: Crude extraction by low-temperature distillation.
Crude helium is further separated by multistage cryogenic rectification tower and expansion refrigeration equipment. Remove impurities such as nitrogen and residual methane, increase the purity of helium to 50%-90%, and complete the purification of crude helium.
Step 4: High Purity Upgrade.
A combined process of pressure swing adsorption (PSA), catalytic deoxidation, deep dehydration and secondary rectification was used to strip trace impurities layer by layer. Finally, the purity of helium is purified to 5N-6N, meeting semiconductor mass production standards.
Step 5: Liquefied storage and packaging.
The purified high-purity helium can be cooled into liquid helium by cryogenic liquefaction equipment and stored in vacuum insulated Dewar tanks and cryogenic storage tanks to meet the continuous gas supply requirements of large-scale wafer plants.
First of all, the raw material endowment is limited, the helium content in natural gas is extremely low, the utilization rate of purified raw materials is limited, and large-scale production is difficult. Secondly, the energy consumption is extremely high, ultra-low temperature refrigeration and multi-stage distillation need huge energy consumption support, and the production cost remains high.
At the same time, ultra-low temperature conditions have extremely high requirements on equipment materials, insulation technology and sealing performance, and equipment investment costs are expensive. Real-time purity monitoring is required throughout the process to ensure that each batch of gas source is stable and up to standard, and the production control threshold is extremely high.
Different sizes of wafer fab, different process capacity, suitable helium gas supply mode is very different. Reasonable selection of gas supply scheme can effectively control cost, ensure stable supply and avoid quality risk. with 10-year manufacturer and solution provider of cryogenic and industrial gases, we offers four types of high purity helium solutions: cylinder gas supply, tube bundle trailer, liquid bulk gas supply, and on-site recovery systems.
High purity helium is compressed to 200 – 300bar and supplied in special cylinders for transport. Adapt to small-volume gas consumption scenarios, such as laboratory R & D, medium-sized trial production line, small semiconductor scientific research institutions.
The advantages are convenient transportation, flexible scheduling, wide range of purity options, and no need to build large-scale storage facilities. The disadvantage is that the gas volume of a single bottle is limited, the bottle needs to be changed frequently, and the cost of mass production is extremely high, which cannot meet the continuous production needs of the wafer factory.
Through multi-bottle group integrated tube bundle trailer gas supply, single batch gas supply is much higher than single cylinder, suitable for small and medium-sized production wafer factory, stable medium gas demand.
The unit gas cost of this mode is better than that of steel cylinder, and the field bus system can be built to realize uninterrupted gas supply. However, it still belongs to gaseous gas supply and has limited gas storage capacity, which cannot adapt to advanced production lines such as EUV process and high gas consumption.
It is the mainstream gas supply scheme of large advanced wafer factory to liquefy purified high purity helium at low temperature and transport it by vacuum insulated tanker. 1L of liquid helium can be vaporized into 700 – 750L of gaseous helium, which has a large gas storage capacity.
The advantages are the lowest unit gas cost, stable gas supply, strong endurance, and sustainable support for EUV lithography, large-scale wafer mass production and other high-consumption scenarios. We provide matching field cryogenic ISO liquid helium storage tank, vaporization system, to achieve 24 hours of uninterrupted and stable gas supply.
Accurate selection can be made according to the scale of gas consumption: cylinder gas supply is preferred for small volume R & D and trial production lines; tube bundle trailer gas supply is suitable for small and medium-sized production lines; liquid helium bulk gas supply is preferred for advanced large-scale wafer factories equipped with EUV equipment; large-scale industrial parks can be equipped with on-site recycling systems to reduce costs and avoid risks.
At the same time, it is necessary to comprehensively consider purity requirements, on-site infrastructure, supply chain risks and full life cycle costs, and give priority to suppliers that can provide stable 6N ultra-high purity gas source and one-stop operation and maintenance services.
Q: What purity helium is required for semiconductor manufacturing?
A: Advanced semiconductor processes typically require 5N–6N helium purity to minimize contamination risks and maintain process stability.
Q: What grade of helium must an EUV lithography machine use?
A: EUV lithography belongs to the top precision process of semiconductor, which must use ultra-high purity helium of 6.0N (99.9999%) and above, and strictly control oxygen, water vapor and hydrocarbon impurities ≤0.1ppm. Low-grade helium will cause optical path interference, thermal deformation of equipment, and a sharp drop in photolithography yield, which cannot be used for mass production.
Q: Why is helium used instead of nitrogen in semiconductor processes?
A: Helium offers superior thermal conductivity, chemical inertness, and low molecular weight, making it ideal for precision semiconductor applications.
Q: Can helium be recycled in semiconductor fabs?
A: Yes, helium recovery and purification systems can recycle process helium, reduce consumption costs, and improve supply reliability.
With increasing semiconductor production worldwide, helium supply security has become a major concern for wafer fabs. Helium recovery and purification systems allow manufacturers to recycle helium from processes such as leak detection and cooling applications, reducing operating costs and improving supply reliability. For large semiconductor facilities, combining high-purity helium supply with recovery technology is becoming an important strategy for long-term gas management.
At the moment when the advanced semiconductor process continues to iterate, the stable supply of 5N and 6N ultra-high purity helium is an important cornerstone for the mass production of 3nm, 5nm and 7nm high-end chips.
Contact us, Fullcryo can provide semiconductor dedicated 5.0N-6.0N ultra-high purity helium one-stop gas supply solution, customized storage and maintenance services, helium recovery optimization consulting, to help each major fab stabilize advanced process, improve product yield, avoid supply chain risks.
