How to Buy a Used Nitrogen Generator for Your Semiconductor Fab
Navigating the used market for nitrogen generators and fab utility gas systems? Here’s a no-fluff guide to help you make smart, cost-effective decisions.
This guide is for: Semiconductor fabs looking to cut costs on N2 supply without compromising uptime or purity.
Got a fab running and need nitrogen? Buying the wrong system can set you back $50K in downtime and scrap. Don’t get caught shortchanging your gas setup.
Why Fabs Run Their Own N2 Generation
I once saw a small R&D line lose two full weeks when their bulk liquid supplier couldn't meet demand. You don’t want to be hostage to third-party delivery schedules. Running your own nitrogen generator means you control costs at scale, uptime, and purity.
Scale Costs
Bulk nitrogen can cost $1–$2 per liter delivered, while on-site generation starts around 50 cents per liter once amortized over the system’s life. For a medium-sized fab using 1,000 liters per hour, that’s a savings of $4,380 per month.
Uptime Dependency
Bulk delivery means relying on trucks and suppliers to keep you stocked. On-site generators run continuously, so no more shutdowns from missed deliveries or bad weather.
Purity Control
You need high-purity nitrogen for process tools but can get away with lower purity for purging chambers. Customizing purity levels per application saves money and meets your fab’s needs precisely.
Two Main Technologies: PSA vs Cryogenic
Choosing the right technology depends on your fab’s specific needs.
PSA Pressure Swing Adsorption
Best for general fab nitrogen generation. It uses a sieve bed to filter out impurities as air passes through under pressure, then releases it by reducing pressure. Prices range from $15K-$120K based on flow rate and purity specs.
Example: A Parker Balston PSA74-8 producing 100 SCFH at 99.5% purity costs around $30K.
Cryogenic Air Separation
Ideal for high-volume, high-purity applications like process tool inerting. Liquid nitrogen is produced by cooling air to extremely low temperatures and then separating it through distillation. Prices start at $250K and go up from there based on volume and purity needs.
Example: An Atlas Copco 450-130B cryogenic generator producing 500 SCFH at 99.999% purity costs around $600K.
Membrane Generators
These are cheaper than PSA but produce nitrogen with lower purity (usually around 95%). Good for applications where high purity isn’t critical, like purging or cooling.
Example: An Air Products PR-234 membrane generator producing 15 SCFH at 95% purity costs about $8K.
OEM Choices: Parker Balston vs Atlas Copco vs Air Products
Each major player has strengths and weaknesses.
Parker Balston
Known for reliability and durability. Their PSA generators are popular in fabs due to their consistent performance and ease of maintenance.
Example: The PSA74-8, mentioned earlier, is a workhorse in many fabs.
Atlas Copco
Offer strong cryogenic solutions that can handle very high purity requirements. They also provide robust customer support and service networks.
Example: Their 450-130B cryogenic generator is top-tier for process tool inerting needs.
Air Products
Excellent choice if you need membrane generators or integrated utility gas systems. Their systems are well-engineered, but can be more expensive than competitors'.
Example: The PR-234 membrane generator is a good entry-level option for purging applications.
Purity Specs: What Matters and Why
Choosing the right purity level is crucial to avoid contamination and failures.
99.5% Purity
Suitable for chamber purging, cooling, or any non-process tool application where trace impurities won’t affect outcomes. This saves money without compromising on performance.
Example: Parker Balston PSA74-8 offers this purity level at a reasonable cost.
99.999% Purity
Mandatory for high-end process tools where even minute impurities can ruin wafers or contaminate critical layers. Cryogenic systems are typically the only way to achieve such high purities economically.
Example: Atlas Copco’s 450-130B cryogenic generator meets this requirement.
Inspection Criteria for Used Systems
Buying used? Here’s what to check to ensure you’re getting a system that will last.
Sieve Bed Condition
For PSA generators, the sieve beds are the heart. They should be clean and free of contamination. A well-maintained sieve bed can last over 10 years.
Tip: Look for systems with documented maintenance records showing regular cleaning and replacement cycles.
Compressor Hours
Compressors wear out over time. Check the compressor hours to gauge remaining lifespan. Systems with low compressor hours are more reliable but also cost more.
Example: A Parker Balston PSA74-8 with 10,000 compressor hours is likely still good for several years of use.
Valve Cycling Count
Valves in PSA systems cycle frequently and can wear over time. High valve cycling counts indicate the system has been used extensively.
Tip: Aim for systems with low valve cycling counts to ensure long-term reliability.
H2 and CDA Equivalents
Building out a complete utility gas system? Don’t forget hydrogen (H2) and clean dry air (CDA).
Hydrogen Generators
Used hydrogen generators from companies like On Site Gas Systems range from $10K-$80K depending on flow rate. They produce H2 through electrolysis, steam methane reforming, or partial oxidation.
Example: An OSG ES-350 electrolyzer producing 6 SCFH of 99.99% purity hydrogen costs around $40K.
Clean Dry Air (CDA) Systems
Used CDA systems from Parker and Atlas Copco typically range from $10K-$200K based on airflow capacity and filtration stages. They remove moisture, oil, and particulates from compressed air to provide clean, dry air for various fab applications.
Example: A Parker AP-65 air dryer producing 8 SCFM of CDA at -40°F dew point costs around $12K.
What to Do Next
Armed with this knowledge, you’re ready to make a smart purchase. Start by defining your exact needs in terms of flow rate, purity, and application. Then compare prices across different models and OEMs to find the best fit within your budget. Finally, inspect used systems thoroughly or buy new if reliability is paramount.
Related reading: Semiconductor Fab Gas Supply: What You Need to Know
Used Semiconductor Equipment Buying Guide 101
FAQs
Q: How much does a used PSA nitrogen generator cost?
A: Prices range from $15K-$120K depending on flow rate and purity specification.
Q: Can membrane generators be used in fabs?
A: Yes, but they are best suited for applications where high purity is not critical, such as purging or cooling.
Q: What’s the difference between PSA and cryogenic nitrogen generation?
A: PSA uses pressure swing adsorption to filter impurities from air, while cryogenic systems cool air to extremely low temperatures and separate nitrogen through distillation. Cryogenic systems provide higher purity at a higher cost.
Q: How long do sieve beds in PSA generators last?
A: Well-maintained sieve beds can last over 10 years.
Q: What purity level is needed for process tool inerting?
A: For high-end process tools, you need nitrogen with 99.999% purity to avoid contamination and failures.