On-site Generation of Ultra High Pure Ammonium Hydroxide With Reduced Environmental Impact
Karl Urquhart recently presented at the 2022 Semicon Europa, Smart and Green Manufacturing Summit in Munich, Germany. At a time when supply chain issues continue to dominate the narrative within the industry, Karl's presentation about on-site generation of semiconductor wet chemical supply directly addressed some of the foremost topics including resiliency, cost and sustainability.
Traditionally, semiconductor Ammonium Hydroxide (NH4OH) is produced off-site and delivered to chip makers in intermediary vessels and containers (isotainers, totes, drums and bottles). These ultimately are connected to the Fab’s chemical distribution networks which then pipe the chemical supply to the individual tools manufacturing the devices. Each part of the process from its origin to the final connection carries a potential risk of contamination or supply disruption.
- Intermediary vessels have to be ordered and stored to keep up with usage.
- Ever-increasing volume increases transportation, warehousing or staging areas.
- Many sites having on-site quantity limitations.
- This leads to increased chances of developing quality issues in assay and purity of the supply sources.
- Long lead time to order – approx. a year to add 1 new ISO
- Urgent supply can increase cost 2x to 4x depending on distance between supplier and customer.
- High cost tied directly to the unit price of purchased NH4OH.
These are just some of the challenges and risks associated with off-site supply of raw material.
With DIversified Fluid Solutions' integrated NH4OH on-site chemical generation technology, semiconductor fabs can significantly improve their overall chemical supply costs, resiliency and sustainability.
- Logistical issues are reduced by using the factory’s own UHP H2O supply.
- A system on-site purifier allows the use of low grade NH3 gas source while still producing NH4OH of the highest tier quality in assay stability and purity.
- Closed-loop process integrated with existing chemical distribution network or as stand-alone unit provides the least amount of risk in assay stability, loss, purity or contamination.
- Shipping and material handling costs are vastly reduced.
And it is through the dramatic reduction in shipping and material handling that the environmental benefits begin to emerge.
- Reduce shipment by 71% - No transport of UHP H2O component in NH4OH (only liquified NH3 needs to be transported)
- Assuming 14K L/ day usage → eliminate ~500 iso container trips between the fab and the chemical supplier location per year.
- Reduce the fleet of stainless steel iso tankers.
- Reduce plastic containers needed in the case of non-isotainer supply lines.
- Assuming 14K L/ day usage → eliminate 6,400 (200L) drums or 1,300 (1000L) totes every 3 years.
EMISSIONS AND WASTE REDUCTION
- No NH3 is lost to head space of shipping containers or environment.
- The closed-loop structure of the tank vent design reduces scrubbed exhaust flow associated to NH3
H2O isolation boxes installed between the tank and the exhaust flow path to scrub and remove any NH3 for the exhaust flow stream. Thereby, keeping the NH3 in the products being supplied to the fab tools.
- The system is configurable to allow < 20L of NH4OH waste per year in scrubber column volume. Allowing captured scrub impurities to be sent to a fab industrial waste flow.
Normal supply chain generates more waste at the chemical factory when empty vessels are received and refilled.
By concentrating as much of the incoming chemicals and gases as possible, then purifying, diluting or mixing as required on-site, semi fabs can reduce, remove or offset the otherwise related transportation, logistics, intermediate vessels and storage requirements in the operations. This directly reduces or removes the carbon footprint by the dilution factors of these incoming supplies, while improving the product quality to the factories.
Example: 29% w/w NH4OH = requirement of 20,000 liters a day would result in the below number vessels moving daily at a site:
- 100 individual drums (200 liter each = 25 pallets of four drums)
- 18 individual totes (1,136 liters each)
- 1 liquid tanker truck (20,000 liters each)
This translates to 700 drums or 126 totes a week, 3,000 drums or 540 totes a month, or 30 liquid tanker trucks per month.
On site generation removes all of the incoming vessels of traditional semiconductor chemical supply.