Based in Oxford, UK
Water for semiconductors is no micro-issue
Samsung Austin Semiconductor has expanded its manufacturing capacity significantly over the last decade as its Korean parent pumps money into the fab in Texas. Reducing water consumption is one of the key targets for the company to help sustain operations.
Original article published as an End-User Perspective article within the Chief Technology Officer section of GWI Magazine (January, 2020)
Samsung Austin Semiconductor, a US-based subsidiary of Samsung Electronics Co. Ltd, has one of the most advanced semiconductor manufacturing facilities in the world with more than 3,000 employees and 2.45 million square feet of floor space. Samsung Austin Semiconductor has broad semiconductor process technology offerings serving customers in various application areas including mobile, consumer, networking/high performance computing, Internet of Things, RF and automotive. Since 1996, the company has invested approximately $17 billion in its Austin, TX campus, making it one of the largest direct foreign investments in United States history. Its first fabrication plant opened in 1997 with a second unit opening in June 2007 to manage increased production demand.
Samsung Austin Semiconductor is constantly looking at ways to reuse the water it purchases from the city supply system and has been recognised for its efforts in treating its wastewater to meet defined discharge limits; it has received wastewater pretreatment compliance awards from the City of Austin every year since 2012. GWI talked to key facilities, engineering and environmental personnel to understand how they continue to meet the challenges of water management for semiconductor manufacturing.
What are your main sources for process water?
The primary source for process water is treated surface water from the Lower Colorado River that is supplied to Samsung Austin Semiconductor through two main water treatment plants located in the Austin area.
What is water used for in your production process?
Primarily, the city water is purified to produce Ultrapure water that is then used to rinse silicon wafers as they are manufactured. The Ultrapure water functions as a solvent to remove particles and residual chemicals from the wafer surface after production steps are performed, and it is also used to dilute high-purity chemical mixtures for use in wafer processing steps. The city water is also used for utility systems, such as cooling tower and exhaust scrubber make-up water.
How do you treat your process water?
Water treatment for Ultrapure water service consists of a primary treatment step that includes multimedia cartridge filtration to remove particles and suspended solids, reverse osmosis to remove dissolved solids, ion exchange to remove ionic contamination, ultraviolet light to control organics, degasification for dissolved oxygen control and ultrafiltration to control sub-micron particles. City water and Ultrapure water also provide a makeup source for cooling and heating water systems that control process temperature loops as well as providing temperature and humidity control in manufacturing spaces.
How do you treat your wastewater? Can you walk us through the wastewater treatment process at your plant?
Samsung Austin Semiconductor’s primary wastewater treatment is segregated into three systems: pH neutralisation, fluoride treatment, and copper treatment. The three wastewater streams are first collected in and distributed to the appropriate waste treatment systems. The pH neutralisation waste stream adjusts pH to meet internal quality requirements prior to discharge. The fluoride waste system uses chemical precipitation and a dewatering process that produces calcium fluoride (CaF2) filter cake, which is sent to a local end-user to be used in their wastewater treatment process. The copper system is in the final stages of being converted to an ion exchange system from a chemical co-precipitation system, improving safety and environmental quality of treatment. Using ion exchange will reduce the chemical treatment by 2 million pounds, eliminate 1.5 million pounds of solids generated by the current system, and reduce the overall system footprint by 65%. Prior to final discharge to the local municipal wastewater treatment plant, the three Samsung Austin Semiconductor waste streams are monitored for quality parameters at several points, which can divert waste and recycle for additional treatment, if necessary.
What are your main challenges when treating the wastewater?
Samsung Austin Semiconductor is balancing the needs of multiple constituents when treating wastewater. Changes in process chemistry come with developing safe and quality methods to pre-treat or treat in parallel to existing systems. The chemistries also present challenges when piloting new treatment technologies such as in the case of the transition from co-precipitation to ion exchange for copper wastewater.
Lastly, meeting Samsung Austin Semiconductor team’s vision and mission requires balancing competing priorities to not impact the production process while continually improving the wastewater treatment technologies to benefit downstream municipal wastewater treatment and other water users of the Lower Colorado River.
In your experience, which treatment technology (or combination of technologies) have suited your operations best?
The preferred approach is collaboration with production teams for source reduction. The impact there is reduced chemical use, lower water consumption, and simplified treatment requirements. Once we have exhausted all means of chemical elimination or reduction, practical treatment options are bench tested and piloted to determine the most effective method to safely treat the waste stream. Criteria that determine the successful treatment methods are those that are robust and combine automation with operator and process engineer monitoring, rather than specialized systems. Robust systems tend to offer more operational flexibility with a focus on lowering chemical use, eliminating solids waste, and improving overall operator safety.
What technologies do you deploy to recycle water?
Samsung Austin Semiconductor’s primary water recycle success is the recovery of Ultrapure water rinse streams from the manufacturing process which are collected and monitored for quality, then treated with activated carbon and ion exchange to remove organic and ionic contamination. The stream is used as a makeup source for Ultrapure water treatment, rather than city water. The reclaimed water is closely monitored and diverted to waste treatment if any quality control parameters are exceeded that may jeopardise production quality. The reclaim source is about 60% of Samsung Austin Semiconductor’s Ultrapure water makeup volume.
We also capture the second pass reverse osmosis reject and final ultrafilter reject to reuse them for scrubbed exhaust systems, while recapturing treated process water to backwash waste system carbon beds. In late 2019, we commissioned a Brine Recovery reverse osmosis (RO) system that treats first pass reject. This system recovers 75% of the 1st pass RO reject to reduce city water makeup use to the UPW system by 90 million gallons per year.
What new technologies have you piloted and what did you find in the process?
We are continuously piloting different treatment technologies and equipment types. Samsung Austin Semiconductor piloting also extends to new instruments and chemical products. The goal is to make better use of resources that improve personnel safety, exceed environmental regulations or standards, and protect production quality. Primary technologies that we have piloted include new membranes and ion exchange resins for UPW systems, different blowdown programming/techniques for exhaust scrubbers, and implementing new ion exchange and innovative precipitation systems for wastewater treatment. When working with proven technologies we always look for a pilot test to ensure that what works elsewhere will also work with our process requirements and waste composition. In doing so, we learn about ancillary equipment requirements or eliminate unnecessary components while providing personnel the opportunity to have hands-on training.
What is your current strategy for procuring new technologies? Are there any factors unique to your industry when considering investments in new technology for water management?
Our strategy typically falls into a multi-phase approach. For technologies that fit wastewater treatment, we first compile multiple water quality samples and discuss with technology vendors. The key is to understand if there are gating constituents in the waste streams and the requirements necessary to properly develop a bench scale test. From there, bench and pilot tests are required to ensure technology efficacy while allowing site personnel to get hands-on training and communicate concepts with all of the stakeholders. Finally, new systems are designed and built to exceed existing operational standards with a focus on safety, quality, and reliability. Throughout the technology development phase, communication among team members and stakeholders of all types is critical. A consistent and uniform communication channel allows stakeholders and decision makers to be involved throughout the process instead of when investment or funding is needed.
Do you think there is a technology gap – do you have specific water challenges that currently can’t be solved by existing technology?
Pathfinding or technology development is a critical part to ensure antiquated or ageing systems are updated to industry best – not simply replaced with “like-for-like” systems. Hydrogen peroxide presents an industry challenge from a cost-effectiveness standpoint as chemical consumption and carbon bed requirements must be addressed to effectively treat waste streams. Another gap is instrumentation that is available to use in a waste system typically requires significant sample pretreatment or use of costly reagents.
There has been a lot of discussion about Industrial Internet of Things. Have you looked into solutions that could help you with your water resources and wastewater management? What issues or challenges have you come up against when implementing them?
Within microelectronics, the focus on security requires extra scrutiny of new technologies that fit within IIoT. We look for applications that meet our security policies to ensure we are protecting the intellectual property. There are emerging technologies under the 4G LTE and 5G, and we are working on a pilot program that will focus on non-critical monitoring points that are low-risk.