Drip by Drip: Semiconductor Water Management Innovations

Estimated reading time: 3 minutes

Not only does semiconductor manufacturing require large volumes of energy, chemicals, and silicon wafers, it also requires vast volumes of water. IDTechEx’s latest report, “Sustainable Electronics and Semiconductor Manufacturing 2025-2035: Players, Markets, Forecasts”, forecasts water usage across semiconductor manufacturing to double by 2035, as demand for integrated circuits continues to rise.  In 2023 alone, semiconductor giant TSMC reported consumption of a staggering 101 million m3 of water, highlighting the scale of thirst in this fast-growing sector.

Furthermore, as node technology advances, so do the number of manufacturing process steps, and the usage of single wafer tools instead of batch tools, making the task of reducing water usage both challenging and even more critical. With many semiconductor fabs located in areas of high-water scarcity, such as Taiwan and Arizona, it is vital that semiconductor manufacturers take action to mitigate this huge consumption as part of the wider search for sustainable electronics.

Water management for semiconductor manufacturers is complex, propagated by the extreme purity requirements for the water used in manufacturing, giving it the name Ultra-Pure Water (UPW). However, water management techniques being implemented have the potential to mitigate water scarcity fears whilst also reducing operational costs.

Increasing volumes of reused water

Most semiconductor manufacturers now recycle or reuse water in some capacity, with annual targets to increase current levels of water reuse and combat increasing water withdrawal rates. Many companies such as NXP, Onsemi, and TI now reuse wastewater in their cooling towers. Reprocessing wastewater back into UPW is more difficult, but implementing new water treatment systems will be necessary to achieve sustainability in water use in semiconductor manufacturing. SK Hynix increased its volume of reused water by 51% between 2020 and 2023, partly motivated by water stress classification of 3 fabs as ‘High’ or ‘Medium-high’. This is expected to also reduce operational costs through reduced municipal water consumption.

Efficiency of water use

Process optimization can also reduce water usage. Many semiconductor manufacturers have cited a reduction in water per wafer as a key target for sustainability and to negate the risk of water shortages. This has been an issue for some, as the increased demand and complexity of wafers required has increased water use per wafer for companies such as SMIC. Reducing consumption per wafer becomes increasingly difficult with advancing node technologies, which often require increasing numbers of process steps.

However, simply reducing rinse times can result in large savings. GlobalFoundries reduced their rinse time from 10 minutes to 5 minutes after etching, resulting in an annual water saving of 10,000 m3, and there are many more examples in the report.

Diversification of water sources

Negation of water scarcity risk can come through diversification of water sources. Installing facilities such as rainwater collection may reduce operational costs due to a decreased requirement for municipal water. Tower Semiconductor has utilized the dehumidification of air required for the dry indoor environment in their factory in Texas. SMIC have also utilized condensate from air conditioning alongside rainwater collection to reduce municipal water consumption and associated costs.

These techniques may only recover a small fraction of total water usage but could still be invaluable. Larger usage could be obtained from seawater, with desalination employed in the Hsinchu TSMC plant. Where fabs are located close to the coast, utilization of onsite desalination could solve many fears surrounding sustainable water usage, although this would require high energy consumption.

Categorization of wastewater

Categorization and separation of wastewater can lead indirectly to increased water reuse. This is because it enables much more efficient treatment processes. Many processes may introduce specific contaminants to the water, which can be treated with simpler water treatment. Wet processing tool provider SCREEN can now implement drain segregation within its machines to enable the categorisation of wastewater. Winbond uses 20 different pipelines to ensure no cross-contamination and allows for individual treatment of contaminants. This could also give the potential for recycling the contaminants contained within the wastewater, which could also be beneficial economically.

Further sustainable semiconductor manufacturing insights

All of the strategies described above have the potential to benefit both the environment and the profit of the manufacturer through reduced water consumption. In many cases, reduced consumption of energy, chemicals and materials can be desirable on multiple fronts for electronics manufacturers seeking to improve sustainability and reduce operational costs.