TSMC is on the ropes and its biggest problem is not competition: it is water

CC Wei, the president and CEO of TSMC, has just participated in the inauguration of the Pingtung technology park, southern Taiwan. The ceremony was held under very intense rain, and the head of the largest chip manufacturing company of the planet has celebrated it publicly: “Last month I was still wondering: what should we do with the water? Should we start using tankers?”

Wei has compelling reasons to be concerned about water. In Taiwan it is a very scarce resource, and it is also essential for its semiconductor factories. The integrated circuit production industry faces five major shortages: water, energy, labor, land and talent. And water is probably the most precious resource of all and the most difficult challenge to overcome. Lai Ching-te, the president of Taiwan, has communicated CC Wei the Government’s plans to connect the island’s reservoirs together in a clear attempt to alleviate this problem.

The water we are familiar with, such as that which comes from the tap, spring water, and even bottled mineral water, is full of impurities. It contains bacteria, dissolved gases, mineral salts and microscopic particles in suspension. This is not a problem for most of the everyday applications for which we usually use it, but this water is not suitable for making chips. Even the smallest impurity invisible to the human eye is pure poison when involved in the production of cutting-edge semiconductors, such as 2nm integrated circuits which are currently being manufactured by TSMC, Intel and Samsung.

Droughts are the biggest threat to TSMC

The integrated circuit manufacturing process requires cleaning silicon wafers dozens of times. Every time a geometric pattern is transferred to wafers using lithography, they need to be cleaned. Also after pouring chemical reagents and photoresist fluids on them.

However, the water used to remove any residue that may have deposited on the wafer cannot have the slightest impurity. It must be absolutely pure. In fact, the industry standard calls for water with an electrical resistivity of 18.2 megaohms per centimeter, which is the theoretical limit of water purity at room temperature.

The problem is that producing ultrapure water is not easy. And it is not because it is necessary to subject it to reverse osmosis in multiple stages and ion exchange treatments. It is also necessary to degas it under vacuum, eliminate any microorganisms that it can contain with ultraviolet light and filter it using membranes expressly designed to capture the slightest impurity.

In this article we do not need to delve into these processes, but there is something that we cannot ignore: this treatment consumes energy and requires the use of a large amount of chemicals. Furthermore, a significant part of the water that is processed is not transformed into ultrapure water, so it cannot be used.

In 2021 Taiwan faced the most aggressive drought in recent decades. The reservoirs that supply the north of the island, which is the region where most of the integrated circuit manufacturing plants are located, reached a critical level. This scenario forced the Government to suspend agricultural irrigation in order to protect industrial supply.

Even so, TSMC had to resort to tanker trucks to transport water from other areas of the island. This crisis passed, but it exposed a structural vulnerability of an industry that is deeply sensitive to extreme climate phenomena and for which water is as valuable as silicon or some rare earth elements.

At the moment TSMC reuses 85% of water that it consumes in its processes, but its plants require so much water daily that the 15% that cannot be reused continues to be a very large amount. Paradoxically, some of the most important chip factories in the US reside in Arizona, which is the second driest state in the country only behind Nevada.

Both Intel and TSMC have state-of-the-art plants in this region, and Samsung manages several state-of-the-art factories in Texas, another state where water is not exactly plentiful. Besides, Intel has several very important plants in Israelagain a country for which water is a scarce resource, and, therefore, of great strategic value.

The choice of these locations responds to geostrategic and geopolitical factors, and not to planning that prioritizes sustainability. In addition, there is another unappealable reality that further complicates this panorama: the most advanced integrated circuit manufacturing nodes. consume more ultrapure water than mature nodes.

As transistors become smaller and chips become more sophisticated, the number of stages required for their production process is higher, making it necessary to clean the wafers with ultrapure water more times. A 3nm semiconductor from TSMC goes through more than 1,000 individual stages, many of which require washing with ultrapure water. 2nm chips are even more demanding, and those that will arrive in the future will surely multiply water consumption.

The problem faced by TSMC, Intel, Samsung, SK Hynix, Micron, GlobalFoundries and other semiconductor manufacturers is daunting. These companies are developing solutions, but at the moment they are not enough. TSMC, Samsung and Intel have very advanced water recycling and reuse programs. In addition, these companies are developing dry cleaning systems for wafers using reactive plasmas instead of water for use in some steps.

And they are even looking for new materials for the ultrapure water distribution pipes with the purpose of minimizing losses in the circulation system. The problem is that these solutions do not eliminate the deep dependence that chip factories have on water. The definitive solution has not yet arrived. And it is urgent. It is very urgent.

Image | TSMC

More information | Reuters

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