Explainer: why is a drought contributing to the silicon chip shortage?

The ongoing computer chip shortage has multifaceted causes, including drought, an uptick in demand following the pandemic, and the closure of factories due to local lockdowns. One of the contributing factors – a drought in Taiwan – has made it harder to manufacture chips as well.

So what’s required to make a computer chip, and why is this threatened by the water shortage from drought?

What are computer chips made of?

In short, computer chips are made of metal and silicon – or something that conducts electricity well, and something that doesn’t conduct it as effectively.

Computer chips are (in very, very brief) a series of transistors: switches, which are used to compute data. These transistors require a substance known as a semiconductor to work – which is why they’re also referred to as semiconductor chips.

Semiconductors are materials that normally don’t conduct electricity (insulators), but can conduct if a small amount of energy is applied.

“Metals are great because they conduct electricity, but they’re not good for switches because there’s really nothing you can do to turn off that conduction,” says Michael Fuhrer, a professor of physics at Monash University and director of the ARC Centre of Excellence for Future Low-Energy Electronics Technologies (FLEET).

“Semiconductors would be insulators and not conductive at all, which is what makes the ‘off state’, but then if you put in an extra charge, they start conducting.”

There are a few materials that can be used as semiconductors, but silicon is the substance of choice.

But the problem is not resources – it’s the skills and technology required to make the chips.

“Silicon is the second most common material [in the Earth’s crust] by mass. The bottle neck here is on the supply-chain,” says Duy Phu Tran, a researcher at the Future Industries Institute at the University of South Australia.

How are they made?

“This is a long and complex process involved using state-of-the art facilities and highly skilled personnel,” says Tran.

The construction of modern computer chips needs very specific expertise and equipment to work, which is why it’s not easy to increase the supply of chips when demand goes up.

“You can’t just simply start making more,” says Fuhrer. “You have to build $10 billion factories in order to make the chips.”

One of the requirements is that conditions need to be very clean. Microchips are now being manufactured on the scale of nanometres. Dust particles are usually micrometres in length – or about 1,000 times that size – so dust alone poses a large risk to the manufacturing process.

To remedy this, most of the manufacturing happens in a cleanroom, with highly purified air and water to keep the process sterile.

“In the cleanroom, chip manufacturing is generally comprised with materials deposition, etching, wafer patterning, and modification of electrical properties,” says Tran.

“Modern chips require more than 300 sequenced processing steps, with zero mistakes.”

They also need a “huge amount of ultra-pure water for cleaning in each step”.

“It is reported that ~8000 litres of ultra-pure water is required to produce ~100 chips. Chip manufacturing plant like TSMC [in Taiwan] alone used 156 megalitres of water daily in 2019.”

Which is why a nation like Taiwan, which usually has abundant water, has focussed on chip production, and why the drought now places this in question.

Do we have any alternative ways to make chips?

Not immediately. Our computing equipment depends on the silicon chip, which means that any changes made at that level of manufacture are going to need entirely new systems to put themselves in.

Fuhrer leads the FLEET research centre, which is searching for basic physics alternatives to silicon chips. “It’s a huge area of basic research around the world,” he says. “There are many competing ideas.”

“New types of semiconductor materials are being researched and prototyped every year,” adds Tran. He highlights quantum chips as a possible solution. “Most notable is silicon qubits, photonic-based qubits and graphene-based qubits.”

But all of these solutions are going to take years, rather than months, to develop. For now, the chip shortage will continue, even if the drought recedes.

“It is hard to imagine what the world will look like without these tiny chips,” says Tran, in summary.

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