The world’s chipmakers are failing to meet an international target to achieve net-zero carbon emissions by 2050, experts told EE Times. The first milestone is for emissions to peak in 2025 and steadily fall, one said.

A consortium created this year by chip-industry association SEMI, with R&D organization imec as a founding member, aims to bring the world’s chipmakers and their ecosystem in line with the 1.5 degree Celsius global-warming target in the Paris Agreement, requiring that global carbon emissions reach net zero around 2050.

The consortium has gathered almost 90 companies from SEMI’s total 3,000 members that have committed to cutting emissions.

“I believe we have all the players we need to make a difference,” said Mousumi Bhat, VP of Sustainability Programs at SEMI. “I’m very impressed with the courage these companies have demonstrated to say, ‘Yes, we want to solve this problem together,’ because it’s not something that you’d normally see. We’re all very protective about the intellectual property we generate, but with sustainability, it has been very refreshing to see how companies want to collaborate.”

Last year, the chipmaking industry used 340 terawatt hours of electricity, or about 1.3% of global demand, Bhat said. That percentage continues to grow, she added.

The first sustainability milestone comes in 2025, when chip-industry emissions should peak and decline steadily, Bhat said. One aspiration is to bring emissions to half of the 2019 level by 2030.

Others are less sanguine.

The top priority for the chip industry is switching completely to renewable energy as a source of electricity, said Sri Samavedam, SVP of CMOS technologies at imec. Chipmaking hubs located on islands where it’s difficult to set up solar and wind power stations must depend heavily on fossil fuels to generate electricity.

“Access to renewable energies is a challenge, so your fabs in Singapore and Taiwan are going to be a problem,” he said.

The islands around the world where fabs are located don’t have the “luxury” of installing solar panels or solar farms, Bhat said: “I’m talking about Singapore, Taiwan, Japan. These are land-limited countries.”

o chipmaker can rely only on wind and solar energy to power their fabs, Bhat added. “If you depend on solar and suddenly it’s a cloudy day, you’re out of business. Any power supply glitch results in millions of dollars of losses within a supply chain or within a fab.”

Hydrogen and small modular nuclear reactors are under consideration as more reliable and green sources of energy, she said.

“The cost per unit of energy is still much higher than traditional fossil fuels,” she added. “That all needs to drive down.”

Chemicals and gases

Another target involves inputs like chemicals and gases. The manufacturing process uses highly destructive greenhouse gases that sometimes leak into the atmosphere, especially in older fabs.

Fabs constructed in the last five years have abatement systems that burn most of the gases into harmless components, Samavedam said. “There’s still a tiny fraction that escapes into the atmosphere. We’re doing our best, but you still have these escapes, and that is something that we need to work on.”

Another challenge is to bring fab equipment, service and material suppliers in line.

“A semiconductor fab is very complicated,” said Cedric Rolin, a program manager at imec. “There’s a huge amount of chemicals coming in, and there’s a very big inventory. The numbers you have, all the assessments, are usually far from being complete.”

Chipmakers need to work with chemical suppliers to develop new processes that don’t compromise chip yields or performance, “because nobody’s going to give up on that,” Samavedam said.

He gives the example of NF3 (nitrogen trifluoride), which is used extensively in chamber cleaning.

The worst offender in a fab is SF6 (sulfur hexafluoride), which is typically used for deep silicon etch. SF6 has a global warming potential of about 23,900, which means that one kilogram released into the atmosphere is equivalent to releasing 23,900 kilograms of CO2 over 100 years.

“Those are really high numbers,” Rolin said. “It’s really important to destroy those greenhouse gases before they are emitted.”

The chip supply chain is going to take years to change, Samavedam said.

“There’s a lot of work that needs to happen now so that 10 years from now, we are in a position to say that we’re making a difference.”

If the world’s fabs switch to renewable energy and install new greenhouse gas abatement systems, the industry will still fall short of sustainability targets, he said. “It looks bleak, but I have hope that people are aware, and people are taking action.”

Electronic devices

Still, experts say there’s a bigger problem. Few dare to estimate the carbon emissions of devices running semiconductors like datacenters, cryptocurrency gear or gaming equipment. That problem involves what’s called the “rebound effect,” Rolin said. The steadily increasing efficiency of electronic products like smartphones creates more demand, and that creates more pollution.

To be sure, electronics can accelerate the use of green energy in things like solar panels and smart grids.

“A lot of the renewables solutions that are put forward do need electronics,” Rolin said.

He remains doubtful, however, about the net environmental effect of electronic devices.

“It would be very complex to characterize our system as part of the solution,” he said. “We need to make a complete list of all the technologies that are helping and then to start to characterize them. It’s really a gigantic amount of work.”

EUV equipment

While EUV lithography tools are often mentioned as huge energy consumers in a fab, they also help save energy, Rolin said.

“EUV, indeed, is a huge consumer of electricity,” he said. “It’s above 1 megawatt [per tool], which is about 10 times higher than the typical electricity consumption of semiconductor equipment.”

Typically, including one EUV lithography process step removes multiple DUV lithography process steps and all of the other processes associated with multi-patterning, such as etch, deposition, cleans and metrology. The net effect is reduced energy and cycle time, he said.

“Before EUV, there was, for example, multiple patterning where you would use three DUV steps in a row to define a certain nanometer-scale dimension. With EUV, you need less etching, less cleaning, and you save a lot of other steps.”

Even so, the rebound effect kicks in when EUV is used to make chips at the highest transistor densities, he said. “My 2-nm chip is doing a lot more than my 5-nm chip, so I can make it smaller. This is not what is happening. We are not making the chips smaller. We are just making them the same size. Just more powerful.”

Improvement

Some of the world’s top chipmakers are renewing their efforts.

Intel has committed to net-zero emissions in its global operations by 2040 and aims to achieve 100% use of renewable electricity as an interim milestone by 2030.

Taiwan Semiconductor Manufacturing Co. (TSMC) in September pulled in its target for adoption of 100% renewable energy for all global operations to 2040 from 2050. As part of that effort, the world’s largest chip foundry announced that by 2030, 60% of its energy will come from renewable sources, revising its earlier target of 40%.

According to Samsung, the world’s second-largest foundry met its target of adopting 100% renewable energy for all U.S. and China sites in 2019. The company announced plans to adopt renewable energy in all international markets where it operates, outside of South Korea, within five years.

By: DocMemory
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