Every chip counts: Considering the semiconductor industry's environmental impact
The realm of environment, health and safety (EHS) has been historically separate from that of process development in integrated circuit (IC) chip manufacturing fabs. As the climate changes, this is no longer possible. The Scripps atmospheric CO2 measurements from Mauna Loa in Hawaii indicate that emissions recently exceeded 420 ppm, up from 370 ppm in 1997 when the Kyoto Protocol international treaty was adopted. We are approaching a tipping point as the planet warms beyond conditions to which life has adapted. The effects on ecosystems and on people, while not precisely known, involve climate disasters that will contribute to global and social inequities. Both technology and sustainability are critical to the world’s future.
The information and communication technology industry currently contributes about two percent of yearly global emissions. The increasing demands of AI, wireless communication, and smart devices are driving exponential growth that cannot be sustained without changes in semiconductor fabrication. To reduce the carbon footprint of semiconductor devices, processes must be developed that consume less energy, use fewer resources, and limit emissions of greenhouse gases (GHG) commonly used in chip manufacturing. Making net-zero commitments may seem like a choice for companies seeking positive press for their sustainable initiatives, but it is becoming a business imperative in addition to a humanitarian one. Soon, companies will need to demonstrate their efforts to reduce environmental impact through their operations and their entire value-chain. Semiconductor fabs and their suppliers must both measure and minimize their environmental impact. Legislation will ensure it, and the market will demand it. The semiconductor manufacturing industry has an opportunity to invest in a climate strategy now to reduce costs, reduce climate risk, and establish a competitive advantage in a climate-conscious world.
It is useful to understand the Greenhouse Gas Protocol corporate accounting and reporting standards for emissions, known as “Scopes,” that are defined from a reporting company’s perspective.
Scope 1 Emissions are a company’s direct GHG emissions into the atmosphere.
Scope 2 Emissions are indirect, created by the energy a company uses for manufacturing. Scope 2 emissions can be reduced most easily by using renewable energy, but also using less energy is ideal for both cost and environmental reasons.
Scope 3 Emissions include everything else: Upstream emissions originating in the supply chain before materials and equipment reach a company, and downstream emissions generated during product use and disposal. Scope 3 emissions reporting is the most difficult since these are beyond the direct control of the reporting company. The opportunity to reduce Scope 3 emissions lies in business decisions that put pressure on suppliers to offer lower-impact materials and equipment. Additionally, product designers must take into account the full life cycle of a product, including the use and disposal phase.
Reducing material use and Scope 1 emissions will require semiconductor manufacturers to change their internal processes to make a meaningful impact. Historically, companies developed chips for performance, power, area, and cost. Starting now and going forward, environmental considerations must also be integrated into the design process.
Quantifying the environmental impact of semiconductor devices is complex and demands a large database of unit process steps, materials consumed and their environmental impact, fab model knowledge, and many other details. Without this information, it is impossible to prioritize development or communicate carbon footprints through the value chain. The nanoelectronics R&D hub, imec, created a virtual fab called imec.netzero to help its partners understand the environmental impact of IC high-volume manufacturing and enable them to study how their design and fabrication decisions change that impact. This can be especially important in a pathfinding mode for technologies that don’t yet exist to make strategic decisions like, for example, the carbon intensity of energy used.
The introduction of high-numerical aperture (NA) extreme ultraviolet (EUV) scanners represents another future technology that benefits from high-level sustainable design considerations. EUV illumination has already reduced the feature sizes possible on advanced IC chips. The high-NA generation of EUV scanners have been designed to continue the resolution roadmap, which sets the timeline and technology requirements for ever smaller chips, using larger NA lenses. To maintain throughput over low-NA options, faster stages are used that consume more energy per wafer. So, it is perhaps non-intuitive that high-NA technology could reduce overall emissions. However, the enhanced resolution avoids complex multi-patterning process flows, including many process steps that drive high Scope 1 and 2 emissions like lithography, deposition, and etch. The increase in energy use of the high-NA scanner per lithography step can be offset by reduced energy (Scope 2) and process gas emission (Scope 1) of the simplified process.
Every industry has a role to play in achieving climate goals, and the semiconductor industry is no exception. Fortunately, many companies are developing more sustainable practices, and the truly visionary ones are rebuilding processes from the ground up to reduce their energy use, waste, and emissions. Fabs and their supply chains are beginning to measure and report their environmental impact due to regulatory and business pressures. Additionally, many people entering the workforce insist on meaningful environmental initiatives of prospective employers.
Addressing climate change is a balancing act. If we are too overwhelmed by the global- warming numbers being reported in 2024, it is possible to conclude that the damage has been done and the time for action has passed. On the other hand, if we walk the world denying that there is a problem, we are unlikely to learn, grow, and make a positive impact. It seems best to inhabit the middle and to approach the environment with curiosity and the conviction that what we do matters profoundly.
Emily Gallagher is the director of imec’s sustainable semiconductor technology and systems program.
