Less Is More: Efficient Use of Resources in the Semiconductor Industry
The need to reduce emissions and conserve resources has become increasingly important in the semiconductor industry, as natural resources such as fossil fuels and water are limited. As a specialist in environmental technology, DAS Environmental Experts offers customised solutions for the semiconductor industry in order to protect the environment and reduce the consumption of resources.
In view of climate change, many countries and regions have introduced regulatory requirements to reduce CO2 emissions and the consumption of natural gas and electricity.
In 2021, Germany committed to being greenhouse gas neutral by 2045, which increases the pressure on industry, including semiconductor production. Emissions are to be reduced by 65 per cent by 2030 compared to 1990. The requirements relate to the balancing of greenhouse gas emissions, reduction targets and specific measures to avoid and minimise emissions. This is accompanied by disclosure regulations that require detailed non-financial reporting of social and sustainability-related information from companies (ESG reporting).
In Southeast Asia, Singapore was the first country to adopt a carbon tax in 2019, which will be gradually increased until 2030 in order to incentivise companies and private consumers to reduce their CO2 footprint.
In 2021,Taiwan set itself the goal of achieving climate neutrality in terms of net carbon emissions by 2050 and enacted the Climate Change Response Act to this end. Part of the law is the introduction of a CO2 levy, the so-called ‘carbon fee’, from 2025.
China wants to become climate-neutral by 2060 and has established a national emissions trading law in 2021, among other measures. However, the country expects to reach a peak in CO2 emissions by 2030.
There is no nationwide carbon tax or CO2 levy in the USA. Instead, various regional and state initiatives such as regional emissions trading rights (‘cap-and-trade’) and tax incentives have been in place since the 1990s.
Conserving Resources and Sustainability in Chip Production
In terms of industrial production, the semiconductor industry accounts for around 0.3 per cent of global CO2 emissions along the entire value chain from circuit design to assembly & test. A further one per cent or so of greenhouse gas emissions are caused by upstream processes at suppliers and downstream use by end consumers.
The semiconductor industry, including its suppliers, is aware of its responsibility and is driving forward the conversion of its energy supply to renewable sources such as (green) electricity, optimising energy and water consumption, increasing the water recycling rate and reducing the consumption of gases and chemicals in production and disposal. These measures are aimed at achieving climate-neutral semiconductor production.
Semiconductor Manufacturing
Semiconductor chips make an important contribution to reducing our consumption of energy and resources through intelligent control and sustainable production At the same time, the production of chips is very energy- and water-intensive and requires the use of sometimes highly toxic gases and chemicals, which have to be cleaned at the point of use if possible. For this reason, reducing emissions in semiconductor production is a key aspect of environmental protection in microelectronics.
Chemical and physical processes are used in the production of chips, such as doping, etching, applying photoresists, exposing, cleaning or depositing thin layers. These processes produce various types of emissions and gaseous pollutants that are problematic for the environment and human health if left untreated. These include, for example, climate-damaging fluorocarbons (HFCs), sulphur hexafluoride (SF6) and tetrafluoromethane (CF4) as well as hydrogen fluoride (HF), nitrogen oxides (NOx) and ammonia (NH3). During the production process, these process gases are continuously discharged from the cleanroom systems into the subfab located below the cleanroom, where they are purified in special point-of-use waste gas treatment systems.
Cleanroom, GlobalFoundries Fab 8, Malta (NY)
Optimisation of Process Gas Treatment as a Decisive Lever for Increasing Efficiency and Reducing Consumption Values
Exhaust gas treatment plays a key role in increasing efficiency and reducing consumption in the semiconductor industry. Several approaches are currently being pursued to achieve the industry’s ambitious environmental targets in this area. DAS Environmental Experts offers technology solutions for all these approaches.
- Use of climate-neutral energy sources such as electricity from renewable energies or so-called green hydrogen (H2). The industry is currently undergoing a transformation process that is being accelerated by industrial policy measures and regulatory requirements. As a provider of innovative environmental technology solutions, DAS Environmental Experts is also focussing on climate-neutral and highly efficient energy sources such as green hydrogen. All burn-wet systems can be operated with hydrogen and STYRAX and UPTIMUM systems can be equipped with direct current (DC) plasma burners.
- Efficient utilisation of energy using hydrogen as an example. Although hydrogen (H2) has a lower volumetric energy density compared to natural gas, it has a higher gravimetric energy density, which means that more energy is available per unit weight. This property of H2 enables more efficient energy utilisation in certain applications. For example, hydrogen burns at higher temperatures, enabling a faster and more complete reaction, which leads to more efficient destruction of harmful substances in processes such as exhaust gas treatment. This can increase the efficiency of the entire process by up to 25 %. The combustion of hydrogen produces only water vapour as its main product, unlike CO2 from fossil fuels. This contributes directly to the reduction of greenhouse gas emissions. A practical example of this is the STYRAX burn-wet system from DAS Environmental Experts, which optimally utilises these advantages of hydrogen. The recovery of process heat can also make a significant contribution to sustainable energy utilisation. In the TSUGA catalytic system, energy recovery through heat exchangers ensures a low total energy requirement during operation.
- Efficient water utilisation. The water used in burn-wet systems and scrubber systems can be collected and recycled in DAS systems in a closed-loop scrubbing design. The contaminated water passes through sedimentation, filtration or chemical neutralisation in a special cycle and can then be fed back into the burn-wet system or scrubber. This cycle reduces the consumption of fresh water to around 25 per cent compared to a system with a continuous water flow.
- Intelligent process control through monitoring, data evaluation and flexible adaptation to the requirements of the upstream production steps in the cleanroom. A data link between the process systems in the cleanroom and the abatement systems in the sub-fab can optimise and reduce the consumption of fuel and other substances required for the cleaning process. DAS Environmental Experts offers a range of tools that use customised data to achieve optimum results. The company uses both its own developments and solutions from partners.
DAS Environmental Experts Supports Customers Worldwide in Reducing Their Carbon Footprint
The semiconductor industry is undergoing a process of transformation, accelerated by government policies and societal demands In the face of climate change and resource scarcity, the industry faces several challenges, with a focus on reducing its environmental footprint:
- A key factor is the switch to environmentally friendly energy sources such as green electricity and green hydrogen.
- Efficient waste gas treatment systems with high destruction and removal efficiencies (DRE) are essential to minimise the impact of harmful emissions.
- Recovery of process heat and use of closed water loops are key measures to significantly reduce consumption of energy, water and chemicals.
- Intelligent process control, monitoring and data evaluation directly at the cleaning systems can further optimise resource consumption.
Example from Semiconductor Manufacturing: Impact of High Levels of Destruction and Removal Efficiency
Reducing consumption and increasing efficiency are key priorities for the semiconductor industry. By reducing consumption, we can cut back on the use of resources such as energy and chemicals. On the other hand, increasing efficiency is all about improving process performance. When it comes to purifying process waste gases, these approaches help to reduce costs and minimize environmental impact. The following text explains how these principles can be practically applied, particularly in terms of destruction and removal efficiency (DRE) in waste gas purification and its influence on consumption values and efficiency in chip production. The degree of destruction and removal (DRE) is a critical factor in the cleaning of process exhaust gases. A high DRE means that a high percentage of the harmful substances in the waste gas stream are effectively destroyed or removed without the need for further treatment cycles. This has a direct impact on consumption values, as more efficient waste gas treatment reduces the need for resources such as energy, water and chemicals.
The example of two important process steps in chip production, chemical vapour deposition (CVD) and etching, provides a good illustration of how a high DRE helps to avoid hazardous emissions, minimise harmful effects on the climate and reduce consumption values at the same time.
The CVD process is used to deposit thin layers of materials on a substrate (usually silicon). These layers are crucial for the production of semiconductor components such as transistors, solar cells and integrated circuits. During etching, certain parts of the material applied to the wafer are selectively removed in order to create or modify structures. This can be done using chemical, physical or plasma-assisted processes in which, for example, perfluorocarbons (PFCs) are used.
Both processes utilize Tetrafluoromethane (CF4). This chemical compound has a global warming potential (GWP) of 6500, which means that CF4 contributes 6500 times more to global warming than the same amount of CO₂. For this reason, intensive efforts are being made to reduce the use of CF4 or replace the gas with less harmful alternatives. To remove CF4 efficiently, it is chemically broken down at higher temperatures. Efficiencies of around 95% DRE can currently be achieved. Through improved processes, optimized plant equipment and the use of higher temperatures and energy densities, CF4 is to be completely removed. This is achieved by combustion at high temperatures or by optimized combustion chambers that generate maximum energy density. In thermal flue gas cleaning systems, such as burner scrubber systems, a high DRE leads to better pollutant removal, which reduces the energy requirement for central after-treatment systems.
With STYRAX, DAS Environmental Experts offers a family of systems that can achieve a DRE value of 95 % — 99.9 %, depending on the process and pollutant gas component. This high value makes an important contribution to increasing efficiency and conserving resources in waste gas treatment in semiconductor production, thereby reducing the environmental impact and increasing the sustainability of our customers, particularly with regard to greenhouse gas emissions.
Would you like to find out more about the efficient use of resources in the semiconductor industry?
Our environmental experts look forward to hearing from you.
Dr. Christian Kuhne
Director Sales Global