Fraunhofer Institute for Electronic Nano SystemsNews
A PFAS-Free Future for Semiconductors: Fraunhofer ENAS, the Paul Scherrer Institute PSI and memsstar Limited Develop Sustainable, Ecofriendly Alternative to “Forever Chemicals”
These days, they are an integral part of our lives: They are used to impregnate and weatherproof functional clothing, as non-stick coatings to gently cook the most delicate foods and to extend the shelf lives of cosmetic and hair, skin and body care products. Per- and polyfluoroalkyl substances (PFAS) are both a blessing and a curse. Also known as “forever chemicals,” these compounds are much more than just resistant to water and dirt. They are viewed as persistent, toxic substances that pose significant environmental and health risks. Because they are extremely stable and not biodegradable, they can accumulate in nature and the human body, increasing the risk of disease. However, PFAS chemicals are used not only in consumer and industrial products but also across a wide range of production processes. They have found their way into everything from automotive manufacturing to medical technology and engineering and onto aerospace production lines. In the semiconductor industry in particular, the compounds’ extraordinary heat resistance and chemical stability have made them unsurpassed in applications such as production of functional microstructures and nanostructures. Fraunhofer ENAS, the Paul Scherrer Institute PSI and memsstar Limited are working to reverse course. The three partners are pooling their strengths to identify a PFAS-free, ecofriendly alternative for the chip industry and unlock its potential for industrial use.
The goal of the collaboration is to develop an innovative micro- and nanoscale process for etching silicon, a crucial step in producing semiconductor components. To this end, the partners are focusing on gas-phase metal-assisted chemical etching (Gas-MacEtch) technology, a high-performance semiconductor etching method. This method makes it possible to produce micro- and nanoscale structures with extremely high aspect ratios and very straight, smooth sidewalls in a process that allows for superior control, reproducibility and quality. It combines peerless structural precision and design freedom with extreme speed and is also ideally suited to large-area processing and structuring of wafer surfaces.
Gas-MacEtch technology is based on a catalytic reaction between a metal catalyst applied to the surface of the silicon substrate that is to be etched and a gaseous etching chemical. Contact with the chemical causes a locally accelerated chemical reaction in which the catalyst material penetrates vertically into the silicon substrate, where it is used to zero in and form finely etched functional structures with exact geometric shapes and dimensions.
Ecologically and economically future-proof: Resource-efficient etching method heralds a new era in chip production
“The new method uses no PFAS compounds at all. Using ecofriendly, biodegradable chemicals and gases as an alternative significantly reduces harmful environmental impact during wafer structuring and actively contributes to greater sustainability in semiconductor manufacturing,” explains Micha Haase, head of the “Plasma Etching and Process Diagnostics” group at Fraunhofer ENAS, who is developing the new method in tandem with partners from the Paul Scherrer Institute PSI and memsstar Limited.
These advantages of the Gas-MacEtch process are joined by another environmentally friendly aspect: Compared to established etching methods, this process permits silicon wafers to be structured at considerably lower temperatures. This improves the energy footprint of semiconductor production, reduces greenhouse gas emissions and significantly lowers energy costs.
Global need to switch to PFAS-free products and processes
The increasing complexity of EU legal specifications and new rules put in place by regulatory agencies around the world to reduce the use of PFAS in response to global health and environmental concerns will increase pressure on the industry in the long term, requiring a change of direction. For the semiconductor industry, this means not only new challenges in complying with applicable environmental protection rules but also actively taking on responsibility for developing sustainable production technologies and ecofriendly PFAS alternatives.
“Our research on a PFAS-free etching method for the chip industry is a response to those same international dynamics and trends. The combination of lower environmental impact and advances in technology represents a critical competitive advantage for chip manufacturers. It satisfies recent legal requirements while positioning the European semiconductor industry at the forefront of innovation in the global economy and ensuring that the industry is future-proof for the long term by harnessing innovative technologies,” Micha Haase explains.
Ultimately, he continues, the researchers’ work will have far-reaching positive effects on society at large and on the environment. Consistently eliminating toxic substances in wafer processing actively helps minimize risks to nature and human health. “PFAS have been used for decades, and now they are suspected of harming whole ecosystems, accumulating in the human body and elsewhere via the food chain and causing cancer. Moving away from toxic industrial chemicals and replacing them with substances of no concern also underscores the research sector’s recognition of our responsibility to our communities,” Micha Haase notes.
Three countries, one objective: Strong European partners unlock potential for sustainable semiconductor production
To move closer to the goal of a PFAS-free future in semiconductor production, Fraunhofer ENAS, the Paul Scherrer Institute PSI and memsstar Limited are working closely together.
Fraunhofer ENAS in Chemnitz is developing and optimizing the Gas-MacEtch process and ensuring its seamless integration into industrial production environments as part of the collaborative effort. The Paul Scherrer Institute PSI, which is based in the Swiss city of Villingen, has proven expertise in Gas-MacEtch technology. The institute is using state-of-the-art analytical methods to optimize the catalytic reactants and the chemical interaction between various material systems that takes place during the etching process. memsstar Limited, based in Livingston, UK, is Europe’s leading process and equipment supplier of etch and deposition solutions for semiconductor and MEMS manufacturing processes. It is providing its “Orbis 3000” platform, a cluster tool for vapor etching of silicon oxide and deep reactive-ion etching by means of Gas-MacEtch technology and advancing the technological execution and scaling of this method in industrial facilities. In this way, the partners are combining scientific rigor, process know-how and industry drive to realize the new etching process efficiently and sustainably and establish it in real-world applications.
Innovation at work: Fields of application with bright prospects
As a key technology for the next generation of semiconductor components, the new etching method has the potential to be used in applications such as production of 3D NAND memory, a new form of flash memory chip in which memory cells are stacked vertically for significantly greater storage capacity and speed.
Manufacturing of ultra-precise photonic crystals for optical applications is another potential area of use for the Gas-MacEtch process. These structures require extremely smooth sidewalls and high aspect ratios to conduct and manipulate light efficiently. Established methods have hit their limits in creating structures like this so far. The new Gas-MacEtch technology overcomes the obstacles associated with rough surfaces and geometric limitations, instead enabling precision large-area production of photonic crystals or other photonic components. Going forward, this will open up new applications in the fields of optical data transfer, sensors and quantum communications.
About memsstar Limited
memsstar Limited is a leading provider of deposition and etching systems and of technological products and services for manufacturers of semiconductors and micro-electromechanical systems (MEMS). The company’s etching and deposition systems and technological solutions support the European semiconductor market and the global MEMS market. With its process technologies and systems, memsstar Limited strengthens the MEMS industry in overcoming the challenges that arise from the development and production of increasingly complex and integrated MEMS components.
About the Paul Scherrer Institute PSI
The Paul Scherrer Institute PSI is the largest research institute dedicated to work in the physical and life sciences and engineering in Switzerland. It conducts cutting-edge research in the fields of future technologies, energy and climate, health innovation and the fundamentals of nature. At the Paul Scherrer Institute PSI, researchers seek out previously unknown ways to process and store data, make technologies more sustainable and efficient and devise new methods to push the leading edge of discovery at the micro- and nanoscale. Their findings form the basis for new applications in fields such as medicine, information technology, energy generation and storage and for new industrial production methods.
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