memsstar and TUM: Advancing Quantum Networks
Innovation in semiconductor and MEMS technology often begins in the research lab. New device architectures are often conceived, tested and refined in university R&D departments before they eventually scale into commercial applications. Partnerships with leading research institutions play a key role in helping memsstar push the boundaries of what our process technologies can enable.
One recent example is our collaboration with the Technical University of Munich (TUM), where our ORBIS™ Alpha Xeric Oxide Etch system has been installed at the university’s Quantum Networks Lab in Garching, Germany. The work being carried out there sits at the intersection of integrated photonics, MEMS fabrication and quantum communications—fields that are rapidly converging as researchers look for new ways to build scalable quantum devices and communications
For us, the project reflects both the versatility of our vapour-phase etch technologies and the importance of close collaboration with research groups exploring entirely new device architectures.
From Research Inquiry to ORBIS Deployment
Our relationship with TUM began with a conversation sparked by curiosity. The initial inquiry came through our website in 2022, as researchers at the university began exploring fabrication techniques to support their work in quantum networking.
TUM’s Garching campus hosts a cluster of research institutes and technology centres, including the Walther-Meissner-Institute for Low-Temperature Research (WMI), where semiconductor materials and device technologies are a major focus. Researchers across these institutes frequently collaborate and exchange ideas, and through these connections, the team at TUM identified vapour-phase hydrogen fluoride (HF) etching as a promising process for their device structures.
That led them to memsstar.
The ORBIS system installed at TUM represents the first memsstar platform deployed at the university. But more than a simple equipment delivery, the project was an opportunity to work closely with researchers who are developing entirely new device concepts, helping them understand how vapour-phase etch technology could enable their work. When a research group is exploring new materials, structures or photonic architectures, the fabrication challenges can be very different from those encountered in established MEMS production lines. Working alongside researchers allows us to help them achieve the precision their designs demand.
MEMS Fabrication Challenges in Quantum Devices
At TUM, the ORBIS Alpha system is used by the Department of Quantum Networks, led by Professor Andreas Reiserer. The group is focused on developing technologies that enable quantum communication systems—networks capable of transmitting information in fundamentally new ways.
One important aspect of this work involves the fabrication of silicon nanostructures and photonic devices, including photonic crystals and resonators that control and guide light at extremely small scales. These structures are essential for manipulating photons in quantum networking systems, where the light particles can carry quantum information between nodes .
Fabricating these devices requires extremely precise micro- and nanofabrication techniques. Researchers must create delicate suspended structures with carefully controlled geometry and material composition. In MEMS and nanophotonic devices, this stage of fabrication is critical. If the release process introduces surface tension forces or material incompatibilities, the fragile structures can collapse or adhere to the substrate—an effect known as stiction. Once that happens, the device is effectively unusable.
Why Vapour HF Etching Enables Stiction-Free Release
TUM uses the ORBIS Alpha system’s vapour-phase HF process to perform stiction-free release etching of photonic crystal structures formed on silicon-on-insulator (SOI) substrates. This release step removes sacrificial oxide layers while leaving surrounding materials intact, freeing delicate structures without damaging them.
Vapour HF vs Wet and Plasma Etching
Traditional release etching often uses liquid-phase wet chemistry, but for delicate nanostructures this approach can create significant challenges. Liquid processes introduce surface tension forces during drying, which can pull tiny mechanical structures into contact with the substrate. Once stuck, these structures rarely recover. Wet etching can also make it difficult to precisely control the etch process across complex device geometries.
Another option is isotropic plasma etching, but this approach can suffer from limited selectivity and aspect-ratio constraints. For many emerging device designs, those limitations become problematic.
Vapour-phase HF etching offers a fundamentally different approach. Because the process occurs entirely in the vapour phase, there is no liquid to create surface tension forces. This enables stiction-free release, which is critical when working with nanoscale photonic and mechanical structures. The process also offers exceptional material selectivity, particularly between silica and silicon nitride—an important capability for creating waveguide structures and photonic components used in quantum devices.
ORBIS Platform for Quantum MEMS Fabrication
Equally important is the flexibility vapour-phase etching offers researchers exploring new device architectures. When teams like the one at TUM experiment with different material stacks or novel structural designs, they need an adaptable process platform. This is a key reason the ORBIS Alpha platform was selected for the Quantum Networks Lab.
Expanding MEMS Applications in Quantum Technologies
While the quantum field is still relatively small compared with mainstream semiconductor markets, it is expanding quickly. Our vapour-phase etch technologies are already supporting several research initiatives in this area, pursuing such applications as vapour HF release processes and xenon difluoride (XeF₂) etching.
These diverse projects, which explore a wide range of quantum-related devices—from superconducting structures used in quantum circuits, to MEMS-based quantum sensors capable of detecting extremely small physical signals—highlight an important point: many quantum technologies rely on precise micro- and nanofabrication techniques similar to those used in MEMS and photonics manufacturing. As a result, process technologies developed for those industries can play a significant enabling role in the development of quantum devices.
Industry + Research Collaboration Driving Innovation
memsstar’s partnership with TUM is a tangible example of how industry and academia can work together to accelerate progress in quantum technologies. By combining advanced research with proven process technology, we can help researchers explore new ideas and move them closer to real-world applications.
These collaborations are about more than supplying equipment. They are about building relationships with the scientists and engineers who are shaping the future of micro- and nanotechnology. And as quantum networks, sensors and computing systems continue to evolve, we look forward to supporting the innovations that will bring these technologies from the laboratory into the world.
FAQs
What is vapour HF etching used for in MEMS?
Vapour HF etching is a dry, vapour-phase hydrogen fluoride process used to selectively remove sacrificial silicon dioxide and release delicate MEMS and nanophotonic structures without liquid contact. This process is essential for achieving the stiction-free release of photonic crystal structures, particularly on silicon-on-insulator (SOI) substrates. By etching buried oxide while leaving surrounding materials intact, vapour HF provides exceptional selectivity between silica and silicon nitride. For example, industry-standard systems like the memsstar ORBIS™ Alpha are utilized in high-precision environments, such as TUM’s Quantum Networks Lab, to fabricate suspended devices and photonic components for quantum networking.
Why is stiction-free release important?
Stiction-free release is critical because it prevents fragile, suspended micro-structures from collapsing or permanently adhering to the substrate due to surface tension forces. This phenomenon, known as “stiction,” occurs during the drying phase of liquid-based etching and typically renders the MEMS device unusable. In high-precision fields like quantum photonics, maintaining the mechanical integrity of nanoscale structures—such as photonic crystals—is essential for device performance and manufacturing yield. To address this, vapour-phase HF etching (like that provided by the memsstar ORBIS™ Alpha) eliminates liquid contact entirely. By removing the drying forces associated with wet chemistry, this dry-release approach safeguards the delicate geometries required for advanced quantum communication and SOI components.
How does vapour HF compare to wet etching?
The primary difference between vapour HF and wet etching is the physical state of the chemistry: vapour HF performs the release entirely in the gas phase, whereas wet etching utilizes liquid-phase chemistry. By operating in the gas phase, vapour HF eliminates the surface tension forces that occur during liquid drying, which typically cause “stiction” or structural collapse in delicate MEMS.
Key advantages of vapour-phase HF over wet etching include:
- Stiction-Free Release: Prevents mechanical failure of nanoscale structures.
- Superior Material Selectivity: Offers high precision between silica and silicon nitride, essential for photonic waveguides.
- Geometric Control: Provides more consistent oxide removal across complex, high-aspect-ratio geometries compared to isotropic plasma or wet etchants.
While wet etching remains common for bulk processes, vapour HF systems like the memsstar ORBIS™ Alpha are the preferred choice for advanced quantum research, where structural integrity is paramount.
