Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

IEEE International Interconnect Technology Conference (IITC)

Fabrication of Superconducting Nb Airbridges in a 300 mm Pilot Line for Quantum Technologies

Danny Wan, Massimo Mongillo, Yann Canvel, Daniel Pérez Lozano, Bert Tobback, Tsvetan Ivanov, Antoine Pacco, Xiaoyu Piao, Shana Massar, Anton Potočnik, Kristiaan De Greve

Published Jun 3, 2024• 0 citations
Publisher

Abstract

Superconducting Nb airbridges were fabricated in imec’s 300 mm pilot line utilizing an advanced production toolset. An optimized process flow, which does not rely on liftoff or shadow evaporation, results in high airbridge yield across full wafers, and is compatible with trilayer-based superconducting qubit fabrication methods. Airbridges integrated with resonators were characterized at millikelvin temperatures, showing that the addition of airbridges can have minimal contribution to microwave losses. This work demonstrates that airbridges can be incorporated into foundry compatible qubit fabrication flows.

DOI
10.1109/iitc61274.2024.10732203

Related papers

Advanced CMOS manufacturing of superconducting qubits on 300 mm wafers

Jacques Van Damme, Shana Massar, R. Acharya +13 more

Abstract The development of superconducting qubit technology has shown great potential for the construction of practical quantum computers 1,2 . As the complexity of quantum processors continues to grow, the need for stringent fabrication tolerances becomes increasingly critical 3 . Utilizing advanced industrial fabrication processes could facilitate the necessary level of fabrication control to support the continued scaling of quantum processors. However, at present, these industrial processes are not optimized to produce high-coherence devices, nor are they a priori compatible with the approaches commonly used to make superconducting qubits. Here we demonstrate superconducting transmon qubits manufactured in a 300 mm complementary metal–oxide–semiconductor (CMOS) pilot line using industrial fabrication methods, with resulting relaxation and coherence times exceeding 100 μs. We show across-wafer, large-scale statistics of coherence, yield, variability and ageing that confirm the validity of our approach. The presented industry-scale fabrication process, which uses only optical lithography and reactive-ion etching, has a performance and yield in line with conventional laboratory-style techniques utilizing metal lift-off, angled evaporation and electron-beam writing 4 . Moreover, it offers the potential for further upscaling through three-dimensional integration 5 and more process optimization. This result marks the advent of an alternative and new, large-scale, truly CMOS-compatible fabrication method for superconducting quantum computing processors.

arXiv:2403.01312•Nature•Sep 18, 2024•66 citations

Advanced CMOS manufacturing of superconducting qubits on 300 mm wafers

J. Damme, S. Massar, R. Acharya +13 more

Abstract The development of superconducting qubit technology has shown great potential for the construction of practical quantum computers1, 2. As the complexity of quantum processors continues to grow, the need for stringent fabrication tolerances becomes increasingly critical3. Utilizing advanced industrial fabrication processes could facilitate the necessary level of fabrication control to support the continued scaling of quantum processors. However, at present, these industrial processes are not optimized to produce high-coherence devices, nor are they a priori compatible with the approaches commonly used to make superconducting qubits. Here we demonstrate superconducting transmon qubits manufactured in a 300 mm complementary metal–oxide–semiconductor (CMOS) pilot line using industrial fabrication methods, with resulting relaxation and coherence times exceeding 100 μs. We show across-wafer, large-scale statistics of coherence, yield, variability and ageing that confirm the validity of our approach. The presented industry-scale fabrication process, which uses only optical lithography and reactive-ion etching, has a performance and yield in line with conventional laboratory-style techniques utilizing metal lift-off, angled evaporation and electron-beam writing4. Moreover, it offers the potential for further upscaling through three-dimensional integration5 and more process optimization. This result marks the advent of an alternative and new, large-scale, truly CMOS-compatible fabrication method for superconducting quantum computing processors.

•Jan 1, 2024•0 citations

Fabrication and characterization of low loss niobium airbridges for superconducting quantum circuits

Hao-Ran Tao, Chi Zhang, Lei Du +8 more

Airbridges are extensively employed in superconducting quantum circuits to suppress parasitic slotline modes in coplanar waveguide and minimize crosstalk between control lines. Here, we introduce a fabrication technique for airbridges, leveraging niobium as the bridge layer and aluminum as the sacrificial layer to preclude the introduction of lossy dielectrics or residues upon release. Additionally, we utilize a triangular evaporation method to significantly bolster the structural integrity of the airbridges. Our experimental evaluation, focused on resonators equipped with these airbridges, reveals that the resultant additional loss per bridge is minimal, quantified at (5.0±2.8)×10−9 in the single-photon regime and (6.3±0.9)×10−9 at high drive powers. This advancement underscores the potential of niobium airbridges in facilitating the development of large-scale and high-performance superconducting quantum circuits.

Applied Physics Letters•Jul 15, 2024•7 citations

Fabrication and room temperature characterization of trilayer junctions for the development of superconducting qubits on 300 mm wafers

Danny Wan, Sébastien Couet, Xiaoyu Piao +15 more

Abstract We present the development of Nb/Al–AlO x /Nb trilayer stacks and the implementation of a full 300 mm process flow for the fabrication of trilayer-based superconducting qubits. Room temperature electrical characterization of tens of thousands of Josephson junctions showed good agreement between blanket resistance-area (RA) product and RA product of processed wafers. Cross-bridge Kelvin resistor structures with dimensions ranging from 200 nm to 1.2 μ m were tested and exhibited excellent yield and exceptionally low resistance variability down to <1%. This result is expected to translate to reduced qubit device variability and improved predictability of qubit transition frequencies at cryogenic temperatures.

Japanese Journal of Applied Physics•Feb 12, 2021•20 citations

Low-Loss, High-Coherence Airbridge Interconnects Fabricated by Single-Step Lithography

Jibang Fu, Bo Ren, Jiandong Ouyang +8 more

Airbridges are essential for creating high-performance, low-parasitic interconnects in integrated circuits and quantum devices. Conventional multi-step fabrication methods hinder miniaturization and introduce process-related defects. We report a simplified process for fabricating nanoscale airbridges using only a single electron-beam lithography step. By optimizing a multilayer resist stack with a triple-exposure-dose scheme and a thermal reflow step, we achieve smooth, suspended metallic bridges with sub-200-nm features that exhibit robust mechanical stability. Fabricated within a gradiometric SQUID design for superconducting transmon qubits, these airbridges introduce no measurable additional loss in the relaxation time $T_1$, while enabling a 2.5-fold enhancement of the dephasing time $T_2^*$. This efficient method offers a practical route toward integrating high-performance three-dimensional interconnects in advanced quantum and nano-electronic devices.

quant-pharXiv:2601.16416•Jan 26, 2026•0 citations

Enabling 300 mm Wafer-Scale Fabrication of Superconducting Quantum Devices

Ekta Bhatia, Hunter Frost, Nicholas Pieniazek +13 more

Superconducting quantum computing has demonstrated exponential improvements in coherence times over the past two decades, bringing us to the present Noisy Intermediate Scale Quantum (NISQ) era. Improvements in materials and fabrication techniques are still required along with circuit and algorithm innovations to move beyond the NISQ era. We discuss several aspects of the process development work that enables the fabrication of superconducting quantum devices and circuits at 300 mm wafer scale, using materials, processes and tools that are entirely compatible with high-volume integrated circuit fabs. Damascene structures of superconducting tantalum and aluminum (embedded in high resistivity silicon substrates) are described along with examples of process control. The use of such structures for coplanar waveguide resonators in quantum circuits is described, along with modifications to enable integration of normal metal traps to mitigate quasiparticle poisoning. This paper also includes a description of the considerable process development required to enable ALD-TaN based Josephson junctions fabricated with entirely 300 mm compatible processes, in contrast to the lift-off based processes currently in wide use for qubit fabrication. It concludes with a description of how these efforts help with establishing a Quantum Foundry at NY CREATES (a non-profit organization) that can democratize access to advanced qubit fabrication by offering an open superconducting quantum Process Design Kit (PDK).

ASMC proceedings•May 13, 2024•3 citations
Superconducting Nb airbridges were fabricated in imec’s 300 mm pilot line utilizing an advanced production toolset. An optimized process flow, which does not rely on liftoff or shadow evaporation, results in high airbridge yield across full wafers, and is compatible with trilayer-based superconducting qubit fabrication methods. Airbridges integrated with resonators were characterized at millikelvin temperatures, showing that the addition of airbridges can have minimal contribution to microwave losses. This work demonstrates that airbridges can be incorporated into foundry compatible qubit fabrication flows.
Abstract The development of superconducting qubit technology has shown great potential for the construction of practical quantum computers 1,2 . As the complexity of quantum processors continues to grow, the need for stringent fabrication tolerances becomes increasingly critical 3 . Utilizing advanced industrial fabrication processes could facilitate the necessary level of fabrication control to support the continued scaling of quantum processors. However, at present, these industrial processes are not optimized to produce high-coherence devices, nor are they a priori compatible with the approaches commonly used to make superconducting qubits. Here we demonstrate superconducting transmon qubits manufactured in a 300 mm complementary metal–oxide–semiconductor (CMOS) pilot line using industrial fabrication methods, with resulting relaxation and coherence times exceeding 100 μs. We show across-wafer, large-scale statistics of coherence, yield, variability and ageing that confirm the validity of our approach. The presented industry-scale fabrication process, which uses only optical lithography and reactive-ion etching, has a performance and yield in line with conventional laboratory-style techniques utilizing metal lift-off, angled evaporation and electron-beam writing 4 . Moreover, it offers the potential for further upscaling through three-dimensional integration 5 and more process optimization. This result marks the advent of an alternative and new, large-scale, truly CMOS-compatible fabrication method for superconducting quantum computing processors.
Abstract The development of superconducting qubit technology has shown great potential for the construction of practical quantum computers1, 2. As the complexity of quantum processors continues to grow, the need for stringent fabrication tolerances becomes increasingly critical3. Utilizing advanced industrial fabrication processes could facilitate the necessary level of fabrication control to support the continued scaling of quantum processors. However, at present, these industrial processes are not optimized to produce high-coherence devices, nor are they a priori compatible with the approaches commonly used to make superconducting qubits. Here we demonstrate superconducting transmon qubits manufactured in a 300 mm complementary metal–oxide–semiconductor (CMOS) pilot line using industrial fabrication methods, with resulting relaxation and coherence times exceeding 100 μs. We show across-wafer, large-scale statistics of coherence, yield, variability and ageing that confirm the validity of our approach. The presented industry-scale fabrication process, which uses only optical lithography and reactive-ion etching, has a performance and yield in line with conventional laboratory-style techniques utilizing metal lift-off, angled evaporation and electron-beam writing4. Moreover, it offers the potential for further upscaling through three-dimensional integration5 and more process optimization. This result marks the advent of an alternative and new, large-scale, truly CMOS-compatible fabrication method for superconducting quantum computing processors.
Airbridges are extensively employed in superconducting quantum circuits to suppress parasitic slotline modes in coplanar waveguide and minimize crosstalk between control lines. Here, we introduce a fabrication technique for airbridges, leveraging niobium as the bridge layer and aluminum as the sacrificial layer to preclude the introduction of lossy dielectrics or residues upon release. Additionally, we utilize a triangular evaporation method to significantly bolster the structural integrity of the airbridges. Our experimental evaluation, focused on resonators equipped with these airbridges, reveals that the resultant additional loss per bridge is minimal, quantified at (5.0±2.8)×10−9 in the single-photon regime and (6.3±0.9)×10−9 at high drive powers. This advancement underscores the potential of niobium airbridges in facilitating the development of large-scale and high-performance superconducting quantum circuits.
Abstract We present the development of Nb/Al–AlO x /Nb trilayer stacks and the implementation of a full 300 mm process flow for the fabrication of trilayer-based superconducting qubits. Room temperature electrical characterization of tens of thousands of Josephson junctions showed good agreement between blanket resistance-area (RA) product and RA product of processed wafers. Cross-bridge Kelvin resistor structures with dimensions ranging from 200 nm to 1.2 μ m were tested and exhibited excellent yield and exceptionally low resistance variability down to <1%. This result is expected to translate to reduced qubit device variability and improved predictability of qubit transition frequencies at cryogenic temperatures.
Airbridges are essential for creating high-performance, low-parasitic interconnects in integrated circuits and quantum devices. Conventional multi-step fabrication methods hinder miniaturization and introduce process-related defects. We report a simplified process for fabricating nanoscale airbridges using only a single electron-beam lithography step. By optimizing a multilayer resist stack with a triple-exposure-dose scheme and a thermal reflow step, we achieve smooth, suspended metallic bridges with sub-200-nm features that exhibit robust mechanical stability. Fabricated within a gradiometric SQUID design for superconducting transmon qubits, these airbridges introduce no measurable additional loss in the relaxation time T1T_1T1​, while enabling a 2.5-fold enhancement of the dephasing time T2∗T_2^*T2∗​. This efficient method offers a practical route toward integrating high-performance three-dimensional interconnects in advanced quantum and nano-electronic devices.
Superconducting quantum computing has demonstrated exponential improvements in coherence times over the past two decades, bringing us to the present Noisy Intermediate Scale Quantum (NISQ) era. Improvements in materials and fabrication techniques are still required along with circuit and algorithm innovations to move beyond the NISQ era. We discuss several aspects of the process development work that enables the fabrication of superconducting quantum devices and circuits at 300 mm wafer scale, using materials, processes and tools that are entirely compatible with high-volume integrated circuit fabs. Damascene structures of superconducting tantalum and aluminum (embedded in high resistivity silicon substrates) are described along with examples of process control. The use of such structures for coplanar waveguide resonators in quantum circuits is described, along with modifications to enable integration of normal metal traps to mitigate quasiparticle poisoning. This paper also includes a description of the considerable process development required to enable ALD-TaN based Josephson junctions fabricated with entirely 300 mm compatible processes, in contrast to the lift-off based processes currently in wide use for qubit fabrication. It concludes with a description of how these efforts help with establishing a Quantum Foundry at NY CREATES (a non-profit organization) that can democratize access to advanced qubit fabrication by offering an open superconducting quantum Process Design Kit (PDK).