High-throughput wafer-scale fabrication of temperature-compensated alkali vapor cells
ORAL
Abstract
Chip-scale atomic clocks (CSACs) have been successfully commercialized, offering a long-term frequency stability exceeding that of quartz crystal or MEMS oscillators along with a compact size and low power consumption1. However, their low-volume fabrication and high cost compared to quartz oscillators impede more widespread use in real-world applications.
To scale the fabrication, wafer-level manufacturing processes have been developed for the microfabricated alkali vapor cells that are at the core of CSACs2,3. In this talk, we demonstrate that the wafer-level fabrication is compatible with silicon wafers patterned using a waterjet, reducing the processing time and cost compared to DRIE patterning4. The completed wafers show a yield of >70% of the atomic vapor cells filled with alkali atoms, higher than previously reported values.
Furthermore, we show that the wafer-level fabrication process is suitable for the production of temperature-compensated vapor cells using a mixture of Ar and N2 buffer gases5. The temperature coefficient of the fractional frequency shift of the hyperfine clock resonance is reduced from ≈ 30 × 10-9 / K for cells with pure N2 to below ≈ 3 × 10-9 / K for the buffer gas mixture.
These results are important steps toward low-cost, high-throughput production of temperature-stable CSACs.
[1] J. Kitching, APR 5, 031302 (2018)
[2] D. Bopp et al., JPhys Phot 3, 015002 (2021)
[3] Y. Li et al., Opt Lett 49, 4963 (2024)
[4] S. Dyer et al., JAP 132, 134401 (2022)
[5] Y. Li et al., APL 126, 224001 (2025)
To scale the fabrication, wafer-level manufacturing processes have been developed for the microfabricated alkali vapor cells that are at the core of CSACs2,3. In this talk, we demonstrate that the wafer-level fabrication is compatible with silicon wafers patterned using a waterjet, reducing the processing time and cost compared to DRIE patterning4. The completed wafers show a yield of >70% of the atomic vapor cells filled with alkali atoms, higher than previously reported values.
Furthermore, we show that the wafer-level fabrication process is suitable for the production of temperature-compensated vapor cells using a mixture of Ar and N2 buffer gases5. The temperature coefficient of the fractional frequency shift of the hyperfine clock resonance is reduced from ≈ 30 × 10-9 / K for cells with pure N2 to below ≈ 3 × 10-9 / K for the buffer gas mixture.
These results are important steps toward low-cost, high-throughput production of temperature-stable CSACs.
[1] J. Kitching, APR 5, 031302 (2018)
[2] D. Bopp et al., JPhys Phot 3, 015002 (2021)
[3] Y. Li et al., Opt Lett 49, 4963 (2024)
[4] S. Dyer et al., JAP 132, 134401 (2022)
[5] Y. Li et al., APL 126, 224001 (2025)
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Publication: Yang Li, Marlou R. Slot, Matthew T. Hummon, Susan Schima, John Kitching; Wafer-scale fabrication of temperature-compensated alkali vapor cells. Appl. Phys. Lett. 126, 224001 (2025). https://doi.org/10.1063/5.0264409
Presenters
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Marlou R Slot
- University of Colorado Boulder & NIST Boulder
- University of Colorado Boulder, National Institute of Standards and Technology Boulder