CEA-Leti and STMicroelectronics used this year’s International Electron Devices Meeting in San Francisco to outline a manufacturing route that could push radio-frequency and optical front-end modules towards full monolithic integration on silicon.
The research groups presented a paper describing how silicon-germanium heterojunction bipolar transistors, RF-SOI switches, and high-quality passive components can be sequentially integrated in three dimensions on a single wafer. The approach, they said, offers a path to densely co-integrated, low-parasitic RF systems for next-generation wireless and wireline communications, while reducing the need for complex packaging.
The work demonstrates that SiGe devices can tolerate the thermal requirements of top-tier processing, and that a localised trap-rich layer can deliver RF isolation and linearity comparable with commercial substrates, while surviving thermal cycles up to 600 °C. The team also reported that low-temperature SOI switches fabricated at 600 °C can match state-of-the-art performance, enabling the preservation of the SiGe layer beneath.
Thibaud Fache of CEA-Leti, the paper’s lead author, said the results open the way to an all-silicon RF front-end that is both efficient and cost-effective. Thomas Bordignon of STMicroelectronics added that the collaboration provides a credible bridge from advanced research to industrial solutions, combining CEA-Leti’s integration expertise with ST’s RF device know-how.
A further milestone will detail the fabrication of 400 °C SOI MOSFETs that achieve industry-standard performance at significantly reduced thermal budgets. The devices, targeting More-Than-Moore applications, are positioned for smart sensors, near-memory computing, and RF systems.
CEA-Leti, based in Grenoble and part of the French Alternative Energies and Atomic Energy Commission, focuses on transferring micro- and nanotechnology research to industry, spanning sectors from transport to healthcare and telecommunications.
