Emerging Technology for RF and Millimeter-wave Circuits based on Carbone Nanotubes – TRiCOT

TRICOT is a fundamental research project that proposes an "Emerging technology for the development of RF and millimeter circuits based on carbon nanotubes". This is an ambitious project in the context of Challenge 7, Axis 8, addressing in particular the future technological bottlenecks to be solved in terms of packaging: 3D heterogeneous integration, high frequency interconnection, densification, functionalization, …, which are awaited for the fabrication of millimeter wave modules up to 100 GHz, for wireless applications, high-resolution sensors and ultra-high-speed communication.

Given the changing needs and technologies, this project is in the context of ultra-compact millimeter-wave systems manufacturing. So we are planning to develop E-band demonstrators (71-86 GHz), and we are proposing an original concept of functionalized interposer, in particular by integrating a beamforming circuit (Butler matrix), which is based on two innovations from previous work of the different partners:

- the first one deals with the design of slow-wave waveguides. This principle has been developed and validated experimentally by UGA-IMEP-LAHC. In particular, it leads to a reduction in the lateral and longitudinal dimensions of the slow-wave waveguides compared with those of conventional guides at a given working frequency. Although it is at millimeter-wave frequency, with relatively small circuit sizes, this aspect remains important for the production of guides which have the advantage of having little radiation losses but which have lateral dimensions that are incompatible with the implementation of feeding networks for antenna arrays, which are essential for achieving an acceptable link budget.

- the other innovation concerns a maturing technology of carbon nanotubes growth and transfer, compatible with CMOS technology. This technique has been developed and validated by CINTRA and XLIM for the packaging and realization of components up to millimeter frequencies. We will extend this technology for obtaining the slow-wave effect in waveguides. Finally, the industrial partner III-V Lab will bring its expertise in terms of technological testing in order to validate the quality of implemented processes.

By pooling these skills, the project will lead to a real alternative in terms of realization and packaging of high-performance circuits, from millimeter-wave up to THz frequencies, with high impact for strategic sectors (high-speed wireless communications, security, defense, space ...)

The project is structured around 5 workpackages:
(1) project management,
(2) demonstrator specifications and constraints,
(3) modeling and design (carbon nanotube forests and design of elementary circuits and the final demonstrator),
(4) fabrication of structures based on carbon nanotubes,
(5) high frequency characterization of fabricated structures.

The complementarity of the partners and their unique expertise recognized by the international community in this field is a major asset for the success of this project.

The project's intended outcomes include:
(i) new heterogeneous 3D integration solutions requested by the industry of micro- and nanoelectronics,
(ii) development of a library of circuits which will ultimately enable the realization of various types of systems,
(iii) publications in major international conferences and conferences,
(iv) use of the main results to feed our master's and doctoral school courses.