Summary of the context and overall objectives of the project
The main objective of the M3TERA project is to develop a novel microsystem platform which provides a new way for fabricating complex systems working at terahertz (THz) frequencies. The envisioned THz microsystems are very compact and of extremely low weight, are (high-)volume manufacturable with high product uniformity, and thus are of low cost as compared to conventional ways of manufacturing THz systems. They contain integrated active circuits and micro-electromechanically reconfigurable circuit elements such as tuneable filters. This technology envisions a true break-through in THz technology, which could finally enable a wide-spread utilization of THz technology in society. As implementation demonstrators, the project focuses primarily on a telecom demonstrator for a beyond-100 GHz high speed communication link, and secondary on sensing applications. The THz Microsystem platform is implemented comprising of micromachined waveguides, filters and diplexers, MMICs mounted with MMIC to micromachined waveguide transitions, bias lines and RF transmission lines for feeding the MMICs and flip-chip mounted components such as bypass capacitors. Both manual and automated assembly of the MMICs have been successfully tested keeping in line with the volume-manufacturability of the system. Moreover, for secondary sensing applications, the micromachined platform provided antenna/sensor interface which is successfully tested with 3-D printed antenna solutions. The entire fabrication process is compatible with high-volume production methods as it was transferred to commercial production facility.
The main technical achievements in the first period of the project are: completion of specifications, design kit, microsystem concept, antenna and sensor interfaces, concept studies of interfaces between the microsystem platform and integrated circuits, fabrication and characterization of preliminary test devices of MMIC-to-waveguide transitions.. During the first period of the project, the M3TERA consortium has participated in a large number of dissemination events, including ESSCIRC 2015, ISSCC 2016, GeMiC 2016, IEEE DML, IEEE IMS 2016, MEMSWAVE 2016.
The design of a second MMIC-waveguide transition was completed in autumn 2016; this design was chosen to be the primary design upon which the microsystem platform was to be based. The design of the transition was revised in spring 2017 based on the outcome of the initial characterisation. Design of the diplexer and filter for the telecom demonstrator were also completed during this period of the project. Work undertaken during this period led to the publication of a conference article at IMS 2017.
Characterisation of the initial diplexer and filter designs was completed in autumn 2017; results from these measurements were disseminated at IMS 2018. A revised design of the diplexer was undertaken following the measurements; fabrication of this revised design was completed in June 2018. During the same period of the project, several revisions to the design of the MMIC-waveguide interface used in the microsystem platform were carried out, with measurements of each revision being performed from June 2017 – June 2018. Following successful verification of the transition, the design of the microsystem platform to be used in the telecommunications demonstrator was undertaken, based on input from multiple consortium partners. This work continued to September 2018, whereby the required modules were fabricated and transferred to Ericsson for implementation of the telecommunication demonstrator. A separate type of contactless waveguide-waveguide transition was designed by Ericsson and KTH between November 2017 – February 2018. The designed components were successfully fabricated by KTH in July 2018. Characterisation was performed by Ericsson in July 2018 and showed very promising performance. A novel eWLB interconnection based on dielectric waveguides was designed by Chalmers during autumn 2018, with fabrication performed by KTH during the same period. Fabricated prototypes were delivered to Chalmers in November 2018.
The main technical achievements in the final period of the project are: successful fabrication and measurement of the prototype of the microsystem platform, fabrication and measurement of the diplexer and filter, fabrication and measurement of four different interface concepts between the MMIC and THz microsystem platform, the verification of the proposed THz microsystem platform with integrated MMICs, verification of highly integrated front-end MMICs for the telecom and sensor demonstrator, design fabrication and measurement of three different antenna alternatives (aluminium reflector antenna, a plastic 3D printed reflector solution and a lens horn antenna) for the telecommunication link, microsystem sensor interface fabricated and measured with 3-D printed antenna, development of the sensor prototype for measurement of respiration and heart rate together with CMOS sensor readout circuit, fabrication process transfer to commercial production facility. The M3TERA consortium has participated in a large number of dissemination events, including RFIT 2016, EMBS 2016, EUMW 2016, IMS 2017, IRMMW-THz 2017, EuMW 2017, APMC 2017, SMD 2018, RFIC 2018, IMS 2018, EuMW 2018. Several articles have been submitted and are under review.
Progress beyond the state of the art and expected potential impact
The concepts of a microsystem technology platform for THz systems developed in M3TERA clearly go beyond the state of the art, including micro-electromechanical reconfigurable sub-systems. A major step beyond state of the art is also the interfaces between active circuits and the waveguides developed in this project, which is a bottleneck for any MMIC integration into a THz waveguide system. In summary, the main impact of the disruptive THz technology developed in M3TERA is still given as follows: highly-miniaturized, volume-manufacturable, low cost (as compared to state-of-the-art THz technology), low-weight, highly integrated THz with high product uniformity, enabling the large-scale exploitation of the THz frequency spectrum and thus a wide-spread use of THz technology in many applications in society, which is not possible by current expensive THz technology which is limited to high-end scientific and security applications.