This research topic is devoted to the development of Si-based technology modules for very high frequencies. Special attention is paid to demonstrate the capabilities and benefits of these technologies with benchmark circuits and advanced system applications in the range from 0.1 up to 1 THz such as THz imaging and sensing, wireless Gb/s communications and millimeter-wave radar.
This work is motivated by the increasing interest in the sub-mm-wave frequency spectrum within the so-called THz gap (which ranges from 0.3 to 30 THz) for a wide variety of applications such as health care and biology, mass transportation (e.g., security screening, automotive radar, in-seat entertainment), industrial automation (e.g., sensors), communications (e.g., high-bandwidth terrestrial point-to-point wireless, satellites).
Circuits operating at mm-wave frequencies have traditionally been fabricated in III-V semiconductors due to the higher mobility and higher saturation velocity in these materials. Although III-V devices do have certain advantages over Si devices such as higher breakdown voltage (at the same speed) and the potential of combined optical/electronic operation, it was shown that “at comparable fT and fmax, there is very little difference in their performance in narrow-band mm-wave and in broadband and high-speed digital circuits”. Generally, III-V technologies exhibit fairly low integration levels and yield and, hence, cannot leverage today’s process scaling to its full extend to enable both more complex mm-wave systems and mass-market wafer volume in the future.
A first substantial step for entering the THz-gap spectrum with silicon-based technology was made within the DOTFIVE project. In collaboration with the DOTFIVE project partners IHP succeeded in demonstrating the first SiGeC HBTs with 500GHz operating frequency at room temperature and CML ring oscillators with a gate delay below 2 ps. Recent theoretical investigations point the way for further performance improvements letting appear a THz SiGeC HBT as a realistic goal.
At IHP, the next step towards THz SiGe HBTs will be prepared by transferring the DOTFIVE achievements to the 0.13 µm BiCMOS platform. First results were presented recently. The creation of Si devices with highest performance will have also positive effects on the development of new technologies for system-on-chip solutions. Exemplarily, the integration of photonic components into a high-speed BiCMOS technology within the CATRENE project RF2THzSiSOC pursues this goal.