A 300-GHz Band Chip-to-Waveguide Transition on Proton-Irradiated Standard 65nm CMOS Si Substrate for Flip-Chip Packaging Implementation

This paper presents a 300GHz band probe-type chip-to-waveguide transition implemented on standard 65nm CMOS process. This design utilizes the bump from flip-chip packaging process and the PCB top metal to form a back-short structure. The Si substrate around the transition is proton-irradiated to increase substrate resistivity and minimize substrate loss. A back-to-back prototype was manufactured and measured both before and after irradiation. The prototypes exhibit a minimum insertion loss of 4.9dB before irradiation and 2.8dB after irradiation at 240GHz. Both prototypes achieve 63GHz 3-dB bandwidth with less than 10-dB return loss across the operating frequency.