THz bandwidth InP HBT technologies and heterogeneous integration with Si CMOS

Through aggressive lithographical and epitaxial scaling, the bandwidths of InP-based heterojunction bipolar transistors have been extended to THz frequencies. At 130nm emitter dimensions, transistors with maximum frequencies of oscillation (fmax) of >1THz have been demonstrated with accompanying circuit demonstrations at 670GHz. At 250nm emitter dimensions, high efficiency and high power density mm-wave power amplifiers covering E-band (71GHz) to G-band (235GHz) have been fabricated. The utility of these high performance transistors can be further enhanced through heterogeneous integration with Si CMOS. We have demonstrated wafer-scale 3D integration of InP and Si using a low temperature oxide-to-oxide bonding process with embedded Cu interconnects.