Monolithic 3D Integrated InGaAs HEMTs on Si for Next-Generation Communication: Record fMAX and Relaxed Self-Heating of Top Devices by a Novel M3D Structure

Abstract

In this work, we have demonstrated monolithic 3-dimensional (M3D) InGaAs high electron mobility transistor (HEMT) on Si with back metal gate for M3D analog/RF-digital mixed-signal platform, which is realized by wafer bonding and low process temperature (below 300 °C). InGaAs top HEMTs with LG=95 nm showed a current gain cutoff frequency ( fT ) of 301 GHz and maximum oscillation frequency ( fMAX ) of 716 GHz. The fMAX value is the highest ever reported in M3D RF transistors. Furthermore, for the first time, we experimentally demonstrated that the self-heating of top devices can be significantly relaxed by a back metal structure in the M3D platform. Also, we have investigated the effects of back metal structure not only on the self-heating effect of top devices but also on the RF performance of top devices and crosstalk between the top and bottom devices, showing the performance improvement in the M3D analog/Rf-digital mixed-signal platform.