Blocking Flying Crosstalk in BEOL Validated in Antenna Switches in 45-nm SOI CMOS

Flying crosstalk through the back-end-of-the-line (BEOL) above the silicon substrate is an emerging design challenge to RF ICs, which cannot be addressed by conventional in-Si noise reduction structures. This letter reports a new concept of using in-BEOL metal wall structures, implemented by 3-D heterogeneous integration, to efficiently suppress the above-Si flying global crosstalk. It was validated using a set of single-pole-double-throw transmitter/receiver (T/Rx) antenna switches fabricated in a foundry 45-nm silicon-on-insulator CMOS process. Measurement shows significant interswitch crosstalk reduction of ~18.5 dB or ~98.6% suppression clearly.