Low resistivity SOI for substrate crosstalk reduction

Crosstalk in silicon-on-insulator (SOI)-substrates has been investigated using different equivalent circuit models and measurements on crosstalk test structures. The models reveal that a very low resistivity (LR) substrate (LR-SOI) can have significantly lower crosstalk, compared to both high resistivity and medium resistivity substrate. The low crosstalk for the LR-SOI is the result of effective shunting of the signal to ground through the low resistive substrate, which means that an effective substrate ground is crucial. Measurements on the crosstalk test structures also confirmed the results predicted by the models. The measurements show an improvement in the range of 20-40 dB for very low resistivity SOI substrates compared to high resistivity SOI substrates.