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We have exploited a recently-developed, through-wafer via technology in silicon to implement a novel Faraday cage scheme for substrate crosstalk suppression in system-on-chip (SOC) applications. The Faraday cage structure consists of a ring of grounded vias encircling sensitive or noisy portions of a chip. The via technology features high aspect ratio, through-wafer holes filled with electroplated Cu and lined with a silicon nitride barrier layer. The new Faraday cage structure has shown crosstalk suppression of 40 dB at 1 GHz and 36 dB at 5 GHz at a distance of 100 /spl mu/m. This is about 10 dB better than any other isolation technique previously reported.