of integrated circuits that is used for cellular telephones portable electronics high speed modems and data storage devices such as computer hard drives a first application provides one or more metallized posts 18 on the substrate as low impedance paths to ground which is typically located at the backside of the chip these posts 18 can be used as u201c true ground u201d points i e points with very low impedance contact to the ground potential outside the chip across the substrate 10 such posts 18 have very short paths to ground points as compared to typical ground lines in conventional si integrated circuit technology as a result these posts 18 have much lower impedance to ground especially for high frequency signals a second application creates the metallized moat 16 from a metallized porous si region alternatively the second application creates the metallized moat 16 by etching deep v grooves or trenches in the si substrate 10 and then depositing metals in the v grooves or electroplating the trenches in this second application the metallized moat 16 shields the noise sensitive circuits 14 from high frequency noise generated by the noisy circuits 12 the metallized moat 16 in essence creates a conducting cage which is an electromagnetic shield that reduces rf crosstalk between the circuits 12 and 14 as noted above metallized porous si regions can be used for both the first and second applications whereas the metal filled deep v grooves and trenches are more suited for the noise isolation of the second application moreover while the preferred embodiment uses.