Electronic elements with very low resistance back-side coupling are provided by forming one or more narrow trenches or pipes, preferably dielectric lined, in front sides of substrates, filling the trenches or pipes with a conductor having a coefficient of expansion not too different from that of the substrate but of higher conductivity, forming an epitaxial SC layer over the front side of the substrate in Ohmic contact with the conductor the trenches or pipes, forming various semiconductor (SC) devices in the epi-layer, back grinding the substrate to expose bottoms of the conductor filled trenches or pipes, and providing a back-side conductor contacting the conductor in the trenches or pipes. For silicon SCs, tungsten is a suitable conductor for filling the trenches or pipes to minimize substrate stress. Series ON-resistance of the elements due to the substrate resistance is substantially reduced.