A through via in an ultra high resistivity wafer and related methods are disclosed. A method for forming a through via comprises: providing a semiconductor wafer including a first silicon layer, a buried dielectric layer, and a substrate; forming a device on the first silicon; and forming a via from a side of the substrate opposite to the buried dielectric layer and through the substrate. Also disclosed is a method for providing a wafer varied resistivity using the through vias and buried dielectric.