Structures with contact trenches and isolation trenches

Structures that include contact trenches and isolation trenches, as well as methods for forming structures including contact trenches and isolation trenches. A contact trench is formed that extends through a device layer of a silicon-on-insulator (SOI) substrate to a buried oxide layer of the SOI substrate. An isolation trench is formed that extends through the device layer to the buried oxide layer. An electrical insulator is deposited that fills the contact trench and the first isolation trench. The electrical insulator is removed from the contact trench. After the electrical insulator is removed from the contact trench, an electrical conductor is formed in the contact trench. The electrical contact may be coupled with a doped region in a handle wafer of the SOI substrate.