Semiconductor devices and methods of manufacture thereof are disclosed. In one embodiment, a semiconductor device includes a workpiece having a buried layer disposed beneath a top portion thereof. A trench is disposed in the workpiece extending at least through the buried layer. At least one sinker contact is disposed in the top portion of the workpiece. The at least one sinker contact is proximate sidewalls of at least a portion of the trench and is adjacent the buried layer. An insulating material is disposed on the sidewalls of the trench. A conductive material is disposed within the trench and is coupled to a lower portion of the workpiece.