A semiconductor device has a driver device (10) in proximity to a power device (12). In making the semiconductor device, an N+ layer (24) is formed on a substrate (22). A portion of the N+ layer is removed, substantially down to the substrate, to provide a layer offset (28) between the driver device area and power device area. An epi region of uniform thickness is formed over the driver device and power device areas. A portion of the epi layer is removed to provide another layer offset (70). An oxide layer (68) of uniform thickness is formed over the epi region. The oxide layer is planarized to remove oxide layer over the N+ layer. An oxide-filled trench (80) is formed between the driver device and the power device. The oxide-filled trench extends down to the oxide layer to isolate the driver device from the power device.