A semiconductor device having an edge termination region, the device comprising: a central active region forming at least one field effect transistor with a semiconductor body having a source, drain and gate, an edge termination region including at least one deep trench region extending to a depth of between 1.0μm and 8.0μm having insulated side walls and being filled with a conductive material and a plurality of edge gate trench regions, the edge gate trench regions comprising an insulated gate in a trench having insulated side walls and being filled with a conductive material; and an isolation region between the edge termination region and the central active region, the isolation region comprising gate fingers extending from the edge gate trench regions to gate trenches in the central region to electrically connect the edge gate trench regions to the gate trenches in the central region wherein the gate trenches include insulated side walls and being filled with a conductive gate material and the isolation region further comprising conductive isolation fingers (22,24) extending from the edge termination region towards the central region and between the gate fingers; wherein: the conductive isolation fingers (22,24) and the gate fingers each comprise trenches including insulated side walls and filled with a conductive material; the deep trench region and the conductive isolation fingers (22,24) extend to a greater depth as compared to the edge gate trench regions; and the conductive isolation fingers (22,24) are connected to the source or left floating. a central active region forming at least one field effect transistor with a semiconductor body having a source, drain and gate, an edge termination region including at least one deep trench region extending to a depth of between 1.0μm and 8.0μm having insulated side walls and being filled with a conductive material and a plurality of edge gate trench regions, the edge gate trench regions comprising an insulated gate in a trench having insulated side walls and being filled with a conductive material; and an isolation region between the edge termination region and the central active region, the isolation region comprising gate fingers extending from the edge gate trench regions to gate trenches in the central region to electrically connect the edge gate trench regions to the gate trenches in the central region wherein the gate trenches include insulated side walls and being filled with a conductive gate material and the isolation region further comprising conductive isolation fingers (22,24) extending from the edge termination region towards the central region and between the gate fingers; wherein: the conductive isolation fingers (22,24) and the gate fingers each comprise trenches including insulated side walls and filled with a conductive material; the deep trench region and the conductive isolation fingers (22,24) extend to a greater depth as compared to the edge gate trench regions; and the conductive isolation fingers (22,24) are connected to the source or left floating. the conductive isolation fingers (22,24) and the gate fingers each comprise trenches including insulated side walls and filled with a conductive material; the deep trench region and the conductive isolation fingers (22,24) extend to a greater depth as compared to the edge gate trench regions; and the conductive isolation fingers (22,24) are connected to the source or left floating.