10 is characterized in part by the trenches disposed between the electrodes as well as the trenches disposed between the electrodes and the substrate shown in fig2 is trench 36 disposed between substrate 12 and electrode 14 trench 38 disposed between electrodes 14 and 16 and trench 40 disposed between electrodes 16 and substrate 12 insulating layers 20 22 and 24 are formed so as to extend from the bottom surface of trenches 36 38 and 40 respectively the heights and widths of oxide extensions respectively shown as h and w are selected so as to increase the total path length along the insulator surfaces that separate the electrodes from each other and from the rest of the substrate furthermore the width a of each of the trenches and dimensions h and w are selected to maximize the voltage that can be applied between each adjacent electrode pairs as discussed further below fig1 shows the breakdown voltage as a function of the trench width a commonly referred to as paschen curve for both air 62 and nitrogen 64 for example when trench width a is approximately 80 90 u03bcm the breakdown voltage is approximately 800 volts to provide additional operating margins in some embodiments a maximum voltage of for example 400 volts is applied between each adjacent electrode pairs when a trench width of 80 u03bcm is selected another reason to add additional margin is that the curve in fig1 assumes that the electrodes are infinite in extent real electrodes are finite in size and the fringe fields caused by sharp edges could significantly increase the local electric fields compared to the.