A semiconductor device comprising: a silicon-on-insulator substrate including a base substrate layer, a first insulator layer located on the base substrate layer, and a silicon layer located on the insulator layer, a second insulator layer disposed on the silicon layer of the silicon-on-insulator substrate, and an oxide resistant film layer disposed on the second insulator layer, and a trench capacitor extending through the oxide resistant film layer, the second insulator layer, the silicon layer and the first insulator layer and into the base substrate layer, and a capacitor contact trench located in the silicon-on-insulator substrate and extending through the silicon layer and the first insulator layer into the base substrate, the capacitor contact trench providing electrical contact to the trench capacitor through the base substrate layer, characterized in that a first conductive layer is formed at a bottom of the trench capacitor and the capacitor contact trench, respectively, said first conductive layer being formed on the base substrate layer and extending up to the first insulator layer, a Si3N4 layer is formed on the surface of the trenches of the trench capacitor and the capacitor contact trench, respectively, the Si3N4 layer extending from an upper surface of the oxide resistant film layer and terminating at the first conductive layer in the trench capacitor and the capacitor contact trench, for preventing electrical shorting which may occur between the base substrate layer and the silicon layer, and a third insulator layer is located in the trench capacitor on the first conductive layer, and a second conductive layer is located in the trench capacitor over the third insulator layer and in the capacitor contact trench over the first conductive layer, and a dielectric layer is deposited on the oxide resistant film layer and on the Si3N4 layers, and conductive contacts are formed on the upper surface of the device to contact the second conductive layer. a silicon-on-insulator substrate including a base substrate layer, a first insulator layer located on the base substrate layer, and a silicon layer located on the insulator layer, a second insulator layer disposed on the silicon layer of the silicon-on-insulator substrate, and an oxide resistant film layer disposed on the second insulator layer, and a trench capacitor extending through the oxide resistant film layer, the second insulator layer, the silicon layer and the first insulator layer and into the base substrate layer, and a capacitor contact trench located in the silicon-on-insulator substrate and extending through the silicon layer and the first insulator layer into the base substrate, the capacitor contact trench providing electrical contact to the trench capacitor through the base substrate layer, characterized in that a first conductive layer is formed at a bottom of the trench capacitor and the capacitor contact trench, respectively, said first conductive layer being formed on the base substrate layer and extending up to the first insulator layer, a Si3N4 layer is formed on the surface of the trenches of the trench capacitor and the capacitor contact trench, respectively, the Si3N4 layer extending from an upper surface of the oxide resistant film layer and terminating at the first conductive layer in the trench capacitor and the capacitor contact trench, for preventing electrical shorting which may occur between the base substrate layer and the silicon layer, and a third insulator layer is located in the trench capacitor on the first conductive layer, and a second conductive layer is located in the trench capacitor over the third insulator layer and in the capacitor contact trench over the first conductive layer, and a dielectric layer is deposited on the oxide resistant film layer and on the Si3N4 layers, and conductive contacts are formed on the upper surface of the device to contact the second conductive layer.