n-channel and p-channel silicon-gate FET's are fabricated using a 300-Å SiO2-300-Å Si3N4gate insulator. These devices have low leakage and are suitable for dynamic FET-memory applications. Very low n-channel leakage is achieved by using an n- or p-doped polycrystalline-silicon field shield. One-device dynamic memory cells exhibit long average retention times: 158 s for the n-channel cell and 34 s for the p-channel cell. An oxygen or steam anneal of the Si3N4is necessary to prevent a large Vtshift during bias-temperature stress.