Silicon nitride (Si3N4) is an important VLSI material owing to its high resistivity and breakdown strength and its use in surface encapsulation during ion implantation and annealing. Previous work has focused on films prepared by low-pressure and plasma-enhanced chemical vapour deposition (LPCVD and PECVD), but in the present work the DC electrical properties of films prepared by r.f. magnetron sputtering were investigated. Al-Si3N4-Al sandwich structures were fabricated from a Si3N4 target at a discharge power of 100 W using N-2 as the sputtering gas at a pressure of approximately 0.5 Pa. Capacitance was independent of voltage, indicating the absence of a Schottky barrier at the Al/Si3N4 interface. Measurements of the capacitance as a function of inverse dielectric thickness implied a relative permittivity value of 6.3. However, although films prepared using PECVD exhibited Poole-Frenkel conductivity and tunnelling at higher voltages, the present sputtered films showed space-charge-limited conductivity (SCLC). Conductivity was dominated by an exponential distribution of trap levels, as indicated by a power-law dependence of current density J on applied voltage V, with a typical exponent value of 3.2. Measurements of J as a function of temperature confirmed the appearance of SCLC and indicated that the bulk trap density was of the order of 2 x 10(24)m(-3) as observed in LPCVD and PECVD films, with the appearance of hopping conductivity at low temperatures.