Diamond coated silicon tip arrays, with and without a self-aligned gate, were fabricated, and current-voltage characteristics of 400 tips were measured. Diamond films were grown uniformly on Si tips using microwave plasma after nucleation with 10 nm diamond suspension and substrate bias. An emission current of 57?A was obtained at 5 V from the ungated array tips separated from an anode at 2?m. In the case of the gated arrays with 1.5?m aperture, an emission current of 3.4?A was measured at a gate voltage of 80 V for an anode separation of 200?m. The turn-on voltages for these two types of devices were 0.2 and 40 V, respectively. Diamond coated Si tip arrays have potential applications in field emission based low voltage vacuum electronic devices and microsensors.