A capacitive probe array with a p(+) polycystalline-Si/HfO2/Si- probe capacitor structure was fabricated. The small signal capacitance-voltage characteristics of the array were measured under various bias voltages applied to an Al electrode which was capacitively coupled with the probe by an interlayer SiO2 dielectric. The capacitance of the probe changed with the Al electrode bias voltage offering the feasibility of the probe as a sensor for surface charge detection. With the increase in the Al bias to a large positive or negative value the capacitance abruptly changed to a constant value by charge injection into the polycrystalline- Si electrode. (c) 2006 The Electrochemical Society.