The chances of attaching organic molecules to silicon surfaces can be considerably enhanced if a robust nanogap structure with silicon electrodes can be used to connect the molecules. We describe the electrical properties of such an electrode structure, with a separation of the silicon surfaces in the 3-7 nm range. These silicon nanogaps are manufactured by partly removing the silicon dioxide insulator from a silicon-oxide-silicon material stack, by using a selective oxide etchant. After the activation of the gap (the etching), current instabilities appear, which are comparable to the properties of thin oxides after soft breakdown. Applying a constant voltage can reduce these current instabilities. We also address the issue of surface leakage currents for these nanogap structures.