Tapered sidewall Schottky diodes with very low taper angles have been demonstrated to have considerably higher breakdown voltage than the conventional metal-overlap diodes by numerical analysis as well as experimental results. Potential and electric field distribution within the Schottky diode have been obtained by three-dimensional numerical analysis. The results of calculation show two peaks of the electric field, one at the contact edge and the other at the edge of the metal electrode. As the taper angle decreases, the principal peak of the electric field at the contact edge diminishes, while the secondary peak at the metal edge remains nearly unchanged. The Schottky diode with a taper angle of 6° or less brings about four-fold increase in breakdown voltage when compared with the metal-overlap diode. Also, aluminum-silicon tapered sidewall Schottky diodes have been fabricated using the graded etching process with silica film. The experimental results on the breakdown voltages of Schottky diodes are compared with the theoretical results for taper angles between 3° and 90°. Experimental results have shown good agreement with the theoretical ones.