An inorganic electron beam resist process for nanofabrication is described. Si-based bilayer inorganic electron beam resists, SixOy/Si3N4, Si3N4/SiO2, and SiO2/poly-Si were investigated. The SiO2/poly-Si system was found to be the most suitable for attaining deep undercut structures with fine patterns for metal-insulator-metal ultrasmall tunnel junction fabrication. Utilizing the multiple-angle deposition-oxidation deposition method, we have fabricated Al/Al2O3/Al tunnel junctions for which a clear Coulomb staircase was observed in the I-V characteristics at 12 K.