The Electron Beam (EB) direct writing of a SiO2 thin film is one of the promising methods to realize sub-10nm scale patterning. These ultrafine dimensions are required only when we want to observe quantum effects in the devices or to fabricate devices which operate on quantum phenomenon. However, in order to apply a SiO2 resist or other Si- based inorganic resists in quantum device fabrication, it is necessary to develop a process for them, first. In this paper, we describe the Si-technology compatible process developed for the Si-based inorganic EB resist made of SiO2 and c-Si layers. The process is optimized for 10-nm scale patterning. Further the developed process is used to demonstrate the fabrication of ultrafine Metal-insulator- metal tunnel junctions to be applicable to metallic devices operating on quantum effects, especially, the Single Electron Tunneling effect. So far, using this process, the Ti-TiOx-Ti overlapping type tunnel junction structures with minimum size approximately 9 nm X 9 nm could be fabricated successfully. Recently, we have applied this process to demonstrate lateral type, Ti-Air gap-Ti, tunnel junctions in which we could clearly observe a single electron coulomb blockage effect at approximately 160 K.