This article describes the electron beam direct processing system developed for patterning beyond the resolution limit of conventional resists by using inorganic resists or electron beam induced surface reactions. A probe beam with a probe current of 120 pA was focused into 3 nm with the newly developed optical column. An ultrahigh vacuum sample chamber, which can coexist with a precise stage driving mechanism and a laser measuring system, was constructed by adapting a double chamber stage system. The base pressure of the sample chamber after baking was 1.5 × 10 -6Pa and differential evacuation of the sample chamber and the mechanism chamber was demonstrated. The stability of the stage was evaluated with a laser measuring system. The standard deviations of stitching and overlay accuracy measured by an exposure of PMMA were 20 nm and 40 nm, respectively. An exposure of PMMA resists revealed that this EB system can delineate the lines with the ultimate resolution of PMMA resists.