Coulomb interactions have been discussed as an obstacle for 0.13 mu m line and space (L/S) resolutions in the block exposure or the cell projection lithography. In this article, effects of the Coulomb interactions are experimentally analyzed in the 50 kV block exposure lithography system. Blurs of the e-beam profiles, which characterize the Coulomb interactions, were obtained by knife-edge experiments. From the results, the following theoretically predicted facts have been clarified. The blur increases with the increasing current monotonously. We have obtained Linear relationships, delta=0.03xI(b)+0.05(mu m) between the blurs and an a-beam current. The dynamic refocusing technique can suppress the Coulomb interactions only partially. In order to resolve 0.13 mu m L/S, practical methods to reduce the Coulomb interactions by reducing the current are needed. It is clarified that mask biasing, where widths of the mask openings are narrowed, is more effective to achieve high contrast than current density reduction or shot size reduction. It is also clarified that the mask biasing is effective to resolve 0.13 and 0.10 mu m L/S patterns. We have applied the current reduction techniques and have successfully obtained fine 0.13, 0.12 and 0.10 mu m L/S patterns.